11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/buffer.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992, 2002 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds * Removed a lot of unnecessary code and simplified things now that 111da177e4SLinus Torvalds * the buffer cache isn't our primary cache - Andrew Tridgell 12/96 121da177e4SLinus Torvalds * 131da177e4SLinus Torvalds * Speed up hash, lru, and free list operations. Use gfp() for allocating 141da177e4SLinus Torvalds * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM 151da177e4SLinus Torvalds * 161da177e4SLinus Torvalds * Added 32k buffer block sizes - these are required older ARM systems. - RMK 171da177e4SLinus Torvalds * 181da177e4SLinus Torvalds * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds #include <linux/kernel.h> 22f361bf4aSIngo Molnar #include <linux/sched/signal.h> 231da177e4SLinus Torvalds #include <linux/syscalls.h> 241da177e4SLinus Torvalds #include <linux/fs.h> 25ae259a9cSChristoph Hellwig #include <linux/iomap.h> 261da177e4SLinus Torvalds #include <linux/mm.h> 271da177e4SLinus Torvalds #include <linux/percpu.h> 281da177e4SLinus Torvalds #include <linux/slab.h> 2916f7e0feSRandy Dunlap #include <linux/capability.h> 301da177e4SLinus Torvalds #include <linux/blkdev.h> 311da177e4SLinus Torvalds #include <linux/file.h> 321da177e4SLinus Torvalds #include <linux/quotaops.h> 331da177e4SLinus Torvalds #include <linux/highmem.h> 34630d9c47SPaul Gortmaker #include <linux/export.h> 35bafc0dbaSTejun Heo #include <linux/backing-dev.h> 361da177e4SLinus Torvalds #include <linux/writeback.h> 371da177e4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <linux/suspend.h> 391da177e4SLinus Torvalds #include <linux/buffer_head.h> 4055e829afSAndrew Morton #include <linux/task_io_accounting_ops.h> 411da177e4SLinus Torvalds #include <linux/bio.h> 421da177e4SLinus Torvalds #include <linux/notifier.h> 431da177e4SLinus Torvalds #include <linux/cpu.h> 441da177e4SLinus Torvalds #include <linux/bitops.h> 451da177e4SLinus Torvalds #include <linux/mpage.h> 46fb1c8f93SIngo Molnar #include <linux/bit_spinlock.h> 4729f3ad7dSJan Kara #include <linux/pagevec.h> 485305cb83STejun Heo #include <trace/events/block.h> 491da177e4SLinus Torvalds 501da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 512a222ca9SMike Christie static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, 528e8f9298SJens Axboe enum rw_hint hint, struct writeback_control *wbc); 531da177e4SLinus Torvalds 541da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 551da177e4SLinus Torvalds 56f0059afdSTejun Heo inline void touch_buffer(struct buffer_head *bh) 57f0059afdSTejun Heo { 585305cb83STejun Heo trace_block_touch_buffer(bh); 59f0059afdSTejun Heo mark_page_accessed(bh->b_page); 60f0059afdSTejun Heo } 61f0059afdSTejun Heo EXPORT_SYMBOL(touch_buffer); 62f0059afdSTejun Heo 63fc9b52cdSHarvey Harrison void __lock_buffer(struct buffer_head *bh) 641da177e4SLinus Torvalds { 6574316201SNeilBrown wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 661da177e4SLinus Torvalds } 671da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 681da177e4SLinus Torvalds 69fc9b52cdSHarvey Harrison void unlock_buffer(struct buffer_head *bh) 701da177e4SLinus Torvalds { 7151b07fc3SNick Piggin clear_bit_unlock(BH_Lock, &bh->b_state); 724e857c58SPeter Zijlstra smp_mb__after_atomic(); 731da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 741da177e4SLinus Torvalds } 751fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(unlock_buffer); 761da177e4SLinus Torvalds 771da177e4SLinus Torvalds /* 78b4597226SMel Gorman * Returns if the page has dirty or writeback buffers. If all the buffers 79b4597226SMel Gorman * are unlocked and clean then the PageDirty information is stale. If 80b4597226SMel Gorman * any of the pages are locked, it is assumed they are locked for IO. 81b4597226SMel Gorman */ 82b4597226SMel Gorman void buffer_check_dirty_writeback(struct page *page, 83b4597226SMel Gorman bool *dirty, bool *writeback) 84b4597226SMel Gorman { 85b4597226SMel Gorman struct buffer_head *head, *bh; 86b4597226SMel Gorman *dirty = false; 87b4597226SMel Gorman *writeback = false; 88b4597226SMel Gorman 89b4597226SMel Gorman BUG_ON(!PageLocked(page)); 90b4597226SMel Gorman 91b4597226SMel Gorman if (!page_has_buffers(page)) 92b4597226SMel Gorman return; 93b4597226SMel Gorman 94b4597226SMel Gorman if (PageWriteback(page)) 95b4597226SMel Gorman *writeback = true; 96b4597226SMel Gorman 97b4597226SMel Gorman head = page_buffers(page); 98b4597226SMel Gorman bh = head; 99b4597226SMel Gorman do { 100b4597226SMel Gorman if (buffer_locked(bh)) 101b4597226SMel Gorman *writeback = true; 102b4597226SMel Gorman 103b4597226SMel Gorman if (buffer_dirty(bh)) 104b4597226SMel Gorman *dirty = true; 105b4597226SMel Gorman 106b4597226SMel Gorman bh = bh->b_this_page; 107b4597226SMel Gorman } while (bh != head); 108b4597226SMel Gorman } 109b4597226SMel Gorman EXPORT_SYMBOL(buffer_check_dirty_writeback); 110b4597226SMel Gorman 111b4597226SMel Gorman /* 1121da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 1131da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 1141da177e4SLinus Torvalds * if you want to preserve its state. 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 1171da177e4SLinus Torvalds { 11874316201SNeilBrown wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 1191da177e4SLinus Torvalds } 1201fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__wait_on_buffer); 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds static void 1231da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 1241da177e4SLinus Torvalds { 1251da177e4SLinus Torvalds ClearPagePrivate(page); 1264c21e2f2SHugh Dickins set_page_private(page, 0); 12709cbfeafSKirill A. Shutemov put_page(page); 1281da177e4SLinus Torvalds } 1291da177e4SLinus Torvalds 130b744c2acSRobert Elliott static void buffer_io_error(struct buffer_head *bh, char *msg) 1311da177e4SLinus Torvalds { 132432f16e6SRobert Elliott if (!test_bit(BH_Quiet, &bh->b_state)) 133432f16e6SRobert Elliott printk_ratelimited(KERN_ERR 134a1c6f057SDmitry Monakhov "Buffer I/O error on dev %pg, logical block %llu%s\n", 135a1c6f057SDmitry Monakhov bh->b_bdev, (unsigned long long)bh->b_blocknr, msg); 1361da177e4SLinus Torvalds } 1371da177e4SLinus Torvalds 1381da177e4SLinus Torvalds /* 13968671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 14068671f35SDmitry Monakhov * unlocking it. 14168671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 14268671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 14368671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 14468671f35SDmitry Monakhov * itself. 1451da177e4SLinus Torvalds */ 14668671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1471da177e4SLinus Torvalds { 1481da177e4SLinus Torvalds if (uptodate) { 1491da177e4SLinus Torvalds set_buffer_uptodate(bh); 1501da177e4SLinus Torvalds } else { 15170246286SChristoph Hellwig /* This happens, due to failed read-ahead attempts. */ 1521da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds unlock_buffer(bh); 15568671f35SDmitry Monakhov } 15668671f35SDmitry Monakhov 15768671f35SDmitry Monakhov /* 15868671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 15968671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 16068671f35SDmitry Monakhov */ 16168671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 16268671f35SDmitry Monakhov { 16368671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1641da177e4SLinus Torvalds put_bh(bh); 1651da177e4SLinus Torvalds } 1661fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_read_sync); 1671da177e4SLinus Torvalds 1681da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1691da177e4SLinus Torvalds { 1701da177e4SLinus Torvalds if (uptodate) { 1711da177e4SLinus Torvalds set_buffer_uptodate(bh); 1721da177e4SLinus Torvalds } else { 173b744c2acSRobert Elliott buffer_io_error(bh, ", lost sync page write"); 17487354e5dSJeff Layton mark_buffer_write_io_error(bh); 1751da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1761da177e4SLinus Torvalds } 1771da177e4SLinus Torvalds unlock_buffer(bh); 1781da177e4SLinus Torvalds put_bh(bh); 1791da177e4SLinus Torvalds } 1801fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_write_sync); 1811da177e4SLinus Torvalds 1821da177e4SLinus Torvalds /* 1831da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 1841da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 1851da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 1861da177e4SLinus Torvalds * private_lock. 1871da177e4SLinus Torvalds * 188b93b0163SMatthew Wilcox * Hack idea: for the blockdev mapping, private_lock contention 1891da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 190b93b0163SMatthew Wilcox * succeeds, there is no need to take private_lock. 1911da177e4SLinus Torvalds */ 1921da177e4SLinus Torvalds static struct buffer_head * 193385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 1941da177e4SLinus Torvalds { 1951da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 1961da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 1971da177e4SLinus Torvalds struct buffer_head *ret = NULL; 1981da177e4SLinus Torvalds pgoff_t index; 1991da177e4SLinus Torvalds struct buffer_head *bh; 2001da177e4SLinus Torvalds struct buffer_head *head; 2011da177e4SLinus Torvalds struct page *page; 2021da177e4SLinus Torvalds int all_mapped = 1; 2031da177e4SLinus Torvalds 20409cbfeafSKirill A. Shutemov index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); 2052457aec6SMel Gorman page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); 2061da177e4SLinus Torvalds if (!page) 2071da177e4SLinus Torvalds goto out; 2081da177e4SLinus Torvalds 2091da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2101da177e4SLinus Torvalds if (!page_has_buffers(page)) 2111da177e4SLinus Torvalds goto out_unlock; 2121da177e4SLinus Torvalds head = page_buffers(page); 2131da177e4SLinus Torvalds bh = head; 2141da177e4SLinus Torvalds do { 21597f76d3dSNikanth Karthikesan if (!buffer_mapped(bh)) 21697f76d3dSNikanth Karthikesan all_mapped = 0; 21797f76d3dSNikanth Karthikesan else if (bh->b_blocknr == block) { 2181da177e4SLinus Torvalds ret = bh; 2191da177e4SLinus Torvalds get_bh(bh); 2201da177e4SLinus Torvalds goto out_unlock; 2211da177e4SLinus Torvalds } 2221da177e4SLinus Torvalds bh = bh->b_this_page; 2231da177e4SLinus Torvalds } while (bh != head); 2241da177e4SLinus Torvalds 2251da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2261da177e4SLinus Torvalds * not mapped. This is due to various races between 2271da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2281da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2291da177e4SLinus Torvalds */ 2301da177e4SLinus Torvalds if (all_mapped) { 2311da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2321da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 233205f87f6SBadari Pulavarty (unsigned long long)block, 234205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 235205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 236205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 237a1c6f057SDmitry Monakhov printk("device %pg blocksize: %d\n", bdev, 23872a2ebd8STao Ma 1 << bd_inode->i_blkbits); 2391da177e4SLinus Torvalds } 2401da177e4SLinus Torvalds out_unlock: 2411da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 24209cbfeafSKirill A. Shutemov put_page(page); 2431da177e4SLinus Torvalds out: 2441da177e4SLinus Torvalds return ret; 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds /* 2481da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 2491da177e4SLinus Torvalds * which come unlocked at the end of I/O. 2501da177e4SLinus Torvalds */ 2511da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 2521da177e4SLinus Torvalds { 2531da177e4SLinus Torvalds unsigned long flags; 254a3972203SNick Piggin struct buffer_head *first; 2551da177e4SLinus Torvalds struct buffer_head *tmp; 2561da177e4SLinus Torvalds struct page *page; 2571da177e4SLinus Torvalds int page_uptodate = 1; 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds page = bh->b_page; 2621da177e4SLinus Torvalds if (uptodate) { 2631da177e4SLinus Torvalds set_buffer_uptodate(bh); 2641da177e4SLinus Torvalds } else { 2651da177e4SLinus Torvalds clear_buffer_uptodate(bh); 266b744c2acSRobert Elliott buffer_io_error(bh, ", async page read"); 2671da177e4SLinus Torvalds SetPageError(page); 2681da177e4SLinus Torvalds } 2691da177e4SLinus Torvalds 2701da177e4SLinus Torvalds /* 2711da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 2721da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 2731da177e4SLinus Torvalds * decide that the page is now completely done. 2741da177e4SLinus Torvalds */ 275a3972203SNick Piggin first = page_buffers(page); 276a3972203SNick Piggin local_irq_save(flags); 277a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 2781da177e4SLinus Torvalds clear_buffer_async_read(bh); 2791da177e4SLinus Torvalds unlock_buffer(bh); 2801da177e4SLinus Torvalds tmp = bh; 2811da177e4SLinus Torvalds do { 2821da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 2831da177e4SLinus Torvalds page_uptodate = 0; 2841da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 2851da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 2861da177e4SLinus Torvalds goto still_busy; 2871da177e4SLinus Torvalds } 2881da177e4SLinus Torvalds tmp = tmp->b_this_page; 2891da177e4SLinus Torvalds } while (tmp != bh); 290a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 291a3972203SNick Piggin local_irq_restore(flags); 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds /* 2941da177e4SLinus Torvalds * If none of the buffers had errors and they are all 2951da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 2961da177e4SLinus Torvalds */ 2971da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 2981da177e4SLinus Torvalds SetPageUptodate(page); 2991da177e4SLinus Torvalds unlock_page(page); 3001da177e4SLinus Torvalds return; 3011da177e4SLinus Torvalds 3021da177e4SLinus Torvalds still_busy: 303a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 304a3972203SNick Piggin local_irq_restore(flags); 3051da177e4SLinus Torvalds return; 3061da177e4SLinus Torvalds } 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds /* 3091da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 3101da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 3111da177e4SLinus Torvalds */ 31235c80d5fSChris Mason void end_buffer_async_write(struct buffer_head *bh, int uptodate) 3131da177e4SLinus Torvalds { 3141da177e4SLinus Torvalds unsigned long flags; 315a3972203SNick Piggin struct buffer_head *first; 3161da177e4SLinus Torvalds struct buffer_head *tmp; 3171da177e4SLinus Torvalds struct page *page; 3181da177e4SLinus Torvalds 3191da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 3201da177e4SLinus Torvalds 3211da177e4SLinus Torvalds page = bh->b_page; 3221da177e4SLinus Torvalds if (uptodate) { 3231da177e4SLinus Torvalds set_buffer_uptodate(bh); 3241da177e4SLinus Torvalds } else { 325b744c2acSRobert Elliott buffer_io_error(bh, ", lost async page write"); 32687354e5dSJeff Layton mark_buffer_write_io_error(bh); 3271da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3281da177e4SLinus Torvalds SetPageError(page); 3291da177e4SLinus Torvalds } 3301da177e4SLinus Torvalds 331a3972203SNick Piggin first = page_buffers(page); 332a3972203SNick Piggin local_irq_save(flags); 333a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 334a3972203SNick Piggin 3351da177e4SLinus Torvalds clear_buffer_async_write(bh); 3361da177e4SLinus Torvalds unlock_buffer(bh); 3371da177e4SLinus Torvalds tmp = bh->b_this_page; 3381da177e4SLinus Torvalds while (tmp != bh) { 3391da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 3401da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3411da177e4SLinus Torvalds goto still_busy; 3421da177e4SLinus Torvalds } 3431da177e4SLinus Torvalds tmp = tmp->b_this_page; 3441da177e4SLinus Torvalds } 345a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 346a3972203SNick Piggin local_irq_restore(flags); 3471da177e4SLinus Torvalds end_page_writeback(page); 3481da177e4SLinus Torvalds return; 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds still_busy: 351a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 352a3972203SNick Piggin local_irq_restore(flags); 3531da177e4SLinus Torvalds return; 3541da177e4SLinus Torvalds } 3551fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_async_write); 3561da177e4SLinus Torvalds 3571da177e4SLinus Torvalds /* 3581da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 3591da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 3601da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 3611da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 3621da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 3631da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 3641da177e4SLinus Torvalds * that this buffer is not under async I/O. 3651da177e4SLinus Torvalds * 3661da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 3671da177e4SLinus Torvalds * left. 3681da177e4SLinus Torvalds * 3691da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 3701da177e4SLinus Torvalds * the buffers. 3711da177e4SLinus Torvalds * 3721da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 3731da177e4SLinus Torvalds * page. 3741da177e4SLinus Torvalds * 3751da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 3761da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 3771da177e4SLinus Torvalds */ 3781da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 3791da177e4SLinus Torvalds { 3801da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 3811da177e4SLinus Torvalds set_buffer_async_read(bh); 3821da177e4SLinus Torvalds } 3831da177e4SLinus Torvalds 3841fe72eaaSH Hartley Sweeten static void mark_buffer_async_write_endio(struct buffer_head *bh, 38535c80d5fSChris Mason bh_end_io_t *handler) 38635c80d5fSChris Mason { 38735c80d5fSChris Mason bh->b_end_io = handler; 38835c80d5fSChris Mason set_buffer_async_write(bh); 38935c80d5fSChris Mason } 39035c80d5fSChris Mason 3911da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 3921da177e4SLinus Torvalds { 39335c80d5fSChris Mason mark_buffer_async_write_endio(bh, end_buffer_async_write); 3941da177e4SLinus Torvalds } 3951da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 3961da177e4SLinus Torvalds 3971da177e4SLinus Torvalds 3981da177e4SLinus Torvalds /* 3991da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 4001da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 4011da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 4021da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 4031da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 4041da177e4SLinus Torvalds * 4051da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 4061da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 4071da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 4081da177e4SLinus Torvalds * 4091da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 4101da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 4111da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 4121da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 4131da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 4141da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 4151da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 4161da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 4171da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 4181da177e4SLinus Torvalds * ->private_lock. 4191da177e4SLinus Torvalds * 4201da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 4211da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 4221da177e4SLinus Torvalds * 4231da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 4241da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 4251da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 4261da177e4SLinus Torvalds * be true at clear_inode() time. 4271da177e4SLinus Torvalds * 4281da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 4291da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 4301da177e4SLinus Torvalds * BUG_ON(!list_empty). 4311da177e4SLinus Torvalds * 4321da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 4331da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 4341da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 4351da177e4SLinus Torvalds * queued up. 4361da177e4SLinus Torvalds * 4371da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 4381da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 4391da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 4401da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 4411da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 4421da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 4431da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 4441da177e4SLinus Torvalds * b_inode back. 4451da177e4SLinus Torvalds */ 4461da177e4SLinus Torvalds 4471da177e4SLinus Torvalds /* 4481da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 4491da177e4SLinus Torvalds */ 450dbacefc9SThomas Petazzoni static void __remove_assoc_queue(struct buffer_head *bh) 4511da177e4SLinus Torvalds { 4521da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 45358ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 45458ff407bSJan Kara bh->b_assoc_map = NULL; 4551da177e4SLinus Torvalds } 4561da177e4SLinus Torvalds 4571da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 4581da177e4SLinus Torvalds { 4591da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 4601da177e4SLinus Torvalds } 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds /* 4631da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 4641da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 4651da177e4SLinus Torvalds * writes to the disk. 4661da177e4SLinus Torvalds * 4671da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 4681da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 4691da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 4701da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 4711da177e4SLinus Torvalds */ 4721da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 4731da177e4SLinus Torvalds { 4741da177e4SLinus Torvalds struct buffer_head *bh; 4751da177e4SLinus Torvalds struct list_head *p; 4761da177e4SLinus Torvalds int err = 0; 4771da177e4SLinus Torvalds 4781da177e4SLinus Torvalds spin_lock(lock); 4791da177e4SLinus Torvalds repeat: 4801da177e4SLinus Torvalds list_for_each_prev(p, list) { 4811da177e4SLinus Torvalds bh = BH_ENTRY(p); 4821da177e4SLinus Torvalds if (buffer_locked(bh)) { 4831da177e4SLinus Torvalds get_bh(bh); 4841da177e4SLinus Torvalds spin_unlock(lock); 4851da177e4SLinus Torvalds wait_on_buffer(bh); 4861da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 4871da177e4SLinus Torvalds err = -EIO; 4881da177e4SLinus Torvalds brelse(bh); 4891da177e4SLinus Torvalds spin_lock(lock); 4901da177e4SLinus Torvalds goto repeat; 4911da177e4SLinus Torvalds } 4921da177e4SLinus Torvalds } 4931da177e4SLinus Torvalds spin_unlock(lock); 4941da177e4SLinus Torvalds return err; 4951da177e4SLinus Torvalds } 4961da177e4SLinus Torvalds 49708fdc8a0SMateusz Guzik void emergency_thaw_bdev(struct super_block *sb) 498c2d75438SEric Sandeen { 499c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 500a1c6f057SDmitry Monakhov printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev); 501c2d75438SEric Sandeen } 50201a05b33SAl Viro 5031da177e4SLinus Torvalds /** 50478a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 50567be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 5061da177e4SLinus Torvalds * 5071da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 5081da177e4SLinus Torvalds * that I/O. 5091da177e4SLinus Torvalds * 51067be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 51167be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 51267be2dd1SMartin Waitz * a successful fsync(). 5131da177e4SLinus Torvalds */ 5141da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 5151da177e4SLinus Torvalds { 516252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 5171da177e4SLinus Torvalds 5181da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 5191da177e4SLinus Torvalds return 0; 5201da177e4SLinus Torvalds 5211da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 5221da177e4SLinus Torvalds &mapping->private_list); 5231da177e4SLinus Torvalds } 5241da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 5251da177e4SLinus Torvalds 5261da177e4SLinus Torvalds /* 5271da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 5281da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 5291da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 5301da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 5311da177e4SLinus Torvalds */ 5321da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 5331da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 5341da177e4SLinus Torvalds { 5351da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 5361da177e4SLinus Torvalds if (bh) { 5371da177e4SLinus Torvalds if (buffer_dirty(bh)) 538dfec8a14SMike Christie ll_rw_block(REQ_OP_WRITE, 0, 1, &bh); 5391da177e4SLinus Torvalds put_bh(bh); 5401da177e4SLinus Torvalds } 5411da177e4SLinus Torvalds } 5421da177e4SLinus Torvalds 5431da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 5441da177e4SLinus Torvalds { 5451da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 5461da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 5471da177e4SLinus Torvalds 5481da177e4SLinus Torvalds mark_buffer_dirty(bh); 549252aa6f5SRafael Aquini if (!mapping->private_data) { 550252aa6f5SRafael Aquini mapping->private_data = buffer_mapping; 5511da177e4SLinus Torvalds } else { 552252aa6f5SRafael Aquini BUG_ON(mapping->private_data != buffer_mapping); 5531da177e4SLinus Torvalds } 554535ee2fbSJan Kara if (!bh->b_assoc_map) { 5551da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 5561da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 5571da177e4SLinus Torvalds &mapping->private_list); 55858ff407bSJan Kara bh->b_assoc_map = mapping; 5591da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 5601da177e4SLinus Torvalds } 5611da177e4SLinus Torvalds } 5621da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 5631da177e4SLinus Torvalds 5641da177e4SLinus Torvalds /* 565787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 566787d2214SNick Piggin * dirty. 567787d2214SNick Piggin * 568787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 569787d2214SNick Piggin * not been truncated. 570c4843a75SGreg Thelen * 57181f8c3a4SJohannes Weiner * The caller must hold lock_page_memcg(). 572787d2214SNick Piggin */ 573f82b3764SMatthew Wilcox void __set_page_dirty(struct page *page, struct address_space *mapping, 57462cccb8cSJohannes Weiner int warn) 575787d2214SNick Piggin { 576227d53b3SKOSAKI Motohiro unsigned long flags; 577227d53b3SKOSAKI Motohiro 578b93b0163SMatthew Wilcox xa_lock_irqsave(&mapping->i_pages, flags); 579787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 580787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 58162cccb8cSJohannes Weiner account_page_dirtied(page, mapping); 582b93b0163SMatthew Wilcox radix_tree_tag_set(&mapping->i_pages, 583787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 584787d2214SNick Piggin } 585b93b0163SMatthew Wilcox xa_unlock_irqrestore(&mapping->i_pages, flags); 586787d2214SNick Piggin } 587f82b3764SMatthew Wilcox EXPORT_SYMBOL_GPL(__set_page_dirty); 588787d2214SNick Piggin 589787d2214SNick Piggin /* 5901da177e4SLinus Torvalds * Add a page to the dirty page list. 5911da177e4SLinus Torvalds * 5921da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 5931da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 5941da177e4SLinus Torvalds * 5951da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 5961da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 5971da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 5981da177e4SLinus Torvalds * dirty. 5991da177e4SLinus Torvalds * 6001da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6011da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6021da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6031da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6041da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 6051da177e4SLinus Torvalds * page on the dirty page list. 6061da177e4SLinus Torvalds * 6071da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 6081da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 6091da177e4SLinus Torvalds * added to the page after it was set dirty. 6101da177e4SLinus Torvalds * 6111da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 6121da177e4SLinus Torvalds * address_space though. 6131da177e4SLinus Torvalds */ 6141da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 6151da177e4SLinus Torvalds { 616a8e7d49aSLinus Torvalds int newly_dirty; 617787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 618ebf7a227SNick Piggin 619ebf7a227SNick Piggin if (unlikely(!mapping)) 620ebf7a227SNick Piggin return !TestSetPageDirty(page); 6211da177e4SLinus Torvalds 6221da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 6231da177e4SLinus Torvalds if (page_has_buffers(page)) { 6241da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 6251da177e4SLinus Torvalds struct buffer_head *bh = head; 6261da177e4SLinus Torvalds 6271da177e4SLinus Torvalds do { 6281da177e4SLinus Torvalds set_buffer_dirty(bh); 6291da177e4SLinus Torvalds bh = bh->b_this_page; 6301da177e4SLinus Torvalds } while (bh != head); 6311da177e4SLinus Torvalds } 632c4843a75SGreg Thelen /* 63381f8c3a4SJohannes Weiner * Lock out page->mem_cgroup migration to keep PageDirty 63481f8c3a4SJohannes Weiner * synchronized with per-memcg dirty page counters. 635c4843a75SGreg Thelen */ 63662cccb8cSJohannes Weiner lock_page_memcg(page); 637a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 6381da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 6391da177e4SLinus Torvalds 640a8e7d49aSLinus Torvalds if (newly_dirty) 64162cccb8cSJohannes Weiner __set_page_dirty(page, mapping, 1); 642c4843a75SGreg Thelen 64362cccb8cSJohannes Weiner unlock_page_memcg(page); 644c4843a75SGreg Thelen 645c4843a75SGreg Thelen if (newly_dirty) 646c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 647c4843a75SGreg Thelen 648a8e7d49aSLinus Torvalds return newly_dirty; 6491da177e4SLinus Torvalds } 6501da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 6511da177e4SLinus Torvalds 6521da177e4SLinus Torvalds /* 6531da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 6541da177e4SLinus Torvalds * 6551da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 6561da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 6571da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 6581da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 6591da177e4SLinus Torvalds * 6601da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 6611da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 6621da177e4SLinus Torvalds * up, waiting for those writes to complete. 6631da177e4SLinus Torvalds * 6641da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 6651da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 6661da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 6671da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 6681da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 6691da177e4SLinus Torvalds * any newly dirty buffers for write. 6701da177e4SLinus Torvalds */ 6711da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 6721da177e4SLinus Torvalds { 6731da177e4SLinus Torvalds struct buffer_head *bh; 6741da177e4SLinus Torvalds struct list_head tmp; 6757eaceaccSJens Axboe struct address_space *mapping; 6761da177e4SLinus Torvalds int err = 0, err2; 6774ee2491eSJens Axboe struct blk_plug plug; 6781da177e4SLinus Torvalds 6791da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 6804ee2491eSJens Axboe blk_start_plug(&plug); 6811da177e4SLinus Torvalds 6821da177e4SLinus Torvalds spin_lock(lock); 6831da177e4SLinus Torvalds while (!list_empty(list)) { 6841da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 685535ee2fbSJan Kara mapping = bh->b_assoc_map; 68658ff407bSJan Kara __remove_assoc_queue(bh); 687535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 688535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 689535ee2fbSJan Kara smp_mb(); 6901da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 6911da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 692535ee2fbSJan Kara bh->b_assoc_map = mapping; 6931da177e4SLinus Torvalds if (buffer_dirty(bh)) { 6941da177e4SLinus Torvalds get_bh(bh); 6951da177e4SLinus Torvalds spin_unlock(lock); 6961da177e4SLinus Torvalds /* 6971da177e4SLinus Torvalds * Ensure any pending I/O completes so that 6989cb569d6SChristoph Hellwig * write_dirty_buffer() actually writes the 6999cb569d6SChristoph Hellwig * current contents - it is a noop if I/O is 7009cb569d6SChristoph Hellwig * still in flight on potentially older 7019cb569d6SChristoph Hellwig * contents. 7021da177e4SLinus Torvalds */ 70370fd7614SChristoph Hellwig write_dirty_buffer(bh, REQ_SYNC); 7049cf6b720SJens Axboe 7059cf6b720SJens Axboe /* 7069cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7079cf6b720SJens Axboe * that we will not run the very last mapping, 7089cf6b720SJens Axboe * wait_on_buffer() will do that for us 7099cf6b720SJens Axboe * through sync_buffer(). 7109cf6b720SJens Axboe */ 7111da177e4SLinus Torvalds brelse(bh); 7121da177e4SLinus Torvalds spin_lock(lock); 7131da177e4SLinus Torvalds } 7141da177e4SLinus Torvalds } 7151da177e4SLinus Torvalds } 7161da177e4SLinus Torvalds 7174ee2491eSJens Axboe spin_unlock(lock); 7184ee2491eSJens Axboe blk_finish_plug(&plug); 7194ee2491eSJens Axboe spin_lock(lock); 7204ee2491eSJens Axboe 7211da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7221da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 7231da177e4SLinus Torvalds get_bh(bh); 724535ee2fbSJan Kara mapping = bh->b_assoc_map; 725535ee2fbSJan Kara __remove_assoc_queue(bh); 726535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 727535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 728535ee2fbSJan Kara smp_mb(); 729535ee2fbSJan Kara if (buffer_dirty(bh)) { 730535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 731e3892296SJan Kara &mapping->private_list); 732535ee2fbSJan Kara bh->b_assoc_map = mapping; 733535ee2fbSJan Kara } 7341da177e4SLinus Torvalds spin_unlock(lock); 7351da177e4SLinus Torvalds wait_on_buffer(bh); 7361da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 7371da177e4SLinus Torvalds err = -EIO; 7381da177e4SLinus Torvalds brelse(bh); 7391da177e4SLinus Torvalds spin_lock(lock); 7401da177e4SLinus Torvalds } 7411da177e4SLinus Torvalds 7421da177e4SLinus Torvalds spin_unlock(lock); 7431da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 7441da177e4SLinus Torvalds if (err) 7451da177e4SLinus Torvalds return err; 7461da177e4SLinus Torvalds else 7471da177e4SLinus Torvalds return err2; 7481da177e4SLinus Torvalds } 7491da177e4SLinus Torvalds 7501da177e4SLinus Torvalds /* 7511da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 7521da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 7531da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 7541da177e4SLinus Torvalds * 7551da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 7561da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 7571da177e4SLinus Torvalds * for reiserfs. 7581da177e4SLinus Torvalds */ 7591da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 7601da177e4SLinus Torvalds { 7611da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 7621da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 7631da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 764252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 7651da177e4SLinus Torvalds 7661da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 7671da177e4SLinus Torvalds while (!list_empty(list)) 7681da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 7691da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 7701da177e4SLinus Torvalds } 7711da177e4SLinus Torvalds } 77252b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 7731da177e4SLinus Torvalds 7741da177e4SLinus Torvalds /* 7751da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 7761da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 7771da177e4SLinus Torvalds * 7781da177e4SLinus Torvalds * Returns true if all buffers were removed. 7791da177e4SLinus Torvalds */ 7801da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 7811da177e4SLinus Torvalds { 7821da177e4SLinus Torvalds int ret = 1; 7831da177e4SLinus Torvalds 7841da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 7851da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 7861da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 787252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 7881da177e4SLinus Torvalds 7891da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 7901da177e4SLinus Torvalds while (!list_empty(list)) { 7911da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 7921da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7931da177e4SLinus Torvalds ret = 0; 7941da177e4SLinus Torvalds break; 7951da177e4SLinus Torvalds } 7961da177e4SLinus Torvalds __remove_assoc_queue(bh); 7971da177e4SLinus Torvalds } 7981da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 7991da177e4SLinus Torvalds } 8001da177e4SLinus Torvalds return ret; 8011da177e4SLinus Torvalds } 8021da177e4SLinus Torvalds 8031da177e4SLinus Torvalds /* 8041da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8051da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8061da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8071da177e4SLinus Torvalds * buffers. 8081da177e4SLinus Torvalds * 8091da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8101da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8111da177e4SLinus Torvalds */ 8121da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 813640ab98fSJens Axboe bool retry) 8141da177e4SLinus Torvalds { 8151da177e4SLinus Torvalds struct buffer_head *bh, *head; 816640ab98fSJens Axboe gfp_t gfp = GFP_NOFS; 8171da177e4SLinus Torvalds long offset; 8181da177e4SLinus Torvalds 819640ab98fSJens Axboe if (retry) 820640ab98fSJens Axboe gfp |= __GFP_NOFAIL; 821640ab98fSJens Axboe 8221da177e4SLinus Torvalds head = NULL; 8231da177e4SLinus Torvalds offset = PAGE_SIZE; 8241da177e4SLinus Torvalds while ((offset -= size) >= 0) { 825640ab98fSJens Axboe bh = alloc_buffer_head(gfp); 8261da177e4SLinus Torvalds if (!bh) 8271da177e4SLinus Torvalds goto no_grow; 8281da177e4SLinus Torvalds 8291da177e4SLinus Torvalds bh->b_this_page = head; 8301da177e4SLinus Torvalds bh->b_blocknr = -1; 8311da177e4SLinus Torvalds head = bh; 8321da177e4SLinus Torvalds 8331da177e4SLinus Torvalds bh->b_size = size; 8341da177e4SLinus Torvalds 8351da177e4SLinus Torvalds /* Link the buffer to its page */ 8361da177e4SLinus Torvalds set_bh_page(bh, page, offset); 8371da177e4SLinus Torvalds } 8381da177e4SLinus Torvalds return head; 8391da177e4SLinus Torvalds /* 8401da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 8411da177e4SLinus Torvalds */ 8421da177e4SLinus Torvalds no_grow: 8431da177e4SLinus Torvalds if (head) { 8441da177e4SLinus Torvalds do { 8451da177e4SLinus Torvalds bh = head; 8461da177e4SLinus Torvalds head = head->b_this_page; 8471da177e4SLinus Torvalds free_buffer_head(bh); 8481da177e4SLinus Torvalds } while (head); 8491da177e4SLinus Torvalds } 8501da177e4SLinus Torvalds 8511da177e4SLinus Torvalds return NULL; 8521da177e4SLinus Torvalds } 8531da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 8541da177e4SLinus Torvalds 8551da177e4SLinus Torvalds static inline void 8561da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 8571da177e4SLinus Torvalds { 8581da177e4SLinus Torvalds struct buffer_head *bh, *tail; 8591da177e4SLinus Torvalds 8601da177e4SLinus Torvalds bh = head; 8611da177e4SLinus Torvalds do { 8621da177e4SLinus Torvalds tail = bh; 8631da177e4SLinus Torvalds bh = bh->b_this_page; 8641da177e4SLinus Torvalds } while (bh); 8651da177e4SLinus Torvalds tail->b_this_page = head; 8661da177e4SLinus Torvalds attach_page_buffers(page, head); 8671da177e4SLinus Torvalds } 8681da177e4SLinus Torvalds 869bbec0270SLinus Torvalds static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) 870bbec0270SLinus Torvalds { 871bbec0270SLinus Torvalds sector_t retval = ~((sector_t)0); 872bbec0270SLinus Torvalds loff_t sz = i_size_read(bdev->bd_inode); 873bbec0270SLinus Torvalds 874bbec0270SLinus Torvalds if (sz) { 875bbec0270SLinus Torvalds unsigned int sizebits = blksize_bits(size); 876bbec0270SLinus Torvalds retval = (sz >> sizebits); 877bbec0270SLinus Torvalds } 878bbec0270SLinus Torvalds return retval; 879bbec0270SLinus Torvalds } 880bbec0270SLinus Torvalds 8811da177e4SLinus Torvalds /* 8821da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 8831da177e4SLinus Torvalds */ 884676ce6d5SHugh Dickins static sector_t 8851da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 8861da177e4SLinus Torvalds sector_t block, int size) 8871da177e4SLinus Torvalds { 8881da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 8891da177e4SLinus Torvalds struct buffer_head *bh = head; 8901da177e4SLinus Torvalds int uptodate = PageUptodate(page); 891bbec0270SLinus Torvalds sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); 8921da177e4SLinus Torvalds 8931da177e4SLinus Torvalds do { 8941da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 89501950a34SEric Biggers bh->b_end_io = NULL; 89601950a34SEric Biggers bh->b_private = NULL; 8971da177e4SLinus Torvalds bh->b_bdev = bdev; 8981da177e4SLinus Torvalds bh->b_blocknr = block; 8991da177e4SLinus Torvalds if (uptodate) 9001da177e4SLinus Torvalds set_buffer_uptodate(bh); 901080399aaSJeff Moyer if (block < end_block) 9021da177e4SLinus Torvalds set_buffer_mapped(bh); 9031da177e4SLinus Torvalds } 9041da177e4SLinus Torvalds block++; 9051da177e4SLinus Torvalds bh = bh->b_this_page; 9061da177e4SLinus Torvalds } while (bh != head); 907676ce6d5SHugh Dickins 908676ce6d5SHugh Dickins /* 909676ce6d5SHugh Dickins * Caller needs to validate requested block against end of device. 910676ce6d5SHugh Dickins */ 911676ce6d5SHugh Dickins return end_block; 9121da177e4SLinus Torvalds } 9131da177e4SLinus Torvalds 9141da177e4SLinus Torvalds /* 9151da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9161da177e4SLinus Torvalds * 917676ce6d5SHugh Dickins * This is used purely for blockdev mappings. 9181da177e4SLinus Torvalds */ 919676ce6d5SHugh Dickins static int 9201da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 9213b5e6454SGioh Kim pgoff_t index, int size, int sizebits, gfp_t gfp) 9221da177e4SLinus Torvalds { 9231da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9241da177e4SLinus Torvalds struct page *page; 9251da177e4SLinus Torvalds struct buffer_head *bh; 926676ce6d5SHugh Dickins sector_t end_block; 927676ce6d5SHugh Dickins int ret = 0; /* Will call free_more_memory() */ 92884235de3SJohannes Weiner gfp_t gfp_mask; 9291da177e4SLinus Torvalds 930c62d2555SMichal Hocko gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; 9313b5e6454SGioh Kim 93284235de3SJohannes Weiner /* 93384235de3SJohannes Weiner * XXX: __getblk_slow() can not really deal with failure and 93484235de3SJohannes Weiner * will endlessly loop on improvised global reclaim. Prefer 93584235de3SJohannes Weiner * looping in the allocator rather than here, at least that 93684235de3SJohannes Weiner * code knows what it's doing. 93784235de3SJohannes Weiner */ 93884235de3SJohannes Weiner gfp_mask |= __GFP_NOFAIL; 93984235de3SJohannes Weiner 94084235de3SJohannes Weiner page = find_or_create_page(inode->i_mapping, index, gfp_mask); 9411da177e4SLinus Torvalds 942e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 9431da177e4SLinus Torvalds 9441da177e4SLinus Torvalds if (page_has_buffers(page)) { 9451da177e4SLinus Torvalds bh = page_buffers(page); 9461da177e4SLinus Torvalds if (bh->b_size == size) { 947676ce6d5SHugh Dickins end_block = init_page_buffers(page, bdev, 948f2d5a944SAnton Altaparmakov (sector_t)index << sizebits, 949f2d5a944SAnton Altaparmakov size); 950676ce6d5SHugh Dickins goto done; 9511da177e4SLinus Torvalds } 9521da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 9531da177e4SLinus Torvalds goto failed; 9541da177e4SLinus Torvalds } 9551da177e4SLinus Torvalds 9561da177e4SLinus Torvalds /* 9571da177e4SLinus Torvalds * Allocate some buffers for this page 9581da177e4SLinus Torvalds */ 95994dc24c0SJens Axboe bh = alloc_page_buffers(page, size, true); 9601da177e4SLinus Torvalds 9611da177e4SLinus Torvalds /* 9621da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 9631da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 9641da177e4SLinus Torvalds * run under the page lock. 9651da177e4SLinus Torvalds */ 9661da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 9671da177e4SLinus Torvalds link_dev_buffers(page, bh); 968f2d5a944SAnton Altaparmakov end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, 969f2d5a944SAnton Altaparmakov size); 9701da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 971676ce6d5SHugh Dickins done: 972676ce6d5SHugh Dickins ret = (block < end_block) ? 1 : -ENXIO; 9731da177e4SLinus Torvalds failed: 9741da177e4SLinus Torvalds unlock_page(page); 97509cbfeafSKirill A. Shutemov put_page(page); 976676ce6d5SHugh Dickins return ret; 9771da177e4SLinus Torvalds } 9781da177e4SLinus Torvalds 9791da177e4SLinus Torvalds /* 9801da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 9811da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 9821da177e4SLinus Torvalds */ 983858119e1SArjan van de Ven static int 9843b5e6454SGioh Kim grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) 9851da177e4SLinus Torvalds { 9861da177e4SLinus Torvalds pgoff_t index; 9871da177e4SLinus Torvalds int sizebits; 9881da177e4SLinus Torvalds 9891da177e4SLinus Torvalds sizebits = -1; 9901da177e4SLinus Torvalds do { 9911da177e4SLinus Torvalds sizebits++; 9921da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 9931da177e4SLinus Torvalds 9941da177e4SLinus Torvalds index = block >> sizebits; 9951da177e4SLinus Torvalds 996e5657933SAndrew Morton /* 997e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 998e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 999e5657933SAndrew Morton */ 1000e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1001e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1002a1c6f057SDmitry Monakhov "device %pg\n", 10038e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1004a1c6f057SDmitry Monakhov bdev); 1005e5657933SAndrew Morton return -EIO; 1006e5657933SAndrew Morton } 1007676ce6d5SHugh Dickins 10081da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10093b5e6454SGioh Kim return grow_dev_page(bdev, block, index, size, sizebits, gfp); 10101da177e4SLinus Torvalds } 10111da177e4SLinus Torvalds 10120026ba40SEric Biggers static struct buffer_head * 10133b5e6454SGioh Kim __getblk_slow(struct block_device *bdev, sector_t block, 10143b5e6454SGioh Kim unsigned size, gfp_t gfp) 10151da177e4SLinus Torvalds { 10161da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1017e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10181da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10191da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10201da177e4SLinus Torvalds size); 1021e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1022e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 10231da177e4SLinus Torvalds 10241da177e4SLinus Torvalds dump_stack(); 10251da177e4SLinus Torvalds return NULL; 10261da177e4SLinus Torvalds } 10271da177e4SLinus Torvalds 1028676ce6d5SHugh Dickins for (;;) { 1029676ce6d5SHugh Dickins struct buffer_head *bh; 1030676ce6d5SHugh Dickins int ret; 1031676ce6d5SHugh Dickins 10321da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 10331da177e4SLinus Torvalds if (bh) 10341da177e4SLinus Torvalds return bh; 10351da177e4SLinus Torvalds 10363b5e6454SGioh Kim ret = grow_buffers(bdev, block, size, gfp); 1037676ce6d5SHugh Dickins if (ret < 0) 103891f68c89SJeff Moyer return NULL; 1039676ce6d5SHugh Dickins } 10401da177e4SLinus Torvalds } 10411da177e4SLinus Torvalds 10421da177e4SLinus Torvalds /* 10431da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 10441da177e4SLinus Torvalds * 10451da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 10461da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 10471da177e4SLinus Torvalds * 10481da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 10491da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 10501da177e4SLinus Torvalds * merely a hint about the true dirty state. 10511da177e4SLinus Torvalds * 10521da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 10531da177e4SLinus Torvalds * (if the page has buffers). 10541da177e4SLinus Torvalds * 10551da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 10561da177e4SLinus Torvalds * buffers are not. 10571da177e4SLinus Torvalds * 10581da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 10591da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 10601da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 10611da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 10621da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 10631da177e4SLinus Torvalds */ 10641da177e4SLinus Torvalds 10651da177e4SLinus Torvalds /** 10661da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 106767be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 10681da177e4SLinus Torvalds * 10691da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 10701da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 10711da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 10721da177e4SLinus Torvalds * inode list. 10731da177e4SLinus Torvalds * 10741da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 1075b93b0163SMatthew Wilcox * i_pages lock and mapping->host->i_lock. 10761da177e4SLinus Torvalds */ 1077fc9b52cdSHarvey Harrison void mark_buffer_dirty(struct buffer_head *bh) 10781da177e4SLinus Torvalds { 1079787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 10801be62dc1SLinus Torvalds 10815305cb83STejun Heo trace_block_dirty_buffer(bh); 10825305cb83STejun Heo 10831be62dc1SLinus Torvalds /* 10841be62dc1SLinus Torvalds * Very *carefully* optimize the it-is-already-dirty case. 10851be62dc1SLinus Torvalds * 10861be62dc1SLinus Torvalds * Don't let the final "is it dirty" escape to before we 10871be62dc1SLinus Torvalds * perhaps modified the buffer. 10881be62dc1SLinus Torvalds */ 10891be62dc1SLinus Torvalds if (buffer_dirty(bh)) { 10901be62dc1SLinus Torvalds smp_mb(); 10911be62dc1SLinus Torvalds if (buffer_dirty(bh)) 10921be62dc1SLinus Torvalds return; 10931be62dc1SLinus Torvalds } 10941be62dc1SLinus Torvalds 1095a8e7d49aSLinus Torvalds if (!test_set_buffer_dirty(bh)) { 1096a8e7d49aSLinus Torvalds struct page *page = bh->b_page; 1097c4843a75SGreg Thelen struct address_space *mapping = NULL; 1098c4843a75SGreg Thelen 109962cccb8cSJohannes Weiner lock_page_memcg(page); 11008e9d78edSLinus Torvalds if (!TestSetPageDirty(page)) { 1101c4843a75SGreg Thelen mapping = page_mapping(page); 11028e9d78edSLinus Torvalds if (mapping) 110362cccb8cSJohannes Weiner __set_page_dirty(page, mapping, 0); 11048e9d78edSLinus Torvalds } 110562cccb8cSJohannes Weiner unlock_page_memcg(page); 1106c4843a75SGreg Thelen if (mapping) 1107c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 1108a8e7d49aSLinus Torvalds } 11091da177e4SLinus Torvalds } 11101fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(mark_buffer_dirty); 11111da177e4SLinus Torvalds 111287354e5dSJeff Layton void mark_buffer_write_io_error(struct buffer_head *bh) 111387354e5dSJeff Layton { 111487354e5dSJeff Layton set_buffer_write_io_error(bh); 111587354e5dSJeff Layton /* FIXME: do we need to set this in both places? */ 111687354e5dSJeff Layton if (bh->b_page && bh->b_page->mapping) 111787354e5dSJeff Layton mapping_set_error(bh->b_page->mapping, -EIO); 111887354e5dSJeff Layton if (bh->b_assoc_map) 111987354e5dSJeff Layton mapping_set_error(bh->b_assoc_map, -EIO); 112087354e5dSJeff Layton } 112187354e5dSJeff Layton EXPORT_SYMBOL(mark_buffer_write_io_error); 112287354e5dSJeff Layton 11231da177e4SLinus Torvalds /* 11241da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11251da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11261da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11271da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11281da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11291da177e4SLinus Torvalds */ 11301da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11311da177e4SLinus Torvalds { 11321da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11331da177e4SLinus Torvalds put_bh(buf); 11341da177e4SLinus Torvalds return; 11351da177e4SLinus Torvalds } 11365c752ad9SArjan van de Ven WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 11371da177e4SLinus Torvalds } 11381fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__brelse); 11391da177e4SLinus Torvalds 11401da177e4SLinus Torvalds /* 11411da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 11421da177e4SLinus Torvalds * potentially dirty data. 11431da177e4SLinus Torvalds */ 11441da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 11451da177e4SLinus Torvalds { 11461da177e4SLinus Torvalds clear_buffer_dirty(bh); 1147535ee2fbSJan Kara if (bh->b_assoc_map) { 11481da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 11491da177e4SLinus Torvalds 11501da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 11511da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 115258ff407bSJan Kara bh->b_assoc_map = NULL; 11531da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 11541da177e4SLinus Torvalds } 11551da177e4SLinus Torvalds __brelse(bh); 11561da177e4SLinus Torvalds } 11571fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__bforget); 11581da177e4SLinus Torvalds 11591da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 11601da177e4SLinus Torvalds { 11611da177e4SLinus Torvalds lock_buffer(bh); 11621da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 11631da177e4SLinus Torvalds unlock_buffer(bh); 11641da177e4SLinus Torvalds return bh; 11651da177e4SLinus Torvalds } else { 11661da177e4SLinus Torvalds get_bh(bh); 11671da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 11682a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 11691da177e4SLinus Torvalds wait_on_buffer(bh); 11701da177e4SLinus Torvalds if (buffer_uptodate(bh)) 11711da177e4SLinus Torvalds return bh; 11721da177e4SLinus Torvalds } 11731da177e4SLinus Torvalds brelse(bh); 11741da177e4SLinus Torvalds return NULL; 11751da177e4SLinus Torvalds } 11761da177e4SLinus Torvalds 11771da177e4SLinus Torvalds /* 11781da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 11791da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 11801da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 11811da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 11821da177e4SLinus Torvalds * CPU's LRUs at the same time. 11831da177e4SLinus Torvalds * 11841da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 11851da177e4SLinus Torvalds * sb_find_get_block(). 11861da177e4SLinus Torvalds * 11871da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 11881da177e4SLinus Torvalds * a local interrupt disable for that. 11891da177e4SLinus Torvalds */ 11901da177e4SLinus Torvalds 119186cf78d7SSebastien Buisson #define BH_LRU_SIZE 16 11921da177e4SLinus Torvalds 11931da177e4SLinus Torvalds struct bh_lru { 11941da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 11951da177e4SLinus Torvalds }; 11961da177e4SLinus Torvalds 11971da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 11981da177e4SLinus Torvalds 11991da177e4SLinus Torvalds #ifdef CONFIG_SMP 12001da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12011da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12021da177e4SLinus Torvalds #else 12031da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12041da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12051da177e4SLinus Torvalds #endif 12061da177e4SLinus Torvalds 12071da177e4SLinus Torvalds static inline void check_irqs_on(void) 12081da177e4SLinus Torvalds { 12091da177e4SLinus Torvalds #ifdef irqs_disabled 12101da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12111da177e4SLinus Torvalds #endif 12121da177e4SLinus Torvalds } 12131da177e4SLinus Torvalds 12141da177e4SLinus Torvalds /* 1215241f01fbSEric Biggers * Install a buffer_head into this cpu's LRU. If not already in the LRU, it is 1216241f01fbSEric Biggers * inserted at the front, and the buffer_head at the back if any is evicted. 1217241f01fbSEric Biggers * Or, if already in the LRU it is moved to the front. 12181da177e4SLinus Torvalds */ 12191da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12201da177e4SLinus Torvalds { 1221241f01fbSEric Biggers struct buffer_head *evictee = bh; 1222241f01fbSEric Biggers struct bh_lru *b; 1223241f01fbSEric Biggers int i; 12241da177e4SLinus Torvalds 12251da177e4SLinus Torvalds check_irqs_on(); 12261da177e4SLinus Torvalds bh_lru_lock(); 1227241f01fbSEric Biggers 1228241f01fbSEric Biggers b = this_cpu_ptr(&bh_lrus); 1229241f01fbSEric Biggers for (i = 0; i < BH_LRU_SIZE; i++) { 1230241f01fbSEric Biggers swap(evictee, b->bhs[i]); 1231241f01fbSEric Biggers if (evictee == bh) { 1232241f01fbSEric Biggers bh_lru_unlock(); 1233241f01fbSEric Biggers return; 1234241f01fbSEric Biggers } 1235241f01fbSEric Biggers } 12361da177e4SLinus Torvalds 12371da177e4SLinus Torvalds get_bh(bh); 12381da177e4SLinus Torvalds bh_lru_unlock(); 1239241f01fbSEric Biggers brelse(evictee); 12401da177e4SLinus Torvalds } 12411da177e4SLinus Torvalds 12421da177e4SLinus Torvalds /* 12431da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 12441da177e4SLinus Torvalds */ 1245858119e1SArjan van de Ven static struct buffer_head * 12463991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 12471da177e4SLinus Torvalds { 12481da177e4SLinus Torvalds struct buffer_head *ret = NULL; 12493991d3bdSTomasz Kvarsin unsigned int i; 12501da177e4SLinus Torvalds 12511da177e4SLinus Torvalds check_irqs_on(); 12521da177e4SLinus Torvalds bh_lru_lock(); 12531da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 1254c7b92516SChristoph Lameter struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); 12551da177e4SLinus Torvalds 12569470dd5dSZach Brown if (bh && bh->b_blocknr == block && bh->b_bdev == bdev && 12579470dd5dSZach Brown bh->b_size == size) { 12581da177e4SLinus Torvalds if (i) { 12591da177e4SLinus Torvalds while (i) { 1260c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[i], 1261c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[i - 1])); 12621da177e4SLinus Torvalds i--; 12631da177e4SLinus Torvalds } 1264c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[0], bh); 12651da177e4SLinus Torvalds } 12661da177e4SLinus Torvalds get_bh(bh); 12671da177e4SLinus Torvalds ret = bh; 12681da177e4SLinus Torvalds break; 12691da177e4SLinus Torvalds } 12701da177e4SLinus Torvalds } 12711da177e4SLinus Torvalds bh_lru_unlock(); 12721da177e4SLinus Torvalds return ret; 12731da177e4SLinus Torvalds } 12741da177e4SLinus Torvalds 12751da177e4SLinus Torvalds /* 12761da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 12771da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 12781da177e4SLinus Torvalds * NULL 12791da177e4SLinus Torvalds */ 12801da177e4SLinus Torvalds struct buffer_head * 12813991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 12821da177e4SLinus Torvalds { 12831da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 12841da177e4SLinus Torvalds 12851da177e4SLinus Torvalds if (bh == NULL) { 12862457aec6SMel Gorman /* __find_get_block_slow will mark the page accessed */ 1287385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 12881da177e4SLinus Torvalds if (bh) 12891da177e4SLinus Torvalds bh_lru_install(bh); 12902457aec6SMel Gorman } else 12911da177e4SLinus Torvalds touch_buffer(bh); 12922457aec6SMel Gorman 12931da177e4SLinus Torvalds return bh; 12941da177e4SLinus Torvalds } 12951da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 12961da177e4SLinus Torvalds 12971da177e4SLinus Torvalds /* 12983b5e6454SGioh Kim * __getblk_gfp() will locate (and, if necessary, create) the buffer_head 12991da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13001da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13011da177e4SLinus Torvalds * 13023b5e6454SGioh Kim * __getblk_gfp() will lock up the machine if grow_dev_page's 13033b5e6454SGioh Kim * try_to_free_buffers() attempt is failing. FIXME, perhaps? 13041da177e4SLinus Torvalds */ 13051da177e4SLinus Torvalds struct buffer_head * 13063b5e6454SGioh Kim __getblk_gfp(struct block_device *bdev, sector_t block, 13073b5e6454SGioh Kim unsigned size, gfp_t gfp) 13081da177e4SLinus Torvalds { 13091da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13101da177e4SLinus Torvalds 13111da177e4SLinus Torvalds might_sleep(); 13121da177e4SLinus Torvalds if (bh == NULL) 13133b5e6454SGioh Kim bh = __getblk_slow(bdev, block, size, gfp); 13141da177e4SLinus Torvalds return bh; 13151da177e4SLinus Torvalds } 13163b5e6454SGioh Kim EXPORT_SYMBOL(__getblk_gfp); 13171da177e4SLinus Torvalds 13181da177e4SLinus Torvalds /* 13191da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13201da177e4SLinus Torvalds */ 13213991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 13221da177e4SLinus Torvalds { 13231da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1324a3e713b5SAndrew Morton if (likely(bh)) { 132570246286SChristoph Hellwig ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh); 13261da177e4SLinus Torvalds brelse(bh); 13271da177e4SLinus Torvalds } 1328a3e713b5SAndrew Morton } 13291da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 13301da177e4SLinus Torvalds 13311da177e4SLinus Torvalds /** 13323b5e6454SGioh Kim * __bread_gfp() - reads a specified block and returns the bh 133367be2dd1SMartin Waitz * @bdev: the block_device to read from 13341da177e4SLinus Torvalds * @block: number of block 13351da177e4SLinus Torvalds * @size: size (in bytes) to read 13363b5e6454SGioh Kim * @gfp: page allocation flag 13371da177e4SLinus Torvalds * 13381da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 13393b5e6454SGioh Kim * The page cache can be allocated from non-movable area 13403b5e6454SGioh Kim * not to prevent page migration if you set gfp to zero. 13411da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 13421da177e4SLinus Torvalds */ 13431da177e4SLinus Torvalds struct buffer_head * 13443b5e6454SGioh Kim __bread_gfp(struct block_device *bdev, sector_t block, 13453b5e6454SGioh Kim unsigned size, gfp_t gfp) 13461da177e4SLinus Torvalds { 13473b5e6454SGioh Kim struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); 13481da177e4SLinus Torvalds 1349a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 13501da177e4SLinus Torvalds bh = __bread_slow(bh); 13511da177e4SLinus Torvalds return bh; 13521da177e4SLinus Torvalds } 13533b5e6454SGioh Kim EXPORT_SYMBOL(__bread_gfp); 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds /* 13561da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 13571da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 13581da177e4SLinus Torvalds * or with preempt disabled. 13591da177e4SLinus Torvalds */ 13601da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 13611da177e4SLinus Torvalds { 13621da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 13631da177e4SLinus Torvalds int i; 13641da177e4SLinus Torvalds 13651da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 13661da177e4SLinus Torvalds brelse(b->bhs[i]); 13671da177e4SLinus Torvalds b->bhs[i] = NULL; 13681da177e4SLinus Torvalds } 13691da177e4SLinus Torvalds put_cpu_var(bh_lrus); 13701da177e4SLinus Torvalds } 13711da177e4SLinus Torvalds 137242be35d0SGilad Ben-Yossef static bool has_bh_in_lru(int cpu, void *dummy) 137342be35d0SGilad Ben-Yossef { 137442be35d0SGilad Ben-Yossef struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); 137542be35d0SGilad Ben-Yossef int i; 137642be35d0SGilad Ben-Yossef 137742be35d0SGilad Ben-Yossef for (i = 0; i < BH_LRU_SIZE; i++) { 137842be35d0SGilad Ben-Yossef if (b->bhs[i]) 137942be35d0SGilad Ben-Yossef return 1; 138042be35d0SGilad Ben-Yossef } 138142be35d0SGilad Ben-Yossef 138242be35d0SGilad Ben-Yossef return 0; 138342be35d0SGilad Ben-Yossef } 138442be35d0SGilad Ben-Yossef 1385f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 13861da177e4SLinus Torvalds { 138742be35d0SGilad Ben-Yossef on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); 13881da177e4SLinus Torvalds } 13899db5579bSNick Piggin EXPORT_SYMBOL_GPL(invalidate_bh_lrus); 13901da177e4SLinus Torvalds 13911da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 13921da177e4SLinus Torvalds struct page *page, unsigned long offset) 13931da177e4SLinus Torvalds { 13941da177e4SLinus Torvalds bh->b_page = page; 1395e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 13961da177e4SLinus Torvalds if (PageHighMem(page)) 13971da177e4SLinus Torvalds /* 13981da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 13991da177e4SLinus Torvalds */ 14001da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14011da177e4SLinus Torvalds else 14021da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14031da177e4SLinus Torvalds } 14041da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14051da177e4SLinus Torvalds 14061da177e4SLinus Torvalds /* 14071da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14081da177e4SLinus Torvalds */ 1409e7470ee8SMel Gorman 1410e7470ee8SMel Gorman /* Bits that are cleared during an invalidate */ 1411e7470ee8SMel Gorman #define BUFFER_FLAGS_DISCARD \ 1412e7470ee8SMel Gorman (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ 1413e7470ee8SMel Gorman 1 << BH_Delay | 1 << BH_Unwritten) 1414e7470ee8SMel Gorman 1415858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14161da177e4SLinus Torvalds { 1417e7470ee8SMel Gorman unsigned long b_state, b_state_old; 1418e7470ee8SMel Gorman 14191da177e4SLinus Torvalds lock_buffer(bh); 14201da177e4SLinus Torvalds clear_buffer_dirty(bh); 14211da177e4SLinus Torvalds bh->b_bdev = NULL; 1422e7470ee8SMel Gorman b_state = bh->b_state; 1423e7470ee8SMel Gorman for (;;) { 1424e7470ee8SMel Gorman b_state_old = cmpxchg(&bh->b_state, b_state, 1425e7470ee8SMel Gorman (b_state & ~BUFFER_FLAGS_DISCARD)); 1426e7470ee8SMel Gorman if (b_state_old == b_state) 1427e7470ee8SMel Gorman break; 1428e7470ee8SMel Gorman b_state = b_state_old; 1429e7470ee8SMel Gorman } 14301da177e4SLinus Torvalds unlock_buffer(bh); 14311da177e4SLinus Torvalds } 14321da177e4SLinus Torvalds 14331da177e4SLinus Torvalds /** 1434814e1d25SWang Sheng-Hui * block_invalidatepage - invalidate part or all of a buffer-backed page 14351da177e4SLinus Torvalds * 14361da177e4SLinus Torvalds * @page: the page which is affected 1437d47992f8SLukas Czerner * @offset: start of the range to invalidate 1438d47992f8SLukas Czerner * @length: length of the range to invalidate 14391da177e4SLinus Torvalds * 14401da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 14411da177e4SLinus Torvalds * invalidated by a truncate operation. 14421da177e4SLinus Torvalds * 14431da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 14441da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 14451da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 14461da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 14471da177e4SLinus Torvalds * blocks on-disk. 14481da177e4SLinus Torvalds */ 1449d47992f8SLukas Czerner void block_invalidatepage(struct page *page, unsigned int offset, 1450d47992f8SLukas Czerner unsigned int length) 14511da177e4SLinus Torvalds { 14521da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 14531da177e4SLinus Torvalds unsigned int curr_off = 0; 1454d47992f8SLukas Czerner unsigned int stop = length + offset; 14551da177e4SLinus Torvalds 14561da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 14571da177e4SLinus Torvalds if (!page_has_buffers(page)) 14581da177e4SLinus Torvalds goto out; 14591da177e4SLinus Torvalds 1460d47992f8SLukas Czerner /* 1461d47992f8SLukas Czerner * Check for overflow 1462d47992f8SLukas Czerner */ 146309cbfeafSKirill A. Shutemov BUG_ON(stop > PAGE_SIZE || stop < length); 1464d47992f8SLukas Czerner 14651da177e4SLinus Torvalds head = page_buffers(page); 14661da177e4SLinus Torvalds bh = head; 14671da177e4SLinus Torvalds do { 14681da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 14691da177e4SLinus Torvalds next = bh->b_this_page; 14701da177e4SLinus Torvalds 14711da177e4SLinus Torvalds /* 1472d47992f8SLukas Czerner * Are we still fully in range ? 1473d47992f8SLukas Czerner */ 1474d47992f8SLukas Czerner if (next_off > stop) 1475d47992f8SLukas Czerner goto out; 1476d47992f8SLukas Czerner 1477d47992f8SLukas Czerner /* 14781da177e4SLinus Torvalds * is this block fully invalidated? 14791da177e4SLinus Torvalds */ 14801da177e4SLinus Torvalds if (offset <= curr_off) 14811da177e4SLinus Torvalds discard_buffer(bh); 14821da177e4SLinus Torvalds curr_off = next_off; 14831da177e4SLinus Torvalds bh = next; 14841da177e4SLinus Torvalds } while (bh != head); 14851da177e4SLinus Torvalds 14861da177e4SLinus Torvalds /* 14871da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 14881da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 14891da177e4SLinus Torvalds * so real IO is not possible anymore. 14901da177e4SLinus Torvalds */ 14913172485fSJeff Moyer if (length == PAGE_SIZE) 14922ff28e22SNeilBrown try_to_release_page(page, 0); 14931da177e4SLinus Torvalds out: 14942ff28e22SNeilBrown return; 14951da177e4SLinus Torvalds } 14961da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 14971da177e4SLinus Torvalds 1498d47992f8SLukas Czerner 14991da177e4SLinus Torvalds /* 15001da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15011da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15021da177e4SLinus Torvalds * is already excluded via the page lock. 15031da177e4SLinus Torvalds */ 15041da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15051da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15061da177e4SLinus Torvalds { 15071da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15081da177e4SLinus Torvalds 1509640ab98fSJens Axboe head = alloc_page_buffers(page, blocksize, true); 15101da177e4SLinus Torvalds bh = head; 15111da177e4SLinus Torvalds do { 15121da177e4SLinus Torvalds bh->b_state |= b_state; 15131da177e4SLinus Torvalds tail = bh; 15141da177e4SLinus Torvalds bh = bh->b_this_page; 15151da177e4SLinus Torvalds } while (bh); 15161da177e4SLinus Torvalds tail->b_this_page = head; 15171da177e4SLinus Torvalds 15181da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15191da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15201da177e4SLinus Torvalds bh = head; 15211da177e4SLinus Torvalds do { 15221da177e4SLinus Torvalds if (PageDirty(page)) 15231da177e4SLinus Torvalds set_buffer_dirty(bh); 15241da177e4SLinus Torvalds if (PageUptodate(page)) 15251da177e4SLinus Torvalds set_buffer_uptodate(bh); 15261da177e4SLinus Torvalds bh = bh->b_this_page; 15271da177e4SLinus Torvalds } while (bh != head); 15281da177e4SLinus Torvalds } 15291da177e4SLinus Torvalds attach_page_buffers(page, head); 15301da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 15311da177e4SLinus Torvalds } 15321da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 15331da177e4SLinus Torvalds 153429f3ad7dSJan Kara /** 153529f3ad7dSJan Kara * clean_bdev_aliases: clean a range of buffers in block device 153629f3ad7dSJan Kara * @bdev: Block device to clean buffers in 153729f3ad7dSJan Kara * @block: Start of a range of blocks to clean 153829f3ad7dSJan Kara * @len: Number of blocks to clean 15391da177e4SLinus Torvalds * 154029f3ad7dSJan Kara * We are taking a range of blocks for data and we don't want writeback of any 154129f3ad7dSJan Kara * buffer-cache aliases starting from return from this function and until the 154229f3ad7dSJan Kara * moment when something will explicitly mark the buffer dirty (hopefully that 154329f3ad7dSJan Kara * will not happen until we will free that block ;-) We don't even need to mark 154429f3ad7dSJan Kara * it not-uptodate - nobody can expect anything from a newly allocated buffer 154529f3ad7dSJan Kara * anyway. We used to use unmap_buffer() for such invalidation, but that was 154629f3ad7dSJan Kara * wrong. We definitely don't want to mark the alias unmapped, for example - it 154729f3ad7dSJan Kara * would confuse anyone who might pick it with bread() afterwards... 154829f3ad7dSJan Kara * 154929f3ad7dSJan Kara * Also.. Note that bforget() doesn't lock the buffer. So there can be 155029f3ad7dSJan Kara * writeout I/O going on against recently-freed buffers. We don't wait on that 155129f3ad7dSJan Kara * I/O in bforget() - it's more efficient to wait on the I/O only if we really 155229f3ad7dSJan Kara * need to. That happens here. 15531da177e4SLinus Torvalds */ 155429f3ad7dSJan Kara void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) 15551da177e4SLinus Torvalds { 155629f3ad7dSJan Kara struct inode *bd_inode = bdev->bd_inode; 155729f3ad7dSJan Kara struct address_space *bd_mapping = bd_inode->i_mapping; 155829f3ad7dSJan Kara struct pagevec pvec; 155929f3ad7dSJan Kara pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); 156029f3ad7dSJan Kara pgoff_t end; 1561c10f778dSJan Kara int i, count; 156229f3ad7dSJan Kara struct buffer_head *bh; 156329f3ad7dSJan Kara struct buffer_head *head; 15641da177e4SLinus Torvalds 156529f3ad7dSJan Kara end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); 156686679820SMel Gorman pagevec_init(&pvec); 1567397162ffSJan Kara while (pagevec_lookup_range(&pvec, bd_mapping, &index, end)) { 1568c10f778dSJan Kara count = pagevec_count(&pvec); 1569c10f778dSJan Kara for (i = 0; i < count; i++) { 157029f3ad7dSJan Kara struct page *page = pvec.pages[i]; 15711da177e4SLinus Torvalds 157229f3ad7dSJan Kara if (!page_has_buffers(page)) 157329f3ad7dSJan Kara continue; 157429f3ad7dSJan Kara /* 157529f3ad7dSJan Kara * We use page lock instead of bd_mapping->private_lock 157629f3ad7dSJan Kara * to pin buffers here since we can afford to sleep and 157729f3ad7dSJan Kara * it scales better than a global spinlock lock. 157829f3ad7dSJan Kara */ 157929f3ad7dSJan Kara lock_page(page); 158029f3ad7dSJan Kara /* Recheck when the page is locked which pins bhs */ 158129f3ad7dSJan Kara if (!page_has_buffers(page)) 158229f3ad7dSJan Kara goto unlock_page; 158329f3ad7dSJan Kara head = page_buffers(page); 158429f3ad7dSJan Kara bh = head; 158529f3ad7dSJan Kara do { 15866c006a9dSChandan Rajendra if (!buffer_mapped(bh) || (bh->b_blocknr < block)) 158729f3ad7dSJan Kara goto next; 158829f3ad7dSJan Kara if (bh->b_blocknr >= block + len) 158929f3ad7dSJan Kara break; 159029f3ad7dSJan Kara clear_buffer_dirty(bh); 159129f3ad7dSJan Kara wait_on_buffer(bh); 159229f3ad7dSJan Kara clear_buffer_req(bh); 159329f3ad7dSJan Kara next: 159429f3ad7dSJan Kara bh = bh->b_this_page; 159529f3ad7dSJan Kara } while (bh != head); 159629f3ad7dSJan Kara unlock_page: 159729f3ad7dSJan Kara unlock_page(page); 159829f3ad7dSJan Kara } 159929f3ad7dSJan Kara pagevec_release(&pvec); 160029f3ad7dSJan Kara cond_resched(); 1601c10f778dSJan Kara /* End of range already reached? */ 1602c10f778dSJan Kara if (index > end || !index) 1603c10f778dSJan Kara break; 16041da177e4SLinus Torvalds } 16051da177e4SLinus Torvalds } 160629f3ad7dSJan Kara EXPORT_SYMBOL(clean_bdev_aliases); 16071da177e4SLinus Torvalds 16081da177e4SLinus Torvalds /* 160945bce8f3SLinus Torvalds * Size is a power-of-two in the range 512..PAGE_SIZE, 161045bce8f3SLinus Torvalds * and the case we care about most is PAGE_SIZE. 161145bce8f3SLinus Torvalds * 161245bce8f3SLinus Torvalds * So this *could* possibly be written with those 161345bce8f3SLinus Torvalds * constraints in mind (relevant mostly if some 161445bce8f3SLinus Torvalds * architecture has a slow bit-scan instruction) 161545bce8f3SLinus Torvalds */ 161645bce8f3SLinus Torvalds static inline int block_size_bits(unsigned int blocksize) 161745bce8f3SLinus Torvalds { 161845bce8f3SLinus Torvalds return ilog2(blocksize); 161945bce8f3SLinus Torvalds } 162045bce8f3SLinus Torvalds 162145bce8f3SLinus Torvalds static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) 162245bce8f3SLinus Torvalds { 162345bce8f3SLinus Torvalds BUG_ON(!PageLocked(page)); 162445bce8f3SLinus Torvalds 162545bce8f3SLinus Torvalds if (!page_has_buffers(page)) 16266aa7de05SMark Rutland create_empty_buffers(page, 1 << READ_ONCE(inode->i_blkbits), 16276aa7de05SMark Rutland b_state); 162845bce8f3SLinus Torvalds return page_buffers(page); 162945bce8f3SLinus Torvalds } 163045bce8f3SLinus Torvalds 163145bce8f3SLinus Torvalds /* 16321da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 16331da177e4SLinus Torvalds * 16341da177e4SLinus Torvalds * Mapped Uptodate Meaning 16351da177e4SLinus Torvalds * 16361da177e4SLinus Torvalds * No No "unknown" - must do get_block() 16371da177e4SLinus Torvalds * No Yes "hole" - zero-filled 16381da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 16391da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 16401da177e4SLinus Torvalds * 16411da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16421da177e4SLinus Torvalds */ 16431da177e4SLinus Torvalds 16441da177e4SLinus Torvalds /* 16451da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16461da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16471da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16481da177e4SLinus Torvalds * state inside lock_buffer(). 16491da177e4SLinus Torvalds * 16501da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16511da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16521da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16531da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16541da177e4SLinus Torvalds * prevents this contention from occurring. 16556e34eeddSTheodore Ts'o * 16566e34eeddSTheodore Ts'o * If block_write_full_page() is called with wbc->sync_mode == 165770fd7614SChristoph Hellwig * WB_SYNC_ALL, the writes are posted using REQ_SYNC; this 1658721a9602SJens Axboe * causes the writes to be flagged as synchronous writes. 16591da177e4SLinus Torvalds */ 1660b4bba389SBenjamin Marzinski int __block_write_full_page(struct inode *inode, struct page *page, 166135c80d5fSChris Mason get_block_t *get_block, struct writeback_control *wbc, 166235c80d5fSChris Mason bh_end_io_t *handler) 16631da177e4SLinus Torvalds { 16641da177e4SLinus Torvalds int err; 16651da177e4SLinus Torvalds sector_t block; 16661da177e4SLinus Torvalds sector_t last_block; 1667f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 166845bce8f3SLinus Torvalds unsigned int blocksize, bbits; 16691da177e4SLinus Torvalds int nr_underway = 0; 16707637241eSJens Axboe int write_flags = wbc_to_write_flags(wbc); 16711da177e4SLinus Torvalds 167245bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 16731da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 16741da177e4SLinus Torvalds 16751da177e4SLinus Torvalds /* 16761da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 16771da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 16781da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 16791da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 16801da177e4SLinus Torvalds * 16811da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 16821da177e4SLinus Torvalds * handle that here by just cleaning them. 16831da177e4SLinus Torvalds */ 16841da177e4SLinus Torvalds 16851da177e4SLinus Torvalds bh = head; 168645bce8f3SLinus Torvalds blocksize = bh->b_size; 168745bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 168845bce8f3SLinus Torvalds 168909cbfeafSKirill A. Shutemov block = (sector_t)page->index << (PAGE_SHIFT - bbits); 169045bce8f3SLinus Torvalds last_block = (i_size_read(inode) - 1) >> bbits; 16911da177e4SLinus Torvalds 16921da177e4SLinus Torvalds /* 16931da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 16941da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 16951da177e4SLinus Torvalds */ 16961da177e4SLinus Torvalds do { 16971da177e4SLinus Torvalds if (block > last_block) { 16981da177e4SLinus Torvalds /* 16991da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 17001da177e4SLinus Torvalds * this page can be outside i_size when there is a 17011da177e4SLinus Torvalds * truncate in progress. 17021da177e4SLinus Torvalds */ 17031da177e4SLinus Torvalds /* 17041da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 17051da177e4SLinus Torvalds */ 17061da177e4SLinus Torvalds clear_buffer_dirty(bh); 17071da177e4SLinus Torvalds set_buffer_uptodate(bh); 170829a814d2SAlex Tomas } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && 170929a814d2SAlex Tomas buffer_dirty(bh)) { 1710b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 17111da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 17121da177e4SLinus Torvalds if (err) 17131da177e4SLinus Torvalds goto recover; 171429a814d2SAlex Tomas clear_buffer_delay(bh); 17151da177e4SLinus Torvalds if (buffer_new(bh)) { 17161da177e4SLinus Torvalds /* blockdev mappings never come here */ 17171da177e4SLinus Torvalds clear_buffer_new(bh); 1718e64855c6SJan Kara clean_bdev_bh_alias(bh); 17191da177e4SLinus Torvalds } 17201da177e4SLinus Torvalds } 17211da177e4SLinus Torvalds bh = bh->b_this_page; 17221da177e4SLinus Torvalds block++; 17231da177e4SLinus Torvalds } while (bh != head); 17241da177e4SLinus Torvalds 17251da177e4SLinus Torvalds do { 17261da177e4SLinus Torvalds if (!buffer_mapped(bh)) 17271da177e4SLinus Torvalds continue; 17281da177e4SLinus Torvalds /* 17291da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17301da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17315b0830cbSJens Axboe * potentially cause a busy-wait loop from writeback threads 17325b0830cbSJens Axboe * and kswapd activity, but those code paths have their own 17335b0830cbSJens Axboe * higher-level throttling. 17341da177e4SLinus Torvalds */ 17351b430beeSWu Fengguang if (wbc->sync_mode != WB_SYNC_NONE) { 17361da177e4SLinus Torvalds lock_buffer(bh); 1737ca5de404SNick Piggin } else if (!trylock_buffer(bh)) { 17381da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 17391da177e4SLinus Torvalds continue; 17401da177e4SLinus Torvalds } 17411da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 174235c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17431da177e4SLinus Torvalds } else { 17441da177e4SLinus Torvalds unlock_buffer(bh); 17451da177e4SLinus Torvalds } 17461da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17471da177e4SLinus Torvalds 17481da177e4SLinus Torvalds /* 17491da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17501da177e4SLinus Torvalds * drop the bh refcounts early. 17511da177e4SLinus Torvalds */ 17521da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17531da177e4SLinus Torvalds set_page_writeback(page); 17541da177e4SLinus Torvalds 17551da177e4SLinus Torvalds do { 17561da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17571da177e4SLinus Torvalds if (buffer_async_write(bh)) { 17588e8f9298SJens Axboe submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, 17598e8f9298SJens Axboe inode->i_write_hint, wbc); 17601da177e4SLinus Torvalds nr_underway++; 1761ad576e63SNick Piggin } 17621da177e4SLinus Torvalds bh = next; 17631da177e4SLinus Torvalds } while (bh != head); 176405937baaSAndrew Morton unlock_page(page); 17651da177e4SLinus Torvalds 17661da177e4SLinus Torvalds err = 0; 17671da177e4SLinus Torvalds done: 17681da177e4SLinus Torvalds if (nr_underway == 0) { 17691da177e4SLinus Torvalds /* 17701da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 17711da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 17721da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 17731da177e4SLinus Torvalds */ 17741da177e4SLinus Torvalds end_page_writeback(page); 17753d67f2d7SNick Piggin 17761da177e4SLinus Torvalds /* 17771da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 17781da177e4SLinus Torvalds * here on. 17791da177e4SLinus Torvalds */ 17801da177e4SLinus Torvalds } 17811da177e4SLinus Torvalds return err; 17821da177e4SLinus Torvalds 17831da177e4SLinus Torvalds recover: 17841da177e4SLinus Torvalds /* 17851da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 17861da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 17871da177e4SLinus Torvalds * exposing stale data. 17881da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 17891da177e4SLinus Torvalds */ 17901da177e4SLinus Torvalds bh = head; 17911da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 17921da177e4SLinus Torvalds do { 179329a814d2SAlex Tomas if (buffer_mapped(bh) && buffer_dirty(bh) && 179429a814d2SAlex Tomas !buffer_delay(bh)) { 17951da177e4SLinus Torvalds lock_buffer(bh); 179635c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17971da177e4SLinus Torvalds } else { 17981da177e4SLinus Torvalds /* 17991da177e4SLinus Torvalds * The buffer may have been set dirty during 18001da177e4SLinus Torvalds * attachment to a dirty page. 18011da177e4SLinus Torvalds */ 18021da177e4SLinus Torvalds clear_buffer_dirty(bh); 18031da177e4SLinus Torvalds } 18041da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 18051da177e4SLinus Torvalds SetPageError(page); 18061da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 18077e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 18081da177e4SLinus Torvalds set_page_writeback(page); 18091da177e4SLinus Torvalds do { 18101da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18111da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18121da177e4SLinus Torvalds clear_buffer_dirty(bh); 18138e8f9298SJens Axboe submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, 18148e8f9298SJens Axboe inode->i_write_hint, wbc); 18151da177e4SLinus Torvalds nr_underway++; 1816ad576e63SNick Piggin } 18171da177e4SLinus Torvalds bh = next; 18181da177e4SLinus Torvalds } while (bh != head); 1819ffda9d30SNick Piggin unlock_page(page); 18201da177e4SLinus Torvalds goto done; 18211da177e4SLinus Torvalds } 1822b4bba389SBenjamin Marzinski EXPORT_SYMBOL(__block_write_full_page); 18231da177e4SLinus Torvalds 1824afddba49SNick Piggin /* 1825afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1826afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1827afddba49SNick Piggin * block data from leaking). And clear the new bit. 1828afddba49SNick Piggin */ 1829afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1830afddba49SNick Piggin { 1831afddba49SNick Piggin unsigned int block_start, block_end; 1832afddba49SNick Piggin struct buffer_head *head, *bh; 1833afddba49SNick Piggin 1834afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1835afddba49SNick Piggin if (!page_has_buffers(page)) 1836afddba49SNick Piggin return; 1837afddba49SNick Piggin 1838afddba49SNick Piggin bh = head = page_buffers(page); 1839afddba49SNick Piggin block_start = 0; 1840afddba49SNick Piggin do { 1841afddba49SNick Piggin block_end = block_start + bh->b_size; 1842afddba49SNick Piggin 1843afddba49SNick Piggin if (buffer_new(bh)) { 1844afddba49SNick Piggin if (block_end > from && block_start < to) { 1845afddba49SNick Piggin if (!PageUptodate(page)) { 1846afddba49SNick Piggin unsigned start, size; 1847afddba49SNick Piggin 1848afddba49SNick Piggin start = max(from, block_start); 1849afddba49SNick Piggin size = min(to, block_end) - start; 1850afddba49SNick Piggin 1851eebd2aa3SChristoph Lameter zero_user(page, start, size); 1852afddba49SNick Piggin set_buffer_uptodate(bh); 1853afddba49SNick Piggin } 1854afddba49SNick Piggin 1855afddba49SNick Piggin clear_buffer_new(bh); 1856afddba49SNick Piggin mark_buffer_dirty(bh); 1857afddba49SNick Piggin } 1858afddba49SNick Piggin } 1859afddba49SNick Piggin 1860afddba49SNick Piggin block_start = block_end; 1861afddba49SNick Piggin bh = bh->b_this_page; 1862afddba49SNick Piggin } while (bh != head); 1863afddba49SNick Piggin } 1864afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1865afddba49SNick Piggin 1866ae259a9cSChristoph Hellwig static void 1867ae259a9cSChristoph Hellwig iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, 1868ae259a9cSChristoph Hellwig struct iomap *iomap) 1869ae259a9cSChristoph Hellwig { 1870ae259a9cSChristoph Hellwig loff_t offset = block << inode->i_blkbits; 1871ae259a9cSChristoph Hellwig 1872ae259a9cSChristoph Hellwig bh->b_bdev = iomap->bdev; 1873ae259a9cSChristoph Hellwig 1874ae259a9cSChristoph Hellwig /* 1875ae259a9cSChristoph Hellwig * Block points to offset in file we need to map, iomap contains 1876ae259a9cSChristoph Hellwig * the offset at which the map starts. If the map ends before the 1877ae259a9cSChristoph Hellwig * current block, then do not map the buffer and let the caller 1878ae259a9cSChristoph Hellwig * handle it. 1879ae259a9cSChristoph Hellwig */ 1880ae259a9cSChristoph Hellwig BUG_ON(offset >= iomap->offset + iomap->length); 1881ae259a9cSChristoph Hellwig 1882ae259a9cSChristoph Hellwig switch (iomap->type) { 1883ae259a9cSChristoph Hellwig case IOMAP_HOLE: 1884ae259a9cSChristoph Hellwig /* 1885ae259a9cSChristoph Hellwig * If the buffer is not up to date or beyond the current EOF, 1886ae259a9cSChristoph Hellwig * we need to mark it as new to ensure sub-block zeroing is 1887ae259a9cSChristoph Hellwig * executed if necessary. 1888ae259a9cSChristoph Hellwig */ 1889ae259a9cSChristoph Hellwig if (!buffer_uptodate(bh) || 1890ae259a9cSChristoph Hellwig (offset >= i_size_read(inode))) 1891ae259a9cSChristoph Hellwig set_buffer_new(bh); 1892ae259a9cSChristoph Hellwig break; 1893ae259a9cSChristoph Hellwig case IOMAP_DELALLOC: 1894ae259a9cSChristoph Hellwig if (!buffer_uptodate(bh) || 1895ae259a9cSChristoph Hellwig (offset >= i_size_read(inode))) 1896ae259a9cSChristoph Hellwig set_buffer_new(bh); 1897ae259a9cSChristoph Hellwig set_buffer_uptodate(bh); 1898ae259a9cSChristoph Hellwig set_buffer_mapped(bh); 1899ae259a9cSChristoph Hellwig set_buffer_delay(bh); 1900ae259a9cSChristoph Hellwig break; 1901ae259a9cSChristoph Hellwig case IOMAP_UNWRITTEN: 1902ae259a9cSChristoph Hellwig /* 1903ae259a9cSChristoph Hellwig * For unwritten regions, we always need to ensure that 1904ae259a9cSChristoph Hellwig * sub-block writes cause the regions in the block we are not 1905ae259a9cSChristoph Hellwig * writing to are zeroed. Set the buffer as new to ensure this. 1906ae259a9cSChristoph Hellwig */ 1907ae259a9cSChristoph Hellwig set_buffer_new(bh); 1908ae259a9cSChristoph Hellwig set_buffer_unwritten(bh); 1909ae259a9cSChristoph Hellwig /* FALLTHRU */ 1910ae259a9cSChristoph Hellwig case IOMAP_MAPPED: 1911ae259a9cSChristoph Hellwig if (offset >= i_size_read(inode)) 1912ae259a9cSChristoph Hellwig set_buffer_new(bh); 191319fe5f64SAndreas Gruenbacher bh->b_blocknr = (iomap->addr + offset - iomap->offset) >> 191419fe5f64SAndreas Gruenbacher inode->i_blkbits; 1915ae259a9cSChristoph Hellwig set_buffer_mapped(bh); 1916ae259a9cSChristoph Hellwig break; 1917ae259a9cSChristoph Hellwig } 1918ae259a9cSChristoph Hellwig } 1919ae259a9cSChristoph Hellwig 1920ae259a9cSChristoph Hellwig int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, 1921ae259a9cSChristoph Hellwig get_block_t *get_block, struct iomap *iomap) 19221da177e4SLinus Torvalds { 192309cbfeafSKirill A. Shutemov unsigned from = pos & (PAGE_SIZE - 1); 1924ebdec241SChristoph Hellwig unsigned to = from + len; 19256e1db88dSChristoph Hellwig struct inode *inode = page->mapping->host; 19261da177e4SLinus Torvalds unsigned block_start, block_end; 19271da177e4SLinus Torvalds sector_t block; 19281da177e4SLinus Torvalds int err = 0; 19291da177e4SLinus Torvalds unsigned blocksize, bbits; 19301da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 19311da177e4SLinus Torvalds 19321da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 193309cbfeafSKirill A. Shutemov BUG_ON(from > PAGE_SIZE); 193409cbfeafSKirill A. Shutemov BUG_ON(to > PAGE_SIZE); 19351da177e4SLinus Torvalds BUG_ON(from > to); 19361da177e4SLinus Torvalds 193745bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 193845bce8f3SLinus Torvalds blocksize = head->b_size; 193945bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 19401da177e4SLinus Torvalds 194109cbfeafSKirill A. Shutemov block = (sector_t)page->index << (PAGE_SHIFT - bbits); 19421da177e4SLinus Torvalds 19431da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 19441da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 19451da177e4SLinus Torvalds block_end = block_start + blocksize; 19461da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19471da177e4SLinus Torvalds if (PageUptodate(page)) { 19481da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19491da177e4SLinus Torvalds set_buffer_uptodate(bh); 19501da177e4SLinus Torvalds } 19511da177e4SLinus Torvalds continue; 19521da177e4SLinus Torvalds } 19531da177e4SLinus Torvalds if (buffer_new(bh)) 19541da177e4SLinus Torvalds clear_buffer_new(bh); 19551da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1956b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 1957ae259a9cSChristoph Hellwig if (get_block) { 19581da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 19591da177e4SLinus Torvalds if (err) 1960f3ddbdc6SNick Piggin break; 1961ae259a9cSChristoph Hellwig } else { 1962ae259a9cSChristoph Hellwig iomap_to_bh(inode, block, bh, iomap); 1963ae259a9cSChristoph Hellwig } 1964ae259a9cSChristoph Hellwig 19651da177e4SLinus Torvalds if (buffer_new(bh)) { 1966e64855c6SJan Kara clean_bdev_bh_alias(bh); 19671da177e4SLinus Torvalds if (PageUptodate(page)) { 1968637aff46SNick Piggin clear_buffer_new(bh); 19691da177e4SLinus Torvalds set_buffer_uptodate(bh); 1970637aff46SNick Piggin mark_buffer_dirty(bh); 19711da177e4SLinus Torvalds continue; 19721da177e4SLinus Torvalds } 1973eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 1974eebd2aa3SChristoph Lameter zero_user_segments(page, 1975eebd2aa3SChristoph Lameter to, block_end, 1976eebd2aa3SChristoph Lameter block_start, from); 19771da177e4SLinus Torvalds continue; 19781da177e4SLinus Torvalds } 19791da177e4SLinus Torvalds } 19801da177e4SLinus Torvalds if (PageUptodate(page)) { 19811da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19821da177e4SLinus Torvalds set_buffer_uptodate(bh); 19831da177e4SLinus Torvalds continue; 19841da177e4SLinus Torvalds } 19851da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 198633a266ddSDavid Chinner !buffer_unwritten(bh) && 19871da177e4SLinus Torvalds (block_start < from || block_end > to)) { 1988dfec8a14SMike Christie ll_rw_block(REQ_OP_READ, 0, 1, &bh); 19891da177e4SLinus Torvalds *wait_bh++=bh; 19901da177e4SLinus Torvalds } 19911da177e4SLinus Torvalds } 19921da177e4SLinus Torvalds /* 19931da177e4SLinus Torvalds * If we issued read requests - let them complete. 19941da177e4SLinus Torvalds */ 19951da177e4SLinus Torvalds while(wait_bh > wait) { 19961da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 19971da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1998f3ddbdc6SNick Piggin err = -EIO; 19991da177e4SLinus Torvalds } 2000f9f07b6cSJan Kara if (unlikely(err)) 2001afddba49SNick Piggin page_zero_new_buffers(page, from, to); 20021da177e4SLinus Torvalds return err; 20031da177e4SLinus Torvalds } 2004ae259a9cSChristoph Hellwig 2005ae259a9cSChristoph Hellwig int __block_write_begin(struct page *page, loff_t pos, unsigned len, 2006ae259a9cSChristoph Hellwig get_block_t *get_block) 2007ae259a9cSChristoph Hellwig { 2008ae259a9cSChristoph Hellwig return __block_write_begin_int(page, pos, len, get_block, NULL); 2009ae259a9cSChristoph Hellwig } 2010ebdec241SChristoph Hellwig EXPORT_SYMBOL(__block_write_begin); 20111da177e4SLinus Torvalds 20121da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 20131da177e4SLinus Torvalds unsigned from, unsigned to) 20141da177e4SLinus Torvalds { 20151da177e4SLinus Torvalds unsigned block_start, block_end; 20161da177e4SLinus Torvalds int partial = 0; 20171da177e4SLinus Torvalds unsigned blocksize; 20181da177e4SLinus Torvalds struct buffer_head *bh, *head; 20191da177e4SLinus Torvalds 202045bce8f3SLinus Torvalds bh = head = page_buffers(page); 202145bce8f3SLinus Torvalds blocksize = bh->b_size; 20221da177e4SLinus Torvalds 202345bce8f3SLinus Torvalds block_start = 0; 202445bce8f3SLinus Torvalds do { 20251da177e4SLinus Torvalds block_end = block_start + blocksize; 20261da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 20271da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 20281da177e4SLinus Torvalds partial = 1; 20291da177e4SLinus Torvalds } else { 20301da177e4SLinus Torvalds set_buffer_uptodate(bh); 20311da177e4SLinus Torvalds mark_buffer_dirty(bh); 20321da177e4SLinus Torvalds } 2033afddba49SNick Piggin clear_buffer_new(bh); 203445bce8f3SLinus Torvalds 203545bce8f3SLinus Torvalds block_start = block_end; 203645bce8f3SLinus Torvalds bh = bh->b_this_page; 203745bce8f3SLinus Torvalds } while (bh != head); 20381da177e4SLinus Torvalds 20391da177e4SLinus Torvalds /* 20401da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 20411da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 20421da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 20431da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 20441da177e4SLinus Torvalds */ 20451da177e4SLinus Torvalds if (!partial) 20461da177e4SLinus Torvalds SetPageUptodate(page); 20471da177e4SLinus Torvalds return 0; 20481da177e4SLinus Torvalds } 20491da177e4SLinus Torvalds 20501da177e4SLinus Torvalds /* 2051155130a4SChristoph Hellwig * block_write_begin takes care of the basic task of block allocation and 2052155130a4SChristoph Hellwig * bringing partial write blocks uptodate first. 2053155130a4SChristoph Hellwig * 20547bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 2055afddba49SNick Piggin */ 2056155130a4SChristoph Hellwig int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 2057155130a4SChristoph Hellwig unsigned flags, struct page **pagep, get_block_t *get_block) 2058afddba49SNick Piggin { 205909cbfeafSKirill A. Shutemov pgoff_t index = pos >> PAGE_SHIFT; 2060afddba49SNick Piggin struct page *page; 20616e1db88dSChristoph Hellwig int status; 2062afddba49SNick Piggin 206354566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 20646e1db88dSChristoph Hellwig if (!page) 20656e1db88dSChristoph Hellwig return -ENOMEM; 2066afddba49SNick Piggin 20676e1db88dSChristoph Hellwig status = __block_write_begin(page, pos, len, get_block); 2068afddba49SNick Piggin if (unlikely(status)) { 2069afddba49SNick Piggin unlock_page(page); 207009cbfeafSKirill A. Shutemov put_page(page); 20716e1db88dSChristoph Hellwig page = NULL; 2072afddba49SNick Piggin } 2073afddba49SNick Piggin 20746e1db88dSChristoph Hellwig *pagep = page; 2075afddba49SNick Piggin return status; 2076afddba49SNick Piggin } 2077afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2078afddba49SNick Piggin 2079*a6d639daSChristoph Hellwig int __generic_write_end(struct inode *inode, loff_t pos, unsigned copied, 2080*a6d639daSChristoph Hellwig struct page *page) 2081*a6d639daSChristoph Hellwig { 2082*a6d639daSChristoph Hellwig loff_t old_size = inode->i_size; 2083*a6d639daSChristoph Hellwig bool i_size_changed = false; 2084*a6d639daSChristoph Hellwig 2085*a6d639daSChristoph Hellwig /* 2086*a6d639daSChristoph Hellwig * No need to use i_size_read() here, the i_size cannot change under us 2087*a6d639daSChristoph Hellwig * because we hold i_rwsem. 2088*a6d639daSChristoph Hellwig * 2089*a6d639daSChristoph Hellwig * But it's important to update i_size while still holding page lock: 2090*a6d639daSChristoph Hellwig * page writeout could otherwise come in and zero beyond i_size. 2091*a6d639daSChristoph Hellwig */ 2092*a6d639daSChristoph Hellwig if (pos + copied > inode->i_size) { 2093*a6d639daSChristoph Hellwig i_size_write(inode, pos + copied); 2094*a6d639daSChristoph Hellwig i_size_changed = true; 2095*a6d639daSChristoph Hellwig } 2096*a6d639daSChristoph Hellwig 2097*a6d639daSChristoph Hellwig unlock_page(page); 2098*a6d639daSChristoph Hellwig put_page(page); 2099*a6d639daSChristoph Hellwig 2100*a6d639daSChristoph Hellwig if (old_size < pos) 2101*a6d639daSChristoph Hellwig pagecache_isize_extended(inode, old_size, pos); 2102*a6d639daSChristoph Hellwig /* 2103*a6d639daSChristoph Hellwig * Don't mark the inode dirty under page lock. First, it unnecessarily 2104*a6d639daSChristoph Hellwig * makes the holding time of page lock longer. Second, it forces lock 2105*a6d639daSChristoph Hellwig * ordering of page lock and transaction start for journaling 2106*a6d639daSChristoph Hellwig * filesystems. 2107*a6d639daSChristoph Hellwig */ 2108*a6d639daSChristoph Hellwig if (i_size_changed) 2109*a6d639daSChristoph Hellwig mark_inode_dirty(inode); 2110*a6d639daSChristoph Hellwig return copied; 2111*a6d639daSChristoph Hellwig } 2112*a6d639daSChristoph Hellwig 2113afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2114afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2115afddba49SNick Piggin struct page *page, void *fsdata) 2116afddba49SNick Piggin { 2117afddba49SNick Piggin struct inode *inode = mapping->host; 2118afddba49SNick Piggin unsigned start; 2119afddba49SNick Piggin 212009cbfeafSKirill A. Shutemov start = pos & (PAGE_SIZE - 1); 2121afddba49SNick Piggin 2122afddba49SNick Piggin if (unlikely(copied < len)) { 2123afddba49SNick Piggin /* 2124afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2125afddba49SNick Piggin * don't have to worry about a readpage reading them and 2126afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2127afddba49SNick Piggin * a short write and only partially written into a buffer, it 2128afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2129afddba49SNick Piggin * destroy our partial write. 2130afddba49SNick Piggin * 2131afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2132afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2133afddba49SNick Piggin * caller to redo the whole thing. 2134afddba49SNick Piggin */ 2135afddba49SNick Piggin if (!PageUptodate(page)) 2136afddba49SNick Piggin copied = 0; 2137afddba49SNick Piggin 2138afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2139afddba49SNick Piggin } 2140afddba49SNick Piggin flush_dcache_page(page); 2141afddba49SNick Piggin 2142afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2143afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2144afddba49SNick Piggin 2145afddba49SNick Piggin return copied; 2146afddba49SNick Piggin } 2147afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2148afddba49SNick Piggin 2149afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2150afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2151afddba49SNick Piggin struct page *page, void *fsdata) 2152afddba49SNick Piggin { 2153afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2154*a6d639daSChristoph Hellwig return __generic_write_end(mapping->host, pos, copied, page); 2155afddba49SNick Piggin } 2156afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2157afddba49SNick Piggin 2158afddba49SNick Piggin /* 21598ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 21608ab22b9aSHisashi Hifumi * uptodate or not. 21618ab22b9aSHisashi Hifumi * 21628ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 21638ab22b9aSHisashi Hifumi * we want to read are uptodate. 21648ab22b9aSHisashi Hifumi */ 2165c186afb4SAl Viro int block_is_partially_uptodate(struct page *page, unsigned long from, 2166c186afb4SAl Viro unsigned long count) 21678ab22b9aSHisashi Hifumi { 21688ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 21698ab22b9aSHisashi Hifumi unsigned to; 21708ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 21718ab22b9aSHisashi Hifumi int ret = 1; 21728ab22b9aSHisashi Hifumi 21738ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 21748ab22b9aSHisashi Hifumi return 0; 21758ab22b9aSHisashi Hifumi 217645bce8f3SLinus Torvalds head = page_buffers(page); 217745bce8f3SLinus Torvalds blocksize = head->b_size; 217809cbfeafSKirill A. Shutemov to = min_t(unsigned, PAGE_SIZE - from, count); 21798ab22b9aSHisashi Hifumi to = from + to; 218009cbfeafSKirill A. Shutemov if (from < blocksize && to > PAGE_SIZE - blocksize) 21818ab22b9aSHisashi Hifumi return 0; 21828ab22b9aSHisashi Hifumi 21838ab22b9aSHisashi Hifumi bh = head; 21848ab22b9aSHisashi Hifumi block_start = 0; 21858ab22b9aSHisashi Hifumi do { 21868ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 21878ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 21888ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 21898ab22b9aSHisashi Hifumi ret = 0; 21908ab22b9aSHisashi Hifumi break; 21918ab22b9aSHisashi Hifumi } 21928ab22b9aSHisashi Hifumi if (block_end >= to) 21938ab22b9aSHisashi Hifumi break; 21948ab22b9aSHisashi Hifumi } 21958ab22b9aSHisashi Hifumi block_start = block_end; 21968ab22b9aSHisashi Hifumi bh = bh->b_this_page; 21978ab22b9aSHisashi Hifumi } while (bh != head); 21988ab22b9aSHisashi Hifumi 21998ab22b9aSHisashi Hifumi return ret; 22008ab22b9aSHisashi Hifumi } 22018ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 22028ab22b9aSHisashi Hifumi 22038ab22b9aSHisashi Hifumi /* 22041da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 22051da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 22061da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 22071da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 22081da177e4SLinus Torvalds * page struct once IO has completed. 22091da177e4SLinus Torvalds */ 22101da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 22111da177e4SLinus Torvalds { 22121da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22131da177e4SLinus Torvalds sector_t iblock, lblock; 22141da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 221545bce8f3SLinus Torvalds unsigned int blocksize, bbits; 22161da177e4SLinus Torvalds int nr, i; 22171da177e4SLinus Torvalds int fully_mapped = 1; 22181da177e4SLinus Torvalds 221945bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 222045bce8f3SLinus Torvalds blocksize = head->b_size; 222145bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 22221da177e4SLinus Torvalds 222309cbfeafSKirill A. Shutemov iblock = (sector_t)page->index << (PAGE_SHIFT - bbits); 222445bce8f3SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> bbits; 22251da177e4SLinus Torvalds bh = head; 22261da177e4SLinus Torvalds nr = 0; 22271da177e4SLinus Torvalds i = 0; 22281da177e4SLinus Torvalds 22291da177e4SLinus Torvalds do { 22301da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22311da177e4SLinus Torvalds continue; 22321da177e4SLinus Torvalds 22331da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2234c64610baSAndrew Morton int err = 0; 2235c64610baSAndrew Morton 22361da177e4SLinus Torvalds fully_mapped = 0; 22371da177e4SLinus Torvalds if (iblock < lblock) { 2238b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2239c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2240c64610baSAndrew Morton if (err) 22411da177e4SLinus Torvalds SetPageError(page); 22421da177e4SLinus Torvalds } 22431da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2244eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2245c64610baSAndrew Morton if (!err) 22461da177e4SLinus Torvalds set_buffer_uptodate(bh); 22471da177e4SLinus Torvalds continue; 22481da177e4SLinus Torvalds } 22491da177e4SLinus Torvalds /* 22501da177e4SLinus Torvalds * get_block() might have updated the buffer 22511da177e4SLinus Torvalds * synchronously 22521da177e4SLinus Torvalds */ 22531da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22541da177e4SLinus Torvalds continue; 22551da177e4SLinus Torvalds } 22561da177e4SLinus Torvalds arr[nr++] = bh; 22571da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 22581da177e4SLinus Torvalds 22591da177e4SLinus Torvalds if (fully_mapped) 22601da177e4SLinus Torvalds SetPageMappedToDisk(page); 22611da177e4SLinus Torvalds 22621da177e4SLinus Torvalds if (!nr) { 22631da177e4SLinus Torvalds /* 22641da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 22651da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 22661da177e4SLinus Torvalds */ 22671da177e4SLinus Torvalds if (!PageError(page)) 22681da177e4SLinus Torvalds SetPageUptodate(page); 22691da177e4SLinus Torvalds unlock_page(page); 22701da177e4SLinus Torvalds return 0; 22711da177e4SLinus Torvalds } 22721da177e4SLinus Torvalds 22731da177e4SLinus Torvalds /* Stage two: lock the buffers */ 22741da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22751da177e4SLinus Torvalds bh = arr[i]; 22761da177e4SLinus Torvalds lock_buffer(bh); 22771da177e4SLinus Torvalds mark_buffer_async_read(bh); 22781da177e4SLinus Torvalds } 22791da177e4SLinus Torvalds 22801da177e4SLinus Torvalds /* 22811da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 22821da177e4SLinus Torvalds * inside the buffer lock in case another process reading 22831da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 22841da177e4SLinus Torvalds */ 22851da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22861da177e4SLinus Torvalds bh = arr[i]; 22871da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22881da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 22891da177e4SLinus Torvalds else 22902a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 22911da177e4SLinus Torvalds } 22921da177e4SLinus Torvalds return 0; 22931da177e4SLinus Torvalds } 22941fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 22951da177e4SLinus Torvalds 22961da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 229789e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 22981da177e4SLinus Torvalds * deal with the hole. 22991da177e4SLinus Torvalds */ 230089e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 23011da177e4SLinus Torvalds { 23021da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 23031da177e4SLinus Torvalds struct page *page; 230489e10787SNick Piggin void *fsdata; 23051da177e4SLinus Torvalds int err; 23061da177e4SLinus Torvalds 2307c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2308c08d3b0eSnpiggin@suse.de if (err) 23091da177e4SLinus Torvalds goto out; 23101da177e4SLinus Torvalds 231189e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 2312c718a975STetsuo Handa AOP_FLAG_CONT_EXPAND, &page, &fsdata); 231389e10787SNick Piggin if (err) 231405eb0b51SOGAWA Hirofumi goto out; 231505eb0b51SOGAWA Hirofumi 231689e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 231789e10787SNick Piggin BUG_ON(err > 0); 231805eb0b51SOGAWA Hirofumi 231905eb0b51SOGAWA Hirofumi out: 232005eb0b51SOGAWA Hirofumi return err; 232105eb0b51SOGAWA Hirofumi } 23221fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 232305eb0b51SOGAWA Hirofumi 2324f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 232589e10787SNick Piggin loff_t pos, loff_t *bytes) 232605eb0b51SOGAWA Hirofumi { 232789e10787SNick Piggin struct inode *inode = mapping->host; 232893407472SFabian Frederick unsigned int blocksize = i_blocksize(inode); 232989e10787SNick Piggin struct page *page; 233089e10787SNick Piggin void *fsdata; 233189e10787SNick Piggin pgoff_t index, curidx; 233289e10787SNick Piggin loff_t curpos; 233389e10787SNick Piggin unsigned zerofrom, offset, len; 233489e10787SNick Piggin int err = 0; 233505eb0b51SOGAWA Hirofumi 233609cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 233709cbfeafSKirill A. Shutemov offset = pos & ~PAGE_MASK; 233889e10787SNick Piggin 233909cbfeafSKirill A. Shutemov while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) { 234009cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 234189e10787SNick Piggin if (zerofrom & (blocksize-1)) { 234289e10787SNick Piggin *bytes |= (blocksize-1); 234389e10787SNick Piggin (*bytes)++; 234489e10787SNick Piggin } 234509cbfeafSKirill A. Shutemov len = PAGE_SIZE - zerofrom; 234689e10787SNick Piggin 2347c718a975STetsuo Handa err = pagecache_write_begin(file, mapping, curpos, len, 0, 234889e10787SNick Piggin &page, &fsdata); 234989e10787SNick Piggin if (err) 235089e10787SNick Piggin goto out; 2351eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 235289e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 235389e10787SNick Piggin page, fsdata); 235489e10787SNick Piggin if (err < 0) 235589e10787SNick Piggin goto out; 235689e10787SNick Piggin BUG_ON(err != len); 235789e10787SNick Piggin err = 0; 2358061e9746SOGAWA Hirofumi 2359061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 2360c2ca0fcdSMikulas Patocka 2361c2ca0fcdSMikulas Patocka if (unlikely(fatal_signal_pending(current))) { 2362c2ca0fcdSMikulas Patocka err = -EINTR; 2363c2ca0fcdSMikulas Patocka goto out; 2364c2ca0fcdSMikulas Patocka } 236589e10787SNick Piggin } 236689e10787SNick Piggin 236789e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 236889e10787SNick Piggin if (index == curidx) { 236909cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 237089e10787SNick Piggin /* if we will expand the thing last block will be filled */ 237189e10787SNick Piggin if (offset <= zerofrom) { 237289e10787SNick Piggin goto out; 237389e10787SNick Piggin } 237489e10787SNick Piggin if (zerofrom & (blocksize-1)) { 237589e10787SNick Piggin *bytes |= (blocksize-1); 237689e10787SNick Piggin (*bytes)++; 237789e10787SNick Piggin } 237889e10787SNick Piggin len = offset - zerofrom; 237989e10787SNick Piggin 2380c718a975STetsuo Handa err = pagecache_write_begin(file, mapping, curpos, len, 0, 238189e10787SNick Piggin &page, &fsdata); 238289e10787SNick Piggin if (err) 238389e10787SNick Piggin goto out; 2384eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 238589e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 238689e10787SNick Piggin page, fsdata); 238789e10787SNick Piggin if (err < 0) 238889e10787SNick Piggin goto out; 238989e10787SNick Piggin BUG_ON(err != len); 239089e10787SNick Piggin err = 0; 239189e10787SNick Piggin } 239289e10787SNick Piggin out: 239389e10787SNick Piggin return err; 23941da177e4SLinus Torvalds } 23951da177e4SLinus Torvalds 23961da177e4SLinus Torvalds /* 23971da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 23981da177e4SLinus Torvalds * We may have to extend the file. 23991da177e4SLinus Torvalds */ 2400282dc178SChristoph Hellwig int cont_write_begin(struct file *file, struct address_space *mapping, 240189e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 240289e10787SNick Piggin struct page **pagep, void **fsdata, 240389e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 24041da177e4SLinus Torvalds { 24051da177e4SLinus Torvalds struct inode *inode = mapping->host; 240693407472SFabian Frederick unsigned int blocksize = i_blocksize(inode); 240793407472SFabian Frederick unsigned int zerofrom; 240889e10787SNick Piggin int err; 24091da177e4SLinus Torvalds 241089e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 241189e10787SNick Piggin if (err) 2412155130a4SChristoph Hellwig return err; 24131da177e4SLinus Torvalds 241409cbfeafSKirill A. Shutemov zerofrom = *bytes & ~PAGE_MASK; 241589e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 24161da177e4SLinus Torvalds *bytes |= (blocksize-1); 24171da177e4SLinus Torvalds (*bytes)++; 24181da177e4SLinus Torvalds } 24191da177e4SLinus Torvalds 2420155130a4SChristoph Hellwig return block_write_begin(mapping, pos, len, flags, pagep, get_block); 24211da177e4SLinus Torvalds } 24221fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 24231da177e4SLinus Torvalds 24241da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 24251da177e4SLinus Torvalds { 24261da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 24271da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 24281da177e4SLinus Torvalds return 0; 24291da177e4SLinus Torvalds } 24301fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 24311da177e4SLinus Torvalds 243254171690SDavid Chinner /* 243354171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 243454171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 243554171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 243654171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 243754171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 243854171690SDavid Chinner * support these features. 243954171690SDavid Chinner * 244054171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 244154171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 24427bb46a67Snpiggin@suse.de * truncate writes the inode size before removing pages, once we have the 244354171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 244454171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 244554171690SDavid Chinner * unlock the page. 2446ea13a864SJan Kara * 244714da9200SJan Kara * Direct callers of this function should protect against filesystem freezing 24485c500029SRoss Zwisler * using sb_start_pagefault() - sb_end_pagefault() functions. 244954171690SDavid Chinner */ 24505c500029SRoss Zwisler int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 245154171690SDavid Chinner get_block_t get_block) 245254171690SDavid Chinner { 2453c2ec175cSNick Piggin struct page *page = vmf->page; 2454496ad9aaSAl Viro struct inode *inode = file_inode(vma->vm_file); 245554171690SDavid Chinner unsigned long end; 245654171690SDavid Chinner loff_t size; 245724da4fabSJan Kara int ret; 245854171690SDavid Chinner 245954171690SDavid Chinner lock_page(page); 246054171690SDavid Chinner size = i_size_read(inode); 246154171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 246218336338SNick Piggin (page_offset(page) > size)) { 246324da4fabSJan Kara /* We overload EFAULT to mean page got truncated */ 246424da4fabSJan Kara ret = -EFAULT; 246524da4fabSJan Kara goto out_unlock; 246654171690SDavid Chinner } 246754171690SDavid Chinner 246854171690SDavid Chinner /* page is wholly or partially inside EOF */ 246909cbfeafSKirill A. Shutemov if (((page->index + 1) << PAGE_SHIFT) > size) 247009cbfeafSKirill A. Shutemov end = size & ~PAGE_MASK; 247154171690SDavid Chinner else 247209cbfeafSKirill A. Shutemov end = PAGE_SIZE; 247354171690SDavid Chinner 2474ebdec241SChristoph Hellwig ret = __block_write_begin(page, 0, end, get_block); 247554171690SDavid Chinner if (!ret) 247654171690SDavid Chinner ret = block_commit_write(page, 0, end); 247754171690SDavid Chinner 247824da4fabSJan Kara if (unlikely(ret < 0)) 247924da4fabSJan Kara goto out_unlock; 2480ea13a864SJan Kara set_page_dirty(page); 24811d1d1a76SDarrick J. Wong wait_for_stable_page(page); 248224da4fabSJan Kara return 0; 248324da4fabSJan Kara out_unlock: 2484b827e496SNick Piggin unlock_page(page); 248554171690SDavid Chinner return ret; 248654171690SDavid Chinner } 24871fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 24881da177e4SLinus Torvalds 24891da177e4SLinus Torvalds /* 249003158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 24911da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 24921da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 24931da177e4SLinus Torvalds */ 24941da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 24951da177e4SLinus Torvalds { 249668671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 24971da177e4SLinus Torvalds } 24981da177e4SLinus Torvalds 24991da177e4SLinus Torvalds /* 250003158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 250103158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 250203158cd7SNick Piggin * dirty races). 250303158cd7SNick Piggin */ 250403158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 250503158cd7SNick Piggin { 250603158cd7SNick Piggin struct buffer_head *bh; 250703158cd7SNick Piggin 250803158cd7SNick Piggin BUG_ON(!PageLocked(page)); 250903158cd7SNick Piggin 251003158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 251103158cd7SNick Piggin bh = head; 251203158cd7SNick Piggin do { 251303158cd7SNick Piggin if (PageDirty(page)) 251403158cd7SNick Piggin set_buffer_dirty(bh); 251503158cd7SNick Piggin if (!bh->b_this_page) 251603158cd7SNick Piggin bh->b_this_page = head; 251703158cd7SNick Piggin bh = bh->b_this_page; 251803158cd7SNick Piggin } while (bh != head); 251903158cd7SNick Piggin attach_page_buffers(page, head); 252003158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 252103158cd7SNick Piggin } 252203158cd7SNick Piggin 252303158cd7SNick Piggin /* 2524ea0f04e5SChristoph Hellwig * On entry, the page is fully not uptodate. 2525ea0f04e5SChristoph Hellwig * On exit the page is fully uptodate in the areas outside (from,to) 25267bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 25271da177e4SLinus Torvalds */ 2528ea0f04e5SChristoph Hellwig int nobh_write_begin(struct address_space *mapping, 252903158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 253003158cd7SNick Piggin struct page **pagep, void **fsdata, 25311da177e4SLinus Torvalds get_block_t *get_block) 25321da177e4SLinus Torvalds { 253303158cd7SNick Piggin struct inode *inode = mapping->host; 25341da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 25351da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2536a4b0672dSNick Piggin struct buffer_head *head, *bh; 253703158cd7SNick Piggin struct page *page; 253803158cd7SNick Piggin pgoff_t index; 253903158cd7SNick Piggin unsigned from, to; 25401da177e4SLinus Torvalds unsigned block_in_page; 2541a4b0672dSNick Piggin unsigned block_start, block_end; 25421da177e4SLinus Torvalds sector_t block_in_file; 25431da177e4SLinus Torvalds int nr_reads = 0; 25441da177e4SLinus Torvalds int ret = 0; 25451da177e4SLinus Torvalds int is_mapped_to_disk = 1; 25461da177e4SLinus Torvalds 254709cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 254809cbfeafSKirill A. Shutemov from = pos & (PAGE_SIZE - 1); 254903158cd7SNick Piggin to = from + len; 255003158cd7SNick Piggin 255154566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 255203158cd7SNick Piggin if (!page) 255303158cd7SNick Piggin return -ENOMEM; 255403158cd7SNick Piggin *pagep = page; 255503158cd7SNick Piggin *fsdata = NULL; 255603158cd7SNick Piggin 255703158cd7SNick Piggin if (page_has_buffers(page)) { 2558309f77adSNamhyung Kim ret = __block_write_begin(page, pos, len, get_block); 2559309f77adSNamhyung Kim if (unlikely(ret)) 2560309f77adSNamhyung Kim goto out_release; 2561309f77adSNamhyung Kim return ret; 256203158cd7SNick Piggin } 2563a4b0672dSNick Piggin 25641da177e4SLinus Torvalds if (PageMappedToDisk(page)) 25651da177e4SLinus Torvalds return 0; 25661da177e4SLinus Torvalds 2567a4b0672dSNick Piggin /* 2568a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2569a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2570a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2571a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2572a4b0672dSNick Piggin * 2573a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2574a4b0672dSNick Piggin * than the circular one we're used to. 2575a4b0672dSNick Piggin */ 2576640ab98fSJens Axboe head = alloc_page_buffers(page, blocksize, false); 257703158cd7SNick Piggin if (!head) { 257803158cd7SNick Piggin ret = -ENOMEM; 257903158cd7SNick Piggin goto out_release; 258003158cd7SNick Piggin } 2581a4b0672dSNick Piggin 258209cbfeafSKirill A. Shutemov block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); 25831da177e4SLinus Torvalds 25841da177e4SLinus Torvalds /* 25851da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 25861da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 25871da177e4SLinus Torvalds * page is fully mapped-to-disk. 25881da177e4SLinus Torvalds */ 2589a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 259009cbfeafSKirill A. Shutemov block_start < PAGE_SIZE; 2591a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 25921da177e4SLinus Torvalds int create; 25931da177e4SLinus Torvalds 2594a4b0672dSNick Piggin block_end = block_start + blocksize; 2595a4b0672dSNick Piggin bh->b_state = 0; 25961da177e4SLinus Torvalds create = 1; 25971da177e4SLinus Torvalds if (block_start >= to) 25981da177e4SLinus Torvalds create = 0; 25991da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2600a4b0672dSNick Piggin bh, create); 26011da177e4SLinus Torvalds if (ret) 26021da177e4SLinus Torvalds goto failed; 2603a4b0672dSNick Piggin if (!buffer_mapped(bh)) 26041da177e4SLinus Torvalds is_mapped_to_disk = 0; 2605a4b0672dSNick Piggin if (buffer_new(bh)) 2606e64855c6SJan Kara clean_bdev_bh_alias(bh); 2607a4b0672dSNick Piggin if (PageUptodate(page)) { 2608a4b0672dSNick Piggin set_buffer_uptodate(bh); 26091da177e4SLinus Torvalds continue; 2610a4b0672dSNick Piggin } 2611a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2612eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2613eebd2aa3SChristoph Lameter to, block_end); 26141da177e4SLinus Torvalds continue; 26151da177e4SLinus Torvalds } 2616a4b0672dSNick Piggin if (buffer_uptodate(bh)) 26171da177e4SLinus Torvalds continue; /* reiserfs does this */ 26181da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2619a4b0672dSNick Piggin lock_buffer(bh); 2620a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 26212a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 2622a4b0672dSNick Piggin nr_reads++; 26231da177e4SLinus Torvalds } 26241da177e4SLinus Torvalds } 26251da177e4SLinus Torvalds 26261da177e4SLinus Torvalds if (nr_reads) { 26271da177e4SLinus Torvalds /* 26281da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 26291da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 26301da177e4SLinus Torvalds * for the buffer_head refcounts. 26311da177e4SLinus Torvalds */ 2632a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 26331da177e4SLinus Torvalds wait_on_buffer(bh); 26341da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 26351da177e4SLinus Torvalds ret = -EIO; 26361da177e4SLinus Torvalds } 26371da177e4SLinus Torvalds if (ret) 26381da177e4SLinus Torvalds goto failed; 26391da177e4SLinus Torvalds } 26401da177e4SLinus Torvalds 26411da177e4SLinus Torvalds if (is_mapped_to_disk) 26421da177e4SLinus Torvalds SetPageMappedToDisk(page); 26431da177e4SLinus Torvalds 264403158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2645a4b0672dSNick Piggin 26461da177e4SLinus Torvalds return 0; 26471da177e4SLinus Torvalds 26481da177e4SLinus Torvalds failed: 264903158cd7SNick Piggin BUG_ON(!ret); 26501da177e4SLinus Torvalds /* 2651a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2652a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2653a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2654a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2655a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 26561da177e4SLinus Torvalds */ 265703158cd7SNick Piggin attach_nobh_buffers(page, head); 265803158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2659a4b0672dSNick Piggin 266003158cd7SNick Piggin out_release: 266103158cd7SNick Piggin unlock_page(page); 266209cbfeafSKirill A. Shutemov put_page(page); 266303158cd7SNick Piggin *pagep = NULL; 2664a4b0672dSNick Piggin 26657bb46a67Snpiggin@suse.de return ret; 26667bb46a67Snpiggin@suse.de } 266703158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 26681da177e4SLinus Torvalds 266903158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 267003158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 267103158cd7SNick Piggin struct page *page, void *fsdata) 26721da177e4SLinus Torvalds { 26731da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2674efdc3131SNick Piggin struct buffer_head *head = fsdata; 267503158cd7SNick Piggin struct buffer_head *bh; 26765b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 26771da177e4SLinus Torvalds 2678d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 267903158cd7SNick Piggin attach_nobh_buffers(page, head); 2680a4b0672dSNick Piggin if (page_has_buffers(page)) 268103158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 268203158cd7SNick Piggin copied, page, fsdata); 2683a4b0672dSNick Piggin 268422c8ca78SNick Piggin SetPageUptodate(page); 26851da177e4SLinus Torvalds set_page_dirty(page); 268603158cd7SNick Piggin if (pos+copied > inode->i_size) { 268703158cd7SNick Piggin i_size_write(inode, pos+copied); 26881da177e4SLinus Torvalds mark_inode_dirty(inode); 26891da177e4SLinus Torvalds } 269003158cd7SNick Piggin 269103158cd7SNick Piggin unlock_page(page); 269209cbfeafSKirill A. Shutemov put_page(page); 269303158cd7SNick Piggin 269403158cd7SNick Piggin while (head) { 269503158cd7SNick Piggin bh = head; 269603158cd7SNick Piggin head = head->b_this_page; 269703158cd7SNick Piggin free_buffer_head(bh); 26981da177e4SLinus Torvalds } 269903158cd7SNick Piggin 270003158cd7SNick Piggin return copied; 270103158cd7SNick Piggin } 270203158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 27031da177e4SLinus Torvalds 27041da177e4SLinus Torvalds /* 27051da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 27061da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 27071da177e4SLinus Torvalds * the page. 27081da177e4SLinus Torvalds */ 27091da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 27101da177e4SLinus Torvalds struct writeback_control *wbc) 27111da177e4SLinus Torvalds { 27121da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 27131da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 271409cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 27151da177e4SLinus Torvalds unsigned offset; 27161da177e4SLinus Torvalds int ret; 27171da177e4SLinus Torvalds 27181da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 27191da177e4SLinus Torvalds if (page->index < end_index) 27201da177e4SLinus Torvalds goto out; 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 272309cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 27241da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 27251da177e4SLinus Torvalds /* 27261da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 27271da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 27281da177e4SLinus Torvalds * freeable here, so the page does not leak. 27291da177e4SLinus Torvalds */ 27301da177e4SLinus Torvalds #if 0 27311da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 27321da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 27331da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 27341da177e4SLinus Torvalds #endif 27351da177e4SLinus Torvalds unlock_page(page); 27361da177e4SLinus Torvalds return 0; /* don't care */ 27371da177e4SLinus Torvalds } 27381da177e4SLinus Torvalds 27391da177e4SLinus Torvalds /* 27401da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 27411da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 27421da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 27431da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 27441da177e4SLinus Torvalds * writes to that region are not written out to the file." 27451da177e4SLinus Torvalds */ 274609cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 27471da177e4SLinus Torvalds out: 27481da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 27491da177e4SLinus Torvalds if (ret == -EAGAIN) 275035c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 275135c80d5fSChris Mason end_buffer_async_write); 27521da177e4SLinus Torvalds return ret; 27531da177e4SLinus Torvalds } 27541da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27551da177e4SLinus Torvalds 275603158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 275703158cd7SNick Piggin loff_t from, get_block_t *get_block) 27581da177e4SLinus Torvalds { 275909cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 276009cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 276103158cd7SNick Piggin unsigned blocksize; 276203158cd7SNick Piggin sector_t iblock; 276303158cd7SNick Piggin unsigned length, pos; 276403158cd7SNick Piggin struct inode *inode = mapping->host; 27651da177e4SLinus Torvalds struct page *page; 276603158cd7SNick Piggin struct buffer_head map_bh; 276703158cd7SNick Piggin int err; 27681da177e4SLinus Torvalds 276993407472SFabian Frederick blocksize = i_blocksize(inode); 277003158cd7SNick Piggin length = offset & (blocksize - 1); 27711da177e4SLinus Torvalds 277203158cd7SNick Piggin /* Block boundary? Nothing to do */ 277303158cd7SNick Piggin if (!length) 277403158cd7SNick Piggin return 0; 277503158cd7SNick Piggin 277603158cd7SNick Piggin length = blocksize - length; 277709cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 277803158cd7SNick Piggin 27791da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 278003158cd7SNick Piggin err = -ENOMEM; 27811da177e4SLinus Torvalds if (!page) 27821da177e4SLinus Torvalds goto out; 27831da177e4SLinus Torvalds 278403158cd7SNick Piggin if (page_has_buffers(page)) { 278503158cd7SNick Piggin has_buffers: 278603158cd7SNick Piggin unlock_page(page); 278709cbfeafSKirill A. Shutemov put_page(page); 278803158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 27891da177e4SLinus Torvalds } 279003158cd7SNick Piggin 279103158cd7SNick Piggin /* Find the buffer that contains "offset" */ 279203158cd7SNick Piggin pos = blocksize; 279303158cd7SNick Piggin while (offset >= pos) { 279403158cd7SNick Piggin iblock++; 279503158cd7SNick Piggin pos += blocksize; 279603158cd7SNick Piggin } 279703158cd7SNick Piggin 2798460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2799460bcf57STheodore Ts'o map_bh.b_state = 0; 280003158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 280103158cd7SNick Piggin if (err) 280203158cd7SNick Piggin goto unlock; 280303158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 280403158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 280503158cd7SNick Piggin goto unlock; 280603158cd7SNick Piggin 280703158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 280803158cd7SNick Piggin if (!PageUptodate(page)) { 280903158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 281003158cd7SNick Piggin if (err) { 281109cbfeafSKirill A. Shutemov put_page(page); 281203158cd7SNick Piggin goto out; 281303158cd7SNick Piggin } 281403158cd7SNick Piggin lock_page(page); 281503158cd7SNick Piggin if (!PageUptodate(page)) { 281603158cd7SNick Piggin err = -EIO; 281703158cd7SNick Piggin goto unlock; 281803158cd7SNick Piggin } 281903158cd7SNick Piggin if (page_has_buffers(page)) 282003158cd7SNick Piggin goto has_buffers; 282103158cd7SNick Piggin } 2822eebd2aa3SChristoph Lameter zero_user(page, offset, length); 282303158cd7SNick Piggin set_page_dirty(page); 282403158cd7SNick Piggin err = 0; 282503158cd7SNick Piggin 282603158cd7SNick Piggin unlock: 28271da177e4SLinus Torvalds unlock_page(page); 282809cbfeafSKirill A. Shutemov put_page(page); 28291da177e4SLinus Torvalds out: 283003158cd7SNick Piggin return err; 28311da177e4SLinus Torvalds } 28321da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 28331da177e4SLinus Torvalds 28341da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 28351da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 28361da177e4SLinus Torvalds { 283709cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 283809cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 28391da177e4SLinus Torvalds unsigned blocksize; 284054b21a79SAndrew Morton sector_t iblock; 28411da177e4SLinus Torvalds unsigned length, pos; 28421da177e4SLinus Torvalds struct inode *inode = mapping->host; 28431da177e4SLinus Torvalds struct page *page; 28441da177e4SLinus Torvalds struct buffer_head *bh; 28451da177e4SLinus Torvalds int err; 28461da177e4SLinus Torvalds 284793407472SFabian Frederick blocksize = i_blocksize(inode); 28481da177e4SLinus Torvalds length = offset & (blocksize - 1); 28491da177e4SLinus Torvalds 28501da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 28511da177e4SLinus Torvalds if (!length) 28521da177e4SLinus Torvalds return 0; 28531da177e4SLinus Torvalds 28541da177e4SLinus Torvalds length = blocksize - length; 285509cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 28561da177e4SLinus Torvalds 28571da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 28581da177e4SLinus Torvalds err = -ENOMEM; 28591da177e4SLinus Torvalds if (!page) 28601da177e4SLinus Torvalds goto out; 28611da177e4SLinus Torvalds 28621da177e4SLinus Torvalds if (!page_has_buffers(page)) 28631da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 28641da177e4SLinus Torvalds 28651da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 28661da177e4SLinus Torvalds bh = page_buffers(page); 28671da177e4SLinus Torvalds pos = blocksize; 28681da177e4SLinus Torvalds while (offset >= pos) { 28691da177e4SLinus Torvalds bh = bh->b_this_page; 28701da177e4SLinus Torvalds iblock++; 28711da177e4SLinus Torvalds pos += blocksize; 28721da177e4SLinus Torvalds } 28731da177e4SLinus Torvalds 28741da177e4SLinus Torvalds err = 0; 28751da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2876b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 28771da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 28781da177e4SLinus Torvalds if (err) 28791da177e4SLinus Torvalds goto unlock; 28801da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 28811da177e4SLinus Torvalds if (!buffer_mapped(bh)) 28821da177e4SLinus Torvalds goto unlock; 28831da177e4SLinus Torvalds } 28841da177e4SLinus Torvalds 28851da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 28861da177e4SLinus Torvalds if (PageUptodate(page)) 28871da177e4SLinus Torvalds set_buffer_uptodate(bh); 28881da177e4SLinus Torvalds 288933a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 28901da177e4SLinus Torvalds err = -EIO; 2891dfec8a14SMike Christie ll_rw_block(REQ_OP_READ, 0, 1, &bh); 28921da177e4SLinus Torvalds wait_on_buffer(bh); 28931da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 28941da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 28951da177e4SLinus Torvalds goto unlock; 28961da177e4SLinus Torvalds } 28971da177e4SLinus Torvalds 2898eebd2aa3SChristoph Lameter zero_user(page, offset, length); 28991da177e4SLinus Torvalds mark_buffer_dirty(bh); 29001da177e4SLinus Torvalds err = 0; 29011da177e4SLinus Torvalds 29021da177e4SLinus Torvalds unlock: 29031da177e4SLinus Torvalds unlock_page(page); 290409cbfeafSKirill A. Shutemov put_page(page); 29051da177e4SLinus Torvalds out: 29061da177e4SLinus Torvalds return err; 29071da177e4SLinus Torvalds } 29081fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 29091da177e4SLinus Torvalds 29101da177e4SLinus Torvalds /* 29111da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 29121da177e4SLinus Torvalds */ 29131b938c08SMatthew Wilcox int block_write_full_page(struct page *page, get_block_t *get_block, 29141b938c08SMatthew Wilcox struct writeback_control *wbc) 29151da177e4SLinus Torvalds { 29161da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 29171da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 291809cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 29191da177e4SLinus Torvalds unsigned offset; 29201da177e4SLinus Torvalds 29211da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 29221da177e4SLinus Torvalds if (page->index < end_index) 292335c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 29241b938c08SMatthew Wilcox end_buffer_async_write); 29251da177e4SLinus Torvalds 29261da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 292709cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 29281da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 29291da177e4SLinus Torvalds /* 29301da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 29311da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 29321da177e4SLinus Torvalds * freeable here, so the page does not leak. 29331da177e4SLinus Torvalds */ 293409cbfeafSKirill A. Shutemov do_invalidatepage(page, 0, PAGE_SIZE); 29351da177e4SLinus Torvalds unlock_page(page); 29361da177e4SLinus Torvalds return 0; /* don't care */ 29371da177e4SLinus Torvalds } 29381da177e4SLinus Torvalds 29391da177e4SLinus Torvalds /* 29401da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 29412a61aa40SAdam Buchbinder * writepage invocation because it may be mmapped. "A file is mapped 29421da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 29431da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 29441da177e4SLinus Torvalds * writes to that region are not written out to the file." 29451da177e4SLinus Torvalds */ 294609cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 29471b938c08SMatthew Wilcox return __block_write_full_page(inode, page, get_block, wbc, 294835c80d5fSChris Mason end_buffer_async_write); 294935c80d5fSChris Mason } 29501fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 295135c80d5fSChris Mason 29521da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29531da177e4SLinus Torvalds get_block_t *get_block) 29541da177e4SLinus Torvalds { 29551da177e4SLinus Torvalds struct inode *inode = mapping->host; 29562a527d68SAlexander Potapenko struct buffer_head tmp = { 29572a527d68SAlexander Potapenko .b_size = i_blocksize(inode), 29582a527d68SAlexander Potapenko }; 29592a527d68SAlexander Potapenko 29601da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 29611da177e4SLinus Torvalds return tmp.b_blocknr; 29621da177e4SLinus Torvalds } 29631fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 29641da177e4SLinus Torvalds 29654246a0b6SChristoph Hellwig static void end_bio_bh_io_sync(struct bio *bio) 29661da177e4SLinus Torvalds { 29671da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 29681da177e4SLinus Torvalds 2969b7c44ed9SJens Axboe if (unlikely(bio_flagged(bio, BIO_QUIET))) 297008bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 297108bafc03SKeith Mannthey 29724e4cbee9SChristoph Hellwig bh->b_end_io(bh, !bio->bi_status); 29731da177e4SLinus Torvalds bio_put(bio); 29741da177e4SLinus Torvalds } 29751da177e4SLinus Torvalds 297657302e0dSLinus Torvalds /* 297757302e0dSLinus Torvalds * This allows us to do IO even on the odd last sectors 297859d43914SAkinobu Mita * of a device, even if the block size is some multiple 297957302e0dSLinus Torvalds * of the physical sector size. 298057302e0dSLinus Torvalds * 298157302e0dSLinus Torvalds * We'll just truncate the bio to the size of the device, 298257302e0dSLinus Torvalds * and clear the end of the buffer head manually. 298357302e0dSLinus Torvalds * 298457302e0dSLinus Torvalds * Truly out-of-range accesses will turn into actual IO 298557302e0dSLinus Torvalds * errors, this only handles the "we need to be able to 298657302e0dSLinus Torvalds * do IO at the final sector" case. 298757302e0dSLinus Torvalds */ 29882a222ca9SMike Christie void guard_bio_eod(int op, struct bio *bio) 298957302e0dSLinus Torvalds { 299057302e0dSLinus Torvalds sector_t maxsector; 2991c45a8f2dSMing Lei struct bio_vec *bvec = bio_last_bvec_all(bio); 299259d43914SAkinobu Mita unsigned truncated_bytes; 299367f2519fSGreg Edwards struct hd_struct *part; 299457302e0dSLinus Torvalds 299567f2519fSGreg Edwards rcu_read_lock(); 299667f2519fSGreg Edwards part = __disk_get_part(bio->bi_disk, bio->bi_partno); 299767f2519fSGreg Edwards if (part) 299867f2519fSGreg Edwards maxsector = part_nr_sects_read(part); 299967f2519fSGreg Edwards else 300074d46992SChristoph Hellwig maxsector = get_capacity(bio->bi_disk); 300167f2519fSGreg Edwards rcu_read_unlock(); 300267f2519fSGreg Edwards 300357302e0dSLinus Torvalds if (!maxsector) 300457302e0dSLinus Torvalds return; 300557302e0dSLinus Torvalds 300657302e0dSLinus Torvalds /* 300757302e0dSLinus Torvalds * If the *whole* IO is past the end of the device, 300857302e0dSLinus Torvalds * let it through, and the IO layer will turn it into 300957302e0dSLinus Torvalds * an EIO. 301057302e0dSLinus Torvalds */ 30114f024f37SKent Overstreet if (unlikely(bio->bi_iter.bi_sector >= maxsector)) 301257302e0dSLinus Torvalds return; 301357302e0dSLinus Torvalds 30144f024f37SKent Overstreet maxsector -= bio->bi_iter.bi_sector; 301559d43914SAkinobu Mita if (likely((bio->bi_iter.bi_size >> 9) <= maxsector)) 301657302e0dSLinus Torvalds return; 301757302e0dSLinus Torvalds 301859d43914SAkinobu Mita /* Uhhuh. We've got a bio that straddles the device size! */ 301959d43914SAkinobu Mita truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9); 302057302e0dSLinus Torvalds 302157302e0dSLinus Torvalds /* Truncate the bio.. */ 302259d43914SAkinobu Mita bio->bi_iter.bi_size -= truncated_bytes; 302359d43914SAkinobu Mita bvec->bv_len -= truncated_bytes; 302457302e0dSLinus Torvalds 302557302e0dSLinus Torvalds /* ..and clear the end of the buffer for reads */ 30262a222ca9SMike Christie if (op == REQ_OP_READ) { 302759d43914SAkinobu Mita zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len, 302859d43914SAkinobu Mita truncated_bytes); 302957302e0dSLinus Torvalds } 303057302e0dSLinus Torvalds } 303157302e0dSLinus Torvalds 30322a222ca9SMike Christie static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, 30338e8f9298SJens Axboe enum rw_hint write_hint, struct writeback_control *wbc) 30341da177e4SLinus Torvalds { 30351da177e4SLinus Torvalds struct bio *bio; 30361da177e4SLinus Torvalds 30371da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 30381da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 30391da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 30408fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 30418fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 30421da177e4SLinus Torvalds 304348fd4f93SJens Axboe /* 304448fd4f93SJens Axboe * Only clear out a write error when rewriting 30451da177e4SLinus Torvalds */ 30462a222ca9SMike Christie if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE)) 30471da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 30481da177e4SLinus Torvalds 30491da177e4SLinus Torvalds /* 30501da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 30511da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 30521da177e4SLinus Torvalds */ 30531da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 30541da177e4SLinus Torvalds 30552a814908STejun Heo if (wbc) { 3056b16b1debSTejun Heo wbc_init_bio(wbc, bio); 30572a814908STejun Heo wbc_account_io(wbc, bh->b_page, bh->b_size); 30582a814908STejun Heo } 3059bafc0dbaSTejun Heo 30604f024f37SKent Overstreet bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); 306174d46992SChristoph Hellwig bio_set_dev(bio, bh->b_bdev); 30628e8f9298SJens Axboe bio->bi_write_hint = write_hint; 30631da177e4SLinus Torvalds 30646cf66b4cSKent Overstreet bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); 30656cf66b4cSKent Overstreet BUG_ON(bio->bi_iter.bi_size != bh->b_size); 30661da177e4SLinus Torvalds 30671da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 30681da177e4SLinus Torvalds bio->bi_private = bh; 30691da177e4SLinus Torvalds 307057302e0dSLinus Torvalds /* Take care of bh's that straddle the end of the device */ 30712a222ca9SMike Christie guard_bio_eod(op, bio); 307257302e0dSLinus Torvalds 3073877f962cSTheodore Ts'o if (buffer_meta(bh)) 30742a222ca9SMike Christie op_flags |= REQ_META; 3075877f962cSTheodore Ts'o if (buffer_prio(bh)) 30762a222ca9SMike Christie op_flags |= REQ_PRIO; 30772a222ca9SMike Christie bio_set_op_attrs(bio, op, op_flags); 3078877f962cSTheodore Ts'o 30794e49ea4aSMike Christie submit_bio(bio); 3080f6454b04SJulia Lawall return 0; 30811da177e4SLinus Torvalds } 3082bafc0dbaSTejun Heo 30832a222ca9SMike Christie int submit_bh(int op, int op_flags, struct buffer_head *bh) 308471368511SDarrick J. Wong { 30858e8f9298SJens Axboe return submit_bh_wbc(op, op_flags, bh, 0, NULL); 308671368511SDarrick J. Wong } 30871fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 30881da177e4SLinus Torvalds 30891da177e4SLinus Torvalds /** 30901da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 3091dfec8a14SMike Christie * @op: whether to %READ or %WRITE 3092ef295ecfSChristoph Hellwig * @op_flags: req_flag_bits 30931da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 30941da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 30951da177e4SLinus Torvalds * 3096a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 309770246286SChristoph Hellwig * requests an I/O operation on them, either a %REQ_OP_READ or a %REQ_OP_WRITE. 309870246286SChristoph Hellwig * @op_flags contains flags modifying the detailed I/O behavior, most notably 309970246286SChristoph Hellwig * %REQ_RAHEAD. 31001da177e4SLinus Torvalds * 31011da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 31029cb569d6SChristoph Hellwig * BH_Lock state bit), any buffer that appears to be clean when doing a write 31039cb569d6SChristoph Hellwig * request, and any buffer that appears to be up-to-date when doing read 31049cb569d6SChristoph Hellwig * request. Further it marks as clean buffers that are processed for 31059cb569d6SChristoph Hellwig * writing (the buffer cache won't assume that they are actually clean 31069cb569d6SChristoph Hellwig * until the buffer gets unlocked). 31071da177e4SLinus Torvalds * 31081da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 3109e227867fSMasanari Iida * the buffer up-to-date (if appropriate), unlocks the buffer and wakes 31101da177e4SLinus Torvalds * any waiters. 31111da177e4SLinus Torvalds * 31121da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 31131da177e4SLinus Torvalds * multiple of the current approved size for the device. 31141da177e4SLinus Torvalds */ 3115dfec8a14SMike Christie void ll_rw_block(int op, int op_flags, int nr, struct buffer_head *bhs[]) 31161da177e4SLinus Torvalds { 31171da177e4SLinus Torvalds int i; 31181da177e4SLinus Torvalds 31191da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 31201da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 31211da177e4SLinus Torvalds 31229cb569d6SChristoph Hellwig if (!trylock_buffer(bh)) 31231da177e4SLinus Torvalds continue; 3124dfec8a14SMike Christie if (op == WRITE) { 31251da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 312676c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3127e60e5c50SOGAWA Hirofumi get_bh(bh); 3128dfec8a14SMike Christie submit_bh(op, op_flags, bh); 31291da177e4SLinus Torvalds continue; 31301da177e4SLinus Torvalds } 31311da177e4SLinus Torvalds } else { 31321da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 313376c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3134e60e5c50SOGAWA Hirofumi get_bh(bh); 3135dfec8a14SMike Christie submit_bh(op, op_flags, bh); 31361da177e4SLinus Torvalds continue; 31371da177e4SLinus Torvalds } 31381da177e4SLinus Torvalds } 31391da177e4SLinus Torvalds unlock_buffer(bh); 31401da177e4SLinus Torvalds } 31411da177e4SLinus Torvalds } 31421fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 31431da177e4SLinus Torvalds 31442a222ca9SMike Christie void write_dirty_buffer(struct buffer_head *bh, int op_flags) 31459cb569d6SChristoph Hellwig { 31469cb569d6SChristoph Hellwig lock_buffer(bh); 31479cb569d6SChristoph Hellwig if (!test_clear_buffer_dirty(bh)) { 31489cb569d6SChristoph Hellwig unlock_buffer(bh); 31499cb569d6SChristoph Hellwig return; 31509cb569d6SChristoph Hellwig } 31519cb569d6SChristoph Hellwig bh->b_end_io = end_buffer_write_sync; 31529cb569d6SChristoph Hellwig get_bh(bh); 31532a222ca9SMike Christie submit_bh(REQ_OP_WRITE, op_flags, bh); 31549cb569d6SChristoph Hellwig } 31559cb569d6SChristoph Hellwig EXPORT_SYMBOL(write_dirty_buffer); 31569cb569d6SChristoph Hellwig 31571da177e4SLinus Torvalds /* 31581da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 31591da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 31601da177e4SLinus Torvalds * the buffer_head. 31611da177e4SLinus Torvalds */ 31622a222ca9SMike Christie int __sync_dirty_buffer(struct buffer_head *bh, int op_flags) 31631da177e4SLinus Torvalds { 31641da177e4SLinus Torvalds int ret = 0; 31651da177e4SLinus Torvalds 31661da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 31671da177e4SLinus Torvalds lock_buffer(bh); 31681da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 31691da177e4SLinus Torvalds get_bh(bh); 31701da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 31712a222ca9SMike Christie ret = submit_bh(REQ_OP_WRITE, op_flags, bh); 31721da177e4SLinus Torvalds wait_on_buffer(bh); 31731da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 31741da177e4SLinus Torvalds ret = -EIO; 31751da177e4SLinus Torvalds } else { 31761da177e4SLinus Torvalds unlock_buffer(bh); 31771da177e4SLinus Torvalds } 31781da177e4SLinus Torvalds return ret; 31791da177e4SLinus Torvalds } 318087e99511SChristoph Hellwig EXPORT_SYMBOL(__sync_dirty_buffer); 318187e99511SChristoph Hellwig 318287e99511SChristoph Hellwig int sync_dirty_buffer(struct buffer_head *bh) 318387e99511SChristoph Hellwig { 318470fd7614SChristoph Hellwig return __sync_dirty_buffer(bh, REQ_SYNC); 318587e99511SChristoph Hellwig } 31861fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 31871da177e4SLinus Torvalds 31881da177e4SLinus Torvalds /* 31891da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 31901da177e4SLinus Torvalds * are unused, and releases them if so. 31911da177e4SLinus Torvalds * 31921da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 31931da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 31941da177e4SLinus Torvalds * 31951da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 31961da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 31971da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 31981da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 31991da177e4SLinus Torvalds * filesystem data on the same device. 32001da177e4SLinus Torvalds * 32011da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 32021da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 32031da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 32041da177e4SLinus Torvalds * private_lock. 32051da177e4SLinus Torvalds * 32061da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 32071da177e4SLinus Torvalds */ 32081da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 32091da177e4SLinus Torvalds { 32101da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 32111da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 32121da177e4SLinus Torvalds } 32131da177e4SLinus Torvalds 32141da177e4SLinus Torvalds static int 32151da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 32161da177e4SLinus Torvalds { 32171da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 32181da177e4SLinus Torvalds struct buffer_head *bh; 32191da177e4SLinus Torvalds 32201da177e4SLinus Torvalds bh = head; 32211da177e4SLinus Torvalds do { 32221da177e4SLinus Torvalds if (buffer_busy(bh)) 32231da177e4SLinus Torvalds goto failed; 32241da177e4SLinus Torvalds bh = bh->b_this_page; 32251da177e4SLinus Torvalds } while (bh != head); 32261da177e4SLinus Torvalds 32271da177e4SLinus Torvalds do { 32281da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32291da177e4SLinus Torvalds 3230535ee2fbSJan Kara if (bh->b_assoc_map) 32311da177e4SLinus Torvalds __remove_assoc_queue(bh); 32321da177e4SLinus Torvalds bh = next; 32331da177e4SLinus Torvalds } while (bh != head); 32341da177e4SLinus Torvalds *buffers_to_free = head; 32351da177e4SLinus Torvalds __clear_page_buffers(page); 32361da177e4SLinus Torvalds return 1; 32371da177e4SLinus Torvalds failed: 32381da177e4SLinus Torvalds return 0; 32391da177e4SLinus Torvalds } 32401da177e4SLinus Torvalds 32411da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 32421da177e4SLinus Torvalds { 32431da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 32441da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 32451da177e4SLinus Torvalds int ret = 0; 32461da177e4SLinus Torvalds 32471da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3248ecdfc978SLinus Torvalds if (PageWriteback(page)) 32491da177e4SLinus Torvalds return 0; 32501da177e4SLinus Torvalds 32511da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 32521da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 32531da177e4SLinus Torvalds goto out; 32541da177e4SLinus Torvalds } 32551da177e4SLinus Torvalds 32561da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 32571da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3258ecdfc978SLinus Torvalds 3259ecdfc978SLinus Torvalds /* 3260ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3261ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3262ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3263ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3264ecdfc978SLinus Torvalds * 3265ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3266ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3267ecdfc978SLinus Torvalds * the page also. 326887df7241SNick Piggin * 326987df7241SNick Piggin * private_lock must be held over this entire operation in order 327087df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 327187df7241SNick Piggin * dirty bit from being lost. 3272ecdfc978SLinus Torvalds */ 327311f81becSTejun Heo if (ret) 327411f81becSTejun Heo cancel_dirty_page(page); 327587df7241SNick Piggin spin_unlock(&mapping->private_lock); 32761da177e4SLinus Torvalds out: 32771da177e4SLinus Torvalds if (buffers_to_free) { 32781da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 32791da177e4SLinus Torvalds 32801da177e4SLinus Torvalds do { 32811da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32821da177e4SLinus Torvalds free_buffer_head(bh); 32831da177e4SLinus Torvalds bh = next; 32841da177e4SLinus Torvalds } while (bh != buffers_to_free); 32851da177e4SLinus Torvalds } 32861da177e4SLinus Torvalds return ret; 32871da177e4SLinus Torvalds } 32881da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 32891da177e4SLinus Torvalds 32901da177e4SLinus Torvalds /* 32911da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 32921da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 32931da177e4SLinus Torvalds * 32941da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 32955b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 32961da177e4SLinus Torvalds */ 3297bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 32981da177e4SLinus Torvalds { 32991da177e4SLinus Torvalds static int msg_count; 33001da177e4SLinus Torvalds 33011da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 33021da177e4SLinus Torvalds return -EPERM; 33031da177e4SLinus Torvalds 33041da177e4SLinus Torvalds if (msg_count < 5) { 33051da177e4SLinus Torvalds msg_count++; 33061da177e4SLinus Torvalds printk(KERN_INFO 33071da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 33081da177e4SLinus Torvalds " system call\n", current->comm); 33091da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 33101da177e4SLinus Torvalds } 33111da177e4SLinus Torvalds 33121da177e4SLinus Torvalds if (func == 1) 33131da177e4SLinus Torvalds do_exit(0); 33141da177e4SLinus Torvalds return 0; 33151da177e4SLinus Torvalds } 33161da177e4SLinus Torvalds 33171da177e4SLinus Torvalds /* 33181da177e4SLinus Torvalds * Buffer-head allocation 33191da177e4SLinus Torvalds */ 3320a0a9b043SShai Fultheim static struct kmem_cache *bh_cachep __read_mostly; 33211da177e4SLinus Torvalds 33221da177e4SLinus Torvalds /* 33231da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 33241da177e4SLinus Torvalds * stripping them in writeback. 33251da177e4SLinus Torvalds */ 332643be594aSZhang Yanfei static unsigned long max_buffer_heads; 33271da177e4SLinus Torvalds 33281da177e4SLinus Torvalds int buffer_heads_over_limit; 33291da177e4SLinus Torvalds 33301da177e4SLinus Torvalds struct bh_accounting { 33311da177e4SLinus Torvalds int nr; /* Number of live bh's */ 33321da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 33331da177e4SLinus Torvalds }; 33341da177e4SLinus Torvalds 33351da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 33361da177e4SLinus Torvalds 33371da177e4SLinus Torvalds static void recalc_bh_state(void) 33381da177e4SLinus Torvalds { 33391da177e4SLinus Torvalds int i; 33401da177e4SLinus Torvalds int tot = 0; 33411da177e4SLinus Torvalds 3342ee1be862SChristoph Lameter if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) 33431da177e4SLinus Torvalds return; 3344c7b92516SChristoph Lameter __this_cpu_write(bh_accounting.ratelimit, 0); 33458a143426SEric Dumazet for_each_online_cpu(i) 33461da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 33471da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 33481da177e4SLinus Torvalds } 33491da177e4SLinus Torvalds 3350dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 33511da177e4SLinus Torvalds { 3352019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 33531da177e4SLinus Torvalds if (ret) { 3354a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3355c7b92516SChristoph Lameter preempt_disable(); 3356c7b92516SChristoph Lameter __this_cpu_inc(bh_accounting.nr); 33571da177e4SLinus Torvalds recalc_bh_state(); 3358c7b92516SChristoph Lameter preempt_enable(); 33591da177e4SLinus Torvalds } 33601da177e4SLinus Torvalds return ret; 33611da177e4SLinus Torvalds } 33621da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 33631da177e4SLinus Torvalds 33641da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 33651da177e4SLinus Torvalds { 33661da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 33671da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3368c7b92516SChristoph Lameter preempt_disable(); 3369c7b92516SChristoph Lameter __this_cpu_dec(bh_accounting.nr); 33701da177e4SLinus Torvalds recalc_bh_state(); 3371c7b92516SChristoph Lameter preempt_enable(); 33721da177e4SLinus Torvalds } 33731da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 33741da177e4SLinus Torvalds 3375fc4d24c9SSebastian Andrzej Siewior static int buffer_exit_cpu_dead(unsigned int cpu) 33761da177e4SLinus Torvalds { 33771da177e4SLinus Torvalds int i; 33781da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 33791da177e4SLinus Torvalds 33801da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 33811da177e4SLinus Torvalds brelse(b->bhs[i]); 33821da177e4SLinus Torvalds b->bhs[i] = NULL; 33831da177e4SLinus Torvalds } 3384c7b92516SChristoph Lameter this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); 33858a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 3386fc4d24c9SSebastian Andrzej Siewior return 0; 33871da177e4SLinus Torvalds } 33881da177e4SLinus Torvalds 3389389d1b08SAneesh Kumar K.V /** 3390a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3391389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3392389d1b08SAneesh Kumar K.V * 3393389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3394389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3395389d1b08SAneesh Kumar K.V */ 3396389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3397389d1b08SAneesh Kumar K.V { 3398389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3399389d1b08SAneesh Kumar K.V lock_buffer(bh); 3400389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3401389d1b08SAneesh Kumar K.V return 0; 3402389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3403389d1b08SAneesh Kumar K.V } 3404389d1b08SAneesh Kumar K.V return 1; 3405389d1b08SAneesh Kumar K.V } 3406389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3407389d1b08SAneesh Kumar K.V 3408389d1b08SAneesh Kumar K.V /** 3409a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3410389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3411389d1b08SAneesh Kumar K.V * 3412389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3413389d1b08SAneesh Kumar K.V */ 3414389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3415389d1b08SAneesh Kumar K.V { 3416389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3417389d1b08SAneesh Kumar K.V 3418389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3419389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3420389d1b08SAneesh Kumar K.V return 0; 3421389d1b08SAneesh Kumar K.V } 3422389d1b08SAneesh Kumar K.V 3423389d1b08SAneesh Kumar K.V get_bh(bh); 3424389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 34252a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 3426389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3427389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3428389d1b08SAneesh Kumar K.V return 0; 3429389d1b08SAneesh Kumar K.V return -EIO; 3430389d1b08SAneesh Kumar K.V } 3431389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3432389d1b08SAneesh Kumar K.V 34331da177e4SLinus Torvalds void __init buffer_init(void) 34341da177e4SLinus Torvalds { 343543be594aSZhang Yanfei unsigned long nrpages; 3436fc4d24c9SSebastian Andrzej Siewior int ret; 34371da177e4SLinus Torvalds 3438b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3439b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3440b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3441b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3442019b4d12SRichard Kennedy NULL); 34431da177e4SLinus Torvalds 34441da177e4SLinus Torvalds /* 34451da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 34461da177e4SLinus Torvalds */ 34471da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 34481da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 3449fc4d24c9SSebastian Andrzej Siewior ret = cpuhp_setup_state_nocalls(CPUHP_FS_BUFF_DEAD, "fs/buffer:dead", 3450fc4d24c9SSebastian Andrzej Siewior NULL, buffer_exit_cpu_dead); 3451fc4d24c9SSebastian Andrzej Siewior WARN_ON(ret < 0); 34521da177e4SLinus Torvalds } 3453