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> 221da177e4SLinus Torvalds #include <linux/syscalls.h> 231da177e4SLinus Torvalds #include <linux/fs.h> 241da177e4SLinus Torvalds #include <linux/mm.h> 251da177e4SLinus Torvalds #include <linux/percpu.h> 261da177e4SLinus Torvalds #include <linux/slab.h> 2716f7e0feSRandy Dunlap #include <linux/capability.h> 281da177e4SLinus Torvalds #include <linux/blkdev.h> 291da177e4SLinus Torvalds #include <linux/file.h> 301da177e4SLinus Torvalds #include <linux/quotaops.h> 311da177e4SLinus Torvalds #include <linux/highmem.h> 32630d9c47SPaul Gortmaker #include <linux/export.h> 331da177e4SLinus Torvalds #include <linux/writeback.h> 341da177e4SLinus Torvalds #include <linux/hash.h> 351da177e4SLinus Torvalds #include <linux/suspend.h> 361da177e4SLinus Torvalds #include <linux/buffer_head.h> 3755e829afSAndrew Morton #include <linux/task_io_accounting_ops.h> 381da177e4SLinus Torvalds #include <linux/bio.h> 391da177e4SLinus Torvalds #include <linux/notifier.h> 401da177e4SLinus Torvalds #include <linux/cpu.h> 411da177e4SLinus Torvalds #include <linux/bitops.h> 421da177e4SLinus Torvalds #include <linux/mpage.h> 43fb1c8f93SIngo Molnar #include <linux/bit_spinlock.h> 445305cb83STejun Heo #include <trace/events/block.h> 451da177e4SLinus Torvalds 461da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 491da177e4SLinus Torvalds 50a3f3c29cSYan Hong void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) 511da177e4SLinus Torvalds { 521da177e4SLinus Torvalds bh->b_end_io = handler; 531da177e4SLinus Torvalds bh->b_private = private; 541da177e4SLinus Torvalds } 551fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(init_buffer); 561da177e4SLinus Torvalds 57f0059afdSTejun Heo inline void touch_buffer(struct buffer_head *bh) 58f0059afdSTejun Heo { 595305cb83STejun Heo trace_block_touch_buffer(bh); 60f0059afdSTejun Heo mark_page_accessed(bh->b_page); 61f0059afdSTejun Heo } 62f0059afdSTejun Heo EXPORT_SYMBOL(touch_buffer); 63f0059afdSTejun Heo 64fc9b52cdSHarvey Harrison void __lock_buffer(struct buffer_head *bh) 651da177e4SLinus Torvalds { 6674316201SNeilBrown wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 671da177e4SLinus Torvalds } 681da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 691da177e4SLinus Torvalds 70fc9b52cdSHarvey Harrison void unlock_buffer(struct buffer_head *bh) 711da177e4SLinus Torvalds { 7251b07fc3SNick Piggin clear_bit_unlock(BH_Lock, &bh->b_state); 734e857c58SPeter Zijlstra smp_mb__after_atomic(); 741da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 751da177e4SLinus Torvalds } 761fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(unlock_buffer); 771da177e4SLinus Torvalds 781da177e4SLinus Torvalds /* 79b4597226SMel Gorman * Returns if the page has dirty or writeback buffers. If all the buffers 80b4597226SMel Gorman * are unlocked and clean then the PageDirty information is stale. If 81b4597226SMel Gorman * any of the pages are locked, it is assumed they are locked for IO. 82b4597226SMel Gorman */ 83b4597226SMel Gorman void buffer_check_dirty_writeback(struct page *page, 84b4597226SMel Gorman bool *dirty, bool *writeback) 85b4597226SMel Gorman { 86b4597226SMel Gorman struct buffer_head *head, *bh; 87b4597226SMel Gorman *dirty = false; 88b4597226SMel Gorman *writeback = false; 89b4597226SMel Gorman 90b4597226SMel Gorman BUG_ON(!PageLocked(page)); 91b4597226SMel Gorman 92b4597226SMel Gorman if (!page_has_buffers(page)) 93b4597226SMel Gorman return; 94b4597226SMel Gorman 95b4597226SMel Gorman if (PageWriteback(page)) 96b4597226SMel Gorman *writeback = true; 97b4597226SMel Gorman 98b4597226SMel Gorman head = page_buffers(page); 99b4597226SMel Gorman bh = head; 100b4597226SMel Gorman do { 101b4597226SMel Gorman if (buffer_locked(bh)) 102b4597226SMel Gorman *writeback = true; 103b4597226SMel Gorman 104b4597226SMel Gorman if (buffer_dirty(bh)) 105b4597226SMel Gorman *dirty = true; 106b4597226SMel Gorman 107b4597226SMel Gorman bh = bh->b_this_page; 108b4597226SMel Gorman } while (bh != head); 109b4597226SMel Gorman } 110b4597226SMel Gorman EXPORT_SYMBOL(buffer_check_dirty_writeback); 111b4597226SMel Gorman 112b4597226SMel Gorman /* 1131da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 1141da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 1151da177e4SLinus Torvalds * if you want to preserve its state. 1161da177e4SLinus Torvalds */ 1171da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 1181da177e4SLinus Torvalds { 11974316201SNeilBrown wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 1201da177e4SLinus Torvalds } 1211fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__wait_on_buffer); 1221da177e4SLinus Torvalds 1231da177e4SLinus Torvalds static void 1241da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 1251da177e4SLinus Torvalds { 1261da177e4SLinus Torvalds ClearPagePrivate(page); 1274c21e2f2SHugh Dickins set_page_private(page, 0); 1281da177e4SLinus Torvalds page_cache_release(page); 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 131b744c2acSRobert Elliott static void buffer_io_error(struct buffer_head *bh, char *msg) 1321da177e4SLinus Torvalds { 1331da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 134432f16e6SRobert Elliott 135432f16e6SRobert Elliott if (!test_bit(BH_Quiet, &bh->b_state)) 136432f16e6SRobert Elliott printk_ratelimited(KERN_ERR 137432f16e6SRobert Elliott "Buffer I/O error on dev %s, logical block %llu%s\n", 1381da177e4SLinus Torvalds bdevname(bh->b_bdev, b), 139b744c2acSRobert Elliott (unsigned long long)bh->b_blocknr, msg); 1401da177e4SLinus Torvalds } 1411da177e4SLinus Torvalds 1421da177e4SLinus Torvalds /* 14368671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 14468671f35SDmitry Monakhov * unlocking it. 14568671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 14668671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 14768671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 14868671f35SDmitry Monakhov * itself. 1491da177e4SLinus Torvalds */ 15068671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1511da177e4SLinus Torvalds { 1521da177e4SLinus Torvalds if (uptodate) { 1531da177e4SLinus Torvalds set_buffer_uptodate(bh); 1541da177e4SLinus Torvalds } else { 1551da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 1561da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1571da177e4SLinus Torvalds } 1581da177e4SLinus Torvalds unlock_buffer(bh); 15968671f35SDmitry Monakhov } 16068671f35SDmitry Monakhov 16168671f35SDmitry Monakhov /* 16268671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 16368671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 16468671f35SDmitry Monakhov */ 16568671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 16668671f35SDmitry Monakhov { 16768671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1681da177e4SLinus Torvalds put_bh(bh); 1691da177e4SLinus Torvalds } 1701fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_read_sync); 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1731da177e4SLinus Torvalds { 1741da177e4SLinus Torvalds if (uptodate) { 1751da177e4SLinus Torvalds set_buffer_uptodate(bh); 1761da177e4SLinus Torvalds } else { 177b744c2acSRobert Elliott buffer_io_error(bh, ", lost sync page write"); 1781da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1791da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1801da177e4SLinus Torvalds } 1811da177e4SLinus Torvalds unlock_buffer(bh); 1821da177e4SLinus Torvalds put_bh(bh); 1831da177e4SLinus Torvalds } 1841fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_write_sync); 1851da177e4SLinus Torvalds 1861da177e4SLinus Torvalds /* 1871da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 1881da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 1891da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 1901da177e4SLinus Torvalds * private_lock. 1911da177e4SLinus Torvalds * 1921da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 1931da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 1941da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 1951da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 1961da177e4SLinus Torvalds */ 1971da177e4SLinus Torvalds static struct buffer_head * 198385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 1991da177e4SLinus Torvalds { 2001da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 2011da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 2021da177e4SLinus Torvalds struct buffer_head *ret = NULL; 2031da177e4SLinus Torvalds pgoff_t index; 2041da177e4SLinus Torvalds struct buffer_head *bh; 2051da177e4SLinus Torvalds struct buffer_head *head; 2061da177e4SLinus Torvalds struct page *page; 2071da177e4SLinus Torvalds int all_mapped = 1; 2081da177e4SLinus Torvalds 2091da177e4SLinus Torvalds index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); 2102457aec6SMel Gorman page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); 2111da177e4SLinus Torvalds if (!page) 2121da177e4SLinus Torvalds goto out; 2131da177e4SLinus Torvalds 2141da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2151da177e4SLinus Torvalds if (!page_has_buffers(page)) 2161da177e4SLinus Torvalds goto out_unlock; 2171da177e4SLinus Torvalds head = page_buffers(page); 2181da177e4SLinus Torvalds bh = head; 2191da177e4SLinus Torvalds do { 22097f76d3dSNikanth Karthikesan if (!buffer_mapped(bh)) 22197f76d3dSNikanth Karthikesan all_mapped = 0; 22297f76d3dSNikanth Karthikesan else if (bh->b_blocknr == block) { 2231da177e4SLinus Torvalds ret = bh; 2241da177e4SLinus Torvalds get_bh(bh); 2251da177e4SLinus Torvalds goto out_unlock; 2261da177e4SLinus Torvalds } 2271da177e4SLinus Torvalds bh = bh->b_this_page; 2281da177e4SLinus Torvalds } while (bh != head); 2291da177e4SLinus Torvalds 2301da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2311da177e4SLinus Torvalds * not mapped. This is due to various races between 2321da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2331da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2341da177e4SLinus Torvalds */ 2351da177e4SLinus Torvalds if (all_mapped) { 23672a2ebd8STao Ma char b[BDEVNAME_SIZE]; 23772a2ebd8STao Ma 2381da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2391da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 240205f87f6SBadari Pulavarty (unsigned long long)block, 241205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 242205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 243205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 24472a2ebd8STao Ma printk("device %s blocksize: %d\n", bdevname(bdev, b), 24572a2ebd8STao Ma 1 << bd_inode->i_blkbits); 2461da177e4SLinus Torvalds } 2471da177e4SLinus Torvalds out_unlock: 2481da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 2491da177e4SLinus Torvalds page_cache_release(page); 2501da177e4SLinus Torvalds out: 2511da177e4SLinus Torvalds return ret; 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 2541da177e4SLinus Torvalds /* 2555b0830cbSJens Axboe * Kick the writeback threads then try to free up some ZONE_NORMAL memory. 2561da177e4SLinus Torvalds */ 2571da177e4SLinus Torvalds static void free_more_memory(void) 2581da177e4SLinus Torvalds { 25919770b32SMel Gorman struct zone *zone; 2600e88460dSMel Gorman int nid; 2611da177e4SLinus Torvalds 2620e175a18SCurt Wohlgemuth wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM); 2631da177e4SLinus Torvalds yield(); 2641da177e4SLinus Torvalds 2650e88460dSMel Gorman for_each_online_node(nid) { 26619770b32SMel Gorman (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS), 26719770b32SMel Gorman gfp_zone(GFP_NOFS), NULL, 26819770b32SMel Gorman &zone); 26919770b32SMel Gorman if (zone) 27054a6eb5cSMel Gorman try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, 271327c0e96SKAMEZAWA Hiroyuki GFP_NOFS, NULL); 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds } 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds /* 2761da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 2771da177e4SLinus Torvalds * which come unlocked at the end of I/O. 2781da177e4SLinus Torvalds */ 2791da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 2801da177e4SLinus Torvalds { 2811da177e4SLinus Torvalds unsigned long flags; 282a3972203SNick Piggin struct buffer_head *first; 2831da177e4SLinus Torvalds struct buffer_head *tmp; 2841da177e4SLinus Torvalds struct page *page; 2851da177e4SLinus Torvalds int page_uptodate = 1; 2861da177e4SLinus Torvalds 2871da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 2881da177e4SLinus Torvalds 2891da177e4SLinus Torvalds page = bh->b_page; 2901da177e4SLinus Torvalds if (uptodate) { 2911da177e4SLinus Torvalds set_buffer_uptodate(bh); 2921da177e4SLinus Torvalds } else { 2931da177e4SLinus Torvalds clear_buffer_uptodate(bh); 294b744c2acSRobert Elliott buffer_io_error(bh, ", async page read"); 2951da177e4SLinus Torvalds SetPageError(page); 2961da177e4SLinus Torvalds } 2971da177e4SLinus Torvalds 2981da177e4SLinus Torvalds /* 2991da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 3001da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 3011da177e4SLinus Torvalds * decide that the page is now completely done. 3021da177e4SLinus Torvalds */ 303a3972203SNick Piggin first = page_buffers(page); 304a3972203SNick Piggin local_irq_save(flags); 305a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 3061da177e4SLinus Torvalds clear_buffer_async_read(bh); 3071da177e4SLinus Torvalds unlock_buffer(bh); 3081da177e4SLinus Torvalds tmp = bh; 3091da177e4SLinus Torvalds do { 3101da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 3111da177e4SLinus Torvalds page_uptodate = 0; 3121da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 3131da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3141da177e4SLinus Torvalds goto still_busy; 3151da177e4SLinus Torvalds } 3161da177e4SLinus Torvalds tmp = tmp->b_this_page; 3171da177e4SLinus Torvalds } while (tmp != bh); 318a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 319a3972203SNick Piggin local_irq_restore(flags); 3201da177e4SLinus Torvalds 3211da177e4SLinus Torvalds /* 3221da177e4SLinus Torvalds * If none of the buffers had errors and they are all 3231da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 3241da177e4SLinus Torvalds */ 3251da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 3261da177e4SLinus Torvalds SetPageUptodate(page); 3271da177e4SLinus Torvalds unlock_page(page); 3281da177e4SLinus Torvalds return; 3291da177e4SLinus Torvalds 3301da177e4SLinus Torvalds still_busy: 331a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 332a3972203SNick Piggin local_irq_restore(flags); 3331da177e4SLinus Torvalds return; 3341da177e4SLinus Torvalds } 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 3371da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 3381da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 3391da177e4SLinus Torvalds */ 34035c80d5fSChris Mason void end_buffer_async_write(struct buffer_head *bh, int uptodate) 3411da177e4SLinus Torvalds { 3421da177e4SLinus Torvalds unsigned long flags; 343a3972203SNick Piggin struct buffer_head *first; 3441da177e4SLinus Torvalds struct buffer_head *tmp; 3451da177e4SLinus Torvalds struct page *page; 3461da177e4SLinus Torvalds 3471da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds page = bh->b_page; 3501da177e4SLinus Torvalds if (uptodate) { 3511da177e4SLinus Torvalds set_buffer_uptodate(bh); 3521da177e4SLinus Torvalds } else { 353b744c2acSRobert Elliott buffer_io_error(bh, ", lost async page write"); 3541da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 35558ff407bSJan Kara set_buffer_write_io_error(bh); 3561da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3571da177e4SLinus Torvalds SetPageError(page); 3581da177e4SLinus Torvalds } 3591da177e4SLinus Torvalds 360a3972203SNick Piggin first = page_buffers(page); 361a3972203SNick Piggin local_irq_save(flags); 362a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 363a3972203SNick Piggin 3641da177e4SLinus Torvalds clear_buffer_async_write(bh); 3651da177e4SLinus Torvalds unlock_buffer(bh); 3661da177e4SLinus Torvalds tmp = bh->b_this_page; 3671da177e4SLinus Torvalds while (tmp != bh) { 3681da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 3691da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3701da177e4SLinus Torvalds goto still_busy; 3711da177e4SLinus Torvalds } 3721da177e4SLinus Torvalds tmp = tmp->b_this_page; 3731da177e4SLinus Torvalds } 374a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 375a3972203SNick Piggin local_irq_restore(flags); 3761da177e4SLinus Torvalds end_page_writeback(page); 3771da177e4SLinus Torvalds return; 3781da177e4SLinus Torvalds 3791da177e4SLinus Torvalds still_busy: 380a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 381a3972203SNick Piggin local_irq_restore(flags); 3821da177e4SLinus Torvalds return; 3831da177e4SLinus Torvalds } 3841fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_async_write); 3851da177e4SLinus Torvalds 3861da177e4SLinus Torvalds /* 3871da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 3881da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 3891da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 3901da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 3911da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 3921da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 3931da177e4SLinus Torvalds * that this buffer is not under async I/O. 3941da177e4SLinus Torvalds * 3951da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 3961da177e4SLinus Torvalds * left. 3971da177e4SLinus Torvalds * 3981da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 3991da177e4SLinus Torvalds * the buffers. 4001da177e4SLinus Torvalds * 4011da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 4021da177e4SLinus Torvalds * page. 4031da177e4SLinus Torvalds * 4041da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 4051da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 4061da177e4SLinus Torvalds */ 4071da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 4081da177e4SLinus Torvalds { 4091da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 4101da177e4SLinus Torvalds set_buffer_async_read(bh); 4111da177e4SLinus Torvalds } 4121da177e4SLinus Torvalds 4131fe72eaaSH Hartley Sweeten static void mark_buffer_async_write_endio(struct buffer_head *bh, 41435c80d5fSChris Mason bh_end_io_t *handler) 41535c80d5fSChris Mason { 41635c80d5fSChris Mason bh->b_end_io = handler; 41735c80d5fSChris Mason set_buffer_async_write(bh); 41835c80d5fSChris Mason } 41935c80d5fSChris Mason 4201da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 4211da177e4SLinus Torvalds { 42235c80d5fSChris Mason mark_buffer_async_write_endio(bh, end_buffer_async_write); 4231da177e4SLinus Torvalds } 4241da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 4251da177e4SLinus Torvalds 4261da177e4SLinus Torvalds 4271da177e4SLinus Torvalds /* 4281da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 4291da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 4301da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 4311da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 4321da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 4331da177e4SLinus Torvalds * 4341da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 4351da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 4361da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 4371da177e4SLinus Torvalds * 4381da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 4391da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 4401da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 4411da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 4421da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 4431da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 4441da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 4451da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 4461da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 4471da177e4SLinus Torvalds * ->private_lock. 4481da177e4SLinus Torvalds * 4491da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 4501da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 4511da177e4SLinus Torvalds * 4521da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 4531da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 4541da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 4551da177e4SLinus Torvalds * be true at clear_inode() time. 4561da177e4SLinus Torvalds * 4571da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 4581da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 4591da177e4SLinus Torvalds * BUG_ON(!list_empty). 4601da177e4SLinus Torvalds * 4611da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 4621da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 4631da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 4641da177e4SLinus Torvalds * queued up. 4651da177e4SLinus Torvalds * 4661da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 4671da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 4681da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 4691da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 4701da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 4711da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 4721da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 4731da177e4SLinus Torvalds * b_inode back. 4741da177e4SLinus Torvalds */ 4751da177e4SLinus Torvalds 4761da177e4SLinus Torvalds /* 4771da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 4781da177e4SLinus Torvalds */ 479dbacefc9SThomas Petazzoni static void __remove_assoc_queue(struct buffer_head *bh) 4801da177e4SLinus Torvalds { 4811da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 48258ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 48358ff407bSJan Kara if (buffer_write_io_error(bh)) 48458ff407bSJan Kara set_bit(AS_EIO, &bh->b_assoc_map->flags); 48558ff407bSJan Kara bh->b_assoc_map = NULL; 4861da177e4SLinus Torvalds } 4871da177e4SLinus Torvalds 4881da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 4891da177e4SLinus Torvalds { 4901da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 4911da177e4SLinus Torvalds } 4921da177e4SLinus Torvalds 4931da177e4SLinus Torvalds /* 4941da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 4951da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 4961da177e4SLinus Torvalds * writes to the disk. 4971da177e4SLinus Torvalds * 4981da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 4991da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 5001da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 5011da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 5021da177e4SLinus Torvalds */ 5031da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 5041da177e4SLinus Torvalds { 5051da177e4SLinus Torvalds struct buffer_head *bh; 5061da177e4SLinus Torvalds struct list_head *p; 5071da177e4SLinus Torvalds int err = 0; 5081da177e4SLinus Torvalds 5091da177e4SLinus Torvalds spin_lock(lock); 5101da177e4SLinus Torvalds repeat: 5111da177e4SLinus Torvalds list_for_each_prev(p, list) { 5121da177e4SLinus Torvalds bh = BH_ENTRY(p); 5131da177e4SLinus Torvalds if (buffer_locked(bh)) { 5141da177e4SLinus Torvalds get_bh(bh); 5151da177e4SLinus Torvalds spin_unlock(lock); 5161da177e4SLinus Torvalds wait_on_buffer(bh); 5171da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 5181da177e4SLinus Torvalds err = -EIO; 5191da177e4SLinus Torvalds brelse(bh); 5201da177e4SLinus Torvalds spin_lock(lock); 5211da177e4SLinus Torvalds goto repeat; 5221da177e4SLinus Torvalds } 5231da177e4SLinus Torvalds } 5241da177e4SLinus Torvalds spin_unlock(lock); 5251da177e4SLinus Torvalds return err; 5261da177e4SLinus Torvalds } 5271da177e4SLinus Torvalds 52801a05b33SAl Viro static void do_thaw_one(struct super_block *sb, void *unused) 529c2d75438SEric Sandeen { 530c2d75438SEric Sandeen char b[BDEVNAME_SIZE]; 531c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 532c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw on %s\n", 533c2d75438SEric Sandeen bdevname(sb->s_bdev, b)); 534c2d75438SEric Sandeen } 53501a05b33SAl Viro 53601a05b33SAl Viro static void do_thaw_all(struct work_struct *work) 53701a05b33SAl Viro { 53801a05b33SAl Viro iterate_supers(do_thaw_one, NULL); 539053c525fSJens Axboe kfree(work); 540c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw complete\n"); 541c2d75438SEric Sandeen } 542c2d75438SEric Sandeen 543c2d75438SEric Sandeen /** 544c2d75438SEric Sandeen * emergency_thaw_all -- forcibly thaw every frozen filesystem 545c2d75438SEric Sandeen * 546c2d75438SEric Sandeen * Used for emergency unfreeze of all filesystems via SysRq 547c2d75438SEric Sandeen */ 548c2d75438SEric Sandeen void emergency_thaw_all(void) 549c2d75438SEric Sandeen { 550053c525fSJens Axboe struct work_struct *work; 551053c525fSJens Axboe 552053c525fSJens Axboe work = kmalloc(sizeof(*work), GFP_ATOMIC); 553053c525fSJens Axboe if (work) { 554053c525fSJens Axboe INIT_WORK(work, do_thaw_all); 555053c525fSJens Axboe schedule_work(work); 556053c525fSJens Axboe } 557c2d75438SEric Sandeen } 558c2d75438SEric Sandeen 5591da177e4SLinus Torvalds /** 56078a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 56167be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 5621da177e4SLinus Torvalds * 5631da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 5641da177e4SLinus Torvalds * that I/O. 5651da177e4SLinus Torvalds * 56667be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 56767be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 56867be2dd1SMartin Waitz * a successful fsync(). 5691da177e4SLinus Torvalds */ 5701da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 5711da177e4SLinus Torvalds { 572252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 5731da177e4SLinus Torvalds 5741da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 5751da177e4SLinus Torvalds return 0; 5761da177e4SLinus Torvalds 5771da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 5781da177e4SLinus Torvalds &mapping->private_list); 5791da177e4SLinus Torvalds } 5801da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 5811da177e4SLinus Torvalds 5821da177e4SLinus Torvalds /* 5831da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 5841da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 5851da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 5861da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 5871da177e4SLinus Torvalds */ 5881da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 5891da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 5901da177e4SLinus Torvalds { 5911da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 5921da177e4SLinus Torvalds if (bh) { 5931da177e4SLinus Torvalds if (buffer_dirty(bh)) 5941da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 5951da177e4SLinus Torvalds put_bh(bh); 5961da177e4SLinus Torvalds } 5971da177e4SLinus Torvalds } 5981da177e4SLinus Torvalds 5991da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 6001da177e4SLinus Torvalds { 6011da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 6021da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6031da177e4SLinus Torvalds 6041da177e4SLinus Torvalds mark_buffer_dirty(bh); 605252aa6f5SRafael Aquini if (!mapping->private_data) { 606252aa6f5SRafael Aquini mapping->private_data = buffer_mapping; 6071da177e4SLinus Torvalds } else { 608252aa6f5SRafael Aquini BUG_ON(mapping->private_data != buffer_mapping); 6091da177e4SLinus Torvalds } 610535ee2fbSJan Kara if (!bh->b_assoc_map) { 6111da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6121da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6131da177e4SLinus Torvalds &mapping->private_list); 61458ff407bSJan Kara bh->b_assoc_map = mapping; 6151da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6161da177e4SLinus Torvalds } 6171da177e4SLinus Torvalds } 6181da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6191da177e4SLinus Torvalds 6201da177e4SLinus Torvalds /* 621787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 622787d2214SNick Piggin * dirty. 623787d2214SNick Piggin * 624787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 625787d2214SNick Piggin * not been truncated. 626*c4843a75SGreg Thelen * 627*c4843a75SGreg Thelen * The caller must hold mem_cgroup_begin_page_stat() lock. 628787d2214SNick Piggin */ 629*c4843a75SGreg Thelen static void __set_page_dirty(struct page *page, struct address_space *mapping, 630*c4843a75SGreg Thelen struct mem_cgroup *memcg, int warn) 631787d2214SNick Piggin { 632227d53b3SKOSAKI Motohiro unsigned long flags; 633227d53b3SKOSAKI Motohiro 634227d53b3SKOSAKI Motohiro spin_lock_irqsave(&mapping->tree_lock, flags); 635787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 636787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 637*c4843a75SGreg Thelen account_page_dirtied(page, mapping, memcg); 638787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 639787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 640787d2214SNick Piggin } 641227d53b3SKOSAKI Motohiro spin_unlock_irqrestore(&mapping->tree_lock, flags); 642787d2214SNick Piggin } 643787d2214SNick Piggin 644787d2214SNick Piggin /* 6451da177e4SLinus Torvalds * Add a page to the dirty page list. 6461da177e4SLinus Torvalds * 6471da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6481da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6491da177e4SLinus Torvalds * 6501da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6511da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6521da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6531da177e4SLinus Torvalds * dirty. 6541da177e4SLinus Torvalds * 6551da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6561da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6571da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6581da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6591da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 6601da177e4SLinus Torvalds * page on the dirty page list. 6611da177e4SLinus Torvalds * 6621da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 6631da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 6641da177e4SLinus Torvalds * added to the page after it was set dirty. 6651da177e4SLinus Torvalds * 6661da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 6671da177e4SLinus Torvalds * address_space though. 6681da177e4SLinus Torvalds */ 6691da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 6701da177e4SLinus Torvalds { 671a8e7d49aSLinus Torvalds int newly_dirty; 672*c4843a75SGreg Thelen struct mem_cgroup *memcg; 673787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 674ebf7a227SNick Piggin 675ebf7a227SNick Piggin if (unlikely(!mapping)) 676ebf7a227SNick Piggin return !TestSetPageDirty(page); 6771da177e4SLinus Torvalds 6781da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 6791da177e4SLinus Torvalds if (page_has_buffers(page)) { 6801da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 6811da177e4SLinus Torvalds struct buffer_head *bh = head; 6821da177e4SLinus Torvalds 6831da177e4SLinus Torvalds do { 6841da177e4SLinus Torvalds set_buffer_dirty(bh); 6851da177e4SLinus Torvalds bh = bh->b_this_page; 6861da177e4SLinus Torvalds } while (bh != head); 6871da177e4SLinus Torvalds } 688*c4843a75SGreg Thelen /* 689*c4843a75SGreg Thelen * Use mem_group_begin_page_stat() to keep PageDirty synchronized with 690*c4843a75SGreg Thelen * per-memcg dirty page counters. 691*c4843a75SGreg Thelen */ 692*c4843a75SGreg Thelen memcg = mem_cgroup_begin_page_stat(page); 693a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 6941da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 6951da177e4SLinus Torvalds 696a8e7d49aSLinus Torvalds if (newly_dirty) 697*c4843a75SGreg Thelen __set_page_dirty(page, mapping, memcg, 1); 698*c4843a75SGreg Thelen 699*c4843a75SGreg Thelen mem_cgroup_end_page_stat(memcg); 700*c4843a75SGreg Thelen 701*c4843a75SGreg Thelen if (newly_dirty) 702*c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 703*c4843a75SGreg Thelen 704a8e7d49aSLinus Torvalds return newly_dirty; 7051da177e4SLinus Torvalds } 7061da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7071da177e4SLinus Torvalds 7081da177e4SLinus Torvalds /* 7091da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7101da177e4SLinus Torvalds * 7111da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7121da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7131da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7141da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7151da177e4SLinus Torvalds * 7161da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7171da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7181da177e4SLinus Torvalds * up, waiting for those writes to complete. 7191da177e4SLinus Torvalds * 7201da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7211da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7221da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7231da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7241da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7251da177e4SLinus Torvalds * any newly dirty buffers for write. 7261da177e4SLinus Torvalds */ 7271da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7281da177e4SLinus Torvalds { 7291da177e4SLinus Torvalds struct buffer_head *bh; 7301da177e4SLinus Torvalds struct list_head tmp; 7317eaceaccSJens Axboe struct address_space *mapping; 7321da177e4SLinus Torvalds int err = 0, err2; 7334ee2491eSJens Axboe struct blk_plug plug; 7341da177e4SLinus Torvalds 7351da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7364ee2491eSJens Axboe blk_start_plug(&plug); 7371da177e4SLinus Torvalds 7381da177e4SLinus Torvalds spin_lock(lock); 7391da177e4SLinus Torvalds while (!list_empty(list)) { 7401da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 741535ee2fbSJan Kara mapping = bh->b_assoc_map; 74258ff407bSJan Kara __remove_assoc_queue(bh); 743535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 744535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 745535ee2fbSJan Kara smp_mb(); 7461da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7471da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 748535ee2fbSJan Kara bh->b_assoc_map = mapping; 7491da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7501da177e4SLinus Torvalds get_bh(bh); 7511da177e4SLinus Torvalds spin_unlock(lock); 7521da177e4SLinus Torvalds /* 7531da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7549cb569d6SChristoph Hellwig * write_dirty_buffer() actually writes the 7559cb569d6SChristoph Hellwig * current contents - it is a noop if I/O is 7569cb569d6SChristoph Hellwig * still in flight on potentially older 7579cb569d6SChristoph Hellwig * contents. 7581da177e4SLinus Torvalds */ 759721a9602SJens Axboe write_dirty_buffer(bh, WRITE_SYNC); 7609cf6b720SJens Axboe 7619cf6b720SJens Axboe /* 7629cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7639cf6b720SJens Axboe * that we will not run the very last mapping, 7649cf6b720SJens Axboe * wait_on_buffer() will do that for us 7659cf6b720SJens Axboe * through sync_buffer(). 7669cf6b720SJens Axboe */ 7671da177e4SLinus Torvalds brelse(bh); 7681da177e4SLinus Torvalds spin_lock(lock); 7691da177e4SLinus Torvalds } 7701da177e4SLinus Torvalds } 7711da177e4SLinus Torvalds } 7721da177e4SLinus Torvalds 7734ee2491eSJens Axboe spin_unlock(lock); 7744ee2491eSJens Axboe blk_finish_plug(&plug); 7754ee2491eSJens Axboe spin_lock(lock); 7764ee2491eSJens Axboe 7771da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7781da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 7791da177e4SLinus Torvalds get_bh(bh); 780535ee2fbSJan Kara mapping = bh->b_assoc_map; 781535ee2fbSJan Kara __remove_assoc_queue(bh); 782535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 783535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 784535ee2fbSJan Kara smp_mb(); 785535ee2fbSJan Kara if (buffer_dirty(bh)) { 786535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 787e3892296SJan Kara &mapping->private_list); 788535ee2fbSJan Kara bh->b_assoc_map = mapping; 789535ee2fbSJan Kara } 7901da177e4SLinus Torvalds spin_unlock(lock); 7911da177e4SLinus Torvalds wait_on_buffer(bh); 7921da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 7931da177e4SLinus Torvalds err = -EIO; 7941da177e4SLinus Torvalds brelse(bh); 7951da177e4SLinus Torvalds spin_lock(lock); 7961da177e4SLinus Torvalds } 7971da177e4SLinus Torvalds 7981da177e4SLinus Torvalds spin_unlock(lock); 7991da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 8001da177e4SLinus Torvalds if (err) 8011da177e4SLinus Torvalds return err; 8021da177e4SLinus Torvalds else 8031da177e4SLinus Torvalds return err2; 8041da177e4SLinus Torvalds } 8051da177e4SLinus Torvalds 8061da177e4SLinus Torvalds /* 8071da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8081da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8091da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8101da177e4SLinus Torvalds * 8111da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8121da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8131da177e4SLinus Torvalds * for reiserfs. 8141da177e4SLinus Torvalds */ 8151da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8161da177e4SLinus Torvalds { 8171da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8181da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8191da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 820252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8211da177e4SLinus Torvalds 8221da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8231da177e4SLinus Torvalds while (!list_empty(list)) 8241da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8251da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8261da177e4SLinus Torvalds } 8271da177e4SLinus Torvalds } 82852b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 8291da177e4SLinus Torvalds 8301da177e4SLinus Torvalds /* 8311da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8321da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8331da177e4SLinus Torvalds * 8341da177e4SLinus Torvalds * Returns true if all buffers were removed. 8351da177e4SLinus Torvalds */ 8361da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8371da177e4SLinus Torvalds { 8381da177e4SLinus Torvalds int ret = 1; 8391da177e4SLinus Torvalds 8401da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8411da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8421da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 843252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8441da177e4SLinus Torvalds 8451da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8461da177e4SLinus Torvalds while (!list_empty(list)) { 8471da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8481da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8491da177e4SLinus Torvalds ret = 0; 8501da177e4SLinus Torvalds break; 8511da177e4SLinus Torvalds } 8521da177e4SLinus Torvalds __remove_assoc_queue(bh); 8531da177e4SLinus Torvalds } 8541da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8551da177e4SLinus Torvalds } 8561da177e4SLinus Torvalds return ret; 8571da177e4SLinus Torvalds } 8581da177e4SLinus Torvalds 8591da177e4SLinus Torvalds /* 8601da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8611da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8621da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8631da177e4SLinus Torvalds * buffers. 8641da177e4SLinus Torvalds * 8651da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8661da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8671da177e4SLinus Torvalds */ 8681da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8691da177e4SLinus Torvalds int retry) 8701da177e4SLinus Torvalds { 8711da177e4SLinus Torvalds struct buffer_head *bh, *head; 8721da177e4SLinus Torvalds long offset; 8731da177e4SLinus Torvalds 8741da177e4SLinus Torvalds try_again: 8751da177e4SLinus Torvalds head = NULL; 8761da177e4SLinus Torvalds offset = PAGE_SIZE; 8771da177e4SLinus Torvalds while ((offset -= size) >= 0) { 8781da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 8791da177e4SLinus Torvalds if (!bh) 8801da177e4SLinus Torvalds goto no_grow; 8811da177e4SLinus Torvalds 8821da177e4SLinus Torvalds bh->b_this_page = head; 8831da177e4SLinus Torvalds bh->b_blocknr = -1; 8841da177e4SLinus Torvalds head = bh; 8851da177e4SLinus Torvalds 8861da177e4SLinus Torvalds bh->b_size = size; 8871da177e4SLinus Torvalds 8881da177e4SLinus Torvalds /* Link the buffer to its page */ 8891da177e4SLinus Torvalds set_bh_page(bh, page, offset); 8901da177e4SLinus Torvalds } 8911da177e4SLinus Torvalds return head; 8921da177e4SLinus Torvalds /* 8931da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 8941da177e4SLinus Torvalds */ 8951da177e4SLinus Torvalds no_grow: 8961da177e4SLinus Torvalds if (head) { 8971da177e4SLinus Torvalds do { 8981da177e4SLinus Torvalds bh = head; 8991da177e4SLinus Torvalds head = head->b_this_page; 9001da177e4SLinus Torvalds free_buffer_head(bh); 9011da177e4SLinus Torvalds } while (head); 9021da177e4SLinus Torvalds } 9031da177e4SLinus Torvalds 9041da177e4SLinus Torvalds /* 9051da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9061da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9071da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9081da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9091da177e4SLinus Torvalds */ 9101da177e4SLinus Torvalds if (!retry) 9111da177e4SLinus Torvalds return NULL; 9121da177e4SLinus Torvalds 9131da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9141da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9151da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9161da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9171da177e4SLinus Torvalds * async buffer heads in use. 9181da177e4SLinus Torvalds */ 9191da177e4SLinus Torvalds free_more_memory(); 9201da177e4SLinus Torvalds goto try_again; 9211da177e4SLinus Torvalds } 9221da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9231da177e4SLinus Torvalds 9241da177e4SLinus Torvalds static inline void 9251da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9261da177e4SLinus Torvalds { 9271da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9281da177e4SLinus Torvalds 9291da177e4SLinus Torvalds bh = head; 9301da177e4SLinus Torvalds do { 9311da177e4SLinus Torvalds tail = bh; 9321da177e4SLinus Torvalds bh = bh->b_this_page; 9331da177e4SLinus Torvalds } while (bh); 9341da177e4SLinus Torvalds tail->b_this_page = head; 9351da177e4SLinus Torvalds attach_page_buffers(page, head); 9361da177e4SLinus Torvalds } 9371da177e4SLinus Torvalds 938bbec0270SLinus Torvalds static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) 939bbec0270SLinus Torvalds { 940bbec0270SLinus Torvalds sector_t retval = ~((sector_t)0); 941bbec0270SLinus Torvalds loff_t sz = i_size_read(bdev->bd_inode); 942bbec0270SLinus Torvalds 943bbec0270SLinus Torvalds if (sz) { 944bbec0270SLinus Torvalds unsigned int sizebits = blksize_bits(size); 945bbec0270SLinus Torvalds retval = (sz >> sizebits); 946bbec0270SLinus Torvalds } 947bbec0270SLinus Torvalds return retval; 948bbec0270SLinus Torvalds } 949bbec0270SLinus Torvalds 9501da177e4SLinus Torvalds /* 9511da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9521da177e4SLinus Torvalds */ 953676ce6d5SHugh Dickins static sector_t 9541da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9551da177e4SLinus Torvalds sector_t block, int size) 9561da177e4SLinus Torvalds { 9571da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9581da177e4SLinus Torvalds struct buffer_head *bh = head; 9591da177e4SLinus Torvalds int uptodate = PageUptodate(page); 960bbec0270SLinus Torvalds sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); 9611da177e4SLinus Torvalds 9621da177e4SLinus Torvalds do { 9631da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9641da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9651da177e4SLinus Torvalds bh->b_bdev = bdev; 9661da177e4SLinus Torvalds bh->b_blocknr = block; 9671da177e4SLinus Torvalds if (uptodate) 9681da177e4SLinus Torvalds set_buffer_uptodate(bh); 969080399aaSJeff Moyer if (block < end_block) 9701da177e4SLinus Torvalds set_buffer_mapped(bh); 9711da177e4SLinus Torvalds } 9721da177e4SLinus Torvalds block++; 9731da177e4SLinus Torvalds bh = bh->b_this_page; 9741da177e4SLinus Torvalds } while (bh != head); 975676ce6d5SHugh Dickins 976676ce6d5SHugh Dickins /* 977676ce6d5SHugh Dickins * Caller needs to validate requested block against end of device. 978676ce6d5SHugh Dickins */ 979676ce6d5SHugh Dickins return end_block; 9801da177e4SLinus Torvalds } 9811da177e4SLinus Torvalds 9821da177e4SLinus Torvalds /* 9831da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9841da177e4SLinus Torvalds * 985676ce6d5SHugh Dickins * This is used purely for blockdev mappings. 9861da177e4SLinus Torvalds */ 987676ce6d5SHugh Dickins static int 9881da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 9893b5e6454SGioh Kim pgoff_t index, int size, int sizebits, gfp_t gfp) 9901da177e4SLinus Torvalds { 9911da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9921da177e4SLinus Torvalds struct page *page; 9931da177e4SLinus Torvalds struct buffer_head *bh; 994676ce6d5SHugh Dickins sector_t end_block; 995676ce6d5SHugh Dickins int ret = 0; /* Will call free_more_memory() */ 99684235de3SJohannes Weiner gfp_t gfp_mask; 9971da177e4SLinus Torvalds 9983b5e6454SGioh Kim gfp_mask = (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS) | gfp; 9993b5e6454SGioh Kim 100084235de3SJohannes Weiner /* 100184235de3SJohannes Weiner * XXX: __getblk_slow() can not really deal with failure and 100284235de3SJohannes Weiner * will endlessly loop on improvised global reclaim. Prefer 100384235de3SJohannes Weiner * looping in the allocator rather than here, at least that 100484235de3SJohannes Weiner * code knows what it's doing. 100584235de3SJohannes Weiner */ 100684235de3SJohannes Weiner gfp_mask |= __GFP_NOFAIL; 100784235de3SJohannes Weiner 100884235de3SJohannes Weiner page = find_or_create_page(inode->i_mapping, index, gfp_mask); 10091da177e4SLinus Torvalds if (!page) 1010676ce6d5SHugh Dickins return ret; 10111da177e4SLinus Torvalds 1012e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 10131da177e4SLinus Torvalds 10141da177e4SLinus Torvalds if (page_has_buffers(page)) { 10151da177e4SLinus Torvalds bh = page_buffers(page); 10161da177e4SLinus Torvalds if (bh->b_size == size) { 1017676ce6d5SHugh Dickins end_block = init_page_buffers(page, bdev, 1018f2d5a944SAnton Altaparmakov (sector_t)index << sizebits, 1019f2d5a944SAnton Altaparmakov size); 1020676ce6d5SHugh Dickins goto done; 10211da177e4SLinus Torvalds } 10221da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10231da177e4SLinus Torvalds goto failed; 10241da177e4SLinus Torvalds } 10251da177e4SLinus Torvalds 10261da177e4SLinus Torvalds /* 10271da177e4SLinus Torvalds * Allocate some buffers for this page 10281da177e4SLinus Torvalds */ 10291da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10301da177e4SLinus Torvalds if (!bh) 10311da177e4SLinus Torvalds goto failed; 10321da177e4SLinus Torvalds 10331da177e4SLinus Torvalds /* 10341da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10351da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10361da177e4SLinus Torvalds * run under the page lock. 10371da177e4SLinus Torvalds */ 10381da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10391da177e4SLinus Torvalds link_dev_buffers(page, bh); 1040f2d5a944SAnton Altaparmakov end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, 1041f2d5a944SAnton Altaparmakov size); 10421da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 1043676ce6d5SHugh Dickins done: 1044676ce6d5SHugh Dickins ret = (block < end_block) ? 1 : -ENXIO; 10451da177e4SLinus Torvalds failed: 10461da177e4SLinus Torvalds unlock_page(page); 10471da177e4SLinus Torvalds page_cache_release(page); 1048676ce6d5SHugh Dickins return ret; 10491da177e4SLinus Torvalds } 10501da177e4SLinus Torvalds 10511da177e4SLinus Torvalds /* 10521da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10531da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10541da177e4SLinus Torvalds */ 1055858119e1SArjan van de Ven static int 10563b5e6454SGioh Kim grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) 10571da177e4SLinus Torvalds { 10581da177e4SLinus Torvalds pgoff_t index; 10591da177e4SLinus Torvalds int sizebits; 10601da177e4SLinus Torvalds 10611da177e4SLinus Torvalds sizebits = -1; 10621da177e4SLinus Torvalds do { 10631da177e4SLinus Torvalds sizebits++; 10641da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10651da177e4SLinus Torvalds 10661da177e4SLinus Torvalds index = block >> sizebits; 10671da177e4SLinus Torvalds 1068e5657933SAndrew Morton /* 1069e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1070e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1071e5657933SAndrew Morton */ 1072e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1073e5657933SAndrew Morton char b[BDEVNAME_SIZE]; 1074e5657933SAndrew Morton 1075e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1076e5657933SAndrew Morton "device %s\n", 10778e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1078e5657933SAndrew Morton bdevname(bdev, b)); 1079e5657933SAndrew Morton return -EIO; 1080e5657933SAndrew Morton } 1081676ce6d5SHugh Dickins 10821da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10833b5e6454SGioh Kim return grow_dev_page(bdev, block, index, size, sizebits, gfp); 10841da177e4SLinus Torvalds } 10851da177e4SLinus Torvalds 10863b5e6454SGioh Kim struct buffer_head * 10873b5e6454SGioh Kim __getblk_slow(struct block_device *bdev, sector_t block, 10883b5e6454SGioh Kim unsigned size, gfp_t gfp) 10891da177e4SLinus Torvalds { 10901da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1091e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10921da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10931da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10941da177e4SLinus Torvalds size); 1095e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1096e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 10971da177e4SLinus Torvalds 10981da177e4SLinus Torvalds dump_stack(); 10991da177e4SLinus Torvalds return NULL; 11001da177e4SLinus Torvalds } 11011da177e4SLinus Torvalds 1102676ce6d5SHugh Dickins for (;;) { 1103676ce6d5SHugh Dickins struct buffer_head *bh; 1104676ce6d5SHugh Dickins int ret; 1105676ce6d5SHugh Dickins 11061da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 11071da177e4SLinus Torvalds if (bh) 11081da177e4SLinus Torvalds return bh; 11091da177e4SLinus Torvalds 11103b5e6454SGioh Kim ret = grow_buffers(bdev, block, size, gfp); 1111676ce6d5SHugh Dickins if (ret < 0) 111291f68c89SJeff Moyer return NULL; 1113676ce6d5SHugh Dickins if (ret == 0) 1114676ce6d5SHugh Dickins free_more_memory(); 1115676ce6d5SHugh Dickins } 11161da177e4SLinus Torvalds } 11173b5e6454SGioh Kim EXPORT_SYMBOL(__getblk_slow); 11181da177e4SLinus Torvalds 11191da177e4SLinus Torvalds /* 11201da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 11211da177e4SLinus Torvalds * 11221da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 11231da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 11241da177e4SLinus Torvalds * 11251da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 11261da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 11271da177e4SLinus Torvalds * merely a hint about the true dirty state. 11281da177e4SLinus Torvalds * 11291da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 11301da177e4SLinus Torvalds * (if the page has buffers). 11311da177e4SLinus Torvalds * 11321da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11331da177e4SLinus Torvalds * buffers are not. 11341da177e4SLinus Torvalds * 11351da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11361da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11371da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11381da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11391da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11401da177e4SLinus Torvalds */ 11411da177e4SLinus Torvalds 11421da177e4SLinus Torvalds /** 11431da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 114467be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11451da177e4SLinus Torvalds * 11461da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11471da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11481da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11491da177e4SLinus Torvalds * inode list. 11501da177e4SLinus Torvalds * 11511da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 1152250df6edSDave Chinner * mapping->tree_lock and mapping->host->i_lock. 11531da177e4SLinus Torvalds */ 1154fc9b52cdSHarvey Harrison void mark_buffer_dirty(struct buffer_head *bh) 11551da177e4SLinus Torvalds { 1156787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 11571be62dc1SLinus Torvalds 11585305cb83STejun Heo trace_block_dirty_buffer(bh); 11595305cb83STejun Heo 11601be62dc1SLinus Torvalds /* 11611be62dc1SLinus Torvalds * Very *carefully* optimize the it-is-already-dirty case. 11621be62dc1SLinus Torvalds * 11631be62dc1SLinus Torvalds * Don't let the final "is it dirty" escape to before we 11641be62dc1SLinus Torvalds * perhaps modified the buffer. 11651be62dc1SLinus Torvalds */ 11661be62dc1SLinus Torvalds if (buffer_dirty(bh)) { 11671be62dc1SLinus Torvalds smp_mb(); 11681be62dc1SLinus Torvalds if (buffer_dirty(bh)) 11691be62dc1SLinus Torvalds return; 11701be62dc1SLinus Torvalds } 11711be62dc1SLinus Torvalds 1172a8e7d49aSLinus Torvalds if (!test_set_buffer_dirty(bh)) { 1173a8e7d49aSLinus Torvalds struct page *page = bh->b_page; 1174*c4843a75SGreg Thelen struct address_space *mapping = NULL; 1175*c4843a75SGreg Thelen struct mem_cgroup *memcg; 1176*c4843a75SGreg Thelen 1177*c4843a75SGreg Thelen memcg = mem_cgroup_begin_page_stat(page); 11788e9d78edSLinus Torvalds if (!TestSetPageDirty(page)) { 1179*c4843a75SGreg Thelen mapping = page_mapping(page); 11808e9d78edSLinus Torvalds if (mapping) 1181*c4843a75SGreg Thelen __set_page_dirty(page, mapping, memcg, 0); 11828e9d78edSLinus Torvalds } 1183*c4843a75SGreg Thelen mem_cgroup_end_page_stat(memcg); 1184*c4843a75SGreg Thelen if (mapping) 1185*c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 1186a8e7d49aSLinus Torvalds } 11871da177e4SLinus Torvalds } 11881fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(mark_buffer_dirty); 11891da177e4SLinus Torvalds 11901da177e4SLinus Torvalds /* 11911da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11921da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11931da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11941da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11951da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11961da177e4SLinus Torvalds */ 11971da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11981da177e4SLinus Torvalds { 11991da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 12001da177e4SLinus Torvalds put_bh(buf); 12011da177e4SLinus Torvalds return; 12021da177e4SLinus Torvalds } 12035c752ad9SArjan van de Ven WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 12041da177e4SLinus Torvalds } 12051fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__brelse); 12061da177e4SLinus Torvalds 12071da177e4SLinus Torvalds /* 12081da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 12091da177e4SLinus Torvalds * potentially dirty data. 12101da177e4SLinus Torvalds */ 12111da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 12121da177e4SLinus Torvalds { 12131da177e4SLinus Torvalds clear_buffer_dirty(bh); 1214535ee2fbSJan Kara if (bh->b_assoc_map) { 12151da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 12161da177e4SLinus Torvalds 12171da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 12181da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 121958ff407bSJan Kara bh->b_assoc_map = NULL; 12201da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12211da177e4SLinus Torvalds } 12221da177e4SLinus Torvalds __brelse(bh); 12231da177e4SLinus Torvalds } 12241fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__bforget); 12251da177e4SLinus Torvalds 12261da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12271da177e4SLinus Torvalds { 12281da177e4SLinus Torvalds lock_buffer(bh); 12291da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12301da177e4SLinus Torvalds unlock_buffer(bh); 12311da177e4SLinus Torvalds return bh; 12321da177e4SLinus Torvalds } else { 12331da177e4SLinus Torvalds get_bh(bh); 12341da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12351da177e4SLinus Torvalds submit_bh(READ, bh); 12361da177e4SLinus Torvalds wait_on_buffer(bh); 12371da177e4SLinus Torvalds if (buffer_uptodate(bh)) 12381da177e4SLinus Torvalds return bh; 12391da177e4SLinus Torvalds } 12401da177e4SLinus Torvalds brelse(bh); 12411da177e4SLinus Torvalds return NULL; 12421da177e4SLinus Torvalds } 12431da177e4SLinus Torvalds 12441da177e4SLinus Torvalds /* 12451da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12461da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12471da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12481da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12491da177e4SLinus Torvalds * CPU's LRUs at the same time. 12501da177e4SLinus Torvalds * 12511da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12521da177e4SLinus Torvalds * sb_find_get_block(). 12531da177e4SLinus Torvalds * 12541da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12551da177e4SLinus Torvalds * a local interrupt disable for that. 12561da177e4SLinus Torvalds */ 12571da177e4SLinus Torvalds 125886cf78d7SSebastien Buisson #define BH_LRU_SIZE 16 12591da177e4SLinus Torvalds 12601da177e4SLinus Torvalds struct bh_lru { 12611da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12621da177e4SLinus Torvalds }; 12631da177e4SLinus Torvalds 12641da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12651da177e4SLinus Torvalds 12661da177e4SLinus Torvalds #ifdef CONFIG_SMP 12671da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12681da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12691da177e4SLinus Torvalds #else 12701da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12711da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12721da177e4SLinus Torvalds #endif 12731da177e4SLinus Torvalds 12741da177e4SLinus Torvalds static inline void check_irqs_on(void) 12751da177e4SLinus Torvalds { 12761da177e4SLinus Torvalds #ifdef irqs_disabled 12771da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12781da177e4SLinus Torvalds #endif 12791da177e4SLinus Torvalds } 12801da177e4SLinus Torvalds 12811da177e4SLinus Torvalds /* 12821da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 12831da177e4SLinus Torvalds */ 12841da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12851da177e4SLinus Torvalds { 12861da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 12871da177e4SLinus Torvalds 12881da177e4SLinus Torvalds check_irqs_on(); 12891da177e4SLinus Torvalds bh_lru_lock(); 1290c7b92516SChristoph Lameter if (__this_cpu_read(bh_lrus.bhs[0]) != bh) { 12911da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12921da177e4SLinus Torvalds int in; 12931da177e4SLinus Torvalds int out = 0; 12941da177e4SLinus Torvalds 12951da177e4SLinus Torvalds get_bh(bh); 12961da177e4SLinus Torvalds bhs[out++] = bh; 12971da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 1298c7b92516SChristoph Lameter struct buffer_head *bh2 = 1299c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[in]); 13001da177e4SLinus Torvalds 13011da177e4SLinus Torvalds if (bh2 == bh) { 13021da177e4SLinus Torvalds __brelse(bh2); 13031da177e4SLinus Torvalds } else { 13041da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 13051da177e4SLinus Torvalds BUG_ON(evictee != NULL); 13061da177e4SLinus Torvalds evictee = bh2; 13071da177e4SLinus Torvalds } else { 13081da177e4SLinus Torvalds bhs[out++] = bh2; 13091da177e4SLinus Torvalds } 13101da177e4SLinus Torvalds } 13111da177e4SLinus Torvalds } 13121da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 13131da177e4SLinus Torvalds bhs[out++] = NULL; 1314ca6673b0SChristoph Lameter memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs)); 13151da177e4SLinus Torvalds } 13161da177e4SLinus Torvalds bh_lru_unlock(); 13171da177e4SLinus Torvalds 13181da177e4SLinus Torvalds if (evictee) 13191da177e4SLinus Torvalds __brelse(evictee); 13201da177e4SLinus Torvalds } 13211da177e4SLinus Torvalds 13221da177e4SLinus Torvalds /* 13231da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 13241da177e4SLinus Torvalds */ 1325858119e1SArjan van de Ven static struct buffer_head * 13263991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 13271da177e4SLinus Torvalds { 13281da177e4SLinus Torvalds struct buffer_head *ret = NULL; 13293991d3bdSTomasz Kvarsin unsigned int i; 13301da177e4SLinus Torvalds 13311da177e4SLinus Torvalds check_irqs_on(); 13321da177e4SLinus Torvalds bh_lru_lock(); 13331da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 1334c7b92516SChristoph Lameter struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); 13351da177e4SLinus Torvalds 13369470dd5dSZach Brown if (bh && bh->b_blocknr == block && bh->b_bdev == bdev && 13379470dd5dSZach Brown bh->b_size == size) { 13381da177e4SLinus Torvalds if (i) { 13391da177e4SLinus Torvalds while (i) { 1340c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[i], 1341c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[i - 1])); 13421da177e4SLinus Torvalds i--; 13431da177e4SLinus Torvalds } 1344c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[0], bh); 13451da177e4SLinus Torvalds } 13461da177e4SLinus Torvalds get_bh(bh); 13471da177e4SLinus Torvalds ret = bh; 13481da177e4SLinus Torvalds break; 13491da177e4SLinus Torvalds } 13501da177e4SLinus Torvalds } 13511da177e4SLinus Torvalds bh_lru_unlock(); 13521da177e4SLinus Torvalds return ret; 13531da177e4SLinus Torvalds } 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds /* 13561da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13571da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13581da177e4SLinus Torvalds * NULL 13591da177e4SLinus Torvalds */ 13601da177e4SLinus Torvalds struct buffer_head * 13613991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 13621da177e4SLinus Torvalds { 13631da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13641da177e4SLinus Torvalds 13651da177e4SLinus Torvalds if (bh == NULL) { 13662457aec6SMel Gorman /* __find_get_block_slow will mark the page accessed */ 1367385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13681da177e4SLinus Torvalds if (bh) 13691da177e4SLinus Torvalds bh_lru_install(bh); 13702457aec6SMel Gorman } else 13711da177e4SLinus Torvalds touch_buffer(bh); 13722457aec6SMel Gorman 13731da177e4SLinus Torvalds return bh; 13741da177e4SLinus Torvalds } 13751da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13761da177e4SLinus Torvalds 13771da177e4SLinus Torvalds /* 13783b5e6454SGioh Kim * __getblk_gfp() will locate (and, if necessary, create) the buffer_head 13791da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13801da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13811da177e4SLinus Torvalds * 13823b5e6454SGioh Kim * __getblk_gfp() will lock up the machine if grow_dev_page's 13833b5e6454SGioh Kim * try_to_free_buffers() attempt is failing. FIXME, perhaps? 13841da177e4SLinus Torvalds */ 13851da177e4SLinus Torvalds struct buffer_head * 13863b5e6454SGioh Kim __getblk_gfp(struct block_device *bdev, sector_t block, 13873b5e6454SGioh Kim unsigned size, gfp_t gfp) 13881da177e4SLinus Torvalds { 13891da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13901da177e4SLinus Torvalds 13911da177e4SLinus Torvalds might_sleep(); 13921da177e4SLinus Torvalds if (bh == NULL) 13933b5e6454SGioh Kim bh = __getblk_slow(bdev, block, size, gfp); 13941da177e4SLinus Torvalds return bh; 13951da177e4SLinus Torvalds } 13963b5e6454SGioh Kim EXPORT_SYMBOL(__getblk_gfp); 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds /* 13991da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 14001da177e4SLinus Torvalds */ 14013991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 14021da177e4SLinus Torvalds { 14031da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1404a3e713b5SAndrew Morton if (likely(bh)) { 14051da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 14061da177e4SLinus Torvalds brelse(bh); 14071da177e4SLinus Torvalds } 1408a3e713b5SAndrew Morton } 14091da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 14101da177e4SLinus Torvalds 14111da177e4SLinus Torvalds /** 14123b5e6454SGioh Kim * __bread_gfp() - reads a specified block and returns the bh 141367be2dd1SMartin Waitz * @bdev: the block_device to read from 14141da177e4SLinus Torvalds * @block: number of block 14151da177e4SLinus Torvalds * @size: size (in bytes) to read 14163b5e6454SGioh Kim * @gfp: page allocation flag 14171da177e4SLinus Torvalds * 14181da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 14193b5e6454SGioh Kim * The page cache can be allocated from non-movable area 14203b5e6454SGioh Kim * not to prevent page migration if you set gfp to zero. 14211da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 14221da177e4SLinus Torvalds */ 14231da177e4SLinus Torvalds struct buffer_head * 14243b5e6454SGioh Kim __bread_gfp(struct block_device *bdev, sector_t block, 14253b5e6454SGioh Kim unsigned size, gfp_t gfp) 14261da177e4SLinus Torvalds { 14273b5e6454SGioh Kim struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); 14281da177e4SLinus Torvalds 1429a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 14301da177e4SLinus Torvalds bh = __bread_slow(bh); 14311da177e4SLinus Torvalds return bh; 14321da177e4SLinus Torvalds } 14333b5e6454SGioh Kim EXPORT_SYMBOL(__bread_gfp); 14341da177e4SLinus Torvalds 14351da177e4SLinus Torvalds /* 14361da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14371da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 14381da177e4SLinus Torvalds * or with preempt disabled. 14391da177e4SLinus Torvalds */ 14401da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 14411da177e4SLinus Torvalds { 14421da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14431da177e4SLinus Torvalds int i; 14441da177e4SLinus Torvalds 14451da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14461da177e4SLinus Torvalds brelse(b->bhs[i]); 14471da177e4SLinus Torvalds b->bhs[i] = NULL; 14481da177e4SLinus Torvalds } 14491da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14501da177e4SLinus Torvalds } 14511da177e4SLinus Torvalds 145242be35d0SGilad Ben-Yossef static bool has_bh_in_lru(int cpu, void *dummy) 145342be35d0SGilad Ben-Yossef { 145442be35d0SGilad Ben-Yossef struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); 145542be35d0SGilad Ben-Yossef int i; 145642be35d0SGilad Ben-Yossef 145742be35d0SGilad Ben-Yossef for (i = 0; i < BH_LRU_SIZE; i++) { 145842be35d0SGilad Ben-Yossef if (b->bhs[i]) 145942be35d0SGilad Ben-Yossef return 1; 146042be35d0SGilad Ben-Yossef } 146142be35d0SGilad Ben-Yossef 146242be35d0SGilad Ben-Yossef return 0; 146342be35d0SGilad Ben-Yossef } 146442be35d0SGilad Ben-Yossef 1465f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 14661da177e4SLinus Torvalds { 146742be35d0SGilad Ben-Yossef on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); 14681da177e4SLinus Torvalds } 14699db5579bSNick Piggin EXPORT_SYMBOL_GPL(invalidate_bh_lrus); 14701da177e4SLinus Torvalds 14711da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14721da177e4SLinus Torvalds struct page *page, unsigned long offset) 14731da177e4SLinus Torvalds { 14741da177e4SLinus Torvalds bh->b_page = page; 1475e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14761da177e4SLinus Torvalds if (PageHighMem(page)) 14771da177e4SLinus Torvalds /* 14781da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14791da177e4SLinus Torvalds */ 14801da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14811da177e4SLinus Torvalds else 14821da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14831da177e4SLinus Torvalds } 14841da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14851da177e4SLinus Torvalds 14861da177e4SLinus Torvalds /* 14871da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14881da177e4SLinus Torvalds */ 1489e7470ee8SMel Gorman 1490e7470ee8SMel Gorman /* Bits that are cleared during an invalidate */ 1491e7470ee8SMel Gorman #define BUFFER_FLAGS_DISCARD \ 1492e7470ee8SMel Gorman (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ 1493e7470ee8SMel Gorman 1 << BH_Delay | 1 << BH_Unwritten) 1494e7470ee8SMel Gorman 1495858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14961da177e4SLinus Torvalds { 1497e7470ee8SMel Gorman unsigned long b_state, b_state_old; 1498e7470ee8SMel Gorman 14991da177e4SLinus Torvalds lock_buffer(bh); 15001da177e4SLinus Torvalds clear_buffer_dirty(bh); 15011da177e4SLinus Torvalds bh->b_bdev = NULL; 1502e7470ee8SMel Gorman b_state = bh->b_state; 1503e7470ee8SMel Gorman for (;;) { 1504e7470ee8SMel Gorman b_state_old = cmpxchg(&bh->b_state, b_state, 1505e7470ee8SMel Gorman (b_state & ~BUFFER_FLAGS_DISCARD)); 1506e7470ee8SMel Gorman if (b_state_old == b_state) 1507e7470ee8SMel Gorman break; 1508e7470ee8SMel Gorman b_state = b_state_old; 1509e7470ee8SMel Gorman } 15101da177e4SLinus Torvalds unlock_buffer(bh); 15111da177e4SLinus Torvalds } 15121da177e4SLinus Torvalds 15131da177e4SLinus Torvalds /** 1514814e1d25SWang Sheng-Hui * block_invalidatepage - invalidate part or all of a buffer-backed page 15151da177e4SLinus Torvalds * 15161da177e4SLinus Torvalds * @page: the page which is affected 1517d47992f8SLukas Czerner * @offset: start of the range to invalidate 1518d47992f8SLukas Czerner * @length: length of the range to invalidate 15191da177e4SLinus Torvalds * 15201da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 15211da177e4SLinus Torvalds * invalidated by a truncate operation. 15221da177e4SLinus Torvalds * 15231da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 15241da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 15251da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 15261da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 15271da177e4SLinus Torvalds * blocks on-disk. 15281da177e4SLinus Torvalds */ 1529d47992f8SLukas Czerner void block_invalidatepage(struct page *page, unsigned int offset, 1530d47992f8SLukas Czerner unsigned int length) 15311da177e4SLinus Torvalds { 15321da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 15331da177e4SLinus Torvalds unsigned int curr_off = 0; 1534d47992f8SLukas Czerner unsigned int stop = length + offset; 15351da177e4SLinus Torvalds 15361da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 15371da177e4SLinus Torvalds if (!page_has_buffers(page)) 15381da177e4SLinus Torvalds goto out; 15391da177e4SLinus Torvalds 1540d47992f8SLukas Czerner /* 1541d47992f8SLukas Czerner * Check for overflow 1542d47992f8SLukas Czerner */ 1543d47992f8SLukas Czerner BUG_ON(stop > PAGE_CACHE_SIZE || stop < length); 1544d47992f8SLukas Czerner 15451da177e4SLinus Torvalds head = page_buffers(page); 15461da177e4SLinus Torvalds bh = head; 15471da177e4SLinus Torvalds do { 15481da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 15491da177e4SLinus Torvalds next = bh->b_this_page; 15501da177e4SLinus Torvalds 15511da177e4SLinus Torvalds /* 1552d47992f8SLukas Czerner * Are we still fully in range ? 1553d47992f8SLukas Czerner */ 1554d47992f8SLukas Czerner if (next_off > stop) 1555d47992f8SLukas Czerner goto out; 1556d47992f8SLukas Czerner 1557d47992f8SLukas Czerner /* 15581da177e4SLinus Torvalds * is this block fully invalidated? 15591da177e4SLinus Torvalds */ 15601da177e4SLinus Torvalds if (offset <= curr_off) 15611da177e4SLinus Torvalds discard_buffer(bh); 15621da177e4SLinus Torvalds curr_off = next_off; 15631da177e4SLinus Torvalds bh = next; 15641da177e4SLinus Torvalds } while (bh != head); 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds /* 15671da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 15681da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 15691da177e4SLinus Torvalds * so real IO is not possible anymore. 15701da177e4SLinus Torvalds */ 15711da177e4SLinus Torvalds if (offset == 0) 15722ff28e22SNeilBrown try_to_release_page(page, 0); 15731da177e4SLinus Torvalds out: 15742ff28e22SNeilBrown return; 15751da177e4SLinus Torvalds } 15761da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 15771da177e4SLinus Torvalds 1578d47992f8SLukas Czerner 15791da177e4SLinus Torvalds /* 15801da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15811da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15821da177e4SLinus Torvalds * is already excluded via the page lock. 15831da177e4SLinus Torvalds */ 15841da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15851da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15861da177e4SLinus Torvalds { 15871da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15881da177e4SLinus Torvalds 15891da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15901da177e4SLinus Torvalds bh = head; 15911da177e4SLinus Torvalds do { 15921da177e4SLinus Torvalds bh->b_state |= b_state; 15931da177e4SLinus Torvalds tail = bh; 15941da177e4SLinus Torvalds bh = bh->b_this_page; 15951da177e4SLinus Torvalds } while (bh); 15961da177e4SLinus Torvalds tail->b_this_page = head; 15971da177e4SLinus Torvalds 15981da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15991da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 16001da177e4SLinus Torvalds bh = head; 16011da177e4SLinus Torvalds do { 16021da177e4SLinus Torvalds if (PageDirty(page)) 16031da177e4SLinus Torvalds set_buffer_dirty(bh); 16041da177e4SLinus Torvalds if (PageUptodate(page)) 16051da177e4SLinus Torvalds set_buffer_uptodate(bh); 16061da177e4SLinus Torvalds bh = bh->b_this_page; 16071da177e4SLinus Torvalds } while (bh != head); 16081da177e4SLinus Torvalds } 16091da177e4SLinus Torvalds attach_page_buffers(page, head); 16101da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 16111da177e4SLinus Torvalds } 16121da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 16131da177e4SLinus Torvalds 16141da177e4SLinus Torvalds /* 16151da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 16161da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 16171da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 16181da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 16191da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 16201da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 16211da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 16221da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 16231da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 16241da177e4SLinus Torvalds * 16251da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 16261da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 16271da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 16281da177e4SLinus Torvalds * only if we really need to. That happens here. 16291da177e4SLinus Torvalds */ 16301da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 16311da177e4SLinus Torvalds { 16321da177e4SLinus Torvalds struct buffer_head *old_bh; 16331da177e4SLinus Torvalds 16341da177e4SLinus Torvalds might_sleep(); 16351da177e4SLinus Torvalds 1636385fd4c5SCoywolf Qi Hunt old_bh = __find_get_block_slow(bdev, block); 16371da177e4SLinus Torvalds if (old_bh) { 16381da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 16391da177e4SLinus Torvalds wait_on_buffer(old_bh); 16401da177e4SLinus Torvalds clear_buffer_req(old_bh); 16411da177e4SLinus Torvalds __brelse(old_bh); 16421da177e4SLinus Torvalds } 16431da177e4SLinus Torvalds } 16441da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 16451da177e4SLinus Torvalds 16461da177e4SLinus Torvalds /* 164745bce8f3SLinus Torvalds * Size is a power-of-two in the range 512..PAGE_SIZE, 164845bce8f3SLinus Torvalds * and the case we care about most is PAGE_SIZE. 164945bce8f3SLinus Torvalds * 165045bce8f3SLinus Torvalds * So this *could* possibly be written with those 165145bce8f3SLinus Torvalds * constraints in mind (relevant mostly if some 165245bce8f3SLinus Torvalds * architecture has a slow bit-scan instruction) 165345bce8f3SLinus Torvalds */ 165445bce8f3SLinus Torvalds static inline int block_size_bits(unsigned int blocksize) 165545bce8f3SLinus Torvalds { 165645bce8f3SLinus Torvalds return ilog2(blocksize); 165745bce8f3SLinus Torvalds } 165845bce8f3SLinus Torvalds 165945bce8f3SLinus Torvalds static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) 166045bce8f3SLinus Torvalds { 166145bce8f3SLinus Torvalds BUG_ON(!PageLocked(page)); 166245bce8f3SLinus Torvalds 166345bce8f3SLinus Torvalds if (!page_has_buffers(page)) 166445bce8f3SLinus Torvalds create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state); 166545bce8f3SLinus Torvalds return page_buffers(page); 166645bce8f3SLinus Torvalds } 166745bce8f3SLinus Torvalds 166845bce8f3SLinus Torvalds /* 16691da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 16701da177e4SLinus Torvalds * 16711da177e4SLinus Torvalds * Mapped Uptodate Meaning 16721da177e4SLinus Torvalds * 16731da177e4SLinus Torvalds * No No "unknown" - must do get_block() 16741da177e4SLinus Torvalds * No Yes "hole" - zero-filled 16751da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 16761da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 16771da177e4SLinus Torvalds * 16781da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16791da177e4SLinus Torvalds */ 16801da177e4SLinus Torvalds 16811da177e4SLinus Torvalds /* 16821da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16831da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16841da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16851da177e4SLinus Torvalds * state inside lock_buffer(). 16861da177e4SLinus Torvalds * 16871da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16881da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16891da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16901da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16911da177e4SLinus Torvalds * prevents this contention from occurring. 16926e34eeddSTheodore Ts'o * 16936e34eeddSTheodore Ts'o * If block_write_full_page() is called with wbc->sync_mode == 1694721a9602SJens Axboe * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this 1695721a9602SJens Axboe * causes the writes to be flagged as synchronous writes. 16961da177e4SLinus Torvalds */ 16971da177e4SLinus Torvalds static int __block_write_full_page(struct inode *inode, struct page *page, 169835c80d5fSChris Mason get_block_t *get_block, struct writeback_control *wbc, 169935c80d5fSChris Mason bh_end_io_t *handler) 17001da177e4SLinus Torvalds { 17011da177e4SLinus Torvalds int err; 17021da177e4SLinus Torvalds sector_t block; 17031da177e4SLinus Torvalds sector_t last_block; 1704f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 170545bce8f3SLinus Torvalds unsigned int blocksize, bbits; 17061da177e4SLinus Torvalds int nr_underway = 0; 17076e34eeddSTheodore Ts'o int write_op = (wbc->sync_mode == WB_SYNC_ALL ? 1708721a9602SJens Axboe WRITE_SYNC : WRITE); 17091da177e4SLinus Torvalds 171045bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 17111da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 17121da177e4SLinus Torvalds 17131da177e4SLinus Torvalds /* 17141da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 17151da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 17161da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 17171da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 17181da177e4SLinus Torvalds * 17191da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 17201da177e4SLinus Torvalds * handle that here by just cleaning them. 17211da177e4SLinus Torvalds */ 17221da177e4SLinus Torvalds 17231da177e4SLinus Torvalds bh = head; 172445bce8f3SLinus Torvalds blocksize = bh->b_size; 172545bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 172645bce8f3SLinus Torvalds 172745bce8f3SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 172845bce8f3SLinus Torvalds last_block = (i_size_read(inode) - 1) >> bbits; 17291da177e4SLinus Torvalds 17301da177e4SLinus Torvalds /* 17311da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 17321da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 17331da177e4SLinus Torvalds */ 17341da177e4SLinus Torvalds do { 17351da177e4SLinus Torvalds if (block > last_block) { 17361da177e4SLinus Torvalds /* 17371da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 17381da177e4SLinus Torvalds * this page can be outside i_size when there is a 17391da177e4SLinus Torvalds * truncate in progress. 17401da177e4SLinus Torvalds */ 17411da177e4SLinus Torvalds /* 17421da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 17431da177e4SLinus Torvalds */ 17441da177e4SLinus Torvalds clear_buffer_dirty(bh); 17451da177e4SLinus Torvalds set_buffer_uptodate(bh); 174629a814d2SAlex Tomas } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && 174729a814d2SAlex Tomas buffer_dirty(bh)) { 1748b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 17491da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 17501da177e4SLinus Torvalds if (err) 17511da177e4SLinus Torvalds goto recover; 175229a814d2SAlex Tomas clear_buffer_delay(bh); 17531da177e4SLinus Torvalds if (buffer_new(bh)) { 17541da177e4SLinus Torvalds /* blockdev mappings never come here */ 17551da177e4SLinus Torvalds clear_buffer_new(bh); 17561da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 17571da177e4SLinus Torvalds bh->b_blocknr); 17581da177e4SLinus Torvalds } 17591da177e4SLinus Torvalds } 17601da177e4SLinus Torvalds bh = bh->b_this_page; 17611da177e4SLinus Torvalds block++; 17621da177e4SLinus Torvalds } while (bh != head); 17631da177e4SLinus Torvalds 17641da177e4SLinus Torvalds do { 17651da177e4SLinus Torvalds if (!buffer_mapped(bh)) 17661da177e4SLinus Torvalds continue; 17671da177e4SLinus Torvalds /* 17681da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17691da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17705b0830cbSJens Axboe * potentially cause a busy-wait loop from writeback threads 17715b0830cbSJens Axboe * and kswapd activity, but those code paths have their own 17725b0830cbSJens Axboe * higher-level throttling. 17731da177e4SLinus Torvalds */ 17741b430beeSWu Fengguang if (wbc->sync_mode != WB_SYNC_NONE) { 17751da177e4SLinus Torvalds lock_buffer(bh); 1776ca5de404SNick Piggin } else if (!trylock_buffer(bh)) { 17771da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 17781da177e4SLinus Torvalds continue; 17791da177e4SLinus Torvalds } 17801da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 178135c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17821da177e4SLinus Torvalds } else { 17831da177e4SLinus Torvalds unlock_buffer(bh); 17841da177e4SLinus Torvalds } 17851da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17861da177e4SLinus Torvalds 17871da177e4SLinus Torvalds /* 17881da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17891da177e4SLinus Torvalds * drop the bh refcounts early. 17901da177e4SLinus Torvalds */ 17911da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17921da177e4SLinus Torvalds set_page_writeback(page); 17931da177e4SLinus Torvalds 17941da177e4SLinus Torvalds do { 17951da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17961da177e4SLinus Torvalds if (buffer_async_write(bh)) { 1797a64c8610STheodore Ts'o submit_bh(write_op, bh); 17981da177e4SLinus Torvalds nr_underway++; 1799ad576e63SNick Piggin } 18001da177e4SLinus Torvalds bh = next; 18011da177e4SLinus Torvalds } while (bh != head); 180205937baaSAndrew Morton unlock_page(page); 18031da177e4SLinus Torvalds 18041da177e4SLinus Torvalds err = 0; 18051da177e4SLinus Torvalds done: 18061da177e4SLinus Torvalds if (nr_underway == 0) { 18071da177e4SLinus Torvalds /* 18081da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 18091da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 18101da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 18111da177e4SLinus Torvalds */ 18121da177e4SLinus Torvalds end_page_writeback(page); 18133d67f2d7SNick Piggin 18141da177e4SLinus Torvalds /* 18151da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 18161da177e4SLinus Torvalds * here on. 18171da177e4SLinus Torvalds */ 18181da177e4SLinus Torvalds } 18191da177e4SLinus Torvalds return err; 18201da177e4SLinus Torvalds 18211da177e4SLinus Torvalds recover: 18221da177e4SLinus Torvalds /* 18231da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 18241da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 18251da177e4SLinus Torvalds * exposing stale data. 18261da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 18271da177e4SLinus Torvalds */ 18281da177e4SLinus Torvalds bh = head; 18291da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 18301da177e4SLinus Torvalds do { 183129a814d2SAlex Tomas if (buffer_mapped(bh) && buffer_dirty(bh) && 183229a814d2SAlex Tomas !buffer_delay(bh)) { 18331da177e4SLinus Torvalds lock_buffer(bh); 183435c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 18351da177e4SLinus Torvalds } else { 18361da177e4SLinus Torvalds /* 18371da177e4SLinus Torvalds * The buffer may have been set dirty during 18381da177e4SLinus Torvalds * attachment to a dirty page. 18391da177e4SLinus Torvalds */ 18401da177e4SLinus Torvalds clear_buffer_dirty(bh); 18411da177e4SLinus Torvalds } 18421da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 18431da177e4SLinus Torvalds SetPageError(page); 18441da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 18457e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 18461da177e4SLinus Torvalds set_page_writeback(page); 18471da177e4SLinus Torvalds do { 18481da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18491da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18501da177e4SLinus Torvalds clear_buffer_dirty(bh); 1851a64c8610STheodore Ts'o submit_bh(write_op, bh); 18521da177e4SLinus Torvalds nr_underway++; 1853ad576e63SNick Piggin } 18541da177e4SLinus Torvalds bh = next; 18551da177e4SLinus Torvalds } while (bh != head); 1856ffda9d30SNick Piggin unlock_page(page); 18571da177e4SLinus Torvalds goto done; 18581da177e4SLinus Torvalds } 18591da177e4SLinus Torvalds 1860afddba49SNick Piggin /* 1861afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1862afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1863afddba49SNick Piggin * block data from leaking). And clear the new bit. 1864afddba49SNick Piggin */ 1865afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1866afddba49SNick Piggin { 1867afddba49SNick Piggin unsigned int block_start, block_end; 1868afddba49SNick Piggin struct buffer_head *head, *bh; 1869afddba49SNick Piggin 1870afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1871afddba49SNick Piggin if (!page_has_buffers(page)) 1872afddba49SNick Piggin return; 1873afddba49SNick Piggin 1874afddba49SNick Piggin bh = head = page_buffers(page); 1875afddba49SNick Piggin block_start = 0; 1876afddba49SNick Piggin do { 1877afddba49SNick Piggin block_end = block_start + bh->b_size; 1878afddba49SNick Piggin 1879afddba49SNick Piggin if (buffer_new(bh)) { 1880afddba49SNick Piggin if (block_end > from && block_start < to) { 1881afddba49SNick Piggin if (!PageUptodate(page)) { 1882afddba49SNick Piggin unsigned start, size; 1883afddba49SNick Piggin 1884afddba49SNick Piggin start = max(from, block_start); 1885afddba49SNick Piggin size = min(to, block_end) - start; 1886afddba49SNick Piggin 1887eebd2aa3SChristoph Lameter zero_user(page, start, size); 1888afddba49SNick Piggin set_buffer_uptodate(bh); 1889afddba49SNick Piggin } 1890afddba49SNick Piggin 1891afddba49SNick Piggin clear_buffer_new(bh); 1892afddba49SNick Piggin mark_buffer_dirty(bh); 1893afddba49SNick Piggin } 1894afddba49SNick Piggin } 1895afddba49SNick Piggin 1896afddba49SNick Piggin block_start = block_end; 1897afddba49SNick Piggin bh = bh->b_this_page; 1898afddba49SNick Piggin } while (bh != head); 1899afddba49SNick Piggin } 1900afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1901afddba49SNick Piggin 1902ebdec241SChristoph Hellwig int __block_write_begin(struct page *page, loff_t pos, unsigned len, 19036e1db88dSChristoph Hellwig get_block_t *get_block) 19041da177e4SLinus Torvalds { 1905ebdec241SChristoph Hellwig unsigned from = pos & (PAGE_CACHE_SIZE - 1); 1906ebdec241SChristoph Hellwig unsigned to = from + len; 19076e1db88dSChristoph Hellwig struct inode *inode = page->mapping->host; 19081da177e4SLinus Torvalds unsigned block_start, block_end; 19091da177e4SLinus Torvalds sector_t block; 19101da177e4SLinus Torvalds int err = 0; 19111da177e4SLinus Torvalds unsigned blocksize, bbits; 19121da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 19131da177e4SLinus Torvalds 19141da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 19151da177e4SLinus Torvalds BUG_ON(from > PAGE_CACHE_SIZE); 19161da177e4SLinus Torvalds BUG_ON(to > PAGE_CACHE_SIZE); 19171da177e4SLinus Torvalds BUG_ON(from > to); 19181da177e4SLinus Torvalds 191945bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 192045bce8f3SLinus Torvalds blocksize = head->b_size; 192145bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 19221da177e4SLinus Torvalds 19231da177e4SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 19241da177e4SLinus Torvalds 19251da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 19261da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 19271da177e4SLinus Torvalds block_end = block_start + blocksize; 19281da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19291da177e4SLinus Torvalds if (PageUptodate(page)) { 19301da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19311da177e4SLinus Torvalds set_buffer_uptodate(bh); 19321da177e4SLinus Torvalds } 19331da177e4SLinus Torvalds continue; 19341da177e4SLinus Torvalds } 19351da177e4SLinus Torvalds if (buffer_new(bh)) 19361da177e4SLinus Torvalds clear_buffer_new(bh); 19371da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1938b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 19391da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 19401da177e4SLinus Torvalds if (err) 1941f3ddbdc6SNick Piggin break; 19421da177e4SLinus Torvalds if (buffer_new(bh)) { 19431da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 19441da177e4SLinus Torvalds bh->b_blocknr); 19451da177e4SLinus Torvalds if (PageUptodate(page)) { 1946637aff46SNick Piggin clear_buffer_new(bh); 19471da177e4SLinus Torvalds set_buffer_uptodate(bh); 1948637aff46SNick Piggin mark_buffer_dirty(bh); 19491da177e4SLinus Torvalds continue; 19501da177e4SLinus Torvalds } 1951eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 1952eebd2aa3SChristoph Lameter zero_user_segments(page, 1953eebd2aa3SChristoph Lameter to, block_end, 1954eebd2aa3SChristoph Lameter block_start, from); 19551da177e4SLinus Torvalds continue; 19561da177e4SLinus Torvalds } 19571da177e4SLinus Torvalds } 19581da177e4SLinus Torvalds if (PageUptodate(page)) { 19591da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19601da177e4SLinus Torvalds set_buffer_uptodate(bh); 19611da177e4SLinus Torvalds continue; 19621da177e4SLinus Torvalds } 19631da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 196433a266ddSDavid Chinner !buffer_unwritten(bh) && 19651da177e4SLinus Torvalds (block_start < from || block_end > to)) { 19661da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 19671da177e4SLinus Torvalds *wait_bh++=bh; 19681da177e4SLinus Torvalds } 19691da177e4SLinus Torvalds } 19701da177e4SLinus Torvalds /* 19711da177e4SLinus Torvalds * If we issued read requests - let them complete. 19721da177e4SLinus Torvalds */ 19731da177e4SLinus Torvalds while(wait_bh > wait) { 19741da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 19751da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1976f3ddbdc6SNick Piggin err = -EIO; 19771da177e4SLinus Torvalds } 1978f9f07b6cSJan Kara if (unlikely(err)) 1979afddba49SNick Piggin page_zero_new_buffers(page, from, to); 19801da177e4SLinus Torvalds return err; 19811da177e4SLinus Torvalds } 1982ebdec241SChristoph Hellwig EXPORT_SYMBOL(__block_write_begin); 19831da177e4SLinus Torvalds 19841da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 19851da177e4SLinus Torvalds unsigned from, unsigned to) 19861da177e4SLinus Torvalds { 19871da177e4SLinus Torvalds unsigned block_start, block_end; 19881da177e4SLinus Torvalds int partial = 0; 19891da177e4SLinus Torvalds unsigned blocksize; 19901da177e4SLinus Torvalds struct buffer_head *bh, *head; 19911da177e4SLinus Torvalds 199245bce8f3SLinus Torvalds bh = head = page_buffers(page); 199345bce8f3SLinus Torvalds blocksize = bh->b_size; 19941da177e4SLinus Torvalds 199545bce8f3SLinus Torvalds block_start = 0; 199645bce8f3SLinus Torvalds do { 19971da177e4SLinus Torvalds block_end = block_start + blocksize; 19981da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19991da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 20001da177e4SLinus Torvalds partial = 1; 20011da177e4SLinus Torvalds } else { 20021da177e4SLinus Torvalds set_buffer_uptodate(bh); 20031da177e4SLinus Torvalds mark_buffer_dirty(bh); 20041da177e4SLinus Torvalds } 2005afddba49SNick Piggin clear_buffer_new(bh); 200645bce8f3SLinus Torvalds 200745bce8f3SLinus Torvalds block_start = block_end; 200845bce8f3SLinus Torvalds bh = bh->b_this_page; 200945bce8f3SLinus Torvalds } while (bh != head); 20101da177e4SLinus Torvalds 20111da177e4SLinus Torvalds /* 20121da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 20131da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 20141da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 20151da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 20161da177e4SLinus Torvalds */ 20171da177e4SLinus Torvalds if (!partial) 20181da177e4SLinus Torvalds SetPageUptodate(page); 20191da177e4SLinus Torvalds return 0; 20201da177e4SLinus Torvalds } 20211da177e4SLinus Torvalds 20221da177e4SLinus Torvalds /* 2023155130a4SChristoph Hellwig * block_write_begin takes care of the basic task of block allocation and 2024155130a4SChristoph Hellwig * bringing partial write blocks uptodate first. 2025155130a4SChristoph Hellwig * 20267bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 2027afddba49SNick Piggin */ 2028155130a4SChristoph Hellwig int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 2029155130a4SChristoph Hellwig unsigned flags, struct page **pagep, get_block_t *get_block) 2030afddba49SNick Piggin { 20316e1db88dSChristoph Hellwig pgoff_t index = pos >> PAGE_CACHE_SHIFT; 2032afddba49SNick Piggin struct page *page; 20336e1db88dSChristoph Hellwig int status; 2034afddba49SNick Piggin 203554566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 20366e1db88dSChristoph Hellwig if (!page) 20376e1db88dSChristoph Hellwig return -ENOMEM; 2038afddba49SNick Piggin 20396e1db88dSChristoph Hellwig status = __block_write_begin(page, pos, len, get_block); 2040afddba49SNick Piggin if (unlikely(status)) { 2041afddba49SNick Piggin unlock_page(page); 2042afddba49SNick Piggin page_cache_release(page); 20436e1db88dSChristoph Hellwig page = NULL; 2044afddba49SNick Piggin } 2045afddba49SNick Piggin 20466e1db88dSChristoph Hellwig *pagep = page; 2047afddba49SNick Piggin return status; 2048afddba49SNick Piggin } 2049afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2050afddba49SNick Piggin 2051afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2052afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2053afddba49SNick Piggin struct page *page, void *fsdata) 2054afddba49SNick Piggin { 2055afddba49SNick Piggin struct inode *inode = mapping->host; 2056afddba49SNick Piggin unsigned start; 2057afddba49SNick Piggin 2058afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 2059afddba49SNick Piggin 2060afddba49SNick Piggin if (unlikely(copied < len)) { 2061afddba49SNick Piggin /* 2062afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2063afddba49SNick Piggin * don't have to worry about a readpage reading them and 2064afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2065afddba49SNick Piggin * a short write and only partially written into a buffer, it 2066afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2067afddba49SNick Piggin * destroy our partial write. 2068afddba49SNick Piggin * 2069afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2070afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2071afddba49SNick Piggin * caller to redo the whole thing. 2072afddba49SNick Piggin */ 2073afddba49SNick Piggin if (!PageUptodate(page)) 2074afddba49SNick Piggin copied = 0; 2075afddba49SNick Piggin 2076afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2077afddba49SNick Piggin } 2078afddba49SNick Piggin flush_dcache_page(page); 2079afddba49SNick Piggin 2080afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2081afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2082afddba49SNick Piggin 2083afddba49SNick Piggin return copied; 2084afddba49SNick Piggin } 2085afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2086afddba49SNick Piggin 2087afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2088afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2089afddba49SNick Piggin struct page *page, void *fsdata) 2090afddba49SNick Piggin { 2091afddba49SNick Piggin struct inode *inode = mapping->host; 209290a80202SJan Kara loff_t old_size = inode->i_size; 2093c7d206b3SJan Kara int i_size_changed = 0; 2094afddba49SNick Piggin 2095afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2096afddba49SNick Piggin 2097afddba49SNick Piggin /* 2098afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2099afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2100afddba49SNick Piggin * 2101afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2102afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2103afddba49SNick Piggin */ 2104afddba49SNick Piggin if (pos+copied > inode->i_size) { 2105afddba49SNick Piggin i_size_write(inode, pos+copied); 2106c7d206b3SJan Kara i_size_changed = 1; 2107afddba49SNick Piggin } 2108afddba49SNick Piggin 2109afddba49SNick Piggin unlock_page(page); 2110afddba49SNick Piggin page_cache_release(page); 2111afddba49SNick Piggin 211290a80202SJan Kara if (old_size < pos) 211390a80202SJan Kara pagecache_isize_extended(inode, old_size, pos); 2114c7d206b3SJan Kara /* 2115c7d206b3SJan Kara * Don't mark the inode dirty under page lock. First, it unnecessarily 2116c7d206b3SJan Kara * makes the holding time of page lock longer. Second, it forces lock 2117c7d206b3SJan Kara * ordering of page lock and transaction start for journaling 2118c7d206b3SJan Kara * filesystems. 2119c7d206b3SJan Kara */ 2120c7d206b3SJan Kara if (i_size_changed) 2121c7d206b3SJan Kara mark_inode_dirty(inode); 2122c7d206b3SJan Kara 2123afddba49SNick Piggin return copied; 2124afddba49SNick Piggin } 2125afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2126afddba49SNick Piggin 2127afddba49SNick Piggin /* 21288ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 21298ab22b9aSHisashi Hifumi * uptodate or not. 21308ab22b9aSHisashi Hifumi * 21318ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 21328ab22b9aSHisashi Hifumi * we want to read are uptodate. 21338ab22b9aSHisashi Hifumi */ 2134c186afb4SAl Viro int block_is_partially_uptodate(struct page *page, unsigned long from, 2135c186afb4SAl Viro unsigned long count) 21368ab22b9aSHisashi Hifumi { 21378ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 21388ab22b9aSHisashi Hifumi unsigned to; 21398ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 21408ab22b9aSHisashi Hifumi int ret = 1; 21418ab22b9aSHisashi Hifumi 21428ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 21438ab22b9aSHisashi Hifumi return 0; 21448ab22b9aSHisashi Hifumi 214545bce8f3SLinus Torvalds head = page_buffers(page); 214645bce8f3SLinus Torvalds blocksize = head->b_size; 2147c186afb4SAl Viro to = min_t(unsigned, PAGE_CACHE_SIZE - from, count); 21488ab22b9aSHisashi Hifumi to = from + to; 21498ab22b9aSHisashi Hifumi if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) 21508ab22b9aSHisashi Hifumi return 0; 21518ab22b9aSHisashi Hifumi 21528ab22b9aSHisashi Hifumi bh = head; 21538ab22b9aSHisashi Hifumi block_start = 0; 21548ab22b9aSHisashi Hifumi do { 21558ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 21568ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 21578ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 21588ab22b9aSHisashi Hifumi ret = 0; 21598ab22b9aSHisashi Hifumi break; 21608ab22b9aSHisashi Hifumi } 21618ab22b9aSHisashi Hifumi if (block_end >= to) 21628ab22b9aSHisashi Hifumi break; 21638ab22b9aSHisashi Hifumi } 21648ab22b9aSHisashi Hifumi block_start = block_end; 21658ab22b9aSHisashi Hifumi bh = bh->b_this_page; 21668ab22b9aSHisashi Hifumi } while (bh != head); 21678ab22b9aSHisashi Hifumi 21688ab22b9aSHisashi Hifumi return ret; 21698ab22b9aSHisashi Hifumi } 21708ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 21718ab22b9aSHisashi Hifumi 21728ab22b9aSHisashi Hifumi /* 21731da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 21741da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 21751da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 21761da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 21771da177e4SLinus Torvalds * page struct once IO has completed. 21781da177e4SLinus Torvalds */ 21791da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 21801da177e4SLinus Torvalds { 21811da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21821da177e4SLinus Torvalds sector_t iblock, lblock; 21831da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 218445bce8f3SLinus Torvalds unsigned int blocksize, bbits; 21851da177e4SLinus Torvalds int nr, i; 21861da177e4SLinus Torvalds int fully_mapped = 1; 21871da177e4SLinus Torvalds 218845bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 218945bce8f3SLinus Torvalds blocksize = head->b_size; 219045bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 21911da177e4SLinus Torvalds 219245bce8f3SLinus Torvalds iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 219345bce8f3SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> bbits; 21941da177e4SLinus Torvalds bh = head; 21951da177e4SLinus Torvalds nr = 0; 21961da177e4SLinus Torvalds i = 0; 21971da177e4SLinus Torvalds 21981da177e4SLinus Torvalds do { 21991da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22001da177e4SLinus Torvalds continue; 22011da177e4SLinus Torvalds 22021da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2203c64610baSAndrew Morton int err = 0; 2204c64610baSAndrew Morton 22051da177e4SLinus Torvalds fully_mapped = 0; 22061da177e4SLinus Torvalds if (iblock < lblock) { 2207b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2208c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2209c64610baSAndrew Morton if (err) 22101da177e4SLinus Torvalds SetPageError(page); 22111da177e4SLinus Torvalds } 22121da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2213eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2214c64610baSAndrew Morton if (!err) 22151da177e4SLinus Torvalds set_buffer_uptodate(bh); 22161da177e4SLinus Torvalds continue; 22171da177e4SLinus Torvalds } 22181da177e4SLinus Torvalds /* 22191da177e4SLinus Torvalds * get_block() might have updated the buffer 22201da177e4SLinus Torvalds * synchronously 22211da177e4SLinus Torvalds */ 22221da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22231da177e4SLinus Torvalds continue; 22241da177e4SLinus Torvalds } 22251da177e4SLinus Torvalds arr[nr++] = bh; 22261da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 22271da177e4SLinus Torvalds 22281da177e4SLinus Torvalds if (fully_mapped) 22291da177e4SLinus Torvalds SetPageMappedToDisk(page); 22301da177e4SLinus Torvalds 22311da177e4SLinus Torvalds if (!nr) { 22321da177e4SLinus Torvalds /* 22331da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 22341da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 22351da177e4SLinus Torvalds */ 22361da177e4SLinus Torvalds if (!PageError(page)) 22371da177e4SLinus Torvalds SetPageUptodate(page); 22381da177e4SLinus Torvalds unlock_page(page); 22391da177e4SLinus Torvalds return 0; 22401da177e4SLinus Torvalds } 22411da177e4SLinus Torvalds 22421da177e4SLinus Torvalds /* Stage two: lock the buffers */ 22431da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22441da177e4SLinus Torvalds bh = arr[i]; 22451da177e4SLinus Torvalds lock_buffer(bh); 22461da177e4SLinus Torvalds mark_buffer_async_read(bh); 22471da177e4SLinus Torvalds } 22481da177e4SLinus Torvalds 22491da177e4SLinus Torvalds /* 22501da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 22511da177e4SLinus Torvalds * inside the buffer lock in case another process reading 22521da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 22531da177e4SLinus Torvalds */ 22541da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22551da177e4SLinus Torvalds bh = arr[i]; 22561da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22571da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 22581da177e4SLinus Torvalds else 22591da177e4SLinus Torvalds submit_bh(READ, bh); 22601da177e4SLinus Torvalds } 22611da177e4SLinus Torvalds return 0; 22621da177e4SLinus Torvalds } 22631fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 22641da177e4SLinus Torvalds 22651da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 226689e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 22671da177e4SLinus Torvalds * deal with the hole. 22681da177e4SLinus Torvalds */ 226989e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 22701da177e4SLinus Torvalds { 22711da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 22721da177e4SLinus Torvalds struct page *page; 227389e10787SNick Piggin void *fsdata; 22741da177e4SLinus Torvalds int err; 22751da177e4SLinus Torvalds 2276c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2277c08d3b0eSnpiggin@suse.de if (err) 22781da177e4SLinus Torvalds goto out; 22791da177e4SLinus Torvalds 228089e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 228189e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, 228289e10787SNick Piggin &page, &fsdata); 228389e10787SNick Piggin if (err) 228405eb0b51SOGAWA Hirofumi goto out; 228505eb0b51SOGAWA Hirofumi 228689e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 228789e10787SNick Piggin BUG_ON(err > 0); 228805eb0b51SOGAWA Hirofumi 228905eb0b51SOGAWA Hirofumi out: 229005eb0b51SOGAWA Hirofumi return err; 229105eb0b51SOGAWA Hirofumi } 22921fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 229305eb0b51SOGAWA Hirofumi 2294f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 229589e10787SNick Piggin loff_t pos, loff_t *bytes) 229605eb0b51SOGAWA Hirofumi { 229789e10787SNick Piggin struct inode *inode = mapping->host; 229889e10787SNick Piggin unsigned blocksize = 1 << inode->i_blkbits; 229989e10787SNick Piggin struct page *page; 230089e10787SNick Piggin void *fsdata; 230189e10787SNick Piggin pgoff_t index, curidx; 230289e10787SNick Piggin loff_t curpos; 230389e10787SNick Piggin unsigned zerofrom, offset, len; 230489e10787SNick Piggin int err = 0; 230505eb0b51SOGAWA Hirofumi 230689e10787SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 230789e10787SNick Piggin offset = pos & ~PAGE_CACHE_MASK; 230889e10787SNick Piggin 230989e10787SNick Piggin while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { 231089e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 231189e10787SNick Piggin if (zerofrom & (blocksize-1)) { 231289e10787SNick Piggin *bytes |= (blocksize-1); 231389e10787SNick Piggin (*bytes)++; 231489e10787SNick Piggin } 231589e10787SNick Piggin len = PAGE_CACHE_SIZE - zerofrom; 231689e10787SNick Piggin 231789e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 231889e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 231989e10787SNick Piggin &page, &fsdata); 232089e10787SNick Piggin if (err) 232189e10787SNick Piggin goto out; 2322eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 232389e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 232489e10787SNick Piggin page, fsdata); 232589e10787SNick Piggin if (err < 0) 232689e10787SNick Piggin goto out; 232789e10787SNick Piggin BUG_ON(err != len); 232889e10787SNick Piggin err = 0; 2329061e9746SOGAWA Hirofumi 2330061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 2331c2ca0fcdSMikulas Patocka 2332c2ca0fcdSMikulas Patocka if (unlikely(fatal_signal_pending(current))) { 2333c2ca0fcdSMikulas Patocka err = -EINTR; 2334c2ca0fcdSMikulas Patocka goto out; 2335c2ca0fcdSMikulas Patocka } 233689e10787SNick Piggin } 233789e10787SNick Piggin 233889e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 233989e10787SNick Piggin if (index == curidx) { 234089e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 234189e10787SNick Piggin /* if we will expand the thing last block will be filled */ 234289e10787SNick Piggin if (offset <= zerofrom) { 234389e10787SNick Piggin goto out; 234489e10787SNick Piggin } 234589e10787SNick Piggin if (zerofrom & (blocksize-1)) { 234689e10787SNick Piggin *bytes |= (blocksize-1); 234789e10787SNick Piggin (*bytes)++; 234889e10787SNick Piggin } 234989e10787SNick Piggin len = offset - zerofrom; 235089e10787SNick Piggin 235189e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 235289e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 235389e10787SNick Piggin &page, &fsdata); 235489e10787SNick Piggin if (err) 235589e10787SNick Piggin goto out; 2356eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 235789e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 235889e10787SNick Piggin page, fsdata); 235989e10787SNick Piggin if (err < 0) 236089e10787SNick Piggin goto out; 236189e10787SNick Piggin BUG_ON(err != len); 236289e10787SNick Piggin err = 0; 236389e10787SNick Piggin } 236489e10787SNick Piggin out: 236589e10787SNick Piggin return err; 23661da177e4SLinus Torvalds } 23671da177e4SLinus Torvalds 23681da177e4SLinus Torvalds /* 23691da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 23701da177e4SLinus Torvalds * We may have to extend the file. 23711da177e4SLinus Torvalds */ 2372282dc178SChristoph Hellwig int cont_write_begin(struct file *file, struct address_space *mapping, 237389e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 237489e10787SNick Piggin struct page **pagep, void **fsdata, 237589e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 23761da177e4SLinus Torvalds { 23771da177e4SLinus Torvalds struct inode *inode = mapping->host; 23781da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 237989e10787SNick Piggin unsigned zerofrom; 238089e10787SNick Piggin int err; 23811da177e4SLinus Torvalds 238289e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 238389e10787SNick Piggin if (err) 2384155130a4SChristoph Hellwig return err; 23851da177e4SLinus Torvalds 23861da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 238789e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 23881da177e4SLinus Torvalds *bytes |= (blocksize-1); 23891da177e4SLinus Torvalds (*bytes)++; 23901da177e4SLinus Torvalds } 23911da177e4SLinus Torvalds 2392155130a4SChristoph Hellwig return block_write_begin(mapping, pos, len, flags, pagep, get_block); 23931da177e4SLinus Torvalds } 23941fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 23951da177e4SLinus Torvalds 23961da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 23971da177e4SLinus Torvalds { 23981da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23991da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 24001da177e4SLinus Torvalds return 0; 24011da177e4SLinus Torvalds } 24021fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 24031da177e4SLinus Torvalds 240454171690SDavid Chinner /* 240554171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 240654171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 240754171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 240854171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 240954171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 241054171690SDavid Chinner * support these features. 241154171690SDavid Chinner * 241254171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 241354171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 24147bb46a67Snpiggin@suse.de * truncate writes the inode size before removing pages, once we have the 241554171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 241654171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 241754171690SDavid Chinner * unlock the page. 2418ea13a864SJan Kara * 241914da9200SJan Kara * Direct callers of this function should protect against filesystem freezing 242014da9200SJan Kara * using sb_start_write() - sb_end_write() functions. 242154171690SDavid Chinner */ 242224da4fabSJan Kara int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 242354171690SDavid Chinner get_block_t get_block) 242454171690SDavid Chinner { 2425c2ec175cSNick Piggin struct page *page = vmf->page; 2426496ad9aaSAl Viro struct inode *inode = file_inode(vma->vm_file); 242754171690SDavid Chinner unsigned long end; 242854171690SDavid Chinner loff_t size; 242924da4fabSJan Kara int ret; 243054171690SDavid Chinner 243154171690SDavid Chinner lock_page(page); 243254171690SDavid Chinner size = i_size_read(inode); 243354171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 243418336338SNick Piggin (page_offset(page) > size)) { 243524da4fabSJan Kara /* We overload EFAULT to mean page got truncated */ 243624da4fabSJan Kara ret = -EFAULT; 243724da4fabSJan Kara goto out_unlock; 243854171690SDavid Chinner } 243954171690SDavid Chinner 244054171690SDavid Chinner /* page is wholly or partially inside EOF */ 244154171690SDavid Chinner if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) 244254171690SDavid Chinner end = size & ~PAGE_CACHE_MASK; 244354171690SDavid Chinner else 244454171690SDavid Chinner end = PAGE_CACHE_SIZE; 244554171690SDavid Chinner 2446ebdec241SChristoph Hellwig ret = __block_write_begin(page, 0, end, get_block); 244754171690SDavid Chinner if (!ret) 244854171690SDavid Chinner ret = block_commit_write(page, 0, end); 244954171690SDavid Chinner 245024da4fabSJan Kara if (unlikely(ret < 0)) 245124da4fabSJan Kara goto out_unlock; 2452ea13a864SJan Kara set_page_dirty(page); 24531d1d1a76SDarrick J. Wong wait_for_stable_page(page); 245424da4fabSJan Kara return 0; 245524da4fabSJan Kara out_unlock: 2456b827e496SNick Piggin unlock_page(page); 245754171690SDavid Chinner return ret; 245854171690SDavid Chinner } 245924da4fabSJan Kara EXPORT_SYMBOL(__block_page_mkwrite); 246024da4fabSJan Kara 246124da4fabSJan Kara int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 246224da4fabSJan Kara get_block_t get_block) 246324da4fabSJan Kara { 2464ea13a864SJan Kara int ret; 2465496ad9aaSAl Viro struct super_block *sb = file_inode(vma->vm_file)->i_sb; 246624da4fabSJan Kara 246714da9200SJan Kara sb_start_pagefault(sb); 2468041bbb6dSTheodore Ts'o 2469041bbb6dSTheodore Ts'o /* 2470041bbb6dSTheodore Ts'o * Update file times before taking page lock. We may end up failing the 2471041bbb6dSTheodore Ts'o * fault so this update may be superfluous but who really cares... 2472041bbb6dSTheodore Ts'o */ 2473041bbb6dSTheodore Ts'o file_update_time(vma->vm_file); 2474041bbb6dSTheodore Ts'o 2475ea13a864SJan Kara ret = __block_page_mkwrite(vma, vmf, get_block); 247614da9200SJan Kara sb_end_pagefault(sb); 247724da4fabSJan Kara return block_page_mkwrite_return(ret); 247824da4fabSJan Kara } 24791fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 24801da177e4SLinus Torvalds 24811da177e4SLinus Torvalds /* 248203158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 24831da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 24841da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 24851da177e4SLinus Torvalds */ 24861da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 24871da177e4SLinus Torvalds { 248868671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 24891da177e4SLinus Torvalds } 24901da177e4SLinus Torvalds 24911da177e4SLinus Torvalds /* 249203158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 249303158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 249403158cd7SNick Piggin * dirty races). 249503158cd7SNick Piggin */ 249603158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 249703158cd7SNick Piggin { 249803158cd7SNick Piggin struct buffer_head *bh; 249903158cd7SNick Piggin 250003158cd7SNick Piggin BUG_ON(!PageLocked(page)); 250103158cd7SNick Piggin 250203158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 250303158cd7SNick Piggin bh = head; 250403158cd7SNick Piggin do { 250503158cd7SNick Piggin if (PageDirty(page)) 250603158cd7SNick Piggin set_buffer_dirty(bh); 250703158cd7SNick Piggin if (!bh->b_this_page) 250803158cd7SNick Piggin bh->b_this_page = head; 250903158cd7SNick Piggin bh = bh->b_this_page; 251003158cd7SNick Piggin } while (bh != head); 251103158cd7SNick Piggin attach_page_buffers(page, head); 251203158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 251303158cd7SNick Piggin } 251403158cd7SNick Piggin 251503158cd7SNick Piggin /* 2516ea0f04e5SChristoph Hellwig * On entry, the page is fully not uptodate. 2517ea0f04e5SChristoph Hellwig * On exit the page is fully uptodate in the areas outside (from,to) 25187bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 25191da177e4SLinus Torvalds */ 2520ea0f04e5SChristoph Hellwig int nobh_write_begin(struct address_space *mapping, 252103158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 252203158cd7SNick Piggin struct page **pagep, void **fsdata, 25231da177e4SLinus Torvalds get_block_t *get_block) 25241da177e4SLinus Torvalds { 252503158cd7SNick Piggin struct inode *inode = mapping->host; 25261da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 25271da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2528a4b0672dSNick Piggin struct buffer_head *head, *bh; 252903158cd7SNick Piggin struct page *page; 253003158cd7SNick Piggin pgoff_t index; 253103158cd7SNick Piggin unsigned from, to; 25321da177e4SLinus Torvalds unsigned block_in_page; 2533a4b0672dSNick Piggin unsigned block_start, block_end; 25341da177e4SLinus Torvalds sector_t block_in_file; 25351da177e4SLinus Torvalds int nr_reads = 0; 25361da177e4SLinus Torvalds int ret = 0; 25371da177e4SLinus Torvalds int is_mapped_to_disk = 1; 25381da177e4SLinus Torvalds 253903158cd7SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 254003158cd7SNick Piggin from = pos & (PAGE_CACHE_SIZE - 1); 254103158cd7SNick Piggin to = from + len; 254203158cd7SNick Piggin 254354566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 254403158cd7SNick Piggin if (!page) 254503158cd7SNick Piggin return -ENOMEM; 254603158cd7SNick Piggin *pagep = page; 254703158cd7SNick Piggin *fsdata = NULL; 254803158cd7SNick Piggin 254903158cd7SNick Piggin if (page_has_buffers(page)) { 2550309f77adSNamhyung Kim ret = __block_write_begin(page, pos, len, get_block); 2551309f77adSNamhyung Kim if (unlikely(ret)) 2552309f77adSNamhyung Kim goto out_release; 2553309f77adSNamhyung Kim return ret; 255403158cd7SNick Piggin } 2555a4b0672dSNick Piggin 25561da177e4SLinus Torvalds if (PageMappedToDisk(page)) 25571da177e4SLinus Torvalds return 0; 25581da177e4SLinus Torvalds 2559a4b0672dSNick Piggin /* 2560a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2561a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2562a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2563a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2564a4b0672dSNick Piggin * 2565a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2566a4b0672dSNick Piggin * than the circular one we're used to. 2567a4b0672dSNick Piggin */ 2568a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 256903158cd7SNick Piggin if (!head) { 257003158cd7SNick Piggin ret = -ENOMEM; 257103158cd7SNick Piggin goto out_release; 257203158cd7SNick Piggin } 2573a4b0672dSNick Piggin 25741da177e4SLinus Torvalds block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); 25751da177e4SLinus Torvalds 25761da177e4SLinus Torvalds /* 25771da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 25781da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 25791da177e4SLinus Torvalds * page is fully mapped-to-disk. 25801da177e4SLinus Torvalds */ 2581a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 25821da177e4SLinus Torvalds block_start < PAGE_CACHE_SIZE; 2583a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 25841da177e4SLinus Torvalds int create; 25851da177e4SLinus Torvalds 2586a4b0672dSNick Piggin block_end = block_start + blocksize; 2587a4b0672dSNick Piggin bh->b_state = 0; 25881da177e4SLinus Torvalds create = 1; 25891da177e4SLinus Torvalds if (block_start >= to) 25901da177e4SLinus Torvalds create = 0; 25911da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2592a4b0672dSNick Piggin bh, create); 25931da177e4SLinus Torvalds if (ret) 25941da177e4SLinus Torvalds goto failed; 2595a4b0672dSNick Piggin if (!buffer_mapped(bh)) 25961da177e4SLinus Torvalds is_mapped_to_disk = 0; 2597a4b0672dSNick Piggin if (buffer_new(bh)) 2598a4b0672dSNick Piggin unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 2599a4b0672dSNick Piggin if (PageUptodate(page)) { 2600a4b0672dSNick Piggin set_buffer_uptodate(bh); 26011da177e4SLinus Torvalds continue; 2602a4b0672dSNick Piggin } 2603a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2604eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2605eebd2aa3SChristoph Lameter to, block_end); 26061da177e4SLinus Torvalds continue; 26071da177e4SLinus Torvalds } 2608a4b0672dSNick Piggin if (buffer_uptodate(bh)) 26091da177e4SLinus Torvalds continue; /* reiserfs does this */ 26101da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2611a4b0672dSNick Piggin lock_buffer(bh); 2612a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 2613a4b0672dSNick Piggin submit_bh(READ, bh); 2614a4b0672dSNick Piggin nr_reads++; 26151da177e4SLinus Torvalds } 26161da177e4SLinus Torvalds } 26171da177e4SLinus Torvalds 26181da177e4SLinus Torvalds if (nr_reads) { 26191da177e4SLinus Torvalds /* 26201da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 26211da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 26221da177e4SLinus Torvalds * for the buffer_head refcounts. 26231da177e4SLinus Torvalds */ 2624a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 26251da177e4SLinus Torvalds wait_on_buffer(bh); 26261da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 26271da177e4SLinus Torvalds ret = -EIO; 26281da177e4SLinus Torvalds } 26291da177e4SLinus Torvalds if (ret) 26301da177e4SLinus Torvalds goto failed; 26311da177e4SLinus Torvalds } 26321da177e4SLinus Torvalds 26331da177e4SLinus Torvalds if (is_mapped_to_disk) 26341da177e4SLinus Torvalds SetPageMappedToDisk(page); 26351da177e4SLinus Torvalds 263603158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2637a4b0672dSNick Piggin 26381da177e4SLinus Torvalds return 0; 26391da177e4SLinus Torvalds 26401da177e4SLinus Torvalds failed: 264103158cd7SNick Piggin BUG_ON(!ret); 26421da177e4SLinus Torvalds /* 2643a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2644a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2645a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2646a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2647a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 26481da177e4SLinus Torvalds */ 264903158cd7SNick Piggin attach_nobh_buffers(page, head); 265003158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2651a4b0672dSNick Piggin 265203158cd7SNick Piggin out_release: 265303158cd7SNick Piggin unlock_page(page); 265403158cd7SNick Piggin page_cache_release(page); 265503158cd7SNick Piggin *pagep = NULL; 2656a4b0672dSNick Piggin 26577bb46a67Snpiggin@suse.de return ret; 26587bb46a67Snpiggin@suse.de } 265903158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 26601da177e4SLinus Torvalds 266103158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 266203158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 266303158cd7SNick Piggin struct page *page, void *fsdata) 26641da177e4SLinus Torvalds { 26651da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2666efdc3131SNick Piggin struct buffer_head *head = fsdata; 266703158cd7SNick Piggin struct buffer_head *bh; 26685b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 26691da177e4SLinus Torvalds 2670d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 267103158cd7SNick Piggin attach_nobh_buffers(page, head); 2672a4b0672dSNick Piggin if (page_has_buffers(page)) 267303158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 267403158cd7SNick Piggin copied, page, fsdata); 2675a4b0672dSNick Piggin 267622c8ca78SNick Piggin SetPageUptodate(page); 26771da177e4SLinus Torvalds set_page_dirty(page); 267803158cd7SNick Piggin if (pos+copied > inode->i_size) { 267903158cd7SNick Piggin i_size_write(inode, pos+copied); 26801da177e4SLinus Torvalds mark_inode_dirty(inode); 26811da177e4SLinus Torvalds } 268203158cd7SNick Piggin 268303158cd7SNick Piggin unlock_page(page); 268403158cd7SNick Piggin page_cache_release(page); 268503158cd7SNick Piggin 268603158cd7SNick Piggin while (head) { 268703158cd7SNick Piggin bh = head; 268803158cd7SNick Piggin head = head->b_this_page; 268903158cd7SNick Piggin free_buffer_head(bh); 26901da177e4SLinus Torvalds } 269103158cd7SNick Piggin 269203158cd7SNick Piggin return copied; 269303158cd7SNick Piggin } 269403158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 26951da177e4SLinus Torvalds 26961da177e4SLinus Torvalds /* 26971da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 26981da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 26991da177e4SLinus Torvalds * the page. 27001da177e4SLinus Torvalds */ 27011da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 27021da177e4SLinus Torvalds struct writeback_control *wbc) 27031da177e4SLinus Torvalds { 27041da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 27051da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 27061da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 27071da177e4SLinus Torvalds unsigned offset; 27081da177e4SLinus Torvalds int ret; 27091da177e4SLinus Torvalds 27101da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 27111da177e4SLinus Torvalds if (page->index < end_index) 27121da177e4SLinus Torvalds goto out; 27131da177e4SLinus Torvalds 27141da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 27151da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 27161da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 27171da177e4SLinus Torvalds /* 27181da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 27191da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 27201da177e4SLinus Torvalds * freeable here, so the page does not leak. 27211da177e4SLinus Torvalds */ 27221da177e4SLinus Torvalds #if 0 27231da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 27241da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 27251da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 27261da177e4SLinus Torvalds #endif 27271da177e4SLinus Torvalds unlock_page(page); 27281da177e4SLinus Torvalds return 0; /* don't care */ 27291da177e4SLinus Torvalds } 27301da177e4SLinus Torvalds 27311da177e4SLinus Torvalds /* 27321da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 27331da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 27341da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 27351da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 27361da177e4SLinus Torvalds * writes to that region are not written out to the file." 27371da177e4SLinus Torvalds */ 2738eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 27391da177e4SLinus Torvalds out: 27401da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 27411da177e4SLinus Torvalds if (ret == -EAGAIN) 274235c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 274335c80d5fSChris Mason end_buffer_async_write); 27441da177e4SLinus Torvalds return ret; 27451da177e4SLinus Torvalds } 27461da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27471da177e4SLinus Torvalds 274803158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 274903158cd7SNick Piggin loff_t from, get_block_t *get_block) 27501da177e4SLinus Torvalds { 27511da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 27521da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 275303158cd7SNick Piggin unsigned blocksize; 275403158cd7SNick Piggin sector_t iblock; 275503158cd7SNick Piggin unsigned length, pos; 275603158cd7SNick Piggin struct inode *inode = mapping->host; 27571da177e4SLinus Torvalds struct page *page; 275803158cd7SNick Piggin struct buffer_head map_bh; 275903158cd7SNick Piggin int err; 27601da177e4SLinus Torvalds 276103158cd7SNick Piggin blocksize = 1 << inode->i_blkbits; 276203158cd7SNick Piggin length = offset & (blocksize - 1); 27631da177e4SLinus Torvalds 276403158cd7SNick Piggin /* Block boundary? Nothing to do */ 276503158cd7SNick Piggin if (!length) 276603158cd7SNick Piggin return 0; 276703158cd7SNick Piggin 276803158cd7SNick Piggin length = blocksize - length; 276903158cd7SNick Piggin iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 277003158cd7SNick Piggin 27711da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 277203158cd7SNick Piggin err = -ENOMEM; 27731da177e4SLinus Torvalds if (!page) 27741da177e4SLinus Torvalds goto out; 27751da177e4SLinus Torvalds 277603158cd7SNick Piggin if (page_has_buffers(page)) { 277703158cd7SNick Piggin has_buffers: 277803158cd7SNick Piggin unlock_page(page); 277903158cd7SNick Piggin page_cache_release(page); 278003158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 27811da177e4SLinus Torvalds } 278203158cd7SNick Piggin 278303158cd7SNick Piggin /* Find the buffer that contains "offset" */ 278403158cd7SNick Piggin pos = blocksize; 278503158cd7SNick Piggin while (offset >= pos) { 278603158cd7SNick Piggin iblock++; 278703158cd7SNick Piggin pos += blocksize; 278803158cd7SNick Piggin } 278903158cd7SNick Piggin 2790460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2791460bcf57STheodore Ts'o map_bh.b_state = 0; 279203158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 279303158cd7SNick Piggin if (err) 279403158cd7SNick Piggin goto unlock; 279503158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 279603158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 279703158cd7SNick Piggin goto unlock; 279803158cd7SNick Piggin 279903158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 280003158cd7SNick Piggin if (!PageUptodate(page)) { 280103158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 280203158cd7SNick Piggin if (err) { 280303158cd7SNick Piggin page_cache_release(page); 280403158cd7SNick Piggin goto out; 280503158cd7SNick Piggin } 280603158cd7SNick Piggin lock_page(page); 280703158cd7SNick Piggin if (!PageUptodate(page)) { 280803158cd7SNick Piggin err = -EIO; 280903158cd7SNick Piggin goto unlock; 281003158cd7SNick Piggin } 281103158cd7SNick Piggin if (page_has_buffers(page)) 281203158cd7SNick Piggin goto has_buffers; 281303158cd7SNick Piggin } 2814eebd2aa3SChristoph Lameter zero_user(page, offset, length); 281503158cd7SNick Piggin set_page_dirty(page); 281603158cd7SNick Piggin err = 0; 281703158cd7SNick Piggin 281803158cd7SNick Piggin unlock: 28191da177e4SLinus Torvalds unlock_page(page); 28201da177e4SLinus Torvalds page_cache_release(page); 28211da177e4SLinus Torvalds out: 282203158cd7SNick Piggin return err; 28231da177e4SLinus Torvalds } 28241da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 28251da177e4SLinus Torvalds 28261da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 28271da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 28281da177e4SLinus Torvalds { 28291da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 28301da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 28311da177e4SLinus Torvalds unsigned blocksize; 283254b21a79SAndrew Morton sector_t iblock; 28331da177e4SLinus Torvalds unsigned length, pos; 28341da177e4SLinus Torvalds struct inode *inode = mapping->host; 28351da177e4SLinus Torvalds struct page *page; 28361da177e4SLinus Torvalds struct buffer_head *bh; 28371da177e4SLinus Torvalds int err; 28381da177e4SLinus Torvalds 28391da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 28401da177e4SLinus Torvalds length = offset & (blocksize - 1); 28411da177e4SLinus Torvalds 28421da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 28431da177e4SLinus Torvalds if (!length) 28441da177e4SLinus Torvalds return 0; 28451da177e4SLinus Torvalds 28461da177e4SLinus Torvalds length = blocksize - length; 284754b21a79SAndrew Morton iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 28481da177e4SLinus Torvalds 28491da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 28501da177e4SLinus Torvalds err = -ENOMEM; 28511da177e4SLinus Torvalds if (!page) 28521da177e4SLinus Torvalds goto out; 28531da177e4SLinus Torvalds 28541da177e4SLinus Torvalds if (!page_has_buffers(page)) 28551da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 28561da177e4SLinus Torvalds 28571da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 28581da177e4SLinus Torvalds bh = page_buffers(page); 28591da177e4SLinus Torvalds pos = blocksize; 28601da177e4SLinus Torvalds while (offset >= pos) { 28611da177e4SLinus Torvalds bh = bh->b_this_page; 28621da177e4SLinus Torvalds iblock++; 28631da177e4SLinus Torvalds pos += blocksize; 28641da177e4SLinus Torvalds } 28651da177e4SLinus Torvalds 28661da177e4SLinus Torvalds err = 0; 28671da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2868b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 28691da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 28701da177e4SLinus Torvalds if (err) 28711da177e4SLinus Torvalds goto unlock; 28721da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 28731da177e4SLinus Torvalds if (!buffer_mapped(bh)) 28741da177e4SLinus Torvalds goto unlock; 28751da177e4SLinus Torvalds } 28761da177e4SLinus Torvalds 28771da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 28781da177e4SLinus Torvalds if (PageUptodate(page)) 28791da177e4SLinus Torvalds set_buffer_uptodate(bh); 28801da177e4SLinus Torvalds 288133a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 28821da177e4SLinus Torvalds err = -EIO; 28831da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 28841da177e4SLinus Torvalds wait_on_buffer(bh); 28851da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 28861da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 28871da177e4SLinus Torvalds goto unlock; 28881da177e4SLinus Torvalds } 28891da177e4SLinus Torvalds 2890eebd2aa3SChristoph Lameter zero_user(page, offset, length); 28911da177e4SLinus Torvalds mark_buffer_dirty(bh); 28921da177e4SLinus Torvalds err = 0; 28931da177e4SLinus Torvalds 28941da177e4SLinus Torvalds unlock: 28951da177e4SLinus Torvalds unlock_page(page); 28961da177e4SLinus Torvalds page_cache_release(page); 28971da177e4SLinus Torvalds out: 28981da177e4SLinus Torvalds return err; 28991da177e4SLinus Torvalds } 29001fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 29011da177e4SLinus Torvalds 29021da177e4SLinus Torvalds /* 29031da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 29041da177e4SLinus Torvalds */ 29051b938c08SMatthew Wilcox int block_write_full_page(struct page *page, get_block_t *get_block, 29061b938c08SMatthew Wilcox struct writeback_control *wbc) 29071da177e4SLinus Torvalds { 29081da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 29091da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 29101da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 29111da177e4SLinus Torvalds unsigned offset; 29121da177e4SLinus Torvalds 29131da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 29141da177e4SLinus Torvalds if (page->index < end_index) 291535c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 29161b938c08SMatthew Wilcox end_buffer_async_write); 29171da177e4SLinus Torvalds 29181da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 29191da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 29201da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 29211da177e4SLinus Torvalds /* 29221da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 29231da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 29241da177e4SLinus Torvalds * freeable here, so the page does not leak. 29251da177e4SLinus Torvalds */ 2926d47992f8SLukas Czerner do_invalidatepage(page, 0, PAGE_CACHE_SIZE); 29271da177e4SLinus Torvalds unlock_page(page); 29281da177e4SLinus Torvalds return 0; /* don't care */ 29291da177e4SLinus Torvalds } 29301da177e4SLinus Torvalds 29311da177e4SLinus Torvalds /* 29321da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 29332a61aa40SAdam Buchbinder * writepage invocation because it may be mmapped. "A file is mapped 29341da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 29351da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 29361da177e4SLinus Torvalds * writes to that region are not written out to the file." 29371da177e4SLinus Torvalds */ 2938eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 29391b938c08SMatthew Wilcox return __block_write_full_page(inode, page, get_block, wbc, 294035c80d5fSChris Mason end_buffer_async_write); 294135c80d5fSChris Mason } 29421fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 294335c80d5fSChris Mason 29441da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29451da177e4SLinus Torvalds get_block_t *get_block) 29461da177e4SLinus Torvalds { 29471da177e4SLinus Torvalds struct buffer_head tmp; 29481da177e4SLinus Torvalds struct inode *inode = mapping->host; 29491da177e4SLinus Torvalds tmp.b_state = 0; 29501da177e4SLinus Torvalds tmp.b_blocknr = 0; 2951b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 29521da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 29531da177e4SLinus Torvalds return tmp.b_blocknr; 29541da177e4SLinus Torvalds } 29551fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 29561da177e4SLinus Torvalds 29576712ecf8SNeilBrown static void end_bio_bh_io_sync(struct bio *bio, int err) 29581da177e4SLinus Torvalds { 29591da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 29601da177e4SLinus Torvalds 296108bafc03SKeith Mannthey if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) 296208bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 296308bafc03SKeith Mannthey 29641da177e4SLinus Torvalds bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); 29651da177e4SLinus Torvalds bio_put(bio); 29661da177e4SLinus Torvalds } 29671da177e4SLinus Torvalds 296857302e0dSLinus Torvalds /* 296957302e0dSLinus Torvalds * This allows us to do IO even on the odd last sectors 297059d43914SAkinobu Mita * of a device, even if the block size is some multiple 297157302e0dSLinus Torvalds * of the physical sector size. 297257302e0dSLinus Torvalds * 297357302e0dSLinus Torvalds * We'll just truncate the bio to the size of the device, 297457302e0dSLinus Torvalds * and clear the end of the buffer head manually. 297557302e0dSLinus Torvalds * 297657302e0dSLinus Torvalds * Truly out-of-range accesses will turn into actual IO 297757302e0dSLinus Torvalds * errors, this only handles the "we need to be able to 297857302e0dSLinus Torvalds * do IO at the final sector" case. 297957302e0dSLinus Torvalds */ 29804db96b71SAkinobu Mita void guard_bio_eod(int rw, struct bio *bio) 298157302e0dSLinus Torvalds { 298257302e0dSLinus Torvalds sector_t maxsector; 298359d43914SAkinobu Mita struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1]; 298459d43914SAkinobu Mita unsigned truncated_bytes; 298557302e0dSLinus Torvalds 298657302e0dSLinus Torvalds maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; 298757302e0dSLinus Torvalds if (!maxsector) 298857302e0dSLinus Torvalds return; 298957302e0dSLinus Torvalds 299057302e0dSLinus Torvalds /* 299157302e0dSLinus Torvalds * If the *whole* IO is past the end of the device, 299257302e0dSLinus Torvalds * let it through, and the IO layer will turn it into 299357302e0dSLinus Torvalds * an EIO. 299457302e0dSLinus Torvalds */ 29954f024f37SKent Overstreet if (unlikely(bio->bi_iter.bi_sector >= maxsector)) 299657302e0dSLinus Torvalds return; 299757302e0dSLinus Torvalds 29984f024f37SKent Overstreet maxsector -= bio->bi_iter.bi_sector; 299959d43914SAkinobu Mita if (likely((bio->bi_iter.bi_size >> 9) <= maxsector)) 300057302e0dSLinus Torvalds return; 300157302e0dSLinus Torvalds 300259d43914SAkinobu Mita /* Uhhuh. We've got a bio that straddles the device size! */ 300359d43914SAkinobu Mita truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9); 300457302e0dSLinus Torvalds 300557302e0dSLinus Torvalds /* Truncate the bio.. */ 300659d43914SAkinobu Mita bio->bi_iter.bi_size -= truncated_bytes; 300759d43914SAkinobu Mita bvec->bv_len -= truncated_bytes; 300857302e0dSLinus Torvalds 300957302e0dSLinus Torvalds /* ..and clear the end of the buffer for reads */ 301027d7c2a0SDan Carpenter if ((rw & RW_MASK) == READ) { 301159d43914SAkinobu Mita zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len, 301259d43914SAkinobu Mita truncated_bytes); 301357302e0dSLinus Torvalds } 301457302e0dSLinus Torvalds } 301557302e0dSLinus Torvalds 301671368511SDarrick J. Wong int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags) 30171da177e4SLinus Torvalds { 30181da177e4SLinus Torvalds struct bio *bio; 30191da177e4SLinus Torvalds 30201da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 30211da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 30221da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 30238fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 30248fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 30251da177e4SLinus Torvalds 302648fd4f93SJens Axboe /* 302748fd4f93SJens Axboe * Only clear out a write error when rewriting 30281da177e4SLinus Torvalds */ 302948fd4f93SJens Axboe if (test_set_buffer_req(bh) && (rw & WRITE)) 30301da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 30311da177e4SLinus Torvalds 30321da177e4SLinus Torvalds /* 30331da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 30341da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 30351da177e4SLinus Torvalds */ 30361da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 30371da177e4SLinus Torvalds 30384f024f37SKent Overstreet bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); 30391da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 30401da177e4SLinus Torvalds bio->bi_io_vec[0].bv_page = bh->b_page; 30411da177e4SLinus Torvalds bio->bi_io_vec[0].bv_len = bh->b_size; 30421da177e4SLinus Torvalds bio->bi_io_vec[0].bv_offset = bh_offset(bh); 30431da177e4SLinus Torvalds 30441da177e4SLinus Torvalds bio->bi_vcnt = 1; 30454f024f37SKent Overstreet bio->bi_iter.bi_size = bh->b_size; 30461da177e4SLinus Torvalds 30471da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 30481da177e4SLinus Torvalds bio->bi_private = bh; 304971368511SDarrick J. Wong bio->bi_flags |= bio_flags; 30501da177e4SLinus Torvalds 305157302e0dSLinus Torvalds /* Take care of bh's that straddle the end of the device */ 305259d43914SAkinobu Mita guard_bio_eod(rw, bio); 305357302e0dSLinus Torvalds 3054877f962cSTheodore Ts'o if (buffer_meta(bh)) 3055877f962cSTheodore Ts'o rw |= REQ_META; 3056877f962cSTheodore Ts'o if (buffer_prio(bh)) 3057877f962cSTheodore Ts'o rw |= REQ_PRIO; 3058877f962cSTheodore Ts'o 30591da177e4SLinus Torvalds submit_bio(rw, bio); 3060f6454b04SJulia Lawall return 0; 30611da177e4SLinus Torvalds } 306271368511SDarrick J. Wong EXPORT_SYMBOL_GPL(_submit_bh); 306371368511SDarrick J. Wong 306471368511SDarrick J. Wong int submit_bh(int rw, struct buffer_head *bh) 306571368511SDarrick J. Wong { 306671368511SDarrick J. Wong return _submit_bh(rw, bh, 0); 306771368511SDarrick J. Wong } 30681fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 30691da177e4SLinus Torvalds 30701da177e4SLinus Torvalds /** 30711da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 30729cb569d6SChristoph Hellwig * @rw: whether to %READ or %WRITE or maybe %READA (readahead) 30731da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 30741da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 30751da177e4SLinus Torvalds * 3076a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 3077a7662236SJan Kara * requests an I/O operation on them, either a %READ or a %WRITE. The third 30789cb569d6SChristoph Hellwig * %READA option is described in the documentation for generic_make_request() 30799cb569d6SChristoph Hellwig * which ll_rw_block() calls. 30801da177e4SLinus Torvalds * 30811da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 30829cb569d6SChristoph Hellwig * BH_Lock state bit), any buffer that appears to be clean when doing a write 30839cb569d6SChristoph Hellwig * request, and any buffer that appears to be up-to-date when doing read 30849cb569d6SChristoph Hellwig * request. Further it marks as clean buffers that are processed for 30859cb569d6SChristoph Hellwig * writing (the buffer cache won't assume that they are actually clean 30869cb569d6SChristoph Hellwig * until the buffer gets unlocked). 30871da177e4SLinus Torvalds * 30881da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 3089e227867fSMasanari Iida * the buffer up-to-date (if appropriate), unlocks the buffer and wakes 30901da177e4SLinus Torvalds * any waiters. 30911da177e4SLinus Torvalds * 30921da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 30931da177e4SLinus Torvalds * multiple of the current approved size for the device. 30941da177e4SLinus Torvalds */ 30951da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 30961da177e4SLinus Torvalds { 30971da177e4SLinus Torvalds int i; 30981da177e4SLinus Torvalds 30991da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 31001da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 31011da177e4SLinus Torvalds 31029cb569d6SChristoph Hellwig if (!trylock_buffer(bh)) 31031da177e4SLinus Torvalds continue; 31049cb569d6SChristoph Hellwig if (rw == WRITE) { 31051da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 310676c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3107e60e5c50SOGAWA Hirofumi get_bh(bh); 31081da177e4SLinus Torvalds submit_bh(WRITE, bh); 31091da177e4SLinus Torvalds continue; 31101da177e4SLinus Torvalds } 31111da177e4SLinus Torvalds } else { 31121da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 311376c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3114e60e5c50SOGAWA Hirofumi get_bh(bh); 31151da177e4SLinus Torvalds submit_bh(rw, bh); 31161da177e4SLinus Torvalds continue; 31171da177e4SLinus Torvalds } 31181da177e4SLinus Torvalds } 31191da177e4SLinus Torvalds unlock_buffer(bh); 31201da177e4SLinus Torvalds } 31211da177e4SLinus Torvalds } 31221fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 31231da177e4SLinus Torvalds 31249cb569d6SChristoph Hellwig void write_dirty_buffer(struct buffer_head *bh, int rw) 31259cb569d6SChristoph Hellwig { 31269cb569d6SChristoph Hellwig lock_buffer(bh); 31279cb569d6SChristoph Hellwig if (!test_clear_buffer_dirty(bh)) { 31289cb569d6SChristoph Hellwig unlock_buffer(bh); 31299cb569d6SChristoph Hellwig return; 31309cb569d6SChristoph Hellwig } 31319cb569d6SChristoph Hellwig bh->b_end_io = end_buffer_write_sync; 31329cb569d6SChristoph Hellwig get_bh(bh); 31339cb569d6SChristoph Hellwig submit_bh(rw, bh); 31349cb569d6SChristoph Hellwig } 31359cb569d6SChristoph Hellwig EXPORT_SYMBOL(write_dirty_buffer); 31369cb569d6SChristoph Hellwig 31371da177e4SLinus Torvalds /* 31381da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 31391da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 31401da177e4SLinus Torvalds * the buffer_head. 31411da177e4SLinus Torvalds */ 314287e99511SChristoph Hellwig int __sync_dirty_buffer(struct buffer_head *bh, int rw) 31431da177e4SLinus Torvalds { 31441da177e4SLinus Torvalds int ret = 0; 31451da177e4SLinus Torvalds 31461da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 31471da177e4SLinus Torvalds lock_buffer(bh); 31481da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 31491da177e4SLinus Torvalds get_bh(bh); 31501da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 315187e99511SChristoph Hellwig ret = submit_bh(rw, bh); 31521da177e4SLinus Torvalds wait_on_buffer(bh); 31531da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 31541da177e4SLinus Torvalds ret = -EIO; 31551da177e4SLinus Torvalds } else { 31561da177e4SLinus Torvalds unlock_buffer(bh); 31571da177e4SLinus Torvalds } 31581da177e4SLinus Torvalds return ret; 31591da177e4SLinus Torvalds } 316087e99511SChristoph Hellwig EXPORT_SYMBOL(__sync_dirty_buffer); 316187e99511SChristoph Hellwig 316287e99511SChristoph Hellwig int sync_dirty_buffer(struct buffer_head *bh) 316387e99511SChristoph Hellwig { 316487e99511SChristoph Hellwig return __sync_dirty_buffer(bh, WRITE_SYNC); 316587e99511SChristoph Hellwig } 31661fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 31671da177e4SLinus Torvalds 31681da177e4SLinus Torvalds /* 31691da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 31701da177e4SLinus Torvalds * are unused, and releases them if so. 31711da177e4SLinus Torvalds * 31721da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 31731da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 31741da177e4SLinus Torvalds * 31751da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 31761da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 31771da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 31781da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 31791da177e4SLinus Torvalds * filesystem data on the same device. 31801da177e4SLinus Torvalds * 31811da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 31821da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 31831da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 31841da177e4SLinus Torvalds * private_lock. 31851da177e4SLinus Torvalds * 31861da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 31871da177e4SLinus Torvalds */ 31881da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 31891da177e4SLinus Torvalds { 31901da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 31911da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 31921da177e4SLinus Torvalds } 31931da177e4SLinus Torvalds 31941da177e4SLinus Torvalds static int 31951da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 31961da177e4SLinus Torvalds { 31971da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 31981da177e4SLinus Torvalds struct buffer_head *bh; 31991da177e4SLinus Torvalds 32001da177e4SLinus Torvalds bh = head; 32011da177e4SLinus Torvalds do { 3202de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 32031da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 32041da177e4SLinus Torvalds if (buffer_busy(bh)) 32051da177e4SLinus Torvalds goto failed; 32061da177e4SLinus Torvalds bh = bh->b_this_page; 32071da177e4SLinus Torvalds } while (bh != head); 32081da177e4SLinus Torvalds 32091da177e4SLinus Torvalds do { 32101da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32111da177e4SLinus Torvalds 3212535ee2fbSJan Kara if (bh->b_assoc_map) 32131da177e4SLinus Torvalds __remove_assoc_queue(bh); 32141da177e4SLinus Torvalds bh = next; 32151da177e4SLinus Torvalds } while (bh != head); 32161da177e4SLinus Torvalds *buffers_to_free = head; 32171da177e4SLinus Torvalds __clear_page_buffers(page); 32181da177e4SLinus Torvalds return 1; 32191da177e4SLinus Torvalds failed: 32201da177e4SLinus Torvalds return 0; 32211da177e4SLinus Torvalds } 32221da177e4SLinus Torvalds 32231da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 32241da177e4SLinus Torvalds { 32251da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 32261da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 32271da177e4SLinus Torvalds int ret = 0; 32281da177e4SLinus Torvalds 32291da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3230ecdfc978SLinus Torvalds if (PageWriteback(page)) 32311da177e4SLinus Torvalds return 0; 32321da177e4SLinus Torvalds 32331da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 32341da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 32351da177e4SLinus Torvalds goto out; 32361da177e4SLinus Torvalds } 32371da177e4SLinus Torvalds 32381da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 32391da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3240ecdfc978SLinus Torvalds 3241ecdfc978SLinus Torvalds /* 3242ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3243ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3244ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3245ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3246ecdfc978SLinus Torvalds * 3247ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3248ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3249ecdfc978SLinus Torvalds * the page also. 325087df7241SNick Piggin * 325187df7241SNick Piggin * private_lock must be held over this entire operation in order 325287df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 325387df7241SNick Piggin * dirty bit from being lost. 3254ecdfc978SLinus Torvalds */ 325511f81becSTejun Heo if (ret) 325611f81becSTejun Heo cancel_dirty_page(page); 325787df7241SNick Piggin spin_unlock(&mapping->private_lock); 32581da177e4SLinus Torvalds out: 32591da177e4SLinus Torvalds if (buffers_to_free) { 32601da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 32611da177e4SLinus Torvalds 32621da177e4SLinus Torvalds do { 32631da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32641da177e4SLinus Torvalds free_buffer_head(bh); 32651da177e4SLinus Torvalds bh = next; 32661da177e4SLinus Torvalds } while (bh != buffers_to_free); 32671da177e4SLinus Torvalds } 32681da177e4SLinus Torvalds return ret; 32691da177e4SLinus Torvalds } 32701da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 32711da177e4SLinus Torvalds 32721da177e4SLinus Torvalds /* 32731da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 32741da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 32751da177e4SLinus Torvalds * 32761da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 32775b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 32781da177e4SLinus Torvalds */ 3279bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 32801da177e4SLinus Torvalds { 32811da177e4SLinus Torvalds static int msg_count; 32821da177e4SLinus Torvalds 32831da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 32841da177e4SLinus Torvalds return -EPERM; 32851da177e4SLinus Torvalds 32861da177e4SLinus Torvalds if (msg_count < 5) { 32871da177e4SLinus Torvalds msg_count++; 32881da177e4SLinus Torvalds printk(KERN_INFO 32891da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 32901da177e4SLinus Torvalds " system call\n", current->comm); 32911da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 32921da177e4SLinus Torvalds } 32931da177e4SLinus Torvalds 32941da177e4SLinus Torvalds if (func == 1) 32951da177e4SLinus Torvalds do_exit(0); 32961da177e4SLinus Torvalds return 0; 32971da177e4SLinus Torvalds } 32981da177e4SLinus Torvalds 32991da177e4SLinus Torvalds /* 33001da177e4SLinus Torvalds * Buffer-head allocation 33011da177e4SLinus Torvalds */ 3302a0a9b043SShai Fultheim static struct kmem_cache *bh_cachep __read_mostly; 33031da177e4SLinus Torvalds 33041da177e4SLinus Torvalds /* 33051da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 33061da177e4SLinus Torvalds * stripping them in writeback. 33071da177e4SLinus Torvalds */ 330843be594aSZhang Yanfei static unsigned long max_buffer_heads; 33091da177e4SLinus Torvalds 33101da177e4SLinus Torvalds int buffer_heads_over_limit; 33111da177e4SLinus Torvalds 33121da177e4SLinus Torvalds struct bh_accounting { 33131da177e4SLinus Torvalds int nr; /* Number of live bh's */ 33141da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 33151da177e4SLinus Torvalds }; 33161da177e4SLinus Torvalds 33171da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 33181da177e4SLinus Torvalds 33191da177e4SLinus Torvalds static void recalc_bh_state(void) 33201da177e4SLinus Torvalds { 33211da177e4SLinus Torvalds int i; 33221da177e4SLinus Torvalds int tot = 0; 33231da177e4SLinus Torvalds 3324ee1be862SChristoph Lameter if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) 33251da177e4SLinus Torvalds return; 3326c7b92516SChristoph Lameter __this_cpu_write(bh_accounting.ratelimit, 0); 33278a143426SEric Dumazet for_each_online_cpu(i) 33281da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 33291da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 33301da177e4SLinus Torvalds } 33311da177e4SLinus Torvalds 3332dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 33331da177e4SLinus Torvalds { 3334019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 33351da177e4SLinus Torvalds if (ret) { 3336a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3337c7b92516SChristoph Lameter preempt_disable(); 3338c7b92516SChristoph Lameter __this_cpu_inc(bh_accounting.nr); 33391da177e4SLinus Torvalds recalc_bh_state(); 3340c7b92516SChristoph Lameter preempt_enable(); 33411da177e4SLinus Torvalds } 33421da177e4SLinus Torvalds return ret; 33431da177e4SLinus Torvalds } 33441da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 33451da177e4SLinus Torvalds 33461da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 33471da177e4SLinus Torvalds { 33481da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 33491da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3350c7b92516SChristoph Lameter preempt_disable(); 3351c7b92516SChristoph Lameter __this_cpu_dec(bh_accounting.nr); 33521da177e4SLinus Torvalds recalc_bh_state(); 3353c7b92516SChristoph Lameter preempt_enable(); 33541da177e4SLinus Torvalds } 33551da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 33561da177e4SLinus Torvalds 33571da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 33581da177e4SLinus Torvalds { 33591da177e4SLinus Torvalds int i; 33601da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 33611da177e4SLinus Torvalds 33621da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 33631da177e4SLinus Torvalds brelse(b->bhs[i]); 33641da177e4SLinus Torvalds b->bhs[i] = NULL; 33651da177e4SLinus Torvalds } 3366c7b92516SChristoph Lameter this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); 33678a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 33681da177e4SLinus Torvalds } 33691da177e4SLinus Torvalds 33701da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 33711da177e4SLinus Torvalds unsigned long action, void *hcpu) 33721da177e4SLinus Torvalds { 33738bb78442SRafael J. Wysocki if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) 33741da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 33751da177e4SLinus Torvalds return NOTIFY_OK; 33761da177e4SLinus Torvalds } 33771da177e4SLinus Torvalds 3378389d1b08SAneesh Kumar K.V /** 3379a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3380389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3381389d1b08SAneesh Kumar K.V * 3382389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3383389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3384389d1b08SAneesh Kumar K.V */ 3385389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3386389d1b08SAneesh Kumar K.V { 3387389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3388389d1b08SAneesh Kumar K.V lock_buffer(bh); 3389389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3390389d1b08SAneesh Kumar K.V return 0; 3391389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3392389d1b08SAneesh Kumar K.V } 3393389d1b08SAneesh Kumar K.V return 1; 3394389d1b08SAneesh Kumar K.V } 3395389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3396389d1b08SAneesh Kumar K.V 3397389d1b08SAneesh Kumar K.V /** 3398a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3399389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3400389d1b08SAneesh Kumar K.V * 3401389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3402389d1b08SAneesh Kumar K.V */ 3403389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3404389d1b08SAneesh Kumar K.V { 3405389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3406389d1b08SAneesh Kumar K.V 3407389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3408389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3409389d1b08SAneesh Kumar K.V return 0; 3410389d1b08SAneesh Kumar K.V } 3411389d1b08SAneesh Kumar K.V 3412389d1b08SAneesh Kumar K.V get_bh(bh); 3413389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 3414389d1b08SAneesh Kumar K.V submit_bh(READ, bh); 3415389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3416389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3417389d1b08SAneesh Kumar K.V return 0; 3418389d1b08SAneesh Kumar K.V return -EIO; 3419389d1b08SAneesh Kumar K.V } 3420389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3421389d1b08SAneesh Kumar K.V 34221da177e4SLinus Torvalds void __init buffer_init(void) 34231da177e4SLinus Torvalds { 342443be594aSZhang Yanfei unsigned long nrpages; 34251da177e4SLinus Torvalds 3426b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3427b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3428b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3429b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3430019b4d12SRichard Kennedy NULL); 34311da177e4SLinus Torvalds 34321da177e4SLinus Torvalds /* 34331da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 34341da177e4SLinus Torvalds */ 34351da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 34361da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 34371da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 34381da177e4SLinus Torvalds } 3439