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> 321da177e4SLinus Torvalds #include <linux/module.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> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 461da177e4SLinus Torvalds 471da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 481da177e4SLinus Torvalds 491da177e4SLinus Torvalds inline void 501da177e4SLinus Torvalds 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 571da177e4SLinus Torvalds static int sync_buffer(void *word) 581da177e4SLinus Torvalds { 591da177e4SLinus Torvalds struct block_device *bd; 601da177e4SLinus Torvalds struct buffer_head *bh 611da177e4SLinus Torvalds = container_of(word, struct buffer_head, b_state); 621da177e4SLinus Torvalds 631da177e4SLinus Torvalds smp_mb(); 641da177e4SLinus Torvalds bd = bh->b_bdev; 651da177e4SLinus Torvalds if (bd) 661da177e4SLinus Torvalds blk_run_address_space(bd->bd_inode->i_mapping); 671da177e4SLinus Torvalds io_schedule(); 681da177e4SLinus Torvalds return 0; 691da177e4SLinus Torvalds } 701da177e4SLinus Torvalds 71fc9b52cdSHarvey Harrison void __lock_buffer(struct buffer_head *bh) 721da177e4SLinus Torvalds { 731da177e4SLinus Torvalds wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, 741da177e4SLinus Torvalds TASK_UNINTERRUPTIBLE); 751da177e4SLinus Torvalds } 761da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 771da177e4SLinus Torvalds 78fc9b52cdSHarvey Harrison void unlock_buffer(struct buffer_head *bh) 791da177e4SLinus Torvalds { 8051b07fc3SNick Piggin clear_bit_unlock(BH_Lock, &bh->b_state); 811da177e4SLinus Torvalds smp_mb__after_clear_bit(); 821da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 831da177e4SLinus Torvalds } 841fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(unlock_buffer); 851da177e4SLinus Torvalds 861da177e4SLinus Torvalds /* 871da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 881da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 891da177e4SLinus Torvalds * if you want to preserve its state. 901da177e4SLinus Torvalds */ 911da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 921da177e4SLinus Torvalds { 931da177e4SLinus Torvalds wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); 941da177e4SLinus Torvalds } 951fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__wait_on_buffer); 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds static void 981da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 991da177e4SLinus Torvalds { 1001da177e4SLinus Torvalds ClearPagePrivate(page); 1014c21e2f2SHugh Dickins set_page_private(page, 0); 1021da177e4SLinus Torvalds page_cache_release(page); 1031da177e4SLinus Torvalds } 1041da177e4SLinus Torvalds 10508bafc03SKeith Mannthey 10608bafc03SKeith Mannthey static int quiet_error(struct buffer_head *bh) 10708bafc03SKeith Mannthey { 10808bafc03SKeith Mannthey if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit()) 10908bafc03SKeith Mannthey return 0; 11008bafc03SKeith Mannthey return 1; 11108bafc03SKeith Mannthey } 11208bafc03SKeith Mannthey 11308bafc03SKeith Mannthey 1141da177e4SLinus Torvalds static void buffer_io_error(struct buffer_head *bh) 1151da177e4SLinus Torvalds { 1161da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1171da177e4SLinus Torvalds printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", 1181da177e4SLinus Torvalds bdevname(bh->b_bdev, b), 1191da177e4SLinus Torvalds (unsigned long long)bh->b_blocknr); 1201da177e4SLinus Torvalds } 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds /* 12368671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 12468671f35SDmitry Monakhov * unlocking it. 12568671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 12668671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 12768671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 12868671f35SDmitry Monakhov * itself. 1291da177e4SLinus Torvalds */ 13068671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1311da177e4SLinus Torvalds { 1321da177e4SLinus Torvalds if (uptodate) { 1331da177e4SLinus Torvalds set_buffer_uptodate(bh); 1341da177e4SLinus Torvalds } else { 1351da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 1361da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds unlock_buffer(bh); 13968671f35SDmitry Monakhov } 14068671f35SDmitry Monakhov 14168671f35SDmitry Monakhov /* 14268671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 14368671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 14468671f35SDmitry Monakhov */ 14568671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 14668671f35SDmitry Monakhov { 14768671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1481da177e4SLinus Torvalds put_bh(bh); 1491da177e4SLinus Torvalds } 1501fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_read_sync); 1511da177e4SLinus Torvalds 1521da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1531da177e4SLinus Torvalds { 1541da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1551da177e4SLinus Torvalds 1561da177e4SLinus Torvalds if (uptodate) { 1571da177e4SLinus Torvalds set_buffer_uptodate(bh); 1581da177e4SLinus Torvalds } else { 15908bafc03SKeith Mannthey if (!buffer_eopnotsupp(bh) && !quiet_error(bh)) { 1601da177e4SLinus Torvalds buffer_io_error(bh); 1611da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 1621da177e4SLinus Torvalds "I/O error on %s\n", 1631da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 1641da177e4SLinus Torvalds } 1651da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1661da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1671da177e4SLinus Torvalds } 1681da177e4SLinus Torvalds unlock_buffer(bh); 1691da177e4SLinus Torvalds put_bh(bh); 1701da177e4SLinus Torvalds } 1711fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_write_sync); 1721da177e4SLinus Torvalds 1731da177e4SLinus Torvalds /* 1741da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 1751da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 1761da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 1771da177e4SLinus Torvalds * private_lock. 1781da177e4SLinus Torvalds * 1791da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 1801da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 1811da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 1821da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 1831da177e4SLinus Torvalds */ 1841da177e4SLinus Torvalds static struct buffer_head * 185385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 1861da177e4SLinus Torvalds { 1871da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 1881da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 1891da177e4SLinus Torvalds struct buffer_head *ret = NULL; 1901da177e4SLinus Torvalds pgoff_t index; 1911da177e4SLinus Torvalds struct buffer_head *bh; 1921da177e4SLinus Torvalds struct buffer_head *head; 1931da177e4SLinus Torvalds struct page *page; 1941da177e4SLinus Torvalds int all_mapped = 1; 1951da177e4SLinus Torvalds 1961da177e4SLinus Torvalds index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); 1971da177e4SLinus Torvalds page = find_get_page(bd_mapping, index); 1981da177e4SLinus Torvalds if (!page) 1991da177e4SLinus Torvalds goto out; 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2021da177e4SLinus Torvalds if (!page_has_buffers(page)) 2031da177e4SLinus Torvalds goto out_unlock; 2041da177e4SLinus Torvalds head = page_buffers(page); 2051da177e4SLinus Torvalds bh = head; 2061da177e4SLinus Torvalds do { 20797f76d3dSNikanth Karthikesan if (!buffer_mapped(bh)) 20897f76d3dSNikanth Karthikesan all_mapped = 0; 20997f76d3dSNikanth Karthikesan else if (bh->b_blocknr == block) { 2101da177e4SLinus Torvalds ret = bh; 2111da177e4SLinus Torvalds get_bh(bh); 2121da177e4SLinus Torvalds goto out_unlock; 2131da177e4SLinus Torvalds } 2141da177e4SLinus Torvalds bh = bh->b_this_page; 2151da177e4SLinus Torvalds } while (bh != head); 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2181da177e4SLinus Torvalds * not mapped. This is due to various races between 2191da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2201da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2211da177e4SLinus Torvalds */ 2221da177e4SLinus Torvalds if (all_mapped) { 2231da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2241da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 225205f87f6SBadari Pulavarty (unsigned long long)block, 226205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 227205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 228205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 2291da177e4SLinus Torvalds printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); 2301da177e4SLinus Torvalds } 2311da177e4SLinus Torvalds out_unlock: 2321da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 2331da177e4SLinus Torvalds page_cache_release(page); 2341da177e4SLinus Torvalds out: 2351da177e4SLinus Torvalds return ret; 2361da177e4SLinus Torvalds } 2371da177e4SLinus Torvalds 2381da177e4SLinus Torvalds /* If invalidate_buffers() will trash dirty buffers, it means some kind 2391da177e4SLinus Torvalds of fs corruption is going on. Trashing dirty data always imply losing 2401da177e4SLinus Torvalds information that was supposed to be just stored on the physical layer 2411da177e4SLinus Torvalds by the user. 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds Thus invalidate_buffers in general usage is not allwowed to trash 2441da177e4SLinus Torvalds dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to 2451da177e4SLinus Torvalds be preserved. These buffers are simply skipped. 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds We also skip buffers which are still in use. For example this can 2481da177e4SLinus Torvalds happen if a userspace program is reading the block device. 2491da177e4SLinus Torvalds 2501da177e4SLinus Torvalds NOTE: In the case where the user removed a removable-media-disk even if 2511da177e4SLinus Torvalds there's still dirty data not synced on disk (due a bug in the device driver 2521da177e4SLinus Torvalds or due an error of the user), by not destroying the dirty buffers we could 2531da177e4SLinus Torvalds generate corruption also on the next media inserted, thus a parameter is 2541da177e4SLinus Torvalds necessary to handle this case in the most safe way possible (trying 2551da177e4SLinus Torvalds to not corrupt also the new disk inserted with the data belonging to 2561da177e4SLinus Torvalds the old now corrupted disk). Also for the ramdisk the natural thing 2571da177e4SLinus Torvalds to do in order to release the ramdisk memory is to destroy dirty buffers. 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds These are two special cases. Normal usage imply the device driver 2601da177e4SLinus Torvalds to issue a sync on the device (without waiting I/O completion) and 2611da177e4SLinus Torvalds then an invalidate_buffers call that doesn't trash dirty buffers. 2621da177e4SLinus Torvalds 2631da177e4SLinus Torvalds For handling cache coherency with the blkdev pagecache the 'update' case 2641da177e4SLinus Torvalds is been introduced. It is needed to re-read from disk any pinned 2651da177e4SLinus Torvalds buffer. NOTE: re-reading from disk is destructive so we can do it only 2661da177e4SLinus Torvalds when we assume nobody is changing the buffercache under our I/O and when 2671da177e4SLinus Torvalds we think the disk contains more recent information than the buffercache. 2681da177e4SLinus Torvalds The update == 1 pass marks the buffers we need to update, the update == 2 2691da177e4SLinus Torvalds pass does the actual I/O. */ 270f98393a6SPeter Zijlstra void invalidate_bdev(struct block_device *bdev) 2711da177e4SLinus Torvalds { 2720e1dfc66SAndrew Morton struct address_space *mapping = bdev->bd_inode->i_mapping; 2730e1dfc66SAndrew Morton 2740e1dfc66SAndrew Morton if (mapping->nrpages == 0) 2750e1dfc66SAndrew Morton return; 2760e1dfc66SAndrew Morton 2771da177e4SLinus Torvalds invalidate_bh_lrus(); 278fc0ecff6SAndrew Morton invalidate_mapping_pages(mapping, 0, -1); 2791da177e4SLinus Torvalds } 2801fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(invalidate_bdev); 2811da177e4SLinus Torvalds 2821da177e4SLinus Torvalds /* 2835b0830cbSJens Axboe * Kick the writeback threads then try to free up some ZONE_NORMAL memory. 2841da177e4SLinus Torvalds */ 2851da177e4SLinus Torvalds static void free_more_memory(void) 2861da177e4SLinus Torvalds { 28719770b32SMel Gorman struct zone *zone; 2880e88460dSMel Gorman int nid; 2891da177e4SLinus Torvalds 29003ba3782SJens Axboe wakeup_flusher_threads(1024); 2911da177e4SLinus Torvalds yield(); 2921da177e4SLinus Torvalds 2930e88460dSMel Gorman for_each_online_node(nid) { 29419770b32SMel Gorman (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS), 29519770b32SMel Gorman gfp_zone(GFP_NOFS), NULL, 29619770b32SMel Gorman &zone); 29719770b32SMel Gorman if (zone) 29854a6eb5cSMel Gorman try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, 299327c0e96SKAMEZAWA Hiroyuki GFP_NOFS, NULL); 3001da177e4SLinus Torvalds } 3011da177e4SLinus Torvalds } 3021da177e4SLinus Torvalds 3031da177e4SLinus Torvalds /* 3041da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 3051da177e4SLinus Torvalds * which come unlocked at the end of I/O. 3061da177e4SLinus Torvalds */ 3071da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 3081da177e4SLinus Torvalds { 3091da177e4SLinus Torvalds unsigned long flags; 310a3972203SNick Piggin struct buffer_head *first; 3111da177e4SLinus Torvalds struct buffer_head *tmp; 3121da177e4SLinus Torvalds struct page *page; 3131da177e4SLinus Torvalds int page_uptodate = 1; 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds page = bh->b_page; 3181da177e4SLinus Torvalds if (uptodate) { 3191da177e4SLinus Torvalds set_buffer_uptodate(bh); 3201da177e4SLinus Torvalds } else { 3211da177e4SLinus Torvalds clear_buffer_uptodate(bh); 32208bafc03SKeith Mannthey if (!quiet_error(bh)) 3231da177e4SLinus Torvalds buffer_io_error(bh); 3241da177e4SLinus Torvalds SetPageError(page); 3251da177e4SLinus Torvalds } 3261da177e4SLinus Torvalds 3271da177e4SLinus Torvalds /* 3281da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 3291da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 3301da177e4SLinus Torvalds * decide that the page is now completely done. 3311da177e4SLinus Torvalds */ 332a3972203SNick Piggin first = page_buffers(page); 333a3972203SNick Piggin local_irq_save(flags); 334a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 3351da177e4SLinus Torvalds clear_buffer_async_read(bh); 3361da177e4SLinus Torvalds unlock_buffer(bh); 3371da177e4SLinus Torvalds tmp = bh; 3381da177e4SLinus Torvalds do { 3391da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 3401da177e4SLinus Torvalds page_uptodate = 0; 3411da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 3421da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3431da177e4SLinus Torvalds goto still_busy; 3441da177e4SLinus Torvalds } 3451da177e4SLinus Torvalds tmp = tmp->b_this_page; 3461da177e4SLinus Torvalds } while (tmp != bh); 347a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 348a3972203SNick Piggin local_irq_restore(flags); 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds /* 3511da177e4SLinus Torvalds * If none of the buffers had errors and they are all 3521da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 3531da177e4SLinus Torvalds */ 3541da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 3551da177e4SLinus Torvalds SetPageUptodate(page); 3561da177e4SLinus Torvalds unlock_page(page); 3571da177e4SLinus Torvalds return; 3581da177e4SLinus Torvalds 3591da177e4SLinus Torvalds still_busy: 360a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 361a3972203SNick Piggin local_irq_restore(flags); 3621da177e4SLinus Torvalds return; 3631da177e4SLinus Torvalds } 3641da177e4SLinus Torvalds 3651da177e4SLinus Torvalds /* 3661da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 3671da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 3681da177e4SLinus Torvalds */ 36935c80d5fSChris Mason void end_buffer_async_write(struct buffer_head *bh, int uptodate) 3701da177e4SLinus Torvalds { 3711da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 3721da177e4SLinus Torvalds unsigned long flags; 373a3972203SNick Piggin struct buffer_head *first; 3741da177e4SLinus Torvalds struct buffer_head *tmp; 3751da177e4SLinus Torvalds struct page *page; 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 3781da177e4SLinus Torvalds 3791da177e4SLinus Torvalds page = bh->b_page; 3801da177e4SLinus Torvalds if (uptodate) { 3811da177e4SLinus Torvalds set_buffer_uptodate(bh); 3821da177e4SLinus Torvalds } else { 38308bafc03SKeith Mannthey if (!quiet_error(bh)) { 3841da177e4SLinus Torvalds buffer_io_error(bh); 3851da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 3861da177e4SLinus Torvalds "I/O error on %s\n", 3871da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 3881da177e4SLinus Torvalds } 3891da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 39058ff407bSJan Kara set_buffer_write_io_error(bh); 3911da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3921da177e4SLinus Torvalds SetPageError(page); 3931da177e4SLinus Torvalds } 3941da177e4SLinus Torvalds 395a3972203SNick Piggin first = page_buffers(page); 396a3972203SNick Piggin local_irq_save(flags); 397a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 398a3972203SNick Piggin 3991da177e4SLinus Torvalds clear_buffer_async_write(bh); 4001da177e4SLinus Torvalds unlock_buffer(bh); 4011da177e4SLinus Torvalds tmp = bh->b_this_page; 4021da177e4SLinus Torvalds while (tmp != bh) { 4031da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 4041da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 4051da177e4SLinus Torvalds goto still_busy; 4061da177e4SLinus Torvalds } 4071da177e4SLinus Torvalds tmp = tmp->b_this_page; 4081da177e4SLinus Torvalds } 409a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 410a3972203SNick Piggin local_irq_restore(flags); 4111da177e4SLinus Torvalds end_page_writeback(page); 4121da177e4SLinus Torvalds return; 4131da177e4SLinus Torvalds 4141da177e4SLinus Torvalds still_busy: 415a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 416a3972203SNick Piggin local_irq_restore(flags); 4171da177e4SLinus Torvalds return; 4181da177e4SLinus Torvalds } 4191fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_async_write); 4201da177e4SLinus Torvalds 4211da177e4SLinus Torvalds /* 4221da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 4231da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 4241da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 4251da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 4261da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 4271da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 4281da177e4SLinus Torvalds * that this buffer is not under async I/O. 4291da177e4SLinus Torvalds * 4301da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 4311da177e4SLinus Torvalds * left. 4321da177e4SLinus Torvalds * 4331da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 4341da177e4SLinus Torvalds * the buffers. 4351da177e4SLinus Torvalds * 4361da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 4371da177e4SLinus Torvalds * page. 4381da177e4SLinus Torvalds * 4391da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 4401da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 4411da177e4SLinus Torvalds */ 4421da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 4431da177e4SLinus Torvalds { 4441da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 4451da177e4SLinus Torvalds set_buffer_async_read(bh); 4461da177e4SLinus Torvalds } 4471da177e4SLinus Torvalds 4481fe72eaaSH Hartley Sweeten static void mark_buffer_async_write_endio(struct buffer_head *bh, 44935c80d5fSChris Mason bh_end_io_t *handler) 45035c80d5fSChris Mason { 45135c80d5fSChris Mason bh->b_end_io = handler; 45235c80d5fSChris Mason set_buffer_async_write(bh); 45335c80d5fSChris Mason } 45435c80d5fSChris Mason 4551da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 4561da177e4SLinus Torvalds { 45735c80d5fSChris Mason mark_buffer_async_write_endio(bh, end_buffer_async_write); 4581da177e4SLinus Torvalds } 4591da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 4601da177e4SLinus Torvalds 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds /* 4631da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 4641da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 4651da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 4661da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 4671da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 4681da177e4SLinus Torvalds * 4691da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 4701da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 4711da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 4721da177e4SLinus Torvalds * 4731da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 4741da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 4751da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 4761da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 4771da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 4781da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 4791da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 4801da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 4811da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 4821da177e4SLinus Torvalds * ->private_lock. 4831da177e4SLinus Torvalds * 4841da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 4851da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 4861da177e4SLinus Torvalds * 4871da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 4881da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 4891da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 4901da177e4SLinus Torvalds * be true at clear_inode() time. 4911da177e4SLinus Torvalds * 4921da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 4931da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 4941da177e4SLinus Torvalds * BUG_ON(!list_empty). 4951da177e4SLinus Torvalds * 4961da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 4971da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 4981da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 4991da177e4SLinus Torvalds * queued up. 5001da177e4SLinus Torvalds * 5011da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 5021da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 5031da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 5041da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 5051da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 5061da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 5071da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 5081da177e4SLinus Torvalds * b_inode back. 5091da177e4SLinus Torvalds */ 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds /* 5121da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 5131da177e4SLinus Torvalds */ 514dbacefc9SThomas Petazzoni static void __remove_assoc_queue(struct buffer_head *bh) 5151da177e4SLinus Torvalds { 5161da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 51758ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 51858ff407bSJan Kara if (buffer_write_io_error(bh)) 51958ff407bSJan Kara set_bit(AS_EIO, &bh->b_assoc_map->flags); 52058ff407bSJan Kara bh->b_assoc_map = NULL; 5211da177e4SLinus Torvalds } 5221da177e4SLinus Torvalds 5231da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 5241da177e4SLinus Torvalds { 5251da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 5261da177e4SLinus Torvalds } 5271da177e4SLinus Torvalds 5281da177e4SLinus Torvalds /* 5291da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 5301da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 5311da177e4SLinus Torvalds * writes to the disk. 5321da177e4SLinus Torvalds * 5331da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 5341da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 5351da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 5361da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 5371da177e4SLinus Torvalds */ 5381da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 5391da177e4SLinus Torvalds { 5401da177e4SLinus Torvalds struct buffer_head *bh; 5411da177e4SLinus Torvalds struct list_head *p; 5421da177e4SLinus Torvalds int err = 0; 5431da177e4SLinus Torvalds 5441da177e4SLinus Torvalds spin_lock(lock); 5451da177e4SLinus Torvalds repeat: 5461da177e4SLinus Torvalds list_for_each_prev(p, list) { 5471da177e4SLinus Torvalds bh = BH_ENTRY(p); 5481da177e4SLinus Torvalds if (buffer_locked(bh)) { 5491da177e4SLinus Torvalds get_bh(bh); 5501da177e4SLinus Torvalds spin_unlock(lock); 5511da177e4SLinus Torvalds wait_on_buffer(bh); 5521da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 5531da177e4SLinus Torvalds err = -EIO; 5541da177e4SLinus Torvalds brelse(bh); 5551da177e4SLinus Torvalds spin_lock(lock); 5561da177e4SLinus Torvalds goto repeat; 5571da177e4SLinus Torvalds } 5581da177e4SLinus Torvalds } 5591da177e4SLinus Torvalds spin_unlock(lock); 5601da177e4SLinus Torvalds return err; 5611da177e4SLinus Torvalds } 5621da177e4SLinus Torvalds 563*01a05b33SAl Viro static void do_thaw_one(struct super_block *sb, void *unused) 564c2d75438SEric Sandeen { 565c2d75438SEric Sandeen char b[BDEVNAME_SIZE]; 566c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 567c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw on %s\n", 568c2d75438SEric Sandeen bdevname(sb->s_bdev, b)); 569c2d75438SEric Sandeen } 570*01a05b33SAl Viro 571*01a05b33SAl Viro static void do_thaw_all(struct work_struct *work) 572*01a05b33SAl Viro { 573*01a05b33SAl Viro iterate_supers(do_thaw_one, NULL); 574053c525fSJens Axboe kfree(work); 575c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw complete\n"); 576c2d75438SEric Sandeen } 577c2d75438SEric Sandeen 578c2d75438SEric Sandeen /** 579c2d75438SEric Sandeen * emergency_thaw_all -- forcibly thaw every frozen filesystem 580c2d75438SEric Sandeen * 581c2d75438SEric Sandeen * Used for emergency unfreeze of all filesystems via SysRq 582c2d75438SEric Sandeen */ 583c2d75438SEric Sandeen void emergency_thaw_all(void) 584c2d75438SEric Sandeen { 585053c525fSJens Axboe struct work_struct *work; 586053c525fSJens Axboe 587053c525fSJens Axboe work = kmalloc(sizeof(*work), GFP_ATOMIC); 588053c525fSJens Axboe if (work) { 589053c525fSJens Axboe INIT_WORK(work, do_thaw_all); 590053c525fSJens Axboe schedule_work(work); 591053c525fSJens Axboe } 592c2d75438SEric Sandeen } 593c2d75438SEric Sandeen 5941da177e4SLinus Torvalds /** 59578a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 59667be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 5971da177e4SLinus Torvalds * 5981da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 5991da177e4SLinus Torvalds * that I/O. 6001da177e4SLinus Torvalds * 60167be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 60267be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 60367be2dd1SMartin Waitz * a successful fsync(). 6041da177e4SLinus Torvalds */ 6051da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 6061da177e4SLinus Torvalds { 6071da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 6081da177e4SLinus Torvalds 6091da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 6101da177e4SLinus Torvalds return 0; 6111da177e4SLinus Torvalds 6121da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 6131da177e4SLinus Torvalds &mapping->private_list); 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 6161da177e4SLinus Torvalds 6171da177e4SLinus Torvalds /* 6181da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 6191da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 6201da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 6211da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 6221da177e4SLinus Torvalds */ 6231da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 6241da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 6251da177e4SLinus Torvalds { 6261da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 6271da177e4SLinus Torvalds if (bh) { 6281da177e4SLinus Torvalds if (buffer_dirty(bh)) 6291da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 6301da177e4SLinus Torvalds put_bh(bh); 6311da177e4SLinus Torvalds } 6321da177e4SLinus Torvalds } 6331da177e4SLinus Torvalds 6341da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 6351da177e4SLinus Torvalds { 6361da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 6371da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6381da177e4SLinus Torvalds 6391da177e4SLinus Torvalds mark_buffer_dirty(bh); 6401da177e4SLinus Torvalds if (!mapping->assoc_mapping) { 6411da177e4SLinus Torvalds mapping->assoc_mapping = buffer_mapping; 6421da177e4SLinus Torvalds } else { 643e827f923SEric Sesterhenn BUG_ON(mapping->assoc_mapping != buffer_mapping); 6441da177e4SLinus Torvalds } 645535ee2fbSJan Kara if (!bh->b_assoc_map) { 6461da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6471da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6481da177e4SLinus Torvalds &mapping->private_list); 64958ff407bSJan Kara bh->b_assoc_map = mapping; 6501da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6511da177e4SLinus Torvalds } 6521da177e4SLinus Torvalds } 6531da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6541da177e4SLinus Torvalds 6551da177e4SLinus Torvalds /* 656787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 657787d2214SNick Piggin * dirty. 658787d2214SNick Piggin * 659787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 660787d2214SNick Piggin * not been truncated. 661787d2214SNick Piggin */ 662a8e7d49aSLinus Torvalds static void __set_page_dirty(struct page *page, 663787d2214SNick Piggin struct address_space *mapping, int warn) 664787d2214SNick Piggin { 66519fd6231SNick Piggin spin_lock_irq(&mapping->tree_lock); 666787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 667787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 668e3a7cca1SEdward Shishkin account_page_dirtied(page, mapping); 669787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 670787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 671787d2214SNick Piggin } 67219fd6231SNick Piggin spin_unlock_irq(&mapping->tree_lock); 673787d2214SNick Piggin __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 674787d2214SNick Piggin } 675787d2214SNick Piggin 676787d2214SNick Piggin /* 6771da177e4SLinus Torvalds * Add a page to the dirty page list. 6781da177e4SLinus Torvalds * 6791da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6801da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6811da177e4SLinus Torvalds * 6821da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6831da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6841da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6851da177e4SLinus Torvalds * dirty. 6861da177e4SLinus Torvalds * 6871da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6881da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6891da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6901da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6911da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 6921da177e4SLinus Torvalds * page on the dirty page list. 6931da177e4SLinus Torvalds * 6941da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 6951da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 6961da177e4SLinus Torvalds * added to the page after it was set dirty. 6971da177e4SLinus Torvalds * 6981da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 6991da177e4SLinus Torvalds * address_space though. 7001da177e4SLinus Torvalds */ 7011da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 7021da177e4SLinus Torvalds { 703a8e7d49aSLinus Torvalds int newly_dirty; 704787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 705ebf7a227SNick Piggin 706ebf7a227SNick Piggin if (unlikely(!mapping)) 707ebf7a227SNick Piggin return !TestSetPageDirty(page); 7081da177e4SLinus Torvalds 7091da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 7101da177e4SLinus Torvalds if (page_has_buffers(page)) { 7111da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 7121da177e4SLinus Torvalds struct buffer_head *bh = head; 7131da177e4SLinus Torvalds 7141da177e4SLinus Torvalds do { 7151da177e4SLinus Torvalds set_buffer_dirty(bh); 7161da177e4SLinus Torvalds bh = bh->b_this_page; 7171da177e4SLinus Torvalds } while (bh != head); 7181da177e4SLinus Torvalds } 719a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 7201da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 7211da177e4SLinus Torvalds 722a8e7d49aSLinus Torvalds if (newly_dirty) 723a8e7d49aSLinus Torvalds __set_page_dirty(page, mapping, 1); 724a8e7d49aSLinus Torvalds return newly_dirty; 7251da177e4SLinus Torvalds } 7261da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7271da177e4SLinus Torvalds 7281da177e4SLinus Torvalds /* 7291da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7301da177e4SLinus Torvalds * 7311da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7321da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7331da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7341da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7351da177e4SLinus Torvalds * 7361da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7371da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7381da177e4SLinus Torvalds * up, waiting for those writes to complete. 7391da177e4SLinus Torvalds * 7401da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7411da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7421da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7431da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7441da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7451da177e4SLinus Torvalds * any newly dirty buffers for write. 7461da177e4SLinus Torvalds */ 7471da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7481da177e4SLinus Torvalds { 7491da177e4SLinus Torvalds struct buffer_head *bh; 7501da177e4SLinus Torvalds struct list_head tmp; 7519cf6b720SJens Axboe struct address_space *mapping, *prev_mapping = NULL; 7521da177e4SLinus Torvalds int err = 0, err2; 7531da177e4SLinus Torvalds 7541da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7551da177e4SLinus Torvalds 7561da177e4SLinus Torvalds spin_lock(lock); 7571da177e4SLinus Torvalds while (!list_empty(list)) { 7581da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 759535ee2fbSJan Kara mapping = bh->b_assoc_map; 76058ff407bSJan Kara __remove_assoc_queue(bh); 761535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 762535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 763535ee2fbSJan Kara smp_mb(); 7641da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7651da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 766535ee2fbSJan Kara bh->b_assoc_map = mapping; 7671da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7681da177e4SLinus Torvalds get_bh(bh); 7691da177e4SLinus Torvalds spin_unlock(lock); 7701da177e4SLinus Torvalds /* 7711da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7721da177e4SLinus Torvalds * ll_rw_block() actually writes the current 7731da177e4SLinus Torvalds * contents - it is a noop if I/O is still in 7741da177e4SLinus Torvalds * flight on potentially older contents. 7751da177e4SLinus Torvalds */ 7769cf6b720SJens Axboe ll_rw_block(SWRITE_SYNC_PLUG, 1, &bh); 7779cf6b720SJens Axboe 7789cf6b720SJens Axboe /* 7799cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7809cf6b720SJens Axboe * that we will not run the very last mapping, 7819cf6b720SJens Axboe * wait_on_buffer() will do that for us 7829cf6b720SJens Axboe * through sync_buffer(). 7839cf6b720SJens Axboe */ 7849cf6b720SJens Axboe if (prev_mapping && prev_mapping != mapping) 7859cf6b720SJens Axboe blk_run_address_space(prev_mapping); 7869cf6b720SJens Axboe prev_mapping = mapping; 7879cf6b720SJens Axboe 7881da177e4SLinus Torvalds brelse(bh); 7891da177e4SLinus Torvalds spin_lock(lock); 7901da177e4SLinus Torvalds } 7911da177e4SLinus Torvalds } 7921da177e4SLinus Torvalds } 7931da177e4SLinus Torvalds 7941da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7951da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 7961da177e4SLinus Torvalds get_bh(bh); 797535ee2fbSJan Kara mapping = bh->b_assoc_map; 798535ee2fbSJan Kara __remove_assoc_queue(bh); 799535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 800535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 801535ee2fbSJan Kara smp_mb(); 802535ee2fbSJan Kara if (buffer_dirty(bh)) { 803535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 804e3892296SJan Kara &mapping->private_list); 805535ee2fbSJan Kara bh->b_assoc_map = mapping; 806535ee2fbSJan Kara } 8071da177e4SLinus Torvalds spin_unlock(lock); 8081da177e4SLinus Torvalds wait_on_buffer(bh); 8091da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 8101da177e4SLinus Torvalds err = -EIO; 8111da177e4SLinus Torvalds brelse(bh); 8121da177e4SLinus Torvalds spin_lock(lock); 8131da177e4SLinus Torvalds } 8141da177e4SLinus Torvalds 8151da177e4SLinus Torvalds spin_unlock(lock); 8161da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 8171da177e4SLinus Torvalds if (err) 8181da177e4SLinus Torvalds return err; 8191da177e4SLinus Torvalds else 8201da177e4SLinus Torvalds return err2; 8211da177e4SLinus Torvalds } 8221da177e4SLinus Torvalds 8231da177e4SLinus Torvalds /* 8241da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8251da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8261da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8271da177e4SLinus Torvalds * 8281da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8291da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8301da177e4SLinus Torvalds * for reiserfs. 8311da177e4SLinus Torvalds */ 8321da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8331da177e4SLinus Torvalds { 8341da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8351da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8361da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8371da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8381da177e4SLinus Torvalds 8391da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8401da177e4SLinus Torvalds while (!list_empty(list)) 8411da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8421da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8431da177e4SLinus Torvalds } 8441da177e4SLinus Torvalds } 84552b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 8461da177e4SLinus Torvalds 8471da177e4SLinus Torvalds /* 8481da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8491da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8501da177e4SLinus Torvalds * 8511da177e4SLinus Torvalds * Returns true if all buffers were removed. 8521da177e4SLinus Torvalds */ 8531da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8541da177e4SLinus Torvalds { 8551da177e4SLinus Torvalds int ret = 1; 8561da177e4SLinus Torvalds 8571da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8581da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8591da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8601da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8611da177e4SLinus Torvalds 8621da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8631da177e4SLinus Torvalds while (!list_empty(list)) { 8641da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8651da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8661da177e4SLinus Torvalds ret = 0; 8671da177e4SLinus Torvalds break; 8681da177e4SLinus Torvalds } 8691da177e4SLinus Torvalds __remove_assoc_queue(bh); 8701da177e4SLinus Torvalds } 8711da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8721da177e4SLinus Torvalds } 8731da177e4SLinus Torvalds return ret; 8741da177e4SLinus Torvalds } 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds /* 8771da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8781da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8791da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8801da177e4SLinus Torvalds * buffers. 8811da177e4SLinus Torvalds * 8821da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8831da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8841da177e4SLinus Torvalds */ 8851da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8861da177e4SLinus Torvalds int retry) 8871da177e4SLinus Torvalds { 8881da177e4SLinus Torvalds struct buffer_head *bh, *head; 8891da177e4SLinus Torvalds long offset; 8901da177e4SLinus Torvalds 8911da177e4SLinus Torvalds try_again: 8921da177e4SLinus Torvalds head = NULL; 8931da177e4SLinus Torvalds offset = PAGE_SIZE; 8941da177e4SLinus Torvalds while ((offset -= size) >= 0) { 8951da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 8961da177e4SLinus Torvalds if (!bh) 8971da177e4SLinus Torvalds goto no_grow; 8981da177e4SLinus Torvalds 8991da177e4SLinus Torvalds bh->b_bdev = NULL; 9001da177e4SLinus Torvalds bh->b_this_page = head; 9011da177e4SLinus Torvalds bh->b_blocknr = -1; 9021da177e4SLinus Torvalds head = bh; 9031da177e4SLinus Torvalds 9041da177e4SLinus Torvalds bh->b_state = 0; 9051da177e4SLinus Torvalds atomic_set(&bh->b_count, 0); 906fc5cd582SChris Mason bh->b_private = NULL; 9071da177e4SLinus Torvalds bh->b_size = size; 9081da177e4SLinus Torvalds 9091da177e4SLinus Torvalds /* Link the buffer to its page */ 9101da177e4SLinus Torvalds set_bh_page(bh, page, offset); 9111da177e4SLinus Torvalds 91201ffe339SNathan Scott init_buffer(bh, NULL, NULL); 9131da177e4SLinus Torvalds } 9141da177e4SLinus Torvalds return head; 9151da177e4SLinus Torvalds /* 9161da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 9171da177e4SLinus Torvalds */ 9181da177e4SLinus Torvalds no_grow: 9191da177e4SLinus Torvalds if (head) { 9201da177e4SLinus Torvalds do { 9211da177e4SLinus Torvalds bh = head; 9221da177e4SLinus Torvalds head = head->b_this_page; 9231da177e4SLinus Torvalds free_buffer_head(bh); 9241da177e4SLinus Torvalds } while (head); 9251da177e4SLinus Torvalds } 9261da177e4SLinus Torvalds 9271da177e4SLinus Torvalds /* 9281da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9291da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9301da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9311da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9321da177e4SLinus Torvalds */ 9331da177e4SLinus Torvalds if (!retry) 9341da177e4SLinus Torvalds return NULL; 9351da177e4SLinus Torvalds 9361da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9371da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9381da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9391da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9401da177e4SLinus Torvalds * async buffer heads in use. 9411da177e4SLinus Torvalds */ 9421da177e4SLinus Torvalds free_more_memory(); 9431da177e4SLinus Torvalds goto try_again; 9441da177e4SLinus Torvalds } 9451da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9461da177e4SLinus Torvalds 9471da177e4SLinus Torvalds static inline void 9481da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9491da177e4SLinus Torvalds { 9501da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9511da177e4SLinus Torvalds 9521da177e4SLinus Torvalds bh = head; 9531da177e4SLinus Torvalds do { 9541da177e4SLinus Torvalds tail = bh; 9551da177e4SLinus Torvalds bh = bh->b_this_page; 9561da177e4SLinus Torvalds } while (bh); 9571da177e4SLinus Torvalds tail->b_this_page = head; 9581da177e4SLinus Torvalds attach_page_buffers(page, head); 9591da177e4SLinus Torvalds } 9601da177e4SLinus Torvalds 9611da177e4SLinus Torvalds /* 9621da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9631da177e4SLinus Torvalds */ 9641da177e4SLinus Torvalds static void 9651da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9661da177e4SLinus Torvalds sector_t block, int size) 9671da177e4SLinus Torvalds { 9681da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9691da177e4SLinus Torvalds struct buffer_head *bh = head; 9701da177e4SLinus Torvalds int uptodate = PageUptodate(page); 9711da177e4SLinus Torvalds 9721da177e4SLinus Torvalds do { 9731da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9741da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9751da177e4SLinus Torvalds bh->b_bdev = bdev; 9761da177e4SLinus Torvalds bh->b_blocknr = block; 9771da177e4SLinus Torvalds if (uptodate) 9781da177e4SLinus Torvalds set_buffer_uptodate(bh); 9791da177e4SLinus Torvalds set_buffer_mapped(bh); 9801da177e4SLinus Torvalds } 9811da177e4SLinus Torvalds block++; 9821da177e4SLinus Torvalds bh = bh->b_this_page; 9831da177e4SLinus Torvalds } while (bh != head); 9841da177e4SLinus Torvalds } 9851da177e4SLinus Torvalds 9861da177e4SLinus Torvalds /* 9871da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9881da177e4SLinus Torvalds * 9891da177e4SLinus Torvalds * This is user purely for blockdev mappings. 9901da177e4SLinus Torvalds */ 9911da177e4SLinus Torvalds static struct page * 9921da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 9931da177e4SLinus Torvalds pgoff_t index, int size) 9941da177e4SLinus Torvalds { 9951da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9961da177e4SLinus Torvalds struct page *page; 9971da177e4SLinus Torvalds struct buffer_head *bh; 9981da177e4SLinus Torvalds 999ea125892SChristoph Lameter page = find_or_create_page(inode->i_mapping, index, 1000769848c0SMel Gorman (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); 10011da177e4SLinus Torvalds if (!page) 10021da177e4SLinus Torvalds return NULL; 10031da177e4SLinus Torvalds 1004e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 10051da177e4SLinus Torvalds 10061da177e4SLinus Torvalds if (page_has_buffers(page)) { 10071da177e4SLinus Torvalds bh = page_buffers(page); 10081da177e4SLinus Torvalds if (bh->b_size == size) { 10091da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10101da177e4SLinus Torvalds return page; 10111da177e4SLinus Torvalds } 10121da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10131da177e4SLinus Torvalds goto failed; 10141da177e4SLinus Torvalds } 10151da177e4SLinus Torvalds 10161da177e4SLinus Torvalds /* 10171da177e4SLinus Torvalds * Allocate some buffers for this page 10181da177e4SLinus Torvalds */ 10191da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10201da177e4SLinus Torvalds if (!bh) 10211da177e4SLinus Torvalds goto failed; 10221da177e4SLinus Torvalds 10231da177e4SLinus Torvalds /* 10241da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10251da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10261da177e4SLinus Torvalds * run under the page lock. 10271da177e4SLinus Torvalds */ 10281da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10291da177e4SLinus Torvalds link_dev_buffers(page, bh); 10301da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10311da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 10321da177e4SLinus Torvalds return page; 10331da177e4SLinus Torvalds 10341da177e4SLinus Torvalds failed: 10351da177e4SLinus Torvalds BUG(); 10361da177e4SLinus Torvalds unlock_page(page); 10371da177e4SLinus Torvalds page_cache_release(page); 10381da177e4SLinus Torvalds return NULL; 10391da177e4SLinus Torvalds } 10401da177e4SLinus Torvalds 10411da177e4SLinus Torvalds /* 10421da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10431da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10441da177e4SLinus Torvalds */ 1045858119e1SArjan van de Ven static int 10461da177e4SLinus Torvalds grow_buffers(struct block_device *bdev, sector_t block, int size) 10471da177e4SLinus Torvalds { 10481da177e4SLinus Torvalds struct page *page; 10491da177e4SLinus Torvalds pgoff_t index; 10501da177e4SLinus Torvalds int sizebits; 10511da177e4SLinus Torvalds 10521da177e4SLinus Torvalds sizebits = -1; 10531da177e4SLinus Torvalds do { 10541da177e4SLinus Torvalds sizebits++; 10551da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10561da177e4SLinus Torvalds 10571da177e4SLinus Torvalds index = block >> sizebits; 10581da177e4SLinus Torvalds 1059e5657933SAndrew Morton /* 1060e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1061e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1062e5657933SAndrew Morton */ 1063e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1064e5657933SAndrew Morton char b[BDEVNAME_SIZE]; 1065e5657933SAndrew Morton 1066e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1067e5657933SAndrew Morton "device %s\n", 10688e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1069e5657933SAndrew Morton bdevname(bdev, b)); 1070e5657933SAndrew Morton return -EIO; 1071e5657933SAndrew Morton } 1072e5657933SAndrew Morton block = index << sizebits; 10731da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10741da177e4SLinus Torvalds page = grow_dev_page(bdev, block, index, size); 10751da177e4SLinus Torvalds if (!page) 10761da177e4SLinus Torvalds return 0; 10771da177e4SLinus Torvalds unlock_page(page); 10781da177e4SLinus Torvalds page_cache_release(page); 10791da177e4SLinus Torvalds return 1; 10801da177e4SLinus Torvalds } 10811da177e4SLinus Torvalds 108275c96f85SAdrian Bunk static struct buffer_head * 10831da177e4SLinus Torvalds __getblk_slow(struct block_device *bdev, sector_t block, int size) 10841da177e4SLinus Torvalds { 10851da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1086e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10871da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10881da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10891da177e4SLinus Torvalds size); 1090e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1091e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 10921da177e4SLinus Torvalds 10931da177e4SLinus Torvalds dump_stack(); 10941da177e4SLinus Torvalds return NULL; 10951da177e4SLinus Torvalds } 10961da177e4SLinus Torvalds 10971da177e4SLinus Torvalds for (;;) { 10981da177e4SLinus Torvalds struct buffer_head * bh; 1099e5657933SAndrew Morton int ret; 11001da177e4SLinus Torvalds 11011da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 11021da177e4SLinus Torvalds if (bh) 11031da177e4SLinus Torvalds return bh; 11041da177e4SLinus Torvalds 1105e5657933SAndrew Morton ret = grow_buffers(bdev, block, size); 1106e5657933SAndrew Morton if (ret < 0) 1107e5657933SAndrew Morton return NULL; 1108e5657933SAndrew Morton if (ret == 0) 11091da177e4SLinus Torvalds free_more_memory(); 11101da177e4SLinus Torvalds } 11111da177e4SLinus Torvalds } 11121da177e4SLinus Torvalds 11131da177e4SLinus Torvalds /* 11141da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 11151da177e4SLinus Torvalds * 11161da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 11171da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 11181da177e4SLinus Torvalds * 11191da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 11201da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 11211da177e4SLinus Torvalds * merely a hint about the true dirty state. 11221da177e4SLinus Torvalds * 11231da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 11241da177e4SLinus Torvalds * (if the page has buffers). 11251da177e4SLinus Torvalds * 11261da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11271da177e4SLinus Torvalds * buffers are not. 11281da177e4SLinus Torvalds * 11291da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11301da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11311da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11321da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11331da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11341da177e4SLinus Torvalds */ 11351da177e4SLinus Torvalds 11361da177e4SLinus Torvalds /** 11371da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 113867be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11391da177e4SLinus Torvalds * 11401da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11411da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11421da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11431da177e4SLinus Torvalds * inode list. 11441da177e4SLinus Torvalds * 11451da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 11461da177e4SLinus Torvalds * mapping->tree_lock and the global inode_lock. 11471da177e4SLinus Torvalds */ 1148fc9b52cdSHarvey Harrison void mark_buffer_dirty(struct buffer_head *bh) 11491da177e4SLinus Torvalds { 1150787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 11511be62dc1SLinus Torvalds 11521be62dc1SLinus Torvalds /* 11531be62dc1SLinus Torvalds * Very *carefully* optimize the it-is-already-dirty case. 11541be62dc1SLinus Torvalds * 11551be62dc1SLinus Torvalds * Don't let the final "is it dirty" escape to before we 11561be62dc1SLinus Torvalds * perhaps modified the buffer. 11571be62dc1SLinus Torvalds */ 11581be62dc1SLinus Torvalds if (buffer_dirty(bh)) { 11591be62dc1SLinus Torvalds smp_mb(); 11601be62dc1SLinus Torvalds if (buffer_dirty(bh)) 11611be62dc1SLinus Torvalds return; 11621be62dc1SLinus Torvalds } 11631be62dc1SLinus Torvalds 1164a8e7d49aSLinus Torvalds if (!test_set_buffer_dirty(bh)) { 1165a8e7d49aSLinus Torvalds struct page *page = bh->b_page; 11668e9d78edSLinus Torvalds if (!TestSetPageDirty(page)) { 11678e9d78edSLinus Torvalds struct address_space *mapping = page_mapping(page); 11688e9d78edSLinus Torvalds if (mapping) 11698e9d78edSLinus Torvalds __set_page_dirty(page, mapping, 0); 11708e9d78edSLinus Torvalds } 1171a8e7d49aSLinus Torvalds } 11721da177e4SLinus Torvalds } 11731fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(mark_buffer_dirty); 11741da177e4SLinus Torvalds 11751da177e4SLinus Torvalds /* 11761da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11771da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11781da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11791da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11801da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11811da177e4SLinus Torvalds */ 11821da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11831da177e4SLinus Torvalds { 11841da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11851da177e4SLinus Torvalds put_bh(buf); 11861da177e4SLinus Torvalds return; 11871da177e4SLinus Torvalds } 11885c752ad9SArjan van de Ven WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 11891da177e4SLinus Torvalds } 11901fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__brelse); 11911da177e4SLinus Torvalds 11921da177e4SLinus Torvalds /* 11931da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 11941da177e4SLinus Torvalds * potentially dirty data. 11951da177e4SLinus Torvalds */ 11961da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 11971da177e4SLinus Torvalds { 11981da177e4SLinus Torvalds clear_buffer_dirty(bh); 1199535ee2fbSJan Kara if (bh->b_assoc_map) { 12001da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 12011da177e4SLinus Torvalds 12021da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 12031da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 120458ff407bSJan Kara bh->b_assoc_map = NULL; 12051da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12061da177e4SLinus Torvalds } 12071da177e4SLinus Torvalds __brelse(bh); 12081da177e4SLinus Torvalds } 12091fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__bforget); 12101da177e4SLinus Torvalds 12111da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12121da177e4SLinus Torvalds { 12131da177e4SLinus Torvalds lock_buffer(bh); 12141da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12151da177e4SLinus Torvalds unlock_buffer(bh); 12161da177e4SLinus Torvalds return bh; 12171da177e4SLinus Torvalds } else { 12181da177e4SLinus Torvalds get_bh(bh); 12191da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12201da177e4SLinus Torvalds submit_bh(READ, bh); 12211da177e4SLinus Torvalds wait_on_buffer(bh); 12221da177e4SLinus Torvalds if (buffer_uptodate(bh)) 12231da177e4SLinus Torvalds return bh; 12241da177e4SLinus Torvalds } 12251da177e4SLinus Torvalds brelse(bh); 12261da177e4SLinus Torvalds return NULL; 12271da177e4SLinus Torvalds } 12281da177e4SLinus Torvalds 12291da177e4SLinus Torvalds /* 12301da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12311da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12321da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12331da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12341da177e4SLinus Torvalds * CPU's LRUs at the same time. 12351da177e4SLinus Torvalds * 12361da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12371da177e4SLinus Torvalds * sb_find_get_block(). 12381da177e4SLinus Torvalds * 12391da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12401da177e4SLinus Torvalds * a local interrupt disable for that. 12411da177e4SLinus Torvalds */ 12421da177e4SLinus Torvalds 12431da177e4SLinus Torvalds #define BH_LRU_SIZE 8 12441da177e4SLinus Torvalds 12451da177e4SLinus Torvalds struct bh_lru { 12461da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12471da177e4SLinus Torvalds }; 12481da177e4SLinus Torvalds 12491da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12501da177e4SLinus Torvalds 12511da177e4SLinus Torvalds #ifdef CONFIG_SMP 12521da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12531da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12541da177e4SLinus Torvalds #else 12551da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12561da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12571da177e4SLinus Torvalds #endif 12581da177e4SLinus Torvalds 12591da177e4SLinus Torvalds static inline void check_irqs_on(void) 12601da177e4SLinus Torvalds { 12611da177e4SLinus Torvalds #ifdef irqs_disabled 12621da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12631da177e4SLinus Torvalds #endif 12641da177e4SLinus Torvalds } 12651da177e4SLinus Torvalds 12661da177e4SLinus Torvalds /* 12671da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 12681da177e4SLinus Torvalds */ 12691da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12701da177e4SLinus Torvalds { 12711da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 12721da177e4SLinus Torvalds struct bh_lru *lru; 12731da177e4SLinus Torvalds 12741da177e4SLinus Torvalds check_irqs_on(); 12751da177e4SLinus Torvalds bh_lru_lock(); 12761da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 12771da177e4SLinus Torvalds if (lru->bhs[0] != bh) { 12781da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12791da177e4SLinus Torvalds int in; 12801da177e4SLinus Torvalds int out = 0; 12811da177e4SLinus Torvalds 12821da177e4SLinus Torvalds get_bh(bh); 12831da177e4SLinus Torvalds bhs[out++] = bh; 12841da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 12851da177e4SLinus Torvalds struct buffer_head *bh2 = lru->bhs[in]; 12861da177e4SLinus Torvalds 12871da177e4SLinus Torvalds if (bh2 == bh) { 12881da177e4SLinus Torvalds __brelse(bh2); 12891da177e4SLinus Torvalds } else { 12901da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 12911da177e4SLinus Torvalds BUG_ON(evictee != NULL); 12921da177e4SLinus Torvalds evictee = bh2; 12931da177e4SLinus Torvalds } else { 12941da177e4SLinus Torvalds bhs[out++] = bh2; 12951da177e4SLinus Torvalds } 12961da177e4SLinus Torvalds } 12971da177e4SLinus Torvalds } 12981da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 12991da177e4SLinus Torvalds bhs[out++] = NULL; 13001da177e4SLinus Torvalds memcpy(lru->bhs, bhs, sizeof(bhs)); 13011da177e4SLinus Torvalds } 13021da177e4SLinus Torvalds bh_lru_unlock(); 13031da177e4SLinus Torvalds 13041da177e4SLinus Torvalds if (evictee) 13051da177e4SLinus Torvalds __brelse(evictee); 13061da177e4SLinus Torvalds } 13071da177e4SLinus Torvalds 13081da177e4SLinus Torvalds /* 13091da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 13101da177e4SLinus Torvalds */ 1311858119e1SArjan van de Ven static struct buffer_head * 13123991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 13131da177e4SLinus Torvalds { 13141da177e4SLinus Torvalds struct buffer_head *ret = NULL; 13151da177e4SLinus Torvalds struct bh_lru *lru; 13163991d3bdSTomasz Kvarsin unsigned int i; 13171da177e4SLinus Torvalds 13181da177e4SLinus Torvalds check_irqs_on(); 13191da177e4SLinus Torvalds bh_lru_lock(); 13201da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 13211da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 13221da177e4SLinus Torvalds struct buffer_head *bh = lru->bhs[i]; 13231da177e4SLinus Torvalds 13241da177e4SLinus Torvalds if (bh && bh->b_bdev == bdev && 13251da177e4SLinus Torvalds bh->b_blocknr == block && bh->b_size == size) { 13261da177e4SLinus Torvalds if (i) { 13271da177e4SLinus Torvalds while (i) { 13281da177e4SLinus Torvalds lru->bhs[i] = lru->bhs[i - 1]; 13291da177e4SLinus Torvalds i--; 13301da177e4SLinus Torvalds } 13311da177e4SLinus Torvalds lru->bhs[0] = bh; 13321da177e4SLinus Torvalds } 13331da177e4SLinus Torvalds get_bh(bh); 13341da177e4SLinus Torvalds ret = bh; 13351da177e4SLinus Torvalds break; 13361da177e4SLinus Torvalds } 13371da177e4SLinus Torvalds } 13381da177e4SLinus Torvalds bh_lru_unlock(); 13391da177e4SLinus Torvalds return ret; 13401da177e4SLinus Torvalds } 13411da177e4SLinus Torvalds 13421da177e4SLinus Torvalds /* 13431da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13441da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13451da177e4SLinus Torvalds * NULL 13461da177e4SLinus Torvalds */ 13471da177e4SLinus Torvalds struct buffer_head * 13483991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 13491da177e4SLinus Torvalds { 13501da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13511da177e4SLinus Torvalds 13521da177e4SLinus Torvalds if (bh == NULL) { 1353385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13541da177e4SLinus Torvalds if (bh) 13551da177e4SLinus Torvalds bh_lru_install(bh); 13561da177e4SLinus Torvalds } 13571da177e4SLinus Torvalds if (bh) 13581da177e4SLinus Torvalds touch_buffer(bh); 13591da177e4SLinus Torvalds return bh; 13601da177e4SLinus Torvalds } 13611da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13621da177e4SLinus Torvalds 13631da177e4SLinus Torvalds /* 13641da177e4SLinus Torvalds * __getblk will locate (and, if necessary, create) the buffer_head 13651da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13661da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13671da177e4SLinus Torvalds * 13681da177e4SLinus Torvalds * __getblk() cannot fail - it just keeps trying. If you pass it an 13691da177e4SLinus Torvalds * illegal block number, __getblk() will happily return a buffer_head 13701da177e4SLinus Torvalds * which represents the non-existent block. Very weird. 13711da177e4SLinus Torvalds * 13721da177e4SLinus Torvalds * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() 13731da177e4SLinus Torvalds * attempt is failing. FIXME, perhaps? 13741da177e4SLinus Torvalds */ 13751da177e4SLinus Torvalds struct buffer_head * 13763991d3bdSTomasz Kvarsin __getblk(struct block_device *bdev, sector_t block, unsigned size) 13771da177e4SLinus Torvalds { 13781da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13791da177e4SLinus Torvalds 13801da177e4SLinus Torvalds might_sleep(); 13811da177e4SLinus Torvalds if (bh == NULL) 13821da177e4SLinus Torvalds bh = __getblk_slow(bdev, block, size); 13831da177e4SLinus Torvalds return bh; 13841da177e4SLinus Torvalds } 13851da177e4SLinus Torvalds EXPORT_SYMBOL(__getblk); 13861da177e4SLinus Torvalds 13871da177e4SLinus Torvalds /* 13881da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13891da177e4SLinus Torvalds */ 13903991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 13911da177e4SLinus Torvalds { 13921da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1393a3e713b5SAndrew Morton if (likely(bh)) { 13941da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 13951da177e4SLinus Torvalds brelse(bh); 13961da177e4SLinus Torvalds } 1397a3e713b5SAndrew Morton } 13981da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 13991da177e4SLinus Torvalds 14001da177e4SLinus Torvalds /** 14011da177e4SLinus Torvalds * __bread() - reads a specified block and returns the bh 140267be2dd1SMartin Waitz * @bdev: the block_device to read from 14031da177e4SLinus Torvalds * @block: number of block 14041da177e4SLinus Torvalds * @size: size (in bytes) to read 14051da177e4SLinus Torvalds * 14061da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 14071da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 14081da177e4SLinus Torvalds */ 14091da177e4SLinus Torvalds struct buffer_head * 14103991d3bdSTomasz Kvarsin __bread(struct block_device *bdev, sector_t block, unsigned size) 14111da177e4SLinus Torvalds { 14121da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 14131da177e4SLinus Torvalds 1414a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 14151da177e4SLinus Torvalds bh = __bread_slow(bh); 14161da177e4SLinus Torvalds return bh; 14171da177e4SLinus Torvalds } 14181da177e4SLinus Torvalds EXPORT_SYMBOL(__bread); 14191da177e4SLinus Torvalds 14201da177e4SLinus Torvalds /* 14211da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14221da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 14231da177e4SLinus Torvalds * or with preempt disabled. 14241da177e4SLinus Torvalds */ 14251da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 14261da177e4SLinus Torvalds { 14271da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14281da177e4SLinus Torvalds int i; 14291da177e4SLinus Torvalds 14301da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14311da177e4SLinus Torvalds brelse(b->bhs[i]); 14321da177e4SLinus Torvalds b->bhs[i] = NULL; 14331da177e4SLinus Torvalds } 14341da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14351da177e4SLinus Torvalds } 14361da177e4SLinus Torvalds 1437f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 14381da177e4SLinus Torvalds { 143915c8b6c1SJens Axboe on_each_cpu(invalidate_bh_lru, NULL, 1); 14401da177e4SLinus Torvalds } 14419db5579bSNick Piggin EXPORT_SYMBOL_GPL(invalidate_bh_lrus); 14421da177e4SLinus Torvalds 14431da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14441da177e4SLinus Torvalds struct page *page, unsigned long offset) 14451da177e4SLinus Torvalds { 14461da177e4SLinus Torvalds bh->b_page = page; 1447e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14481da177e4SLinus Torvalds if (PageHighMem(page)) 14491da177e4SLinus Torvalds /* 14501da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14511da177e4SLinus Torvalds */ 14521da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14531da177e4SLinus Torvalds else 14541da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14551da177e4SLinus Torvalds } 14561da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds /* 14591da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14601da177e4SLinus Torvalds */ 1461858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14621da177e4SLinus Torvalds { 14631da177e4SLinus Torvalds lock_buffer(bh); 14641da177e4SLinus Torvalds clear_buffer_dirty(bh); 14651da177e4SLinus Torvalds bh->b_bdev = NULL; 14661da177e4SLinus Torvalds clear_buffer_mapped(bh); 14671da177e4SLinus Torvalds clear_buffer_req(bh); 14681da177e4SLinus Torvalds clear_buffer_new(bh); 14691da177e4SLinus Torvalds clear_buffer_delay(bh); 147033a266ddSDavid Chinner clear_buffer_unwritten(bh); 14711da177e4SLinus Torvalds unlock_buffer(bh); 14721da177e4SLinus Torvalds } 14731da177e4SLinus Torvalds 14741da177e4SLinus Torvalds /** 14751da177e4SLinus Torvalds * block_invalidatepage - invalidate part of all of a buffer-backed page 14761da177e4SLinus Torvalds * 14771da177e4SLinus Torvalds * @page: the page which is affected 14781da177e4SLinus Torvalds * @offset: the index of the truncation point 14791da177e4SLinus Torvalds * 14801da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 14811da177e4SLinus Torvalds * invalidatedby a truncate operation. 14821da177e4SLinus Torvalds * 14831da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 14841da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 14851da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 14861da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 14871da177e4SLinus Torvalds * blocks on-disk. 14881da177e4SLinus Torvalds */ 14892ff28e22SNeilBrown void block_invalidatepage(struct page *page, unsigned long offset) 14901da177e4SLinus Torvalds { 14911da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 14921da177e4SLinus Torvalds unsigned int curr_off = 0; 14931da177e4SLinus Torvalds 14941da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 14951da177e4SLinus Torvalds if (!page_has_buffers(page)) 14961da177e4SLinus Torvalds goto out; 14971da177e4SLinus Torvalds 14981da177e4SLinus Torvalds head = page_buffers(page); 14991da177e4SLinus Torvalds bh = head; 15001da177e4SLinus Torvalds do { 15011da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 15021da177e4SLinus Torvalds next = bh->b_this_page; 15031da177e4SLinus Torvalds 15041da177e4SLinus Torvalds /* 15051da177e4SLinus Torvalds * is this block fully invalidated? 15061da177e4SLinus Torvalds */ 15071da177e4SLinus Torvalds if (offset <= curr_off) 15081da177e4SLinus Torvalds discard_buffer(bh); 15091da177e4SLinus Torvalds curr_off = next_off; 15101da177e4SLinus Torvalds bh = next; 15111da177e4SLinus Torvalds } while (bh != head); 15121da177e4SLinus Torvalds 15131da177e4SLinus Torvalds /* 15141da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 15151da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 15161da177e4SLinus Torvalds * so real IO is not possible anymore. 15171da177e4SLinus Torvalds */ 15181da177e4SLinus Torvalds if (offset == 0) 15192ff28e22SNeilBrown try_to_release_page(page, 0); 15201da177e4SLinus Torvalds out: 15212ff28e22SNeilBrown return; 15221da177e4SLinus Torvalds } 15231da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 15241da177e4SLinus Torvalds 15251da177e4SLinus Torvalds /* 15261da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15271da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15281da177e4SLinus Torvalds * is already excluded via the page lock. 15291da177e4SLinus Torvalds */ 15301da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15311da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15321da177e4SLinus Torvalds { 15331da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15341da177e4SLinus Torvalds 15351da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15361da177e4SLinus Torvalds bh = head; 15371da177e4SLinus Torvalds do { 15381da177e4SLinus Torvalds bh->b_state |= b_state; 15391da177e4SLinus Torvalds tail = bh; 15401da177e4SLinus Torvalds bh = bh->b_this_page; 15411da177e4SLinus Torvalds } while (bh); 15421da177e4SLinus Torvalds tail->b_this_page = head; 15431da177e4SLinus Torvalds 15441da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15451da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15461da177e4SLinus Torvalds bh = head; 15471da177e4SLinus Torvalds do { 15481da177e4SLinus Torvalds if (PageDirty(page)) 15491da177e4SLinus Torvalds set_buffer_dirty(bh); 15501da177e4SLinus Torvalds if (PageUptodate(page)) 15511da177e4SLinus Torvalds set_buffer_uptodate(bh); 15521da177e4SLinus Torvalds bh = bh->b_this_page; 15531da177e4SLinus Torvalds } while (bh != head); 15541da177e4SLinus Torvalds } 15551da177e4SLinus Torvalds attach_page_buffers(page, head); 15561da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 15571da177e4SLinus Torvalds } 15581da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 15591da177e4SLinus Torvalds 15601da177e4SLinus Torvalds /* 15611da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 15621da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 15631da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 15641da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 15651da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 15661da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 15671da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 15681da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 15691da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 15701da177e4SLinus Torvalds * 15711da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 15721da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 15731da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 15741da177e4SLinus Torvalds * only if we really need to. That happens here. 15751da177e4SLinus Torvalds */ 15761da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 15771da177e4SLinus Torvalds { 15781da177e4SLinus Torvalds struct buffer_head *old_bh; 15791da177e4SLinus Torvalds 15801da177e4SLinus Torvalds might_sleep(); 15811da177e4SLinus Torvalds 1582385fd4c5SCoywolf Qi Hunt old_bh = __find_get_block_slow(bdev, block); 15831da177e4SLinus Torvalds if (old_bh) { 15841da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 15851da177e4SLinus Torvalds wait_on_buffer(old_bh); 15861da177e4SLinus Torvalds clear_buffer_req(old_bh); 15871da177e4SLinus Torvalds __brelse(old_bh); 15881da177e4SLinus Torvalds } 15891da177e4SLinus Torvalds } 15901da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 15911da177e4SLinus Torvalds 15921da177e4SLinus Torvalds /* 15931da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 15941da177e4SLinus Torvalds * 15951da177e4SLinus Torvalds * Mapped Uptodate Meaning 15961da177e4SLinus Torvalds * 15971da177e4SLinus Torvalds * No No "unknown" - must do get_block() 15981da177e4SLinus Torvalds * No Yes "hole" - zero-filled 15991da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 16001da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 16011da177e4SLinus Torvalds * 16021da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16031da177e4SLinus Torvalds */ 16041da177e4SLinus Torvalds 16051da177e4SLinus Torvalds /* 16061da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16071da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16081da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16091da177e4SLinus Torvalds * state inside lock_buffer(). 16101da177e4SLinus Torvalds * 16111da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16121da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16131da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16141da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16151da177e4SLinus Torvalds * prevents this contention from occurring. 16166e34eeddSTheodore Ts'o * 16176e34eeddSTheodore Ts'o * If block_write_full_page() is called with wbc->sync_mode == 16186e34eeddSTheodore Ts'o * WB_SYNC_ALL, the writes are posted using WRITE_SYNC_PLUG; this 16196e34eeddSTheodore Ts'o * causes the writes to be flagged as synchronous writes, but the 16206e34eeddSTheodore Ts'o * block device queue will NOT be unplugged, since usually many pages 16216e34eeddSTheodore Ts'o * will be pushed to the out before the higher-level caller actually 16226e34eeddSTheodore Ts'o * waits for the writes to be completed. The various wait functions, 16236e34eeddSTheodore Ts'o * such as wait_on_writeback_range() will ultimately call sync_page() 16246e34eeddSTheodore Ts'o * which will ultimately call blk_run_backing_dev(), which will end up 16256e34eeddSTheodore Ts'o * unplugging the device queue. 16261da177e4SLinus Torvalds */ 16271da177e4SLinus Torvalds static int __block_write_full_page(struct inode *inode, struct page *page, 162835c80d5fSChris Mason get_block_t *get_block, struct writeback_control *wbc, 162935c80d5fSChris Mason bh_end_io_t *handler) 16301da177e4SLinus Torvalds { 16311da177e4SLinus Torvalds int err; 16321da177e4SLinus Torvalds sector_t block; 16331da177e4SLinus Torvalds sector_t last_block; 1634f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 1635b0cf2321SBadari Pulavarty const unsigned blocksize = 1 << inode->i_blkbits; 16361da177e4SLinus Torvalds int nr_underway = 0; 16376e34eeddSTheodore Ts'o int write_op = (wbc->sync_mode == WB_SYNC_ALL ? 16386e34eeddSTheodore Ts'o WRITE_SYNC_PLUG : WRITE); 16391da177e4SLinus Torvalds 16401da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 16411da177e4SLinus Torvalds 16421da177e4SLinus Torvalds last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; 16431da177e4SLinus Torvalds 16441da177e4SLinus Torvalds if (!page_has_buffers(page)) { 1645b0cf2321SBadari Pulavarty create_empty_buffers(page, blocksize, 16461da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 16471da177e4SLinus Torvalds } 16481da177e4SLinus Torvalds 16491da177e4SLinus Torvalds /* 16501da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 16511da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 16521da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 16531da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 16541da177e4SLinus Torvalds * 16551da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 16561da177e4SLinus Torvalds * handle that here by just cleaning them. 16571da177e4SLinus Torvalds */ 16581da177e4SLinus Torvalds 165954b21a79SAndrew Morton block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 16601da177e4SLinus Torvalds head = page_buffers(page); 16611da177e4SLinus Torvalds bh = head; 16621da177e4SLinus Torvalds 16631da177e4SLinus Torvalds /* 16641da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 16651da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 16661da177e4SLinus Torvalds */ 16671da177e4SLinus Torvalds do { 16681da177e4SLinus Torvalds if (block > last_block) { 16691da177e4SLinus Torvalds /* 16701da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 16711da177e4SLinus Torvalds * this page can be outside i_size when there is a 16721da177e4SLinus Torvalds * truncate in progress. 16731da177e4SLinus Torvalds */ 16741da177e4SLinus Torvalds /* 16751da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 16761da177e4SLinus Torvalds */ 16771da177e4SLinus Torvalds clear_buffer_dirty(bh); 16781da177e4SLinus Torvalds set_buffer_uptodate(bh); 167929a814d2SAlex Tomas } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && 168029a814d2SAlex Tomas buffer_dirty(bh)) { 1681b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 16821da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 16831da177e4SLinus Torvalds if (err) 16841da177e4SLinus Torvalds goto recover; 168529a814d2SAlex Tomas clear_buffer_delay(bh); 16861da177e4SLinus Torvalds if (buffer_new(bh)) { 16871da177e4SLinus Torvalds /* blockdev mappings never come here */ 16881da177e4SLinus Torvalds clear_buffer_new(bh); 16891da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 16901da177e4SLinus Torvalds bh->b_blocknr); 16911da177e4SLinus Torvalds } 16921da177e4SLinus Torvalds } 16931da177e4SLinus Torvalds bh = bh->b_this_page; 16941da177e4SLinus Torvalds block++; 16951da177e4SLinus Torvalds } while (bh != head); 16961da177e4SLinus Torvalds 16971da177e4SLinus Torvalds do { 16981da177e4SLinus Torvalds if (!buffer_mapped(bh)) 16991da177e4SLinus Torvalds continue; 17001da177e4SLinus Torvalds /* 17011da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17021da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17035b0830cbSJens Axboe * potentially cause a busy-wait loop from writeback threads 17045b0830cbSJens Axboe * and kswapd activity, but those code paths have their own 17055b0830cbSJens Axboe * higher-level throttling. 17061da177e4SLinus Torvalds */ 17071da177e4SLinus Torvalds if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { 17081da177e4SLinus Torvalds lock_buffer(bh); 1709ca5de404SNick Piggin } else if (!trylock_buffer(bh)) { 17101da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 17111da177e4SLinus Torvalds continue; 17121da177e4SLinus Torvalds } 17131da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 171435c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17151da177e4SLinus Torvalds } else { 17161da177e4SLinus Torvalds unlock_buffer(bh); 17171da177e4SLinus Torvalds } 17181da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17191da177e4SLinus Torvalds 17201da177e4SLinus Torvalds /* 17211da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17221da177e4SLinus Torvalds * drop the bh refcounts early. 17231da177e4SLinus Torvalds */ 17241da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17251da177e4SLinus Torvalds set_page_writeback(page); 17261da177e4SLinus Torvalds 17271da177e4SLinus Torvalds do { 17281da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17291da177e4SLinus Torvalds if (buffer_async_write(bh)) { 1730a64c8610STheodore Ts'o submit_bh(write_op, bh); 17311da177e4SLinus Torvalds nr_underway++; 1732ad576e63SNick Piggin } 17331da177e4SLinus Torvalds bh = next; 17341da177e4SLinus Torvalds } while (bh != head); 173505937baaSAndrew Morton unlock_page(page); 17361da177e4SLinus Torvalds 17371da177e4SLinus Torvalds err = 0; 17381da177e4SLinus Torvalds done: 17391da177e4SLinus Torvalds if (nr_underway == 0) { 17401da177e4SLinus Torvalds /* 17411da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 17421da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 17431da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 17441da177e4SLinus Torvalds */ 17451da177e4SLinus Torvalds end_page_writeback(page); 17463d67f2d7SNick Piggin 17471da177e4SLinus Torvalds /* 17481da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 17491da177e4SLinus Torvalds * here on. 17501da177e4SLinus Torvalds */ 17511da177e4SLinus Torvalds } 17521da177e4SLinus Torvalds return err; 17531da177e4SLinus Torvalds 17541da177e4SLinus Torvalds recover: 17551da177e4SLinus Torvalds /* 17561da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 17571da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 17581da177e4SLinus Torvalds * exposing stale data. 17591da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 17601da177e4SLinus Torvalds */ 17611da177e4SLinus Torvalds bh = head; 17621da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 17631da177e4SLinus Torvalds do { 176429a814d2SAlex Tomas if (buffer_mapped(bh) && buffer_dirty(bh) && 176529a814d2SAlex Tomas !buffer_delay(bh)) { 17661da177e4SLinus Torvalds lock_buffer(bh); 176735c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17681da177e4SLinus Torvalds } else { 17691da177e4SLinus Torvalds /* 17701da177e4SLinus Torvalds * The buffer may have been set dirty during 17711da177e4SLinus Torvalds * attachment to a dirty page. 17721da177e4SLinus Torvalds */ 17731da177e4SLinus Torvalds clear_buffer_dirty(bh); 17741da177e4SLinus Torvalds } 17751da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17761da177e4SLinus Torvalds SetPageError(page); 17771da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17787e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 17791da177e4SLinus Torvalds set_page_writeback(page); 17801da177e4SLinus Torvalds do { 17811da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17821da177e4SLinus Torvalds if (buffer_async_write(bh)) { 17831da177e4SLinus Torvalds clear_buffer_dirty(bh); 1784a64c8610STheodore Ts'o submit_bh(write_op, bh); 17851da177e4SLinus Torvalds nr_underway++; 1786ad576e63SNick Piggin } 17871da177e4SLinus Torvalds bh = next; 17881da177e4SLinus Torvalds } while (bh != head); 1789ffda9d30SNick Piggin unlock_page(page); 17901da177e4SLinus Torvalds goto done; 17911da177e4SLinus Torvalds } 17921da177e4SLinus Torvalds 1793afddba49SNick Piggin /* 1794afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1795afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1796afddba49SNick Piggin * block data from leaking). And clear the new bit. 1797afddba49SNick Piggin */ 1798afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1799afddba49SNick Piggin { 1800afddba49SNick Piggin unsigned int block_start, block_end; 1801afddba49SNick Piggin struct buffer_head *head, *bh; 1802afddba49SNick Piggin 1803afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1804afddba49SNick Piggin if (!page_has_buffers(page)) 1805afddba49SNick Piggin return; 1806afddba49SNick Piggin 1807afddba49SNick Piggin bh = head = page_buffers(page); 1808afddba49SNick Piggin block_start = 0; 1809afddba49SNick Piggin do { 1810afddba49SNick Piggin block_end = block_start + bh->b_size; 1811afddba49SNick Piggin 1812afddba49SNick Piggin if (buffer_new(bh)) { 1813afddba49SNick Piggin if (block_end > from && block_start < to) { 1814afddba49SNick Piggin if (!PageUptodate(page)) { 1815afddba49SNick Piggin unsigned start, size; 1816afddba49SNick Piggin 1817afddba49SNick Piggin start = max(from, block_start); 1818afddba49SNick Piggin size = min(to, block_end) - start; 1819afddba49SNick Piggin 1820eebd2aa3SChristoph Lameter zero_user(page, start, size); 1821afddba49SNick Piggin set_buffer_uptodate(bh); 1822afddba49SNick Piggin } 1823afddba49SNick Piggin 1824afddba49SNick Piggin clear_buffer_new(bh); 1825afddba49SNick Piggin mark_buffer_dirty(bh); 1826afddba49SNick Piggin } 1827afddba49SNick Piggin } 1828afddba49SNick Piggin 1829afddba49SNick Piggin block_start = block_end; 1830afddba49SNick Piggin bh = bh->b_this_page; 1831afddba49SNick Piggin } while (bh != head); 1832afddba49SNick Piggin } 1833afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1834afddba49SNick Piggin 18351da177e4SLinus Torvalds static int __block_prepare_write(struct inode *inode, struct page *page, 18361da177e4SLinus Torvalds unsigned from, unsigned to, get_block_t *get_block) 18371da177e4SLinus Torvalds { 18381da177e4SLinus Torvalds unsigned block_start, block_end; 18391da177e4SLinus Torvalds sector_t block; 18401da177e4SLinus Torvalds int err = 0; 18411da177e4SLinus Torvalds unsigned blocksize, bbits; 18421da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 18431da177e4SLinus Torvalds 18441da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 18451da177e4SLinus Torvalds BUG_ON(from > PAGE_CACHE_SIZE); 18461da177e4SLinus Torvalds BUG_ON(to > PAGE_CACHE_SIZE); 18471da177e4SLinus Torvalds BUG_ON(from > to); 18481da177e4SLinus Torvalds 18491da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 18501da177e4SLinus Torvalds if (!page_has_buffers(page)) 18511da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 18521da177e4SLinus Torvalds head = page_buffers(page); 18531da177e4SLinus Torvalds 18541da177e4SLinus Torvalds bbits = inode->i_blkbits; 18551da177e4SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 18561da177e4SLinus Torvalds 18571da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 18581da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 18591da177e4SLinus Torvalds block_end = block_start + blocksize; 18601da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 18611da177e4SLinus Torvalds if (PageUptodate(page)) { 18621da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 18631da177e4SLinus Torvalds set_buffer_uptodate(bh); 18641da177e4SLinus Torvalds } 18651da177e4SLinus Torvalds continue; 18661da177e4SLinus Torvalds } 18671da177e4SLinus Torvalds if (buffer_new(bh)) 18681da177e4SLinus Torvalds clear_buffer_new(bh); 18691da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1870b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 18711da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 18721da177e4SLinus Torvalds if (err) 1873f3ddbdc6SNick Piggin break; 18741da177e4SLinus Torvalds if (buffer_new(bh)) { 18751da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 18761da177e4SLinus Torvalds bh->b_blocknr); 18771da177e4SLinus Torvalds if (PageUptodate(page)) { 1878637aff46SNick Piggin clear_buffer_new(bh); 18791da177e4SLinus Torvalds set_buffer_uptodate(bh); 1880637aff46SNick Piggin mark_buffer_dirty(bh); 18811da177e4SLinus Torvalds continue; 18821da177e4SLinus Torvalds } 1883eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 1884eebd2aa3SChristoph Lameter zero_user_segments(page, 1885eebd2aa3SChristoph Lameter to, block_end, 1886eebd2aa3SChristoph Lameter block_start, from); 18871da177e4SLinus Torvalds continue; 18881da177e4SLinus Torvalds } 18891da177e4SLinus Torvalds } 18901da177e4SLinus Torvalds if (PageUptodate(page)) { 18911da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 18921da177e4SLinus Torvalds set_buffer_uptodate(bh); 18931da177e4SLinus Torvalds continue; 18941da177e4SLinus Torvalds } 18951da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 189633a266ddSDavid Chinner !buffer_unwritten(bh) && 18971da177e4SLinus Torvalds (block_start < from || block_end > to)) { 18981da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 18991da177e4SLinus Torvalds *wait_bh++=bh; 19001da177e4SLinus Torvalds } 19011da177e4SLinus Torvalds } 19021da177e4SLinus Torvalds /* 19031da177e4SLinus Torvalds * If we issued read requests - let them complete. 19041da177e4SLinus Torvalds */ 19051da177e4SLinus Torvalds while(wait_bh > wait) { 19061da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 19071da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1908f3ddbdc6SNick Piggin err = -EIO; 19091da177e4SLinus Torvalds } 1910afddba49SNick Piggin if (unlikely(err)) 1911afddba49SNick Piggin page_zero_new_buffers(page, from, to); 19121da177e4SLinus Torvalds return err; 19131da177e4SLinus Torvalds } 19141da177e4SLinus Torvalds 19151da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 19161da177e4SLinus Torvalds unsigned from, unsigned to) 19171da177e4SLinus Torvalds { 19181da177e4SLinus Torvalds unsigned block_start, block_end; 19191da177e4SLinus Torvalds int partial = 0; 19201da177e4SLinus Torvalds unsigned blocksize; 19211da177e4SLinus Torvalds struct buffer_head *bh, *head; 19221da177e4SLinus Torvalds 19231da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 19241da177e4SLinus Torvalds 19251da177e4SLinus Torvalds for(bh = head = page_buffers(page), block_start = 0; 19261da177e4SLinus Torvalds bh != head || !block_start; 19271da177e4SLinus Torvalds block_start=block_end, bh = bh->b_this_page) { 19281da177e4SLinus Torvalds block_end = block_start + blocksize; 19291da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19301da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19311da177e4SLinus Torvalds partial = 1; 19321da177e4SLinus Torvalds } else { 19331da177e4SLinus Torvalds set_buffer_uptodate(bh); 19341da177e4SLinus Torvalds mark_buffer_dirty(bh); 19351da177e4SLinus Torvalds } 1936afddba49SNick Piggin clear_buffer_new(bh); 19371da177e4SLinus Torvalds } 19381da177e4SLinus Torvalds 19391da177e4SLinus Torvalds /* 19401da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 19411da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 19421da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 19431da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 19441da177e4SLinus Torvalds */ 19451da177e4SLinus Torvalds if (!partial) 19461da177e4SLinus Torvalds SetPageUptodate(page); 19471da177e4SLinus Torvalds return 0; 19481da177e4SLinus Torvalds } 19491da177e4SLinus Torvalds 19501da177e4SLinus Torvalds /* 1951afddba49SNick Piggin * block_write_begin takes care of the basic task of block allocation and 1952afddba49SNick Piggin * bringing partial write blocks uptodate first. 1953afddba49SNick Piggin * 1954afddba49SNick Piggin * If *pagep is not NULL, then block_write_begin uses the locked page 1955afddba49SNick Piggin * at *pagep rather than allocating its own. In this case, the page will 1956afddba49SNick Piggin * not be unlocked or deallocated on failure. 1957afddba49SNick Piggin */ 1958afddba49SNick Piggin int block_write_begin(struct file *file, struct address_space *mapping, 1959afddba49SNick Piggin loff_t pos, unsigned len, unsigned flags, 1960afddba49SNick Piggin struct page **pagep, void **fsdata, 1961afddba49SNick Piggin get_block_t *get_block) 1962afddba49SNick Piggin { 1963afddba49SNick Piggin struct inode *inode = mapping->host; 1964afddba49SNick Piggin int status = 0; 1965afddba49SNick Piggin struct page *page; 1966afddba49SNick Piggin pgoff_t index; 1967afddba49SNick Piggin unsigned start, end; 1968afddba49SNick Piggin int ownpage = 0; 1969afddba49SNick Piggin 1970afddba49SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 1971afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 1972afddba49SNick Piggin end = start + len; 1973afddba49SNick Piggin 1974afddba49SNick Piggin page = *pagep; 1975afddba49SNick Piggin if (page == NULL) { 1976afddba49SNick Piggin ownpage = 1; 197754566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 1978afddba49SNick Piggin if (!page) { 1979afddba49SNick Piggin status = -ENOMEM; 1980afddba49SNick Piggin goto out; 1981afddba49SNick Piggin } 1982afddba49SNick Piggin *pagep = page; 1983afddba49SNick Piggin } else 1984afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1985afddba49SNick Piggin 1986afddba49SNick Piggin status = __block_prepare_write(inode, page, start, end, get_block); 1987afddba49SNick Piggin if (unlikely(status)) { 1988afddba49SNick Piggin ClearPageUptodate(page); 1989afddba49SNick Piggin 1990afddba49SNick Piggin if (ownpage) { 1991afddba49SNick Piggin unlock_page(page); 1992afddba49SNick Piggin page_cache_release(page); 1993afddba49SNick Piggin *pagep = NULL; 1994afddba49SNick Piggin 1995afddba49SNick Piggin /* 1996afddba49SNick Piggin * prepare_write() may have instantiated a few blocks 1997afddba49SNick Piggin * outside i_size. Trim these off again. Don't need 1998afddba49SNick Piggin * i_size_read because we hold i_mutex. 1999afddba49SNick Piggin */ 2000afddba49SNick Piggin if (pos + len > inode->i_size) 2001afddba49SNick Piggin vmtruncate(inode, inode->i_size); 2002afddba49SNick Piggin } 2003afddba49SNick Piggin } 2004afddba49SNick Piggin 2005afddba49SNick Piggin out: 2006afddba49SNick Piggin return status; 2007afddba49SNick Piggin } 2008afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2009afddba49SNick Piggin 2010afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2011afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2012afddba49SNick Piggin struct page *page, void *fsdata) 2013afddba49SNick Piggin { 2014afddba49SNick Piggin struct inode *inode = mapping->host; 2015afddba49SNick Piggin unsigned start; 2016afddba49SNick Piggin 2017afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 2018afddba49SNick Piggin 2019afddba49SNick Piggin if (unlikely(copied < len)) { 2020afddba49SNick Piggin /* 2021afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2022afddba49SNick Piggin * don't have to worry about a readpage reading them and 2023afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2024afddba49SNick Piggin * a short write and only partially written into a buffer, it 2025afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2026afddba49SNick Piggin * destroy our partial write. 2027afddba49SNick Piggin * 2028afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2029afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2030afddba49SNick Piggin * caller to redo the whole thing. 2031afddba49SNick Piggin */ 2032afddba49SNick Piggin if (!PageUptodate(page)) 2033afddba49SNick Piggin copied = 0; 2034afddba49SNick Piggin 2035afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2036afddba49SNick Piggin } 2037afddba49SNick Piggin flush_dcache_page(page); 2038afddba49SNick Piggin 2039afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2040afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2041afddba49SNick Piggin 2042afddba49SNick Piggin return copied; 2043afddba49SNick Piggin } 2044afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2045afddba49SNick Piggin 2046afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2047afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2048afddba49SNick Piggin struct page *page, void *fsdata) 2049afddba49SNick Piggin { 2050afddba49SNick Piggin struct inode *inode = mapping->host; 2051c7d206b3SJan Kara int i_size_changed = 0; 2052afddba49SNick Piggin 2053afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2054afddba49SNick Piggin 2055afddba49SNick Piggin /* 2056afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2057afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2058afddba49SNick Piggin * 2059afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2060afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2061afddba49SNick Piggin */ 2062afddba49SNick Piggin if (pos+copied > inode->i_size) { 2063afddba49SNick Piggin i_size_write(inode, pos+copied); 2064c7d206b3SJan Kara i_size_changed = 1; 2065afddba49SNick Piggin } 2066afddba49SNick Piggin 2067afddba49SNick Piggin unlock_page(page); 2068afddba49SNick Piggin page_cache_release(page); 2069afddba49SNick Piggin 2070c7d206b3SJan Kara /* 2071c7d206b3SJan Kara * Don't mark the inode dirty under page lock. First, it unnecessarily 2072c7d206b3SJan Kara * makes the holding time of page lock longer. Second, it forces lock 2073c7d206b3SJan Kara * ordering of page lock and transaction start for journaling 2074c7d206b3SJan Kara * filesystems. 2075c7d206b3SJan Kara */ 2076c7d206b3SJan Kara if (i_size_changed) 2077c7d206b3SJan Kara mark_inode_dirty(inode); 2078c7d206b3SJan Kara 2079afddba49SNick Piggin return copied; 2080afddba49SNick Piggin } 2081afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2082afddba49SNick Piggin 2083afddba49SNick Piggin /* 20848ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 20858ab22b9aSHisashi Hifumi * uptodate or not. 20868ab22b9aSHisashi Hifumi * 20878ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 20888ab22b9aSHisashi Hifumi * we want to read are uptodate. 20898ab22b9aSHisashi Hifumi */ 20908ab22b9aSHisashi Hifumi int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, 20918ab22b9aSHisashi Hifumi unsigned long from) 20928ab22b9aSHisashi Hifumi { 20938ab22b9aSHisashi Hifumi struct inode *inode = page->mapping->host; 20948ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 20958ab22b9aSHisashi Hifumi unsigned to; 20968ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 20978ab22b9aSHisashi Hifumi int ret = 1; 20988ab22b9aSHisashi Hifumi 20998ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 21008ab22b9aSHisashi Hifumi return 0; 21018ab22b9aSHisashi Hifumi 21028ab22b9aSHisashi Hifumi blocksize = 1 << inode->i_blkbits; 21038ab22b9aSHisashi Hifumi to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count); 21048ab22b9aSHisashi Hifumi to = from + to; 21058ab22b9aSHisashi Hifumi if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) 21068ab22b9aSHisashi Hifumi return 0; 21078ab22b9aSHisashi Hifumi 21088ab22b9aSHisashi Hifumi head = page_buffers(page); 21098ab22b9aSHisashi Hifumi bh = head; 21108ab22b9aSHisashi Hifumi block_start = 0; 21118ab22b9aSHisashi Hifumi do { 21128ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 21138ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 21148ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 21158ab22b9aSHisashi Hifumi ret = 0; 21168ab22b9aSHisashi Hifumi break; 21178ab22b9aSHisashi Hifumi } 21188ab22b9aSHisashi Hifumi if (block_end >= to) 21198ab22b9aSHisashi Hifumi break; 21208ab22b9aSHisashi Hifumi } 21218ab22b9aSHisashi Hifumi block_start = block_end; 21228ab22b9aSHisashi Hifumi bh = bh->b_this_page; 21238ab22b9aSHisashi Hifumi } while (bh != head); 21248ab22b9aSHisashi Hifumi 21258ab22b9aSHisashi Hifumi return ret; 21268ab22b9aSHisashi Hifumi } 21278ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 21288ab22b9aSHisashi Hifumi 21298ab22b9aSHisashi Hifumi /* 21301da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 21311da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 21321da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 21331da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 21341da177e4SLinus Torvalds * page struct once IO has completed. 21351da177e4SLinus Torvalds */ 21361da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 21371da177e4SLinus Torvalds { 21381da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21391da177e4SLinus Torvalds sector_t iblock, lblock; 21401da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 21411da177e4SLinus Torvalds unsigned int blocksize; 21421da177e4SLinus Torvalds int nr, i; 21431da177e4SLinus Torvalds int fully_mapped = 1; 21441da177e4SLinus Torvalds 2145cd7619d6SMatt Mackall BUG_ON(!PageLocked(page)); 21461da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 21471da177e4SLinus Torvalds if (!page_has_buffers(page)) 21481da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 21491da177e4SLinus Torvalds head = page_buffers(page); 21501da177e4SLinus Torvalds 21511da177e4SLinus Torvalds iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 21521da177e4SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; 21531da177e4SLinus Torvalds bh = head; 21541da177e4SLinus Torvalds nr = 0; 21551da177e4SLinus Torvalds i = 0; 21561da177e4SLinus Torvalds 21571da177e4SLinus Torvalds do { 21581da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21591da177e4SLinus Torvalds continue; 21601da177e4SLinus Torvalds 21611da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2162c64610baSAndrew Morton int err = 0; 2163c64610baSAndrew Morton 21641da177e4SLinus Torvalds fully_mapped = 0; 21651da177e4SLinus Torvalds if (iblock < lblock) { 2166b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2167c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2168c64610baSAndrew Morton if (err) 21691da177e4SLinus Torvalds SetPageError(page); 21701da177e4SLinus Torvalds } 21711da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2172eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2173c64610baSAndrew Morton if (!err) 21741da177e4SLinus Torvalds set_buffer_uptodate(bh); 21751da177e4SLinus Torvalds continue; 21761da177e4SLinus Torvalds } 21771da177e4SLinus Torvalds /* 21781da177e4SLinus Torvalds * get_block() might have updated the buffer 21791da177e4SLinus Torvalds * synchronously 21801da177e4SLinus Torvalds */ 21811da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21821da177e4SLinus Torvalds continue; 21831da177e4SLinus Torvalds } 21841da177e4SLinus Torvalds arr[nr++] = bh; 21851da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 21861da177e4SLinus Torvalds 21871da177e4SLinus Torvalds if (fully_mapped) 21881da177e4SLinus Torvalds SetPageMappedToDisk(page); 21891da177e4SLinus Torvalds 21901da177e4SLinus Torvalds if (!nr) { 21911da177e4SLinus Torvalds /* 21921da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 21931da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 21941da177e4SLinus Torvalds */ 21951da177e4SLinus Torvalds if (!PageError(page)) 21961da177e4SLinus Torvalds SetPageUptodate(page); 21971da177e4SLinus Torvalds unlock_page(page); 21981da177e4SLinus Torvalds return 0; 21991da177e4SLinus Torvalds } 22001da177e4SLinus Torvalds 22011da177e4SLinus Torvalds /* Stage two: lock the buffers */ 22021da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22031da177e4SLinus Torvalds bh = arr[i]; 22041da177e4SLinus Torvalds lock_buffer(bh); 22051da177e4SLinus Torvalds mark_buffer_async_read(bh); 22061da177e4SLinus Torvalds } 22071da177e4SLinus Torvalds 22081da177e4SLinus Torvalds /* 22091da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 22101da177e4SLinus Torvalds * inside the buffer lock in case another process reading 22111da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 22121da177e4SLinus Torvalds */ 22131da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22141da177e4SLinus Torvalds bh = arr[i]; 22151da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22161da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 22171da177e4SLinus Torvalds else 22181da177e4SLinus Torvalds submit_bh(READ, bh); 22191da177e4SLinus Torvalds } 22201da177e4SLinus Torvalds return 0; 22211da177e4SLinus Torvalds } 22221fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 22231da177e4SLinus Torvalds 22241da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 222589e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 22261da177e4SLinus Torvalds * deal with the hole. 22271da177e4SLinus Torvalds */ 222889e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 22291da177e4SLinus Torvalds { 22301da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 22311da177e4SLinus Torvalds struct page *page; 223289e10787SNick Piggin void *fsdata; 22331da177e4SLinus Torvalds int err; 22341da177e4SLinus Torvalds 2235c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2236c08d3b0eSnpiggin@suse.de if (err) 22371da177e4SLinus Torvalds goto out; 22381da177e4SLinus Torvalds 223989e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 224089e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, 224189e10787SNick Piggin &page, &fsdata); 224289e10787SNick Piggin if (err) 224305eb0b51SOGAWA Hirofumi goto out; 224405eb0b51SOGAWA Hirofumi 224589e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 224689e10787SNick Piggin BUG_ON(err > 0); 224705eb0b51SOGAWA Hirofumi 224805eb0b51SOGAWA Hirofumi out: 224905eb0b51SOGAWA Hirofumi return err; 225005eb0b51SOGAWA Hirofumi } 22511fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 225205eb0b51SOGAWA Hirofumi 2253f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 225489e10787SNick Piggin loff_t pos, loff_t *bytes) 225505eb0b51SOGAWA Hirofumi { 225689e10787SNick Piggin struct inode *inode = mapping->host; 225789e10787SNick Piggin unsigned blocksize = 1 << inode->i_blkbits; 225889e10787SNick Piggin struct page *page; 225989e10787SNick Piggin void *fsdata; 226089e10787SNick Piggin pgoff_t index, curidx; 226189e10787SNick Piggin loff_t curpos; 226289e10787SNick Piggin unsigned zerofrom, offset, len; 226389e10787SNick Piggin int err = 0; 226405eb0b51SOGAWA Hirofumi 226589e10787SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 226689e10787SNick Piggin offset = pos & ~PAGE_CACHE_MASK; 226789e10787SNick Piggin 226889e10787SNick Piggin while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { 226989e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 227089e10787SNick Piggin if (zerofrom & (blocksize-1)) { 227189e10787SNick Piggin *bytes |= (blocksize-1); 227289e10787SNick Piggin (*bytes)++; 227389e10787SNick Piggin } 227489e10787SNick Piggin len = PAGE_CACHE_SIZE - zerofrom; 227589e10787SNick Piggin 227689e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 227789e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 227889e10787SNick Piggin &page, &fsdata); 227989e10787SNick Piggin if (err) 228089e10787SNick Piggin goto out; 2281eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 228289e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 228389e10787SNick Piggin page, fsdata); 228489e10787SNick Piggin if (err < 0) 228589e10787SNick Piggin goto out; 228689e10787SNick Piggin BUG_ON(err != len); 228789e10787SNick Piggin err = 0; 2288061e9746SOGAWA Hirofumi 2289061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 229089e10787SNick Piggin } 229189e10787SNick Piggin 229289e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 229389e10787SNick Piggin if (index == curidx) { 229489e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 229589e10787SNick Piggin /* if we will expand the thing last block will be filled */ 229689e10787SNick Piggin if (offset <= zerofrom) { 229789e10787SNick Piggin goto out; 229889e10787SNick Piggin } 229989e10787SNick Piggin if (zerofrom & (blocksize-1)) { 230089e10787SNick Piggin *bytes |= (blocksize-1); 230189e10787SNick Piggin (*bytes)++; 230289e10787SNick Piggin } 230389e10787SNick Piggin len = offset - zerofrom; 230489e10787SNick Piggin 230589e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 230689e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 230789e10787SNick Piggin &page, &fsdata); 230889e10787SNick Piggin if (err) 230989e10787SNick Piggin goto out; 2310eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 231189e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 231289e10787SNick Piggin page, fsdata); 231389e10787SNick Piggin if (err < 0) 231489e10787SNick Piggin goto out; 231589e10787SNick Piggin BUG_ON(err != len); 231689e10787SNick Piggin err = 0; 231789e10787SNick Piggin } 231889e10787SNick Piggin out: 231989e10787SNick Piggin return err; 23201da177e4SLinus Torvalds } 23211da177e4SLinus Torvalds 23221da177e4SLinus Torvalds /* 23231da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 23241da177e4SLinus Torvalds * We may have to extend the file. 23251da177e4SLinus Torvalds */ 232689e10787SNick Piggin int cont_write_begin(struct file *file, struct address_space *mapping, 232789e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 232889e10787SNick Piggin struct page **pagep, void **fsdata, 232989e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 23301da177e4SLinus Torvalds { 23311da177e4SLinus Torvalds struct inode *inode = mapping->host; 23321da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 233389e10787SNick Piggin unsigned zerofrom; 233489e10787SNick Piggin int err; 23351da177e4SLinus Torvalds 233689e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 233789e10787SNick Piggin if (err) 23381da177e4SLinus Torvalds goto out; 23391da177e4SLinus Torvalds 23401da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 234189e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 23421da177e4SLinus Torvalds *bytes |= (blocksize-1); 23431da177e4SLinus Torvalds (*bytes)++; 23441da177e4SLinus Torvalds } 23451da177e4SLinus Torvalds 234689e10787SNick Piggin *pagep = NULL; 234789e10787SNick Piggin err = block_write_begin(file, mapping, pos, len, 234889e10787SNick Piggin flags, pagep, fsdata, get_block); 23491da177e4SLinus Torvalds out: 235089e10787SNick Piggin return err; 23511da177e4SLinus Torvalds } 23521fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 23531da177e4SLinus Torvalds 23541da177e4SLinus Torvalds int block_prepare_write(struct page *page, unsigned from, unsigned to, 23551da177e4SLinus Torvalds get_block_t *get_block) 23561da177e4SLinus Torvalds { 23571da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23581da177e4SLinus Torvalds int err = __block_prepare_write(inode, page, from, to, get_block); 23591da177e4SLinus Torvalds if (err) 23601da177e4SLinus Torvalds ClearPageUptodate(page); 23611da177e4SLinus Torvalds return err; 23621da177e4SLinus Torvalds } 23631fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_prepare_write); 23641da177e4SLinus Torvalds 23651da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 23661da177e4SLinus Torvalds { 23671da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23681da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 23691da177e4SLinus Torvalds return 0; 23701da177e4SLinus Torvalds } 23711fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 23721da177e4SLinus Torvalds 237354171690SDavid Chinner /* 237454171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 237554171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 237654171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 237754171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 237854171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 237954171690SDavid Chinner * support these features. 238054171690SDavid Chinner * 238154171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 238254171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 238354171690SDavid Chinner * vmtruncate() writes the inode size before removing pages, once we have the 238454171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 238554171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 238654171690SDavid Chinner * unlock the page. 238754171690SDavid Chinner */ 238854171690SDavid Chinner int 2389c2ec175cSNick Piggin block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 239054171690SDavid Chinner get_block_t get_block) 239154171690SDavid Chinner { 2392c2ec175cSNick Piggin struct page *page = vmf->page; 239354171690SDavid Chinner struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 239454171690SDavid Chinner unsigned long end; 239554171690SDavid Chinner loff_t size; 239656a76f82SNick Piggin int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ 239754171690SDavid Chinner 239854171690SDavid Chinner lock_page(page); 239954171690SDavid Chinner size = i_size_read(inode); 240054171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 240118336338SNick Piggin (page_offset(page) > size)) { 240254171690SDavid Chinner /* page got truncated out from underneath us */ 2403b827e496SNick Piggin unlock_page(page); 2404b827e496SNick Piggin goto out; 240554171690SDavid Chinner } 240654171690SDavid Chinner 240754171690SDavid Chinner /* page is wholly or partially inside EOF */ 240854171690SDavid Chinner if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) 240954171690SDavid Chinner end = size & ~PAGE_CACHE_MASK; 241054171690SDavid Chinner else 241154171690SDavid Chinner end = PAGE_CACHE_SIZE; 241254171690SDavid Chinner 241354171690SDavid Chinner ret = block_prepare_write(page, 0, end, get_block); 241454171690SDavid Chinner if (!ret) 241554171690SDavid Chinner ret = block_commit_write(page, 0, end); 241654171690SDavid Chinner 241756a76f82SNick Piggin if (unlikely(ret)) { 2418b827e496SNick Piggin unlock_page(page); 241956a76f82SNick Piggin if (ret == -ENOMEM) 242056a76f82SNick Piggin ret = VM_FAULT_OOM; 242156a76f82SNick Piggin else /* -ENOSPC, -EIO, etc */ 2422c2ec175cSNick Piggin ret = VM_FAULT_SIGBUS; 2423b827e496SNick Piggin } else 2424b827e496SNick Piggin ret = VM_FAULT_LOCKED; 2425c2ec175cSNick Piggin 2426b827e496SNick Piggin out: 242754171690SDavid Chinner return ret; 242854171690SDavid Chinner } 24291fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 24301da177e4SLinus Torvalds 24311da177e4SLinus Torvalds /* 243203158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 24331da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 24341da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 24351da177e4SLinus Torvalds */ 24361da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 24371da177e4SLinus Torvalds { 243868671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 24391da177e4SLinus Torvalds } 24401da177e4SLinus Torvalds 24411da177e4SLinus Torvalds /* 244203158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 244303158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 244403158cd7SNick Piggin * dirty races). 244503158cd7SNick Piggin */ 244603158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 244703158cd7SNick Piggin { 244803158cd7SNick Piggin struct buffer_head *bh; 244903158cd7SNick Piggin 245003158cd7SNick Piggin BUG_ON(!PageLocked(page)); 245103158cd7SNick Piggin 245203158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 245303158cd7SNick Piggin bh = head; 245403158cd7SNick Piggin do { 245503158cd7SNick Piggin if (PageDirty(page)) 245603158cd7SNick Piggin set_buffer_dirty(bh); 245703158cd7SNick Piggin if (!bh->b_this_page) 245803158cd7SNick Piggin bh->b_this_page = head; 245903158cd7SNick Piggin bh = bh->b_this_page; 246003158cd7SNick Piggin } while (bh != head); 246103158cd7SNick Piggin attach_page_buffers(page, head); 246203158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 246303158cd7SNick Piggin } 246403158cd7SNick Piggin 246503158cd7SNick Piggin /* 24661da177e4SLinus Torvalds * On entry, the page is fully not uptodate. 24671da177e4SLinus Torvalds * On exit the page is fully uptodate in the areas outside (from,to) 24681da177e4SLinus Torvalds */ 246903158cd7SNick Piggin int nobh_write_begin(struct file *file, struct address_space *mapping, 247003158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 247103158cd7SNick Piggin struct page **pagep, void **fsdata, 24721da177e4SLinus Torvalds get_block_t *get_block) 24731da177e4SLinus Torvalds { 247403158cd7SNick Piggin struct inode *inode = mapping->host; 24751da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 24761da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2477a4b0672dSNick Piggin struct buffer_head *head, *bh; 247803158cd7SNick Piggin struct page *page; 247903158cd7SNick Piggin pgoff_t index; 248003158cd7SNick Piggin unsigned from, to; 24811da177e4SLinus Torvalds unsigned block_in_page; 2482a4b0672dSNick Piggin unsigned block_start, block_end; 24831da177e4SLinus Torvalds sector_t block_in_file; 24841da177e4SLinus Torvalds int nr_reads = 0; 24851da177e4SLinus Torvalds int ret = 0; 24861da177e4SLinus Torvalds int is_mapped_to_disk = 1; 24871da177e4SLinus Torvalds 248803158cd7SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 248903158cd7SNick Piggin from = pos & (PAGE_CACHE_SIZE - 1); 249003158cd7SNick Piggin to = from + len; 249103158cd7SNick Piggin 249254566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 249303158cd7SNick Piggin if (!page) 249403158cd7SNick Piggin return -ENOMEM; 249503158cd7SNick Piggin *pagep = page; 249603158cd7SNick Piggin *fsdata = NULL; 249703158cd7SNick Piggin 249803158cd7SNick Piggin if (page_has_buffers(page)) { 249903158cd7SNick Piggin unlock_page(page); 250003158cd7SNick Piggin page_cache_release(page); 250103158cd7SNick Piggin *pagep = NULL; 250203158cd7SNick Piggin return block_write_begin(file, mapping, pos, len, flags, pagep, 250303158cd7SNick Piggin fsdata, get_block); 250403158cd7SNick Piggin } 2505a4b0672dSNick Piggin 25061da177e4SLinus Torvalds if (PageMappedToDisk(page)) 25071da177e4SLinus Torvalds return 0; 25081da177e4SLinus Torvalds 2509a4b0672dSNick Piggin /* 2510a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2511a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2512a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2513a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2514a4b0672dSNick Piggin * 2515a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2516a4b0672dSNick Piggin * than the circular one we're used to. 2517a4b0672dSNick Piggin */ 2518a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 251903158cd7SNick Piggin if (!head) { 252003158cd7SNick Piggin ret = -ENOMEM; 252103158cd7SNick Piggin goto out_release; 252203158cd7SNick Piggin } 2523a4b0672dSNick Piggin 25241da177e4SLinus Torvalds block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); 25251da177e4SLinus Torvalds 25261da177e4SLinus Torvalds /* 25271da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 25281da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 25291da177e4SLinus Torvalds * page is fully mapped-to-disk. 25301da177e4SLinus Torvalds */ 2531a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 25321da177e4SLinus Torvalds block_start < PAGE_CACHE_SIZE; 2533a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 25341da177e4SLinus Torvalds int create; 25351da177e4SLinus Torvalds 2536a4b0672dSNick Piggin block_end = block_start + blocksize; 2537a4b0672dSNick Piggin bh->b_state = 0; 25381da177e4SLinus Torvalds create = 1; 25391da177e4SLinus Torvalds if (block_start >= to) 25401da177e4SLinus Torvalds create = 0; 25411da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2542a4b0672dSNick Piggin bh, create); 25431da177e4SLinus Torvalds if (ret) 25441da177e4SLinus Torvalds goto failed; 2545a4b0672dSNick Piggin if (!buffer_mapped(bh)) 25461da177e4SLinus Torvalds is_mapped_to_disk = 0; 2547a4b0672dSNick Piggin if (buffer_new(bh)) 2548a4b0672dSNick Piggin unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 2549a4b0672dSNick Piggin if (PageUptodate(page)) { 2550a4b0672dSNick Piggin set_buffer_uptodate(bh); 25511da177e4SLinus Torvalds continue; 2552a4b0672dSNick Piggin } 2553a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2554eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2555eebd2aa3SChristoph Lameter to, block_end); 25561da177e4SLinus Torvalds continue; 25571da177e4SLinus Torvalds } 2558a4b0672dSNick Piggin if (buffer_uptodate(bh)) 25591da177e4SLinus Torvalds continue; /* reiserfs does this */ 25601da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2561a4b0672dSNick Piggin lock_buffer(bh); 2562a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 2563a4b0672dSNick Piggin submit_bh(READ, bh); 2564a4b0672dSNick Piggin nr_reads++; 25651da177e4SLinus Torvalds } 25661da177e4SLinus Torvalds } 25671da177e4SLinus Torvalds 25681da177e4SLinus Torvalds if (nr_reads) { 25691da177e4SLinus Torvalds /* 25701da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 25711da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 25721da177e4SLinus Torvalds * for the buffer_head refcounts. 25731da177e4SLinus Torvalds */ 2574a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 25751da177e4SLinus Torvalds wait_on_buffer(bh); 25761da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 25771da177e4SLinus Torvalds ret = -EIO; 25781da177e4SLinus Torvalds } 25791da177e4SLinus Torvalds if (ret) 25801da177e4SLinus Torvalds goto failed; 25811da177e4SLinus Torvalds } 25821da177e4SLinus Torvalds 25831da177e4SLinus Torvalds if (is_mapped_to_disk) 25841da177e4SLinus Torvalds SetPageMappedToDisk(page); 25851da177e4SLinus Torvalds 258603158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2587a4b0672dSNick Piggin 25881da177e4SLinus Torvalds return 0; 25891da177e4SLinus Torvalds 25901da177e4SLinus Torvalds failed: 259103158cd7SNick Piggin BUG_ON(!ret); 25921da177e4SLinus Torvalds /* 2593a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2594a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2595a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2596a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2597a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 25981da177e4SLinus Torvalds */ 259903158cd7SNick Piggin attach_nobh_buffers(page, head); 260003158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2601a4b0672dSNick Piggin 260203158cd7SNick Piggin out_release: 260303158cd7SNick Piggin unlock_page(page); 260403158cd7SNick Piggin page_cache_release(page); 260503158cd7SNick Piggin *pagep = NULL; 2606a4b0672dSNick Piggin 260703158cd7SNick Piggin if (pos + len > inode->i_size) 260803158cd7SNick Piggin vmtruncate(inode, inode->i_size); 2609a4b0672dSNick Piggin 26101da177e4SLinus Torvalds return ret; 26111da177e4SLinus Torvalds } 261203158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 26131da177e4SLinus Torvalds 261403158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 261503158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 261603158cd7SNick Piggin struct page *page, void *fsdata) 26171da177e4SLinus Torvalds { 26181da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2619efdc3131SNick Piggin struct buffer_head *head = fsdata; 262003158cd7SNick Piggin struct buffer_head *bh; 26215b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 26221da177e4SLinus Torvalds 2623d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 262403158cd7SNick Piggin attach_nobh_buffers(page, head); 2625a4b0672dSNick Piggin if (page_has_buffers(page)) 262603158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 262703158cd7SNick Piggin copied, page, fsdata); 2628a4b0672dSNick Piggin 262922c8ca78SNick Piggin SetPageUptodate(page); 26301da177e4SLinus Torvalds set_page_dirty(page); 263103158cd7SNick Piggin if (pos+copied > inode->i_size) { 263203158cd7SNick Piggin i_size_write(inode, pos+copied); 26331da177e4SLinus Torvalds mark_inode_dirty(inode); 26341da177e4SLinus Torvalds } 263503158cd7SNick Piggin 263603158cd7SNick Piggin unlock_page(page); 263703158cd7SNick Piggin page_cache_release(page); 263803158cd7SNick Piggin 263903158cd7SNick Piggin while (head) { 264003158cd7SNick Piggin bh = head; 264103158cd7SNick Piggin head = head->b_this_page; 264203158cd7SNick Piggin free_buffer_head(bh); 26431da177e4SLinus Torvalds } 264403158cd7SNick Piggin 264503158cd7SNick Piggin return copied; 264603158cd7SNick Piggin } 264703158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 26481da177e4SLinus Torvalds 26491da177e4SLinus Torvalds /* 26501da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 26511da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 26521da177e4SLinus Torvalds * the page. 26531da177e4SLinus Torvalds */ 26541da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 26551da177e4SLinus Torvalds struct writeback_control *wbc) 26561da177e4SLinus Torvalds { 26571da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 26581da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 26591da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 26601da177e4SLinus Torvalds unsigned offset; 26611da177e4SLinus Torvalds int ret; 26621da177e4SLinus Torvalds 26631da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 26641da177e4SLinus Torvalds if (page->index < end_index) 26651da177e4SLinus Torvalds goto out; 26661da177e4SLinus Torvalds 26671da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 26681da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 26691da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 26701da177e4SLinus Torvalds /* 26711da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 26721da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 26731da177e4SLinus Torvalds * freeable here, so the page does not leak. 26741da177e4SLinus Torvalds */ 26751da177e4SLinus Torvalds #if 0 26761da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 26771da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 26781da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 26791da177e4SLinus Torvalds #endif 26801da177e4SLinus Torvalds unlock_page(page); 26811da177e4SLinus Torvalds return 0; /* don't care */ 26821da177e4SLinus Torvalds } 26831da177e4SLinus Torvalds 26841da177e4SLinus Torvalds /* 26851da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 26861da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 26871da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 26881da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 26891da177e4SLinus Torvalds * writes to that region are not written out to the file." 26901da177e4SLinus Torvalds */ 2691eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 26921da177e4SLinus Torvalds out: 26931da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 26941da177e4SLinus Torvalds if (ret == -EAGAIN) 269535c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 269635c80d5fSChris Mason end_buffer_async_write); 26971da177e4SLinus Torvalds return ret; 26981da177e4SLinus Torvalds } 26991da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27001da177e4SLinus Torvalds 270103158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 270203158cd7SNick Piggin loff_t from, get_block_t *get_block) 27031da177e4SLinus Torvalds { 27041da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 27051da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 270603158cd7SNick Piggin unsigned blocksize; 270703158cd7SNick Piggin sector_t iblock; 270803158cd7SNick Piggin unsigned length, pos; 270903158cd7SNick Piggin struct inode *inode = mapping->host; 27101da177e4SLinus Torvalds struct page *page; 271103158cd7SNick Piggin struct buffer_head map_bh; 271203158cd7SNick Piggin int err; 27131da177e4SLinus Torvalds 271403158cd7SNick Piggin blocksize = 1 << inode->i_blkbits; 271503158cd7SNick Piggin length = offset & (blocksize - 1); 27161da177e4SLinus Torvalds 271703158cd7SNick Piggin /* Block boundary? Nothing to do */ 271803158cd7SNick Piggin if (!length) 271903158cd7SNick Piggin return 0; 272003158cd7SNick Piggin 272103158cd7SNick Piggin length = blocksize - length; 272203158cd7SNick Piggin iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 272303158cd7SNick Piggin 27241da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 272503158cd7SNick Piggin err = -ENOMEM; 27261da177e4SLinus Torvalds if (!page) 27271da177e4SLinus Torvalds goto out; 27281da177e4SLinus Torvalds 272903158cd7SNick Piggin if (page_has_buffers(page)) { 273003158cd7SNick Piggin has_buffers: 273103158cd7SNick Piggin unlock_page(page); 273203158cd7SNick Piggin page_cache_release(page); 273303158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 27341da177e4SLinus Torvalds } 273503158cd7SNick Piggin 273603158cd7SNick Piggin /* Find the buffer that contains "offset" */ 273703158cd7SNick Piggin pos = blocksize; 273803158cd7SNick Piggin while (offset >= pos) { 273903158cd7SNick Piggin iblock++; 274003158cd7SNick Piggin pos += blocksize; 274103158cd7SNick Piggin } 274203158cd7SNick Piggin 2743460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2744460bcf57STheodore Ts'o map_bh.b_state = 0; 274503158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 274603158cd7SNick Piggin if (err) 274703158cd7SNick Piggin goto unlock; 274803158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 274903158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 275003158cd7SNick Piggin goto unlock; 275103158cd7SNick Piggin 275203158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 275303158cd7SNick Piggin if (!PageUptodate(page)) { 275403158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 275503158cd7SNick Piggin if (err) { 275603158cd7SNick Piggin page_cache_release(page); 275703158cd7SNick Piggin goto out; 275803158cd7SNick Piggin } 275903158cd7SNick Piggin lock_page(page); 276003158cd7SNick Piggin if (!PageUptodate(page)) { 276103158cd7SNick Piggin err = -EIO; 276203158cd7SNick Piggin goto unlock; 276303158cd7SNick Piggin } 276403158cd7SNick Piggin if (page_has_buffers(page)) 276503158cd7SNick Piggin goto has_buffers; 276603158cd7SNick Piggin } 2767eebd2aa3SChristoph Lameter zero_user(page, offset, length); 276803158cd7SNick Piggin set_page_dirty(page); 276903158cd7SNick Piggin err = 0; 277003158cd7SNick Piggin 277103158cd7SNick Piggin unlock: 27721da177e4SLinus Torvalds unlock_page(page); 27731da177e4SLinus Torvalds page_cache_release(page); 27741da177e4SLinus Torvalds out: 277503158cd7SNick Piggin return err; 27761da177e4SLinus Torvalds } 27771da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 27781da177e4SLinus Torvalds 27791da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 27801da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 27811da177e4SLinus Torvalds { 27821da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 27831da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 27841da177e4SLinus Torvalds unsigned blocksize; 278554b21a79SAndrew Morton sector_t iblock; 27861da177e4SLinus Torvalds unsigned length, pos; 27871da177e4SLinus Torvalds struct inode *inode = mapping->host; 27881da177e4SLinus Torvalds struct page *page; 27891da177e4SLinus Torvalds struct buffer_head *bh; 27901da177e4SLinus Torvalds int err; 27911da177e4SLinus Torvalds 27921da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 27931da177e4SLinus Torvalds length = offset & (blocksize - 1); 27941da177e4SLinus Torvalds 27951da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 27961da177e4SLinus Torvalds if (!length) 27971da177e4SLinus Torvalds return 0; 27981da177e4SLinus Torvalds 27991da177e4SLinus Torvalds length = blocksize - length; 280054b21a79SAndrew Morton iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 28011da177e4SLinus Torvalds 28021da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 28031da177e4SLinus Torvalds err = -ENOMEM; 28041da177e4SLinus Torvalds if (!page) 28051da177e4SLinus Torvalds goto out; 28061da177e4SLinus Torvalds 28071da177e4SLinus Torvalds if (!page_has_buffers(page)) 28081da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 28091da177e4SLinus Torvalds 28101da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 28111da177e4SLinus Torvalds bh = page_buffers(page); 28121da177e4SLinus Torvalds pos = blocksize; 28131da177e4SLinus Torvalds while (offset >= pos) { 28141da177e4SLinus Torvalds bh = bh->b_this_page; 28151da177e4SLinus Torvalds iblock++; 28161da177e4SLinus Torvalds pos += blocksize; 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds 28191da177e4SLinus Torvalds err = 0; 28201da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2821b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 28221da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 28231da177e4SLinus Torvalds if (err) 28241da177e4SLinus Torvalds goto unlock; 28251da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 28261da177e4SLinus Torvalds if (!buffer_mapped(bh)) 28271da177e4SLinus Torvalds goto unlock; 28281da177e4SLinus Torvalds } 28291da177e4SLinus Torvalds 28301da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 28311da177e4SLinus Torvalds if (PageUptodate(page)) 28321da177e4SLinus Torvalds set_buffer_uptodate(bh); 28331da177e4SLinus Torvalds 283433a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 28351da177e4SLinus Torvalds err = -EIO; 28361da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 28371da177e4SLinus Torvalds wait_on_buffer(bh); 28381da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 28391da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 28401da177e4SLinus Torvalds goto unlock; 28411da177e4SLinus Torvalds } 28421da177e4SLinus Torvalds 2843eebd2aa3SChristoph Lameter zero_user(page, offset, length); 28441da177e4SLinus Torvalds mark_buffer_dirty(bh); 28451da177e4SLinus Torvalds err = 0; 28461da177e4SLinus Torvalds 28471da177e4SLinus Torvalds unlock: 28481da177e4SLinus Torvalds unlock_page(page); 28491da177e4SLinus Torvalds page_cache_release(page); 28501da177e4SLinus Torvalds out: 28511da177e4SLinus Torvalds return err; 28521da177e4SLinus Torvalds } 28531fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds /* 28561da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 285735c80d5fSChris Mason * this form passes in the end_io handler used to finish the IO. 28581da177e4SLinus Torvalds */ 285935c80d5fSChris Mason int block_write_full_page_endio(struct page *page, get_block_t *get_block, 286035c80d5fSChris Mason struct writeback_control *wbc, bh_end_io_t *handler) 28611da177e4SLinus Torvalds { 28621da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 28631da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 28641da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 28651da177e4SLinus Torvalds unsigned offset; 28661da177e4SLinus Torvalds 28671da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 28681da177e4SLinus Torvalds if (page->index < end_index) 286935c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 287035c80d5fSChris Mason handler); 28711da177e4SLinus Torvalds 28721da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 28731da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 28741da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 28751da177e4SLinus Torvalds /* 28761da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 28771da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 28781da177e4SLinus Torvalds * freeable here, so the page does not leak. 28791da177e4SLinus Torvalds */ 2880aaa4059bSJan Kara do_invalidatepage(page, 0); 28811da177e4SLinus Torvalds unlock_page(page); 28821da177e4SLinus Torvalds return 0; /* don't care */ 28831da177e4SLinus Torvalds } 28841da177e4SLinus Torvalds 28851da177e4SLinus Torvalds /* 28861da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 28872a61aa40SAdam Buchbinder * writepage invocation because it may be mmapped. "A file is mapped 28881da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 28891da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 28901da177e4SLinus Torvalds * writes to that region are not written out to the file." 28911da177e4SLinus Torvalds */ 2892eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 289335c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, handler); 28941da177e4SLinus Torvalds } 28951fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page_endio); 28961da177e4SLinus Torvalds 289735c80d5fSChris Mason /* 289835c80d5fSChris Mason * The generic ->writepage function for buffer-backed address_spaces 289935c80d5fSChris Mason */ 290035c80d5fSChris Mason int block_write_full_page(struct page *page, get_block_t *get_block, 290135c80d5fSChris Mason struct writeback_control *wbc) 290235c80d5fSChris Mason { 290335c80d5fSChris Mason return block_write_full_page_endio(page, get_block, wbc, 290435c80d5fSChris Mason end_buffer_async_write); 290535c80d5fSChris Mason } 29061fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 290735c80d5fSChris Mason 29081da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29091da177e4SLinus Torvalds get_block_t *get_block) 29101da177e4SLinus Torvalds { 29111da177e4SLinus Torvalds struct buffer_head tmp; 29121da177e4SLinus Torvalds struct inode *inode = mapping->host; 29131da177e4SLinus Torvalds tmp.b_state = 0; 29141da177e4SLinus Torvalds tmp.b_blocknr = 0; 2915b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 29161da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 29171da177e4SLinus Torvalds return tmp.b_blocknr; 29181da177e4SLinus Torvalds } 29191fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 29201da177e4SLinus Torvalds 29216712ecf8SNeilBrown static void end_bio_bh_io_sync(struct bio *bio, int err) 29221da177e4SLinus Torvalds { 29231da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 29241da177e4SLinus Torvalds 29251da177e4SLinus Torvalds if (err == -EOPNOTSUPP) { 29261da177e4SLinus Torvalds set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); 29271da177e4SLinus Torvalds set_bit(BH_Eopnotsupp, &bh->b_state); 29281da177e4SLinus Torvalds } 29291da177e4SLinus Torvalds 293008bafc03SKeith Mannthey if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) 293108bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 293208bafc03SKeith Mannthey 29331da177e4SLinus Torvalds bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); 29341da177e4SLinus Torvalds bio_put(bio); 29351da177e4SLinus Torvalds } 29361da177e4SLinus Torvalds 29371da177e4SLinus Torvalds int submit_bh(int rw, struct buffer_head * bh) 29381da177e4SLinus Torvalds { 29391da177e4SLinus Torvalds struct bio *bio; 29401da177e4SLinus Torvalds int ret = 0; 29411da177e4SLinus Torvalds 29421da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 29431da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 29441da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 29458fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 29468fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 29471da177e4SLinus Torvalds 294848fd4f93SJens Axboe /* 294948fd4f93SJens Axboe * Mask in barrier bit for a write (could be either a WRITE or a 295048fd4f93SJens Axboe * WRITE_SYNC 295148fd4f93SJens Axboe */ 295248fd4f93SJens Axboe if (buffer_ordered(bh) && (rw & WRITE)) 295348fd4f93SJens Axboe rw |= WRITE_BARRIER; 29541da177e4SLinus Torvalds 29551da177e4SLinus Torvalds /* 295648fd4f93SJens Axboe * Only clear out a write error when rewriting 29571da177e4SLinus Torvalds */ 295848fd4f93SJens Axboe if (test_set_buffer_req(bh) && (rw & WRITE)) 29591da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 29601da177e4SLinus Torvalds 29611da177e4SLinus Torvalds /* 29621da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 29631da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 29641da177e4SLinus Torvalds */ 29651da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 29661da177e4SLinus Torvalds 29671da177e4SLinus Torvalds bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 29681da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 29691da177e4SLinus Torvalds bio->bi_io_vec[0].bv_page = bh->b_page; 29701da177e4SLinus Torvalds bio->bi_io_vec[0].bv_len = bh->b_size; 29711da177e4SLinus Torvalds bio->bi_io_vec[0].bv_offset = bh_offset(bh); 29721da177e4SLinus Torvalds 29731da177e4SLinus Torvalds bio->bi_vcnt = 1; 29741da177e4SLinus Torvalds bio->bi_idx = 0; 29751da177e4SLinus Torvalds bio->bi_size = bh->b_size; 29761da177e4SLinus Torvalds 29771da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 29781da177e4SLinus Torvalds bio->bi_private = bh; 29791da177e4SLinus Torvalds 29801da177e4SLinus Torvalds bio_get(bio); 29811da177e4SLinus Torvalds submit_bio(rw, bio); 29821da177e4SLinus Torvalds 29831da177e4SLinus Torvalds if (bio_flagged(bio, BIO_EOPNOTSUPP)) 29841da177e4SLinus Torvalds ret = -EOPNOTSUPP; 29851da177e4SLinus Torvalds 29861da177e4SLinus Torvalds bio_put(bio); 29871da177e4SLinus Torvalds return ret; 29881da177e4SLinus Torvalds } 29891fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 29901da177e4SLinus Torvalds 29911da177e4SLinus Torvalds /** 29921da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 2993a7662236SJan Kara * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) 29941da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 29951da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 29961da177e4SLinus Torvalds * 2997a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 2998a7662236SJan Kara * requests an I/O operation on them, either a %READ or a %WRITE. The third 2999a7662236SJan Kara * %SWRITE is like %WRITE only we make sure that the *current* data in buffers 3000a7662236SJan Kara * are sent to disk. The fourth %READA option is described in the documentation 3001a7662236SJan Kara * for generic_make_request() which ll_rw_block() calls. 30021da177e4SLinus Torvalds * 30031da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 3004a7662236SJan Kara * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be 3005a7662236SJan Kara * clean when doing a write request, and any buffer that appears to be 3006a7662236SJan Kara * up-to-date when doing read request. Further it marks as clean buffers that 3007a7662236SJan Kara * are processed for writing (the buffer cache won't assume that they are 3008a7662236SJan Kara * actually clean until the buffer gets unlocked). 30091da177e4SLinus Torvalds * 30101da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 30111da177e4SLinus Torvalds * the buffer up-to-date (if approriate), unlocks the buffer and wakes 30121da177e4SLinus Torvalds * any waiters. 30131da177e4SLinus Torvalds * 30141da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 30151da177e4SLinus Torvalds * multiple of the current approved size for the device. 30161da177e4SLinus Torvalds */ 30171da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 30181da177e4SLinus Torvalds { 30191da177e4SLinus Torvalds int i; 30201da177e4SLinus Torvalds 30211da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 30221da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 30231da177e4SLinus Torvalds 30249cf6b720SJens Axboe if (rw == SWRITE || rw == SWRITE_SYNC || rw == SWRITE_SYNC_PLUG) 3025a7662236SJan Kara lock_buffer(bh); 3026ca5de404SNick Piggin else if (!trylock_buffer(bh)) 30271da177e4SLinus Torvalds continue; 30281da177e4SLinus Torvalds 30299cf6b720SJens Axboe if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC || 30309cf6b720SJens Axboe rw == SWRITE_SYNC_PLUG) { 30311da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 303276c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3033e60e5c50SOGAWA Hirofumi get_bh(bh); 303418ce3751SJens Axboe if (rw == SWRITE_SYNC) 303518ce3751SJens Axboe submit_bh(WRITE_SYNC, bh); 303618ce3751SJens Axboe else 30371da177e4SLinus Torvalds submit_bh(WRITE, bh); 30381da177e4SLinus Torvalds continue; 30391da177e4SLinus Torvalds } 30401da177e4SLinus Torvalds } else { 30411da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 304276c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3043e60e5c50SOGAWA Hirofumi get_bh(bh); 30441da177e4SLinus Torvalds submit_bh(rw, bh); 30451da177e4SLinus Torvalds continue; 30461da177e4SLinus Torvalds } 30471da177e4SLinus Torvalds } 30481da177e4SLinus Torvalds unlock_buffer(bh); 30491da177e4SLinus Torvalds } 30501da177e4SLinus Torvalds } 30511fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 30521da177e4SLinus Torvalds 30531da177e4SLinus Torvalds /* 30541da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 30551da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 30561da177e4SLinus Torvalds * the buffer_head. 30571da177e4SLinus Torvalds */ 30581da177e4SLinus Torvalds int sync_dirty_buffer(struct buffer_head *bh) 30591da177e4SLinus Torvalds { 30601da177e4SLinus Torvalds int ret = 0; 30611da177e4SLinus Torvalds 30621da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 30631da177e4SLinus Torvalds lock_buffer(bh); 30641da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 30651da177e4SLinus Torvalds get_bh(bh); 30661da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 30671aa2a7ccSJens Axboe ret = submit_bh(WRITE_SYNC, bh); 30681da177e4SLinus Torvalds wait_on_buffer(bh); 30691da177e4SLinus Torvalds if (buffer_eopnotsupp(bh)) { 30701da177e4SLinus Torvalds clear_buffer_eopnotsupp(bh); 30711da177e4SLinus Torvalds ret = -EOPNOTSUPP; 30721da177e4SLinus Torvalds } 30731da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 30741da177e4SLinus Torvalds ret = -EIO; 30751da177e4SLinus Torvalds } else { 30761da177e4SLinus Torvalds unlock_buffer(bh); 30771da177e4SLinus Torvalds } 30781da177e4SLinus Torvalds return ret; 30791da177e4SLinus Torvalds } 30801fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 30811da177e4SLinus Torvalds 30821da177e4SLinus Torvalds /* 30831da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 30841da177e4SLinus Torvalds * are unused, and releases them if so. 30851da177e4SLinus Torvalds * 30861da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 30871da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 30881da177e4SLinus Torvalds * 30891da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 30901da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 30911da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 30921da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 30931da177e4SLinus Torvalds * filesystem data on the same device. 30941da177e4SLinus Torvalds * 30951da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 30961da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 30971da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 30981da177e4SLinus Torvalds * private_lock. 30991da177e4SLinus Torvalds * 31001da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 31011da177e4SLinus Torvalds */ 31021da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 31031da177e4SLinus Torvalds { 31041da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 31051da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 31061da177e4SLinus Torvalds } 31071da177e4SLinus Torvalds 31081da177e4SLinus Torvalds static int 31091da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 31101da177e4SLinus Torvalds { 31111da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 31121da177e4SLinus Torvalds struct buffer_head *bh; 31131da177e4SLinus Torvalds 31141da177e4SLinus Torvalds bh = head; 31151da177e4SLinus Torvalds do { 3116de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 31171da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 31181da177e4SLinus Torvalds if (buffer_busy(bh)) 31191da177e4SLinus Torvalds goto failed; 31201da177e4SLinus Torvalds bh = bh->b_this_page; 31211da177e4SLinus Torvalds } while (bh != head); 31221da177e4SLinus Torvalds 31231da177e4SLinus Torvalds do { 31241da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 31251da177e4SLinus Torvalds 3126535ee2fbSJan Kara if (bh->b_assoc_map) 31271da177e4SLinus Torvalds __remove_assoc_queue(bh); 31281da177e4SLinus Torvalds bh = next; 31291da177e4SLinus Torvalds } while (bh != head); 31301da177e4SLinus Torvalds *buffers_to_free = head; 31311da177e4SLinus Torvalds __clear_page_buffers(page); 31321da177e4SLinus Torvalds return 1; 31331da177e4SLinus Torvalds failed: 31341da177e4SLinus Torvalds return 0; 31351da177e4SLinus Torvalds } 31361da177e4SLinus Torvalds 31371da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 31381da177e4SLinus Torvalds { 31391da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 31401da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 31411da177e4SLinus Torvalds int ret = 0; 31421da177e4SLinus Torvalds 31431da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3144ecdfc978SLinus Torvalds if (PageWriteback(page)) 31451da177e4SLinus Torvalds return 0; 31461da177e4SLinus Torvalds 31471da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 31481da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 31491da177e4SLinus Torvalds goto out; 31501da177e4SLinus Torvalds } 31511da177e4SLinus Torvalds 31521da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 31531da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3154ecdfc978SLinus Torvalds 3155ecdfc978SLinus Torvalds /* 3156ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3157ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3158ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3159ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3160ecdfc978SLinus Torvalds * 3161ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3162ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3163ecdfc978SLinus Torvalds * the page also. 316487df7241SNick Piggin * 316587df7241SNick Piggin * private_lock must be held over this entire operation in order 316687df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 316787df7241SNick Piggin * dirty bit from being lost. 3168ecdfc978SLinus Torvalds */ 3169ecdfc978SLinus Torvalds if (ret) 3170ecdfc978SLinus Torvalds cancel_dirty_page(page, PAGE_CACHE_SIZE); 317187df7241SNick Piggin spin_unlock(&mapping->private_lock); 31721da177e4SLinus Torvalds out: 31731da177e4SLinus Torvalds if (buffers_to_free) { 31741da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 31751da177e4SLinus Torvalds 31761da177e4SLinus Torvalds do { 31771da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 31781da177e4SLinus Torvalds free_buffer_head(bh); 31791da177e4SLinus Torvalds bh = next; 31801da177e4SLinus Torvalds } while (bh != buffers_to_free); 31811da177e4SLinus Torvalds } 31821da177e4SLinus Torvalds return ret; 31831da177e4SLinus Torvalds } 31841da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 31851da177e4SLinus Torvalds 31863978d717SNeilBrown void block_sync_page(struct page *page) 31871da177e4SLinus Torvalds { 31881da177e4SLinus Torvalds struct address_space *mapping; 31891da177e4SLinus Torvalds 31901da177e4SLinus Torvalds smp_mb(); 31911da177e4SLinus Torvalds mapping = page_mapping(page); 31921da177e4SLinus Torvalds if (mapping) 31931da177e4SLinus Torvalds blk_run_backing_dev(mapping->backing_dev_info, page); 31941da177e4SLinus Torvalds } 31951fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_sync_page); 31961da177e4SLinus Torvalds 31971da177e4SLinus Torvalds /* 31981da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 31991da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 32001da177e4SLinus Torvalds * 32011da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 32025b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 32031da177e4SLinus Torvalds */ 3204bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 32051da177e4SLinus Torvalds { 32061da177e4SLinus Torvalds static int msg_count; 32071da177e4SLinus Torvalds 32081da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 32091da177e4SLinus Torvalds return -EPERM; 32101da177e4SLinus Torvalds 32111da177e4SLinus Torvalds if (msg_count < 5) { 32121da177e4SLinus Torvalds msg_count++; 32131da177e4SLinus Torvalds printk(KERN_INFO 32141da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 32151da177e4SLinus Torvalds " system call\n", current->comm); 32161da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 32171da177e4SLinus Torvalds } 32181da177e4SLinus Torvalds 32191da177e4SLinus Torvalds if (func == 1) 32201da177e4SLinus Torvalds do_exit(0); 32211da177e4SLinus Torvalds return 0; 32221da177e4SLinus Torvalds } 32231da177e4SLinus Torvalds 32241da177e4SLinus Torvalds /* 32251da177e4SLinus Torvalds * Buffer-head allocation 32261da177e4SLinus Torvalds */ 3227e18b890bSChristoph Lameter static struct kmem_cache *bh_cachep; 32281da177e4SLinus Torvalds 32291da177e4SLinus Torvalds /* 32301da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 32311da177e4SLinus Torvalds * stripping them in writeback. 32321da177e4SLinus Torvalds */ 32331da177e4SLinus Torvalds static int max_buffer_heads; 32341da177e4SLinus Torvalds 32351da177e4SLinus Torvalds int buffer_heads_over_limit; 32361da177e4SLinus Torvalds 32371da177e4SLinus Torvalds struct bh_accounting { 32381da177e4SLinus Torvalds int nr; /* Number of live bh's */ 32391da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 32401da177e4SLinus Torvalds }; 32411da177e4SLinus Torvalds 32421da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 32431da177e4SLinus Torvalds 32441da177e4SLinus Torvalds static void recalc_bh_state(void) 32451da177e4SLinus Torvalds { 32461da177e4SLinus Torvalds int i; 32471da177e4SLinus Torvalds int tot = 0; 32481da177e4SLinus Torvalds 32491da177e4SLinus Torvalds if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) 32501da177e4SLinus Torvalds return; 32511da177e4SLinus Torvalds __get_cpu_var(bh_accounting).ratelimit = 0; 32528a143426SEric Dumazet for_each_online_cpu(i) 32531da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 32541da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 32551da177e4SLinus Torvalds } 32561da177e4SLinus Torvalds 3257dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 32581da177e4SLinus Torvalds { 3259019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 32601da177e4SLinus Torvalds if (ret) { 3261a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3262736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr++; 32631da177e4SLinus Torvalds recalc_bh_state(); 3264736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 32651da177e4SLinus Torvalds } 32661da177e4SLinus Torvalds return ret; 32671da177e4SLinus Torvalds } 32681da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 32691da177e4SLinus Torvalds 32701da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 32711da177e4SLinus Torvalds { 32721da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 32731da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3274736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr--; 32751da177e4SLinus Torvalds recalc_bh_state(); 3276736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 32771da177e4SLinus Torvalds } 32781da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 32791da177e4SLinus Torvalds 32801da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 32811da177e4SLinus Torvalds { 32821da177e4SLinus Torvalds int i; 32831da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 32841da177e4SLinus Torvalds 32851da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 32861da177e4SLinus Torvalds brelse(b->bhs[i]); 32871da177e4SLinus Torvalds b->bhs[i] = NULL; 32881da177e4SLinus Torvalds } 32898a143426SEric Dumazet get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; 32908a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 32918a143426SEric Dumazet put_cpu_var(bh_accounting); 32921da177e4SLinus Torvalds } 32931da177e4SLinus Torvalds 32941da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 32951da177e4SLinus Torvalds unsigned long action, void *hcpu) 32961da177e4SLinus Torvalds { 32978bb78442SRafael J. Wysocki if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) 32981da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 32991da177e4SLinus Torvalds return NOTIFY_OK; 33001da177e4SLinus Torvalds } 33011da177e4SLinus Torvalds 3302389d1b08SAneesh Kumar K.V /** 3303a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3304389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3305389d1b08SAneesh Kumar K.V * 3306389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3307389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3308389d1b08SAneesh Kumar K.V */ 3309389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3310389d1b08SAneesh Kumar K.V { 3311389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3312389d1b08SAneesh Kumar K.V lock_buffer(bh); 3313389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3314389d1b08SAneesh Kumar K.V return 0; 3315389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3316389d1b08SAneesh Kumar K.V } 3317389d1b08SAneesh Kumar K.V return 1; 3318389d1b08SAneesh Kumar K.V } 3319389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3320389d1b08SAneesh Kumar K.V 3321389d1b08SAneesh Kumar K.V /** 3322a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3323389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3324389d1b08SAneesh Kumar K.V * 3325389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3326389d1b08SAneesh Kumar K.V */ 3327389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3328389d1b08SAneesh Kumar K.V { 3329389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3330389d1b08SAneesh Kumar K.V 3331389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3332389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3333389d1b08SAneesh Kumar K.V return 0; 3334389d1b08SAneesh Kumar K.V } 3335389d1b08SAneesh Kumar K.V 3336389d1b08SAneesh Kumar K.V get_bh(bh); 3337389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 3338389d1b08SAneesh Kumar K.V submit_bh(READ, bh); 3339389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3340389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3341389d1b08SAneesh Kumar K.V return 0; 3342389d1b08SAneesh Kumar K.V return -EIO; 3343389d1b08SAneesh Kumar K.V } 3344389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3345389d1b08SAneesh Kumar K.V 33461da177e4SLinus Torvalds void __init buffer_init(void) 33471da177e4SLinus Torvalds { 33481da177e4SLinus Torvalds int nrpages; 33491da177e4SLinus Torvalds 3350b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3351b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3352b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3353b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3354019b4d12SRichard Kennedy NULL); 33551da177e4SLinus Torvalds 33561da177e4SLinus Torvalds /* 33571da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 33581da177e4SLinus Torvalds */ 33591da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 33601da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 33611da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 33621da177e4SLinus Torvalds } 3363