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 5631fe72eaaSH Hartley Sweeten static void do_thaw_all(struct work_struct *work) 564c2d75438SEric Sandeen { 565c2d75438SEric Sandeen struct super_block *sb; 566c2d75438SEric Sandeen char b[BDEVNAME_SIZE]; 567c2d75438SEric Sandeen 568c2d75438SEric Sandeen spin_lock(&sb_lock); 569c2d75438SEric Sandeen restart: 570c2d75438SEric Sandeen list_for_each_entry(sb, &super_blocks, s_list) { 571c2d75438SEric Sandeen sb->s_count++; 572c2d75438SEric Sandeen spin_unlock(&sb_lock); 573c2d75438SEric Sandeen down_read(&sb->s_umount); 574c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 575c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw on %s\n", 576c2d75438SEric Sandeen bdevname(sb->s_bdev, b)); 577c2d75438SEric Sandeen up_read(&sb->s_umount); 578c2d75438SEric Sandeen spin_lock(&sb_lock); 579c2d75438SEric Sandeen if (__put_super_and_need_restart(sb)) 580c2d75438SEric Sandeen goto restart; 581c2d75438SEric Sandeen } 582c2d75438SEric Sandeen spin_unlock(&sb_lock); 583053c525fSJens Axboe kfree(work); 584c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw complete\n"); 585c2d75438SEric Sandeen } 586c2d75438SEric Sandeen 587c2d75438SEric Sandeen /** 588c2d75438SEric Sandeen * emergency_thaw_all -- forcibly thaw every frozen filesystem 589c2d75438SEric Sandeen * 590c2d75438SEric Sandeen * Used for emergency unfreeze of all filesystems via SysRq 591c2d75438SEric Sandeen */ 592c2d75438SEric Sandeen void emergency_thaw_all(void) 593c2d75438SEric Sandeen { 594053c525fSJens Axboe struct work_struct *work; 595053c525fSJens Axboe 596053c525fSJens Axboe work = kmalloc(sizeof(*work), GFP_ATOMIC); 597053c525fSJens Axboe if (work) { 598053c525fSJens Axboe INIT_WORK(work, do_thaw_all); 599053c525fSJens Axboe schedule_work(work); 600053c525fSJens Axboe } 601c2d75438SEric Sandeen } 602c2d75438SEric Sandeen 6031da177e4SLinus Torvalds /** 60478a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 60567be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 6061da177e4SLinus Torvalds * 6071da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 6081da177e4SLinus Torvalds * that I/O. 6091da177e4SLinus Torvalds * 61067be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 61167be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 61267be2dd1SMartin Waitz * a successful fsync(). 6131da177e4SLinus Torvalds */ 6141da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 6151da177e4SLinus Torvalds { 6161da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 6171da177e4SLinus Torvalds 6181da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 6191da177e4SLinus Torvalds return 0; 6201da177e4SLinus Torvalds 6211da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 6221da177e4SLinus Torvalds &mapping->private_list); 6231da177e4SLinus Torvalds } 6241da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 6251da177e4SLinus Torvalds 6261da177e4SLinus Torvalds /* 6271da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 6281da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 6291da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 6301da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 6311da177e4SLinus Torvalds */ 6321da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 6331da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 6341da177e4SLinus Torvalds { 6351da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 6361da177e4SLinus Torvalds if (bh) { 6371da177e4SLinus Torvalds if (buffer_dirty(bh)) 6381da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 6391da177e4SLinus Torvalds put_bh(bh); 6401da177e4SLinus Torvalds } 6411da177e4SLinus Torvalds } 6421da177e4SLinus Torvalds 6431da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 6441da177e4SLinus Torvalds { 6451da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 6461da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6471da177e4SLinus Torvalds 6481da177e4SLinus Torvalds mark_buffer_dirty(bh); 6491da177e4SLinus Torvalds if (!mapping->assoc_mapping) { 6501da177e4SLinus Torvalds mapping->assoc_mapping = buffer_mapping; 6511da177e4SLinus Torvalds } else { 652e827f923SEric Sesterhenn BUG_ON(mapping->assoc_mapping != buffer_mapping); 6531da177e4SLinus Torvalds } 654535ee2fbSJan Kara if (!bh->b_assoc_map) { 6551da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6561da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6571da177e4SLinus Torvalds &mapping->private_list); 65858ff407bSJan Kara bh->b_assoc_map = mapping; 6591da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6601da177e4SLinus Torvalds } 6611da177e4SLinus Torvalds } 6621da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6631da177e4SLinus Torvalds 6641da177e4SLinus Torvalds /* 665787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 666787d2214SNick Piggin * dirty. 667787d2214SNick Piggin * 668787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 669787d2214SNick Piggin * not been truncated. 670787d2214SNick Piggin */ 671a8e7d49aSLinus Torvalds static void __set_page_dirty(struct page *page, 672787d2214SNick Piggin struct address_space *mapping, int warn) 673787d2214SNick Piggin { 67419fd6231SNick Piggin spin_lock_irq(&mapping->tree_lock); 675787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 676787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 677e3a7cca1SEdward Shishkin account_page_dirtied(page, mapping); 678787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 679787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 680787d2214SNick Piggin } 68119fd6231SNick Piggin spin_unlock_irq(&mapping->tree_lock); 682787d2214SNick Piggin __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 683787d2214SNick Piggin } 684787d2214SNick Piggin 685787d2214SNick Piggin /* 6861da177e4SLinus Torvalds * Add a page to the dirty page list. 6871da177e4SLinus Torvalds * 6881da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6891da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6901da177e4SLinus Torvalds * 6911da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6921da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6931da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6941da177e4SLinus Torvalds * dirty. 6951da177e4SLinus Torvalds * 6961da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6971da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6981da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6991da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 7001da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 7011da177e4SLinus Torvalds * page on the dirty page list. 7021da177e4SLinus Torvalds * 7031da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 7041da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 7051da177e4SLinus Torvalds * added to the page after it was set dirty. 7061da177e4SLinus Torvalds * 7071da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 7081da177e4SLinus Torvalds * address_space though. 7091da177e4SLinus Torvalds */ 7101da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 7111da177e4SLinus Torvalds { 712a8e7d49aSLinus Torvalds int newly_dirty; 713787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 714ebf7a227SNick Piggin 715ebf7a227SNick Piggin if (unlikely(!mapping)) 716ebf7a227SNick Piggin return !TestSetPageDirty(page); 7171da177e4SLinus Torvalds 7181da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 7191da177e4SLinus Torvalds if (page_has_buffers(page)) { 7201da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 7211da177e4SLinus Torvalds struct buffer_head *bh = head; 7221da177e4SLinus Torvalds 7231da177e4SLinus Torvalds do { 7241da177e4SLinus Torvalds set_buffer_dirty(bh); 7251da177e4SLinus Torvalds bh = bh->b_this_page; 7261da177e4SLinus Torvalds } while (bh != head); 7271da177e4SLinus Torvalds } 728a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 7291da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 7301da177e4SLinus Torvalds 731a8e7d49aSLinus Torvalds if (newly_dirty) 732a8e7d49aSLinus Torvalds __set_page_dirty(page, mapping, 1); 733a8e7d49aSLinus Torvalds return newly_dirty; 7341da177e4SLinus Torvalds } 7351da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7361da177e4SLinus Torvalds 7371da177e4SLinus Torvalds /* 7381da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7391da177e4SLinus Torvalds * 7401da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7411da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7421da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7431da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7441da177e4SLinus Torvalds * 7451da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7461da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7471da177e4SLinus Torvalds * up, waiting for those writes to complete. 7481da177e4SLinus Torvalds * 7491da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7501da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7511da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7521da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7531da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7541da177e4SLinus Torvalds * any newly dirty buffers for write. 7551da177e4SLinus Torvalds */ 7561da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7571da177e4SLinus Torvalds { 7581da177e4SLinus Torvalds struct buffer_head *bh; 7591da177e4SLinus Torvalds struct list_head tmp; 7609cf6b720SJens Axboe struct address_space *mapping, *prev_mapping = NULL; 7611da177e4SLinus Torvalds int err = 0, err2; 7621da177e4SLinus Torvalds 7631da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7641da177e4SLinus Torvalds 7651da177e4SLinus Torvalds spin_lock(lock); 7661da177e4SLinus Torvalds while (!list_empty(list)) { 7671da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 768535ee2fbSJan Kara mapping = bh->b_assoc_map; 76958ff407bSJan Kara __remove_assoc_queue(bh); 770535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 771535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 772535ee2fbSJan Kara smp_mb(); 7731da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7741da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 775535ee2fbSJan Kara bh->b_assoc_map = mapping; 7761da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7771da177e4SLinus Torvalds get_bh(bh); 7781da177e4SLinus Torvalds spin_unlock(lock); 7791da177e4SLinus Torvalds /* 7801da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7811da177e4SLinus Torvalds * ll_rw_block() actually writes the current 7821da177e4SLinus Torvalds * contents - it is a noop if I/O is still in 7831da177e4SLinus Torvalds * flight on potentially older contents. 7841da177e4SLinus Torvalds */ 7859cf6b720SJens Axboe ll_rw_block(SWRITE_SYNC_PLUG, 1, &bh); 7869cf6b720SJens Axboe 7879cf6b720SJens Axboe /* 7889cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7899cf6b720SJens Axboe * that we will not run the very last mapping, 7909cf6b720SJens Axboe * wait_on_buffer() will do that for us 7919cf6b720SJens Axboe * through sync_buffer(). 7929cf6b720SJens Axboe */ 7939cf6b720SJens Axboe if (prev_mapping && prev_mapping != mapping) 7949cf6b720SJens Axboe blk_run_address_space(prev_mapping); 7959cf6b720SJens Axboe prev_mapping = mapping; 7969cf6b720SJens Axboe 7971da177e4SLinus Torvalds brelse(bh); 7981da177e4SLinus Torvalds spin_lock(lock); 7991da177e4SLinus Torvalds } 8001da177e4SLinus Torvalds } 8011da177e4SLinus Torvalds } 8021da177e4SLinus Torvalds 8031da177e4SLinus Torvalds while (!list_empty(&tmp)) { 8041da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 8051da177e4SLinus Torvalds get_bh(bh); 806535ee2fbSJan Kara mapping = bh->b_assoc_map; 807535ee2fbSJan Kara __remove_assoc_queue(bh); 808535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 809535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 810535ee2fbSJan Kara smp_mb(); 811535ee2fbSJan Kara if (buffer_dirty(bh)) { 812535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 813e3892296SJan Kara &mapping->private_list); 814535ee2fbSJan Kara bh->b_assoc_map = mapping; 815535ee2fbSJan Kara } 8161da177e4SLinus Torvalds spin_unlock(lock); 8171da177e4SLinus Torvalds wait_on_buffer(bh); 8181da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 8191da177e4SLinus Torvalds err = -EIO; 8201da177e4SLinus Torvalds brelse(bh); 8211da177e4SLinus Torvalds spin_lock(lock); 8221da177e4SLinus Torvalds } 8231da177e4SLinus Torvalds 8241da177e4SLinus Torvalds spin_unlock(lock); 8251da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 8261da177e4SLinus Torvalds if (err) 8271da177e4SLinus Torvalds return err; 8281da177e4SLinus Torvalds else 8291da177e4SLinus Torvalds return err2; 8301da177e4SLinus Torvalds } 8311da177e4SLinus Torvalds 8321da177e4SLinus Torvalds /* 8331da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8341da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8351da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8361da177e4SLinus Torvalds * 8371da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8381da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8391da177e4SLinus Torvalds * for reiserfs. 8401da177e4SLinus Torvalds */ 8411da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8421da177e4SLinus Torvalds { 8431da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8441da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8451da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8461da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8471da177e4SLinus Torvalds 8481da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8491da177e4SLinus Torvalds while (!list_empty(list)) 8501da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8511da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8521da177e4SLinus Torvalds } 8531da177e4SLinus Torvalds } 85452b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 8551da177e4SLinus Torvalds 8561da177e4SLinus Torvalds /* 8571da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8581da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8591da177e4SLinus Torvalds * 8601da177e4SLinus Torvalds * Returns true if all buffers were removed. 8611da177e4SLinus Torvalds */ 8621da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8631da177e4SLinus Torvalds { 8641da177e4SLinus Torvalds int ret = 1; 8651da177e4SLinus Torvalds 8661da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8671da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8681da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8691da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8701da177e4SLinus Torvalds 8711da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8721da177e4SLinus Torvalds while (!list_empty(list)) { 8731da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8741da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8751da177e4SLinus Torvalds ret = 0; 8761da177e4SLinus Torvalds break; 8771da177e4SLinus Torvalds } 8781da177e4SLinus Torvalds __remove_assoc_queue(bh); 8791da177e4SLinus Torvalds } 8801da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8811da177e4SLinus Torvalds } 8821da177e4SLinus Torvalds return ret; 8831da177e4SLinus Torvalds } 8841da177e4SLinus Torvalds 8851da177e4SLinus Torvalds /* 8861da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8871da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8881da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8891da177e4SLinus Torvalds * buffers. 8901da177e4SLinus Torvalds * 8911da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8921da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8931da177e4SLinus Torvalds */ 8941da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8951da177e4SLinus Torvalds int retry) 8961da177e4SLinus Torvalds { 8971da177e4SLinus Torvalds struct buffer_head *bh, *head; 8981da177e4SLinus Torvalds long offset; 8991da177e4SLinus Torvalds 9001da177e4SLinus Torvalds try_again: 9011da177e4SLinus Torvalds head = NULL; 9021da177e4SLinus Torvalds offset = PAGE_SIZE; 9031da177e4SLinus Torvalds while ((offset -= size) >= 0) { 9041da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 9051da177e4SLinus Torvalds if (!bh) 9061da177e4SLinus Torvalds goto no_grow; 9071da177e4SLinus Torvalds 9081da177e4SLinus Torvalds bh->b_bdev = NULL; 9091da177e4SLinus Torvalds bh->b_this_page = head; 9101da177e4SLinus Torvalds bh->b_blocknr = -1; 9111da177e4SLinus Torvalds head = bh; 9121da177e4SLinus Torvalds 9131da177e4SLinus Torvalds bh->b_state = 0; 9141da177e4SLinus Torvalds atomic_set(&bh->b_count, 0); 915fc5cd582SChris Mason bh->b_private = NULL; 9161da177e4SLinus Torvalds bh->b_size = size; 9171da177e4SLinus Torvalds 9181da177e4SLinus Torvalds /* Link the buffer to its page */ 9191da177e4SLinus Torvalds set_bh_page(bh, page, offset); 9201da177e4SLinus Torvalds 92101ffe339SNathan Scott init_buffer(bh, NULL, NULL); 9221da177e4SLinus Torvalds } 9231da177e4SLinus Torvalds return head; 9241da177e4SLinus Torvalds /* 9251da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 9261da177e4SLinus Torvalds */ 9271da177e4SLinus Torvalds no_grow: 9281da177e4SLinus Torvalds if (head) { 9291da177e4SLinus Torvalds do { 9301da177e4SLinus Torvalds bh = head; 9311da177e4SLinus Torvalds head = head->b_this_page; 9321da177e4SLinus Torvalds free_buffer_head(bh); 9331da177e4SLinus Torvalds } while (head); 9341da177e4SLinus Torvalds } 9351da177e4SLinus Torvalds 9361da177e4SLinus Torvalds /* 9371da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9381da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9391da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9401da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9411da177e4SLinus Torvalds */ 9421da177e4SLinus Torvalds if (!retry) 9431da177e4SLinus Torvalds return NULL; 9441da177e4SLinus Torvalds 9451da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9461da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9471da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9481da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9491da177e4SLinus Torvalds * async buffer heads in use. 9501da177e4SLinus Torvalds */ 9511da177e4SLinus Torvalds free_more_memory(); 9521da177e4SLinus Torvalds goto try_again; 9531da177e4SLinus Torvalds } 9541da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9551da177e4SLinus Torvalds 9561da177e4SLinus Torvalds static inline void 9571da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9581da177e4SLinus Torvalds { 9591da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9601da177e4SLinus Torvalds 9611da177e4SLinus Torvalds bh = head; 9621da177e4SLinus Torvalds do { 9631da177e4SLinus Torvalds tail = bh; 9641da177e4SLinus Torvalds bh = bh->b_this_page; 9651da177e4SLinus Torvalds } while (bh); 9661da177e4SLinus Torvalds tail->b_this_page = head; 9671da177e4SLinus Torvalds attach_page_buffers(page, head); 9681da177e4SLinus Torvalds } 9691da177e4SLinus Torvalds 9701da177e4SLinus Torvalds /* 9711da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9721da177e4SLinus Torvalds */ 9731da177e4SLinus Torvalds static void 9741da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9751da177e4SLinus Torvalds sector_t block, int size) 9761da177e4SLinus Torvalds { 9771da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9781da177e4SLinus Torvalds struct buffer_head *bh = head; 9791da177e4SLinus Torvalds int uptodate = PageUptodate(page); 9801da177e4SLinus Torvalds 9811da177e4SLinus Torvalds do { 9821da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9831da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9841da177e4SLinus Torvalds bh->b_bdev = bdev; 9851da177e4SLinus Torvalds bh->b_blocknr = block; 9861da177e4SLinus Torvalds if (uptodate) 9871da177e4SLinus Torvalds set_buffer_uptodate(bh); 9881da177e4SLinus Torvalds set_buffer_mapped(bh); 9891da177e4SLinus Torvalds } 9901da177e4SLinus Torvalds block++; 9911da177e4SLinus Torvalds bh = bh->b_this_page; 9921da177e4SLinus Torvalds } while (bh != head); 9931da177e4SLinus Torvalds } 9941da177e4SLinus Torvalds 9951da177e4SLinus Torvalds /* 9961da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9971da177e4SLinus Torvalds * 9981da177e4SLinus Torvalds * This is user purely for blockdev mappings. 9991da177e4SLinus Torvalds */ 10001da177e4SLinus Torvalds static struct page * 10011da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 10021da177e4SLinus Torvalds pgoff_t index, int size) 10031da177e4SLinus Torvalds { 10041da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 10051da177e4SLinus Torvalds struct page *page; 10061da177e4SLinus Torvalds struct buffer_head *bh; 10071da177e4SLinus Torvalds 1008ea125892SChristoph Lameter page = find_or_create_page(inode->i_mapping, index, 1009769848c0SMel Gorman (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); 10101da177e4SLinus Torvalds if (!page) 10111da177e4SLinus Torvalds return NULL; 10121da177e4SLinus Torvalds 1013e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 10141da177e4SLinus Torvalds 10151da177e4SLinus Torvalds if (page_has_buffers(page)) { 10161da177e4SLinus Torvalds bh = page_buffers(page); 10171da177e4SLinus Torvalds if (bh->b_size == size) { 10181da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10191da177e4SLinus Torvalds return page; 10201da177e4SLinus Torvalds } 10211da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10221da177e4SLinus Torvalds goto failed; 10231da177e4SLinus Torvalds } 10241da177e4SLinus Torvalds 10251da177e4SLinus Torvalds /* 10261da177e4SLinus Torvalds * Allocate some buffers for this page 10271da177e4SLinus Torvalds */ 10281da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10291da177e4SLinus Torvalds if (!bh) 10301da177e4SLinus Torvalds goto failed; 10311da177e4SLinus Torvalds 10321da177e4SLinus Torvalds /* 10331da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10341da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10351da177e4SLinus Torvalds * run under the page lock. 10361da177e4SLinus Torvalds */ 10371da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10381da177e4SLinus Torvalds link_dev_buffers(page, bh); 10391da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10401da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 10411da177e4SLinus Torvalds return page; 10421da177e4SLinus Torvalds 10431da177e4SLinus Torvalds failed: 10441da177e4SLinus Torvalds BUG(); 10451da177e4SLinus Torvalds unlock_page(page); 10461da177e4SLinus Torvalds page_cache_release(page); 10471da177e4SLinus Torvalds return NULL; 10481da177e4SLinus Torvalds } 10491da177e4SLinus Torvalds 10501da177e4SLinus Torvalds /* 10511da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10521da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10531da177e4SLinus Torvalds */ 1054858119e1SArjan van de Ven static int 10551da177e4SLinus Torvalds grow_buffers(struct block_device *bdev, sector_t block, int size) 10561da177e4SLinus Torvalds { 10571da177e4SLinus Torvalds struct page *page; 10581da177e4SLinus Torvalds pgoff_t index; 10591da177e4SLinus Torvalds int sizebits; 10601da177e4SLinus Torvalds 10611da177e4SLinus Torvalds sizebits = -1; 10621da177e4SLinus Torvalds do { 10631da177e4SLinus Torvalds sizebits++; 10641da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10651da177e4SLinus Torvalds 10661da177e4SLinus Torvalds index = block >> sizebits; 10671da177e4SLinus Torvalds 1068e5657933SAndrew Morton /* 1069e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1070e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1071e5657933SAndrew Morton */ 1072e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1073e5657933SAndrew Morton char b[BDEVNAME_SIZE]; 1074e5657933SAndrew Morton 1075e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1076e5657933SAndrew Morton "device %s\n", 10778e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1078e5657933SAndrew Morton bdevname(bdev, b)); 1079e5657933SAndrew Morton return -EIO; 1080e5657933SAndrew Morton } 1081e5657933SAndrew Morton block = index << sizebits; 10821da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10831da177e4SLinus Torvalds page = grow_dev_page(bdev, block, index, size); 10841da177e4SLinus Torvalds if (!page) 10851da177e4SLinus Torvalds return 0; 10861da177e4SLinus Torvalds unlock_page(page); 10871da177e4SLinus Torvalds page_cache_release(page); 10881da177e4SLinus Torvalds return 1; 10891da177e4SLinus Torvalds } 10901da177e4SLinus Torvalds 109175c96f85SAdrian Bunk static struct buffer_head * 10921da177e4SLinus Torvalds __getblk_slow(struct block_device *bdev, sector_t block, int size) 10931da177e4SLinus Torvalds { 10941da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1095e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10961da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10971da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10981da177e4SLinus Torvalds size); 1099e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1100e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 11011da177e4SLinus Torvalds 11021da177e4SLinus Torvalds dump_stack(); 11031da177e4SLinus Torvalds return NULL; 11041da177e4SLinus Torvalds } 11051da177e4SLinus Torvalds 11061da177e4SLinus Torvalds for (;;) { 11071da177e4SLinus Torvalds struct buffer_head * bh; 1108e5657933SAndrew Morton int ret; 11091da177e4SLinus Torvalds 11101da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 11111da177e4SLinus Torvalds if (bh) 11121da177e4SLinus Torvalds return bh; 11131da177e4SLinus Torvalds 1114e5657933SAndrew Morton ret = grow_buffers(bdev, block, size); 1115e5657933SAndrew Morton if (ret < 0) 1116e5657933SAndrew Morton return NULL; 1117e5657933SAndrew Morton if (ret == 0) 11181da177e4SLinus Torvalds free_more_memory(); 11191da177e4SLinus Torvalds } 11201da177e4SLinus Torvalds } 11211da177e4SLinus Torvalds 11221da177e4SLinus Torvalds /* 11231da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 11241da177e4SLinus Torvalds * 11251da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 11261da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 11271da177e4SLinus Torvalds * 11281da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 11291da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 11301da177e4SLinus Torvalds * merely a hint about the true dirty state. 11311da177e4SLinus Torvalds * 11321da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 11331da177e4SLinus Torvalds * (if the page has buffers). 11341da177e4SLinus Torvalds * 11351da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11361da177e4SLinus Torvalds * buffers are not. 11371da177e4SLinus Torvalds * 11381da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11391da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11401da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11411da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11421da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11431da177e4SLinus Torvalds */ 11441da177e4SLinus Torvalds 11451da177e4SLinus Torvalds /** 11461da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 114767be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11481da177e4SLinus Torvalds * 11491da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11501da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11511da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11521da177e4SLinus Torvalds * inode list. 11531da177e4SLinus Torvalds * 11541da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 11551da177e4SLinus Torvalds * mapping->tree_lock and the global inode_lock. 11561da177e4SLinus Torvalds */ 1157fc9b52cdSHarvey Harrison void mark_buffer_dirty(struct buffer_head *bh) 11581da177e4SLinus Torvalds { 1159787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 11601be62dc1SLinus Torvalds 11611be62dc1SLinus Torvalds /* 11621be62dc1SLinus Torvalds * Very *carefully* optimize the it-is-already-dirty case. 11631be62dc1SLinus Torvalds * 11641be62dc1SLinus Torvalds * Don't let the final "is it dirty" escape to before we 11651be62dc1SLinus Torvalds * perhaps modified the buffer. 11661be62dc1SLinus Torvalds */ 11671be62dc1SLinus Torvalds if (buffer_dirty(bh)) { 11681be62dc1SLinus Torvalds smp_mb(); 11691be62dc1SLinus Torvalds if (buffer_dirty(bh)) 11701be62dc1SLinus Torvalds return; 11711be62dc1SLinus Torvalds } 11721be62dc1SLinus Torvalds 1173a8e7d49aSLinus Torvalds if (!test_set_buffer_dirty(bh)) { 1174a8e7d49aSLinus Torvalds struct page *page = bh->b_page; 11758e9d78edSLinus Torvalds if (!TestSetPageDirty(page)) { 11768e9d78edSLinus Torvalds struct address_space *mapping = page_mapping(page); 11778e9d78edSLinus Torvalds if (mapping) 11788e9d78edSLinus Torvalds __set_page_dirty(page, mapping, 0); 11798e9d78edSLinus Torvalds } 1180a8e7d49aSLinus Torvalds } 11811da177e4SLinus Torvalds } 11821fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(mark_buffer_dirty); 11831da177e4SLinus Torvalds 11841da177e4SLinus Torvalds /* 11851da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11861da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11871da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11881da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11891da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11901da177e4SLinus Torvalds */ 11911da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11921da177e4SLinus Torvalds { 11931da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11941da177e4SLinus Torvalds put_bh(buf); 11951da177e4SLinus Torvalds return; 11961da177e4SLinus Torvalds } 11975c752ad9SArjan van de Ven WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 11981da177e4SLinus Torvalds } 11991fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__brelse); 12001da177e4SLinus Torvalds 12011da177e4SLinus Torvalds /* 12021da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 12031da177e4SLinus Torvalds * potentially dirty data. 12041da177e4SLinus Torvalds */ 12051da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 12061da177e4SLinus Torvalds { 12071da177e4SLinus Torvalds clear_buffer_dirty(bh); 1208535ee2fbSJan Kara if (bh->b_assoc_map) { 12091da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 12101da177e4SLinus Torvalds 12111da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 12121da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 121358ff407bSJan Kara bh->b_assoc_map = NULL; 12141da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12151da177e4SLinus Torvalds } 12161da177e4SLinus Torvalds __brelse(bh); 12171da177e4SLinus Torvalds } 12181fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__bforget); 12191da177e4SLinus Torvalds 12201da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12211da177e4SLinus Torvalds { 12221da177e4SLinus Torvalds lock_buffer(bh); 12231da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12241da177e4SLinus Torvalds unlock_buffer(bh); 12251da177e4SLinus Torvalds return bh; 12261da177e4SLinus Torvalds } else { 12271da177e4SLinus Torvalds get_bh(bh); 12281da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12291da177e4SLinus Torvalds submit_bh(READ, bh); 12301da177e4SLinus Torvalds wait_on_buffer(bh); 12311da177e4SLinus Torvalds if (buffer_uptodate(bh)) 12321da177e4SLinus Torvalds return bh; 12331da177e4SLinus Torvalds } 12341da177e4SLinus Torvalds brelse(bh); 12351da177e4SLinus Torvalds return NULL; 12361da177e4SLinus Torvalds } 12371da177e4SLinus Torvalds 12381da177e4SLinus Torvalds /* 12391da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12401da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12411da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12421da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12431da177e4SLinus Torvalds * CPU's LRUs at the same time. 12441da177e4SLinus Torvalds * 12451da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12461da177e4SLinus Torvalds * sb_find_get_block(). 12471da177e4SLinus Torvalds * 12481da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12491da177e4SLinus Torvalds * a local interrupt disable for that. 12501da177e4SLinus Torvalds */ 12511da177e4SLinus Torvalds 12521da177e4SLinus Torvalds #define BH_LRU_SIZE 8 12531da177e4SLinus Torvalds 12541da177e4SLinus Torvalds struct bh_lru { 12551da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12561da177e4SLinus Torvalds }; 12571da177e4SLinus Torvalds 12581da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12591da177e4SLinus Torvalds 12601da177e4SLinus Torvalds #ifdef CONFIG_SMP 12611da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12621da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12631da177e4SLinus Torvalds #else 12641da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12651da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12661da177e4SLinus Torvalds #endif 12671da177e4SLinus Torvalds 12681da177e4SLinus Torvalds static inline void check_irqs_on(void) 12691da177e4SLinus Torvalds { 12701da177e4SLinus Torvalds #ifdef irqs_disabled 12711da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12721da177e4SLinus Torvalds #endif 12731da177e4SLinus Torvalds } 12741da177e4SLinus Torvalds 12751da177e4SLinus Torvalds /* 12761da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 12771da177e4SLinus Torvalds */ 12781da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12791da177e4SLinus Torvalds { 12801da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 12811da177e4SLinus Torvalds struct bh_lru *lru; 12821da177e4SLinus Torvalds 12831da177e4SLinus Torvalds check_irqs_on(); 12841da177e4SLinus Torvalds bh_lru_lock(); 12851da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 12861da177e4SLinus Torvalds if (lru->bhs[0] != bh) { 12871da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12881da177e4SLinus Torvalds int in; 12891da177e4SLinus Torvalds int out = 0; 12901da177e4SLinus Torvalds 12911da177e4SLinus Torvalds get_bh(bh); 12921da177e4SLinus Torvalds bhs[out++] = bh; 12931da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 12941da177e4SLinus Torvalds struct buffer_head *bh2 = lru->bhs[in]; 12951da177e4SLinus Torvalds 12961da177e4SLinus Torvalds if (bh2 == bh) { 12971da177e4SLinus Torvalds __brelse(bh2); 12981da177e4SLinus Torvalds } else { 12991da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 13001da177e4SLinus Torvalds BUG_ON(evictee != NULL); 13011da177e4SLinus Torvalds evictee = bh2; 13021da177e4SLinus Torvalds } else { 13031da177e4SLinus Torvalds bhs[out++] = bh2; 13041da177e4SLinus Torvalds } 13051da177e4SLinus Torvalds } 13061da177e4SLinus Torvalds } 13071da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 13081da177e4SLinus Torvalds bhs[out++] = NULL; 13091da177e4SLinus Torvalds memcpy(lru->bhs, bhs, sizeof(bhs)); 13101da177e4SLinus Torvalds } 13111da177e4SLinus Torvalds bh_lru_unlock(); 13121da177e4SLinus Torvalds 13131da177e4SLinus Torvalds if (evictee) 13141da177e4SLinus Torvalds __brelse(evictee); 13151da177e4SLinus Torvalds } 13161da177e4SLinus Torvalds 13171da177e4SLinus Torvalds /* 13181da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 13191da177e4SLinus Torvalds */ 1320858119e1SArjan van de Ven static struct buffer_head * 13213991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 13221da177e4SLinus Torvalds { 13231da177e4SLinus Torvalds struct buffer_head *ret = NULL; 13241da177e4SLinus Torvalds struct bh_lru *lru; 13253991d3bdSTomasz Kvarsin unsigned int i; 13261da177e4SLinus Torvalds 13271da177e4SLinus Torvalds check_irqs_on(); 13281da177e4SLinus Torvalds bh_lru_lock(); 13291da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 13301da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 13311da177e4SLinus Torvalds struct buffer_head *bh = lru->bhs[i]; 13321da177e4SLinus Torvalds 13331da177e4SLinus Torvalds if (bh && bh->b_bdev == bdev && 13341da177e4SLinus Torvalds bh->b_blocknr == block && bh->b_size == size) { 13351da177e4SLinus Torvalds if (i) { 13361da177e4SLinus Torvalds while (i) { 13371da177e4SLinus Torvalds lru->bhs[i] = lru->bhs[i - 1]; 13381da177e4SLinus Torvalds i--; 13391da177e4SLinus Torvalds } 13401da177e4SLinus Torvalds lru->bhs[0] = bh; 13411da177e4SLinus Torvalds } 13421da177e4SLinus Torvalds get_bh(bh); 13431da177e4SLinus Torvalds ret = bh; 13441da177e4SLinus Torvalds break; 13451da177e4SLinus Torvalds } 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds bh_lru_unlock(); 13481da177e4SLinus Torvalds return ret; 13491da177e4SLinus Torvalds } 13501da177e4SLinus Torvalds 13511da177e4SLinus Torvalds /* 13521da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13531da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13541da177e4SLinus Torvalds * NULL 13551da177e4SLinus Torvalds */ 13561da177e4SLinus Torvalds struct buffer_head * 13573991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 13581da177e4SLinus Torvalds { 13591da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds if (bh == NULL) { 1362385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13631da177e4SLinus Torvalds if (bh) 13641da177e4SLinus Torvalds bh_lru_install(bh); 13651da177e4SLinus Torvalds } 13661da177e4SLinus Torvalds if (bh) 13671da177e4SLinus Torvalds touch_buffer(bh); 13681da177e4SLinus Torvalds return bh; 13691da177e4SLinus Torvalds } 13701da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13711da177e4SLinus Torvalds 13721da177e4SLinus Torvalds /* 13731da177e4SLinus Torvalds * __getblk will locate (and, if necessary, create) the buffer_head 13741da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13751da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13761da177e4SLinus Torvalds * 13771da177e4SLinus Torvalds * __getblk() cannot fail - it just keeps trying. If you pass it an 13781da177e4SLinus Torvalds * illegal block number, __getblk() will happily return a buffer_head 13791da177e4SLinus Torvalds * which represents the non-existent block. Very weird. 13801da177e4SLinus Torvalds * 13811da177e4SLinus Torvalds * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() 13821da177e4SLinus Torvalds * attempt is failing. FIXME, perhaps? 13831da177e4SLinus Torvalds */ 13841da177e4SLinus Torvalds struct buffer_head * 13853991d3bdSTomasz Kvarsin __getblk(struct block_device *bdev, sector_t block, unsigned size) 13861da177e4SLinus Torvalds { 13871da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13881da177e4SLinus Torvalds 13891da177e4SLinus Torvalds might_sleep(); 13901da177e4SLinus Torvalds if (bh == NULL) 13911da177e4SLinus Torvalds bh = __getblk_slow(bdev, block, size); 13921da177e4SLinus Torvalds return bh; 13931da177e4SLinus Torvalds } 13941da177e4SLinus Torvalds EXPORT_SYMBOL(__getblk); 13951da177e4SLinus Torvalds 13961da177e4SLinus Torvalds /* 13971da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13981da177e4SLinus Torvalds */ 13993991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 14001da177e4SLinus Torvalds { 14011da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1402a3e713b5SAndrew Morton if (likely(bh)) { 14031da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 14041da177e4SLinus Torvalds brelse(bh); 14051da177e4SLinus Torvalds } 1406a3e713b5SAndrew Morton } 14071da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds /** 14101da177e4SLinus Torvalds * __bread() - reads a specified block and returns the bh 141167be2dd1SMartin Waitz * @bdev: the block_device to read from 14121da177e4SLinus Torvalds * @block: number of block 14131da177e4SLinus Torvalds * @size: size (in bytes) to read 14141da177e4SLinus Torvalds * 14151da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 14161da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 14171da177e4SLinus Torvalds */ 14181da177e4SLinus Torvalds struct buffer_head * 14193991d3bdSTomasz Kvarsin __bread(struct block_device *bdev, sector_t block, unsigned size) 14201da177e4SLinus Torvalds { 14211da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 14221da177e4SLinus Torvalds 1423a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 14241da177e4SLinus Torvalds bh = __bread_slow(bh); 14251da177e4SLinus Torvalds return bh; 14261da177e4SLinus Torvalds } 14271da177e4SLinus Torvalds EXPORT_SYMBOL(__bread); 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds /* 14301da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14311da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 14321da177e4SLinus Torvalds * or with preempt disabled. 14331da177e4SLinus Torvalds */ 14341da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 14351da177e4SLinus Torvalds { 14361da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14371da177e4SLinus Torvalds int i; 14381da177e4SLinus Torvalds 14391da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14401da177e4SLinus Torvalds brelse(b->bhs[i]); 14411da177e4SLinus Torvalds b->bhs[i] = NULL; 14421da177e4SLinus Torvalds } 14431da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14441da177e4SLinus Torvalds } 14451da177e4SLinus Torvalds 1446f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 14471da177e4SLinus Torvalds { 144815c8b6c1SJens Axboe on_each_cpu(invalidate_bh_lru, NULL, 1); 14491da177e4SLinus Torvalds } 14509db5579bSNick Piggin EXPORT_SYMBOL_GPL(invalidate_bh_lrus); 14511da177e4SLinus Torvalds 14521da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14531da177e4SLinus Torvalds struct page *page, unsigned long offset) 14541da177e4SLinus Torvalds { 14551da177e4SLinus Torvalds bh->b_page = page; 1456e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14571da177e4SLinus Torvalds if (PageHighMem(page)) 14581da177e4SLinus Torvalds /* 14591da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14601da177e4SLinus Torvalds */ 14611da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14621da177e4SLinus Torvalds else 14631da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14641da177e4SLinus Torvalds } 14651da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14661da177e4SLinus Torvalds 14671da177e4SLinus Torvalds /* 14681da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14691da177e4SLinus Torvalds */ 1470858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14711da177e4SLinus Torvalds { 14721da177e4SLinus Torvalds lock_buffer(bh); 14731da177e4SLinus Torvalds clear_buffer_dirty(bh); 14741da177e4SLinus Torvalds bh->b_bdev = NULL; 14751da177e4SLinus Torvalds clear_buffer_mapped(bh); 14761da177e4SLinus Torvalds clear_buffer_req(bh); 14771da177e4SLinus Torvalds clear_buffer_new(bh); 14781da177e4SLinus Torvalds clear_buffer_delay(bh); 147933a266ddSDavid Chinner clear_buffer_unwritten(bh); 14801da177e4SLinus Torvalds unlock_buffer(bh); 14811da177e4SLinus Torvalds } 14821da177e4SLinus Torvalds 14831da177e4SLinus Torvalds /** 14841da177e4SLinus Torvalds * block_invalidatepage - invalidate part of all of a buffer-backed page 14851da177e4SLinus Torvalds * 14861da177e4SLinus Torvalds * @page: the page which is affected 14871da177e4SLinus Torvalds * @offset: the index of the truncation point 14881da177e4SLinus Torvalds * 14891da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 14901da177e4SLinus Torvalds * invalidatedby a truncate operation. 14911da177e4SLinus Torvalds * 14921da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 14931da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 14941da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 14951da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 14961da177e4SLinus Torvalds * blocks on-disk. 14971da177e4SLinus Torvalds */ 14982ff28e22SNeilBrown void block_invalidatepage(struct page *page, unsigned long offset) 14991da177e4SLinus Torvalds { 15001da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 15011da177e4SLinus Torvalds unsigned int curr_off = 0; 15021da177e4SLinus Torvalds 15031da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 15041da177e4SLinus Torvalds if (!page_has_buffers(page)) 15051da177e4SLinus Torvalds goto out; 15061da177e4SLinus Torvalds 15071da177e4SLinus Torvalds head = page_buffers(page); 15081da177e4SLinus Torvalds bh = head; 15091da177e4SLinus Torvalds do { 15101da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 15111da177e4SLinus Torvalds next = bh->b_this_page; 15121da177e4SLinus Torvalds 15131da177e4SLinus Torvalds /* 15141da177e4SLinus Torvalds * is this block fully invalidated? 15151da177e4SLinus Torvalds */ 15161da177e4SLinus Torvalds if (offset <= curr_off) 15171da177e4SLinus Torvalds discard_buffer(bh); 15181da177e4SLinus Torvalds curr_off = next_off; 15191da177e4SLinus Torvalds bh = next; 15201da177e4SLinus Torvalds } while (bh != head); 15211da177e4SLinus Torvalds 15221da177e4SLinus Torvalds /* 15231da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 15241da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 15251da177e4SLinus Torvalds * so real IO is not possible anymore. 15261da177e4SLinus Torvalds */ 15271da177e4SLinus Torvalds if (offset == 0) 15282ff28e22SNeilBrown try_to_release_page(page, 0); 15291da177e4SLinus Torvalds out: 15302ff28e22SNeilBrown return; 15311da177e4SLinus Torvalds } 15321da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 15331da177e4SLinus Torvalds 15341da177e4SLinus Torvalds /* 15351da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15361da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15371da177e4SLinus Torvalds * is already excluded via the page lock. 15381da177e4SLinus Torvalds */ 15391da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15401da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15411da177e4SLinus Torvalds { 15421da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15431da177e4SLinus Torvalds 15441da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15451da177e4SLinus Torvalds bh = head; 15461da177e4SLinus Torvalds do { 15471da177e4SLinus Torvalds bh->b_state |= b_state; 15481da177e4SLinus Torvalds tail = bh; 15491da177e4SLinus Torvalds bh = bh->b_this_page; 15501da177e4SLinus Torvalds } while (bh); 15511da177e4SLinus Torvalds tail->b_this_page = head; 15521da177e4SLinus Torvalds 15531da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15541da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15551da177e4SLinus Torvalds bh = head; 15561da177e4SLinus Torvalds do { 15571da177e4SLinus Torvalds if (PageDirty(page)) 15581da177e4SLinus Torvalds set_buffer_dirty(bh); 15591da177e4SLinus Torvalds if (PageUptodate(page)) 15601da177e4SLinus Torvalds set_buffer_uptodate(bh); 15611da177e4SLinus Torvalds bh = bh->b_this_page; 15621da177e4SLinus Torvalds } while (bh != head); 15631da177e4SLinus Torvalds } 15641da177e4SLinus Torvalds attach_page_buffers(page, head); 15651da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 15661da177e4SLinus Torvalds } 15671da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 15681da177e4SLinus Torvalds 15691da177e4SLinus Torvalds /* 15701da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 15711da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 15721da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 15731da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 15741da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 15751da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 15761da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 15771da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 15781da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 15791da177e4SLinus Torvalds * 15801da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 15811da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 15821da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 15831da177e4SLinus Torvalds * only if we really need to. That happens here. 15841da177e4SLinus Torvalds */ 15851da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 15861da177e4SLinus Torvalds { 15871da177e4SLinus Torvalds struct buffer_head *old_bh; 15881da177e4SLinus Torvalds 15891da177e4SLinus Torvalds might_sleep(); 15901da177e4SLinus Torvalds 1591385fd4c5SCoywolf Qi Hunt old_bh = __find_get_block_slow(bdev, block); 15921da177e4SLinus Torvalds if (old_bh) { 15931da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 15941da177e4SLinus Torvalds wait_on_buffer(old_bh); 15951da177e4SLinus Torvalds clear_buffer_req(old_bh); 15961da177e4SLinus Torvalds __brelse(old_bh); 15971da177e4SLinus Torvalds } 15981da177e4SLinus Torvalds } 15991da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 16001da177e4SLinus Torvalds 16011da177e4SLinus Torvalds /* 16021da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 16031da177e4SLinus Torvalds * 16041da177e4SLinus Torvalds * Mapped Uptodate Meaning 16051da177e4SLinus Torvalds * 16061da177e4SLinus Torvalds * No No "unknown" - must do get_block() 16071da177e4SLinus Torvalds * No Yes "hole" - zero-filled 16081da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 16091da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 16101da177e4SLinus Torvalds * 16111da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16121da177e4SLinus Torvalds */ 16131da177e4SLinus Torvalds 16141da177e4SLinus Torvalds /* 16151da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16161da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16171da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16181da177e4SLinus Torvalds * state inside lock_buffer(). 16191da177e4SLinus Torvalds * 16201da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16211da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16221da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16231da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16241da177e4SLinus Torvalds * prevents this contention from occurring. 16256e34eeddSTheodore Ts'o * 16266e34eeddSTheodore Ts'o * If block_write_full_page() is called with wbc->sync_mode == 16276e34eeddSTheodore Ts'o * WB_SYNC_ALL, the writes are posted using WRITE_SYNC_PLUG; this 16286e34eeddSTheodore Ts'o * causes the writes to be flagged as synchronous writes, but the 16296e34eeddSTheodore Ts'o * block device queue will NOT be unplugged, since usually many pages 16306e34eeddSTheodore Ts'o * will be pushed to the out before the higher-level caller actually 16316e34eeddSTheodore Ts'o * waits for the writes to be completed. The various wait functions, 16326e34eeddSTheodore Ts'o * such as wait_on_writeback_range() will ultimately call sync_page() 16336e34eeddSTheodore Ts'o * which will ultimately call blk_run_backing_dev(), which will end up 16346e34eeddSTheodore Ts'o * unplugging the device queue. 16351da177e4SLinus Torvalds */ 16361da177e4SLinus Torvalds static int __block_write_full_page(struct inode *inode, struct page *page, 163735c80d5fSChris Mason get_block_t *get_block, struct writeback_control *wbc, 163835c80d5fSChris Mason bh_end_io_t *handler) 16391da177e4SLinus Torvalds { 16401da177e4SLinus Torvalds int err; 16411da177e4SLinus Torvalds sector_t block; 16421da177e4SLinus Torvalds sector_t last_block; 1643f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 1644b0cf2321SBadari Pulavarty const unsigned blocksize = 1 << inode->i_blkbits; 16451da177e4SLinus Torvalds int nr_underway = 0; 16466e34eeddSTheodore Ts'o int write_op = (wbc->sync_mode == WB_SYNC_ALL ? 16476e34eeddSTheodore Ts'o WRITE_SYNC_PLUG : WRITE); 16481da177e4SLinus Torvalds 16491da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 16501da177e4SLinus Torvalds 16511da177e4SLinus Torvalds last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; 16521da177e4SLinus Torvalds 16531da177e4SLinus Torvalds if (!page_has_buffers(page)) { 1654b0cf2321SBadari Pulavarty create_empty_buffers(page, blocksize, 16551da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 16561da177e4SLinus Torvalds } 16571da177e4SLinus Torvalds 16581da177e4SLinus Torvalds /* 16591da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 16601da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 16611da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 16621da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 16631da177e4SLinus Torvalds * 16641da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 16651da177e4SLinus Torvalds * handle that here by just cleaning them. 16661da177e4SLinus Torvalds */ 16671da177e4SLinus Torvalds 166854b21a79SAndrew Morton block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 16691da177e4SLinus Torvalds head = page_buffers(page); 16701da177e4SLinus Torvalds bh = head; 16711da177e4SLinus Torvalds 16721da177e4SLinus Torvalds /* 16731da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 16741da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 16751da177e4SLinus Torvalds */ 16761da177e4SLinus Torvalds do { 16771da177e4SLinus Torvalds if (block > last_block) { 16781da177e4SLinus Torvalds /* 16791da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 16801da177e4SLinus Torvalds * this page can be outside i_size when there is a 16811da177e4SLinus Torvalds * truncate in progress. 16821da177e4SLinus Torvalds */ 16831da177e4SLinus Torvalds /* 16841da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 16851da177e4SLinus Torvalds */ 16861da177e4SLinus Torvalds clear_buffer_dirty(bh); 16871da177e4SLinus Torvalds set_buffer_uptodate(bh); 168829a814d2SAlex Tomas } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && 168929a814d2SAlex Tomas buffer_dirty(bh)) { 1690b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 16911da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 16921da177e4SLinus Torvalds if (err) 16931da177e4SLinus Torvalds goto recover; 169429a814d2SAlex Tomas clear_buffer_delay(bh); 16951da177e4SLinus Torvalds if (buffer_new(bh)) { 16961da177e4SLinus Torvalds /* blockdev mappings never come here */ 16971da177e4SLinus Torvalds clear_buffer_new(bh); 16981da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 16991da177e4SLinus Torvalds bh->b_blocknr); 17001da177e4SLinus Torvalds } 17011da177e4SLinus Torvalds } 17021da177e4SLinus Torvalds bh = bh->b_this_page; 17031da177e4SLinus Torvalds block++; 17041da177e4SLinus Torvalds } while (bh != head); 17051da177e4SLinus Torvalds 17061da177e4SLinus Torvalds do { 17071da177e4SLinus Torvalds if (!buffer_mapped(bh)) 17081da177e4SLinus Torvalds continue; 17091da177e4SLinus Torvalds /* 17101da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17111da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17125b0830cbSJens Axboe * potentially cause a busy-wait loop from writeback threads 17135b0830cbSJens Axboe * and kswapd activity, but those code paths have their own 17145b0830cbSJens Axboe * higher-level throttling. 17151da177e4SLinus Torvalds */ 17161da177e4SLinus Torvalds if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { 17171da177e4SLinus Torvalds lock_buffer(bh); 1718ca5de404SNick Piggin } else if (!trylock_buffer(bh)) { 17191da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 17201da177e4SLinus Torvalds continue; 17211da177e4SLinus Torvalds } 17221da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 172335c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17241da177e4SLinus Torvalds } else { 17251da177e4SLinus Torvalds unlock_buffer(bh); 17261da177e4SLinus Torvalds } 17271da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17281da177e4SLinus Torvalds 17291da177e4SLinus Torvalds /* 17301da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17311da177e4SLinus Torvalds * drop the bh refcounts early. 17321da177e4SLinus Torvalds */ 17331da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17341da177e4SLinus Torvalds set_page_writeback(page); 17351da177e4SLinus Torvalds 17361da177e4SLinus Torvalds do { 17371da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17381da177e4SLinus Torvalds if (buffer_async_write(bh)) { 1739a64c8610STheodore Ts'o submit_bh(write_op, bh); 17401da177e4SLinus Torvalds nr_underway++; 1741ad576e63SNick Piggin } 17421da177e4SLinus Torvalds bh = next; 17431da177e4SLinus Torvalds } while (bh != head); 174405937baaSAndrew Morton unlock_page(page); 17451da177e4SLinus Torvalds 17461da177e4SLinus Torvalds err = 0; 17471da177e4SLinus Torvalds done: 17481da177e4SLinus Torvalds if (nr_underway == 0) { 17491da177e4SLinus Torvalds /* 17501da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 17511da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 17521da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 17531da177e4SLinus Torvalds */ 17541da177e4SLinus Torvalds end_page_writeback(page); 17553d67f2d7SNick Piggin 17561da177e4SLinus Torvalds /* 17571da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 17581da177e4SLinus Torvalds * here on. 17591da177e4SLinus Torvalds */ 17601da177e4SLinus Torvalds } 17611da177e4SLinus Torvalds return err; 17621da177e4SLinus Torvalds 17631da177e4SLinus Torvalds recover: 17641da177e4SLinus Torvalds /* 17651da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 17661da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 17671da177e4SLinus Torvalds * exposing stale data. 17681da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 17691da177e4SLinus Torvalds */ 17701da177e4SLinus Torvalds bh = head; 17711da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 17721da177e4SLinus Torvalds do { 177329a814d2SAlex Tomas if (buffer_mapped(bh) && buffer_dirty(bh) && 177429a814d2SAlex Tomas !buffer_delay(bh)) { 17751da177e4SLinus Torvalds lock_buffer(bh); 177635c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17771da177e4SLinus Torvalds } else { 17781da177e4SLinus Torvalds /* 17791da177e4SLinus Torvalds * The buffer may have been set dirty during 17801da177e4SLinus Torvalds * attachment to a dirty page. 17811da177e4SLinus Torvalds */ 17821da177e4SLinus Torvalds clear_buffer_dirty(bh); 17831da177e4SLinus Torvalds } 17841da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17851da177e4SLinus Torvalds SetPageError(page); 17861da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17877e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 17881da177e4SLinus Torvalds set_page_writeback(page); 17891da177e4SLinus Torvalds do { 17901da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17911da177e4SLinus Torvalds if (buffer_async_write(bh)) { 17921da177e4SLinus Torvalds clear_buffer_dirty(bh); 1793a64c8610STheodore Ts'o submit_bh(write_op, bh); 17941da177e4SLinus Torvalds nr_underway++; 1795ad576e63SNick Piggin } 17961da177e4SLinus Torvalds bh = next; 17971da177e4SLinus Torvalds } while (bh != head); 1798ffda9d30SNick Piggin unlock_page(page); 17991da177e4SLinus Torvalds goto done; 18001da177e4SLinus Torvalds } 18011da177e4SLinus Torvalds 1802afddba49SNick Piggin /* 1803afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1804afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1805afddba49SNick Piggin * block data from leaking). And clear the new bit. 1806afddba49SNick Piggin */ 1807afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1808afddba49SNick Piggin { 1809afddba49SNick Piggin unsigned int block_start, block_end; 1810afddba49SNick Piggin struct buffer_head *head, *bh; 1811afddba49SNick Piggin 1812afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1813afddba49SNick Piggin if (!page_has_buffers(page)) 1814afddba49SNick Piggin return; 1815afddba49SNick Piggin 1816afddba49SNick Piggin bh = head = page_buffers(page); 1817afddba49SNick Piggin block_start = 0; 1818afddba49SNick Piggin do { 1819afddba49SNick Piggin block_end = block_start + bh->b_size; 1820afddba49SNick Piggin 1821afddba49SNick Piggin if (buffer_new(bh)) { 1822afddba49SNick Piggin if (block_end > from && block_start < to) { 1823afddba49SNick Piggin if (!PageUptodate(page)) { 1824afddba49SNick Piggin unsigned start, size; 1825afddba49SNick Piggin 1826afddba49SNick Piggin start = max(from, block_start); 1827afddba49SNick Piggin size = min(to, block_end) - start; 1828afddba49SNick Piggin 1829eebd2aa3SChristoph Lameter zero_user(page, start, size); 1830afddba49SNick Piggin set_buffer_uptodate(bh); 1831afddba49SNick Piggin } 1832afddba49SNick Piggin 1833afddba49SNick Piggin clear_buffer_new(bh); 1834afddba49SNick Piggin mark_buffer_dirty(bh); 1835afddba49SNick Piggin } 1836afddba49SNick Piggin } 1837afddba49SNick Piggin 1838afddba49SNick Piggin block_start = block_end; 1839afddba49SNick Piggin bh = bh->b_this_page; 1840afddba49SNick Piggin } while (bh != head); 1841afddba49SNick Piggin } 1842afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1843afddba49SNick Piggin 18441da177e4SLinus Torvalds static int __block_prepare_write(struct inode *inode, struct page *page, 18451da177e4SLinus Torvalds unsigned from, unsigned to, get_block_t *get_block) 18461da177e4SLinus Torvalds { 18471da177e4SLinus Torvalds unsigned block_start, block_end; 18481da177e4SLinus Torvalds sector_t block; 18491da177e4SLinus Torvalds int err = 0; 18501da177e4SLinus Torvalds unsigned blocksize, bbits; 18511da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 18521da177e4SLinus Torvalds 18531da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 18541da177e4SLinus Torvalds BUG_ON(from > PAGE_CACHE_SIZE); 18551da177e4SLinus Torvalds BUG_ON(to > PAGE_CACHE_SIZE); 18561da177e4SLinus Torvalds BUG_ON(from > to); 18571da177e4SLinus Torvalds 18581da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 18591da177e4SLinus Torvalds if (!page_has_buffers(page)) 18601da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 18611da177e4SLinus Torvalds head = page_buffers(page); 18621da177e4SLinus Torvalds 18631da177e4SLinus Torvalds bbits = inode->i_blkbits; 18641da177e4SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 18651da177e4SLinus Torvalds 18661da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 18671da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 18681da177e4SLinus Torvalds block_end = block_start + blocksize; 18691da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 18701da177e4SLinus Torvalds if (PageUptodate(page)) { 18711da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 18721da177e4SLinus Torvalds set_buffer_uptodate(bh); 18731da177e4SLinus Torvalds } 18741da177e4SLinus Torvalds continue; 18751da177e4SLinus Torvalds } 18761da177e4SLinus Torvalds if (buffer_new(bh)) 18771da177e4SLinus Torvalds clear_buffer_new(bh); 18781da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1879b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 18801da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 18811da177e4SLinus Torvalds if (err) 1882f3ddbdc6SNick Piggin break; 18831da177e4SLinus Torvalds if (buffer_new(bh)) { 18841da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 18851da177e4SLinus Torvalds bh->b_blocknr); 18861da177e4SLinus Torvalds if (PageUptodate(page)) { 1887637aff46SNick Piggin clear_buffer_new(bh); 18881da177e4SLinus Torvalds set_buffer_uptodate(bh); 1889637aff46SNick Piggin mark_buffer_dirty(bh); 18901da177e4SLinus Torvalds continue; 18911da177e4SLinus Torvalds } 1892eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 1893eebd2aa3SChristoph Lameter zero_user_segments(page, 1894eebd2aa3SChristoph Lameter to, block_end, 1895eebd2aa3SChristoph Lameter block_start, from); 18961da177e4SLinus Torvalds continue; 18971da177e4SLinus Torvalds } 18981da177e4SLinus Torvalds } 18991da177e4SLinus Torvalds if (PageUptodate(page)) { 19001da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19011da177e4SLinus Torvalds set_buffer_uptodate(bh); 19021da177e4SLinus Torvalds continue; 19031da177e4SLinus Torvalds } 19041da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 190533a266ddSDavid Chinner !buffer_unwritten(bh) && 19061da177e4SLinus Torvalds (block_start < from || block_end > to)) { 19071da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 19081da177e4SLinus Torvalds *wait_bh++=bh; 19091da177e4SLinus Torvalds } 19101da177e4SLinus Torvalds } 19111da177e4SLinus Torvalds /* 19121da177e4SLinus Torvalds * If we issued read requests - let them complete. 19131da177e4SLinus Torvalds */ 19141da177e4SLinus Torvalds while(wait_bh > wait) { 19151da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 19161da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1917f3ddbdc6SNick Piggin err = -EIO; 19181da177e4SLinus Torvalds } 1919afddba49SNick Piggin if (unlikely(err)) 1920afddba49SNick Piggin page_zero_new_buffers(page, from, to); 19211da177e4SLinus Torvalds return err; 19221da177e4SLinus Torvalds } 19231da177e4SLinus Torvalds 19241da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 19251da177e4SLinus Torvalds unsigned from, unsigned to) 19261da177e4SLinus Torvalds { 19271da177e4SLinus Torvalds unsigned block_start, block_end; 19281da177e4SLinus Torvalds int partial = 0; 19291da177e4SLinus Torvalds unsigned blocksize; 19301da177e4SLinus Torvalds struct buffer_head *bh, *head; 19311da177e4SLinus Torvalds 19321da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 19331da177e4SLinus Torvalds 19341da177e4SLinus Torvalds for(bh = head = page_buffers(page), block_start = 0; 19351da177e4SLinus Torvalds bh != head || !block_start; 19361da177e4SLinus Torvalds block_start=block_end, bh = bh->b_this_page) { 19371da177e4SLinus Torvalds block_end = block_start + blocksize; 19381da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19391da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19401da177e4SLinus Torvalds partial = 1; 19411da177e4SLinus Torvalds } else { 19421da177e4SLinus Torvalds set_buffer_uptodate(bh); 19431da177e4SLinus Torvalds mark_buffer_dirty(bh); 19441da177e4SLinus Torvalds } 1945afddba49SNick Piggin clear_buffer_new(bh); 19461da177e4SLinus Torvalds } 19471da177e4SLinus Torvalds 19481da177e4SLinus Torvalds /* 19491da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 19501da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 19511da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 19521da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 19531da177e4SLinus Torvalds */ 19541da177e4SLinus Torvalds if (!partial) 19551da177e4SLinus Torvalds SetPageUptodate(page); 19561da177e4SLinus Torvalds return 0; 19571da177e4SLinus Torvalds } 19581da177e4SLinus Torvalds 19591da177e4SLinus Torvalds /* 1960afddba49SNick Piggin * block_write_begin takes care of the basic task of block allocation and 1961afddba49SNick Piggin * bringing partial write blocks uptodate first. 1962afddba49SNick Piggin * 1963afddba49SNick Piggin * If *pagep is not NULL, then block_write_begin uses the locked page 1964afddba49SNick Piggin * at *pagep rather than allocating its own. In this case, the page will 1965afddba49SNick Piggin * not be unlocked or deallocated on failure. 1966afddba49SNick Piggin */ 1967afddba49SNick Piggin int block_write_begin(struct file *file, struct address_space *mapping, 1968afddba49SNick Piggin loff_t pos, unsigned len, unsigned flags, 1969afddba49SNick Piggin struct page **pagep, void **fsdata, 1970afddba49SNick Piggin get_block_t *get_block) 1971afddba49SNick Piggin { 1972afddba49SNick Piggin struct inode *inode = mapping->host; 1973afddba49SNick Piggin int status = 0; 1974afddba49SNick Piggin struct page *page; 1975afddba49SNick Piggin pgoff_t index; 1976afddba49SNick Piggin unsigned start, end; 1977afddba49SNick Piggin int ownpage = 0; 1978afddba49SNick Piggin 1979afddba49SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 1980afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 1981afddba49SNick Piggin end = start + len; 1982afddba49SNick Piggin 1983afddba49SNick Piggin page = *pagep; 1984afddba49SNick Piggin if (page == NULL) { 1985afddba49SNick Piggin ownpage = 1; 198654566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 1987afddba49SNick Piggin if (!page) { 1988afddba49SNick Piggin status = -ENOMEM; 1989afddba49SNick Piggin goto out; 1990afddba49SNick Piggin } 1991afddba49SNick Piggin *pagep = page; 1992afddba49SNick Piggin } else 1993afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1994afddba49SNick Piggin 1995afddba49SNick Piggin status = __block_prepare_write(inode, page, start, end, get_block); 1996afddba49SNick Piggin if (unlikely(status)) { 1997afddba49SNick Piggin ClearPageUptodate(page); 1998afddba49SNick Piggin 1999afddba49SNick Piggin if (ownpage) { 2000afddba49SNick Piggin unlock_page(page); 2001afddba49SNick Piggin page_cache_release(page); 2002afddba49SNick Piggin *pagep = NULL; 2003afddba49SNick Piggin 2004afddba49SNick Piggin /* 2005afddba49SNick Piggin * prepare_write() may have instantiated a few blocks 2006afddba49SNick Piggin * outside i_size. Trim these off again. Don't need 2007afddba49SNick Piggin * i_size_read because we hold i_mutex. 2008afddba49SNick Piggin */ 2009afddba49SNick Piggin if (pos + len > inode->i_size) 2010afddba49SNick Piggin vmtruncate(inode, inode->i_size); 2011afddba49SNick Piggin } 2012afddba49SNick Piggin } 2013afddba49SNick Piggin 2014afddba49SNick Piggin out: 2015afddba49SNick Piggin return status; 2016afddba49SNick Piggin } 2017afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2018afddba49SNick Piggin 2019afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2020afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2021afddba49SNick Piggin struct page *page, void *fsdata) 2022afddba49SNick Piggin { 2023afddba49SNick Piggin struct inode *inode = mapping->host; 2024afddba49SNick Piggin unsigned start; 2025afddba49SNick Piggin 2026afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 2027afddba49SNick Piggin 2028afddba49SNick Piggin if (unlikely(copied < len)) { 2029afddba49SNick Piggin /* 2030afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2031afddba49SNick Piggin * don't have to worry about a readpage reading them and 2032afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2033afddba49SNick Piggin * a short write and only partially written into a buffer, it 2034afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2035afddba49SNick Piggin * destroy our partial write. 2036afddba49SNick Piggin * 2037afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2038afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2039afddba49SNick Piggin * caller to redo the whole thing. 2040afddba49SNick Piggin */ 2041afddba49SNick Piggin if (!PageUptodate(page)) 2042afddba49SNick Piggin copied = 0; 2043afddba49SNick Piggin 2044afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2045afddba49SNick Piggin } 2046afddba49SNick Piggin flush_dcache_page(page); 2047afddba49SNick Piggin 2048afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2049afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2050afddba49SNick Piggin 2051afddba49SNick Piggin return copied; 2052afddba49SNick Piggin } 2053afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2054afddba49SNick Piggin 2055afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2056afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2057afddba49SNick Piggin struct page *page, void *fsdata) 2058afddba49SNick Piggin { 2059afddba49SNick Piggin struct inode *inode = mapping->host; 2060c7d206b3SJan Kara int i_size_changed = 0; 2061afddba49SNick Piggin 2062afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2063afddba49SNick Piggin 2064afddba49SNick Piggin /* 2065afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2066afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2067afddba49SNick Piggin * 2068afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2069afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2070afddba49SNick Piggin */ 2071afddba49SNick Piggin if (pos+copied > inode->i_size) { 2072afddba49SNick Piggin i_size_write(inode, pos+copied); 2073c7d206b3SJan Kara i_size_changed = 1; 2074afddba49SNick Piggin } 2075afddba49SNick Piggin 2076afddba49SNick Piggin unlock_page(page); 2077afddba49SNick Piggin page_cache_release(page); 2078afddba49SNick Piggin 2079c7d206b3SJan Kara /* 2080c7d206b3SJan Kara * Don't mark the inode dirty under page lock. First, it unnecessarily 2081c7d206b3SJan Kara * makes the holding time of page lock longer. Second, it forces lock 2082c7d206b3SJan Kara * ordering of page lock and transaction start for journaling 2083c7d206b3SJan Kara * filesystems. 2084c7d206b3SJan Kara */ 2085c7d206b3SJan Kara if (i_size_changed) 2086c7d206b3SJan Kara mark_inode_dirty(inode); 2087c7d206b3SJan Kara 2088afddba49SNick Piggin return copied; 2089afddba49SNick Piggin } 2090afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2091afddba49SNick Piggin 2092afddba49SNick Piggin /* 20938ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 20948ab22b9aSHisashi Hifumi * uptodate or not. 20958ab22b9aSHisashi Hifumi * 20968ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 20978ab22b9aSHisashi Hifumi * we want to read are uptodate. 20988ab22b9aSHisashi Hifumi */ 20998ab22b9aSHisashi Hifumi int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, 21008ab22b9aSHisashi Hifumi unsigned long from) 21018ab22b9aSHisashi Hifumi { 21028ab22b9aSHisashi Hifumi struct inode *inode = page->mapping->host; 21038ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 21048ab22b9aSHisashi Hifumi unsigned to; 21058ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 21068ab22b9aSHisashi Hifumi int ret = 1; 21078ab22b9aSHisashi Hifumi 21088ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 21098ab22b9aSHisashi Hifumi return 0; 21108ab22b9aSHisashi Hifumi 21118ab22b9aSHisashi Hifumi blocksize = 1 << inode->i_blkbits; 21128ab22b9aSHisashi Hifumi to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count); 21138ab22b9aSHisashi Hifumi to = from + to; 21148ab22b9aSHisashi Hifumi if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) 21158ab22b9aSHisashi Hifumi return 0; 21168ab22b9aSHisashi Hifumi 21178ab22b9aSHisashi Hifumi head = page_buffers(page); 21188ab22b9aSHisashi Hifumi bh = head; 21198ab22b9aSHisashi Hifumi block_start = 0; 21208ab22b9aSHisashi Hifumi do { 21218ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 21228ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 21238ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 21248ab22b9aSHisashi Hifumi ret = 0; 21258ab22b9aSHisashi Hifumi break; 21268ab22b9aSHisashi Hifumi } 21278ab22b9aSHisashi Hifumi if (block_end >= to) 21288ab22b9aSHisashi Hifumi break; 21298ab22b9aSHisashi Hifumi } 21308ab22b9aSHisashi Hifumi block_start = block_end; 21318ab22b9aSHisashi Hifumi bh = bh->b_this_page; 21328ab22b9aSHisashi Hifumi } while (bh != head); 21338ab22b9aSHisashi Hifumi 21348ab22b9aSHisashi Hifumi return ret; 21358ab22b9aSHisashi Hifumi } 21368ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 21378ab22b9aSHisashi Hifumi 21388ab22b9aSHisashi Hifumi /* 21391da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 21401da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 21411da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 21421da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 21431da177e4SLinus Torvalds * page struct once IO has completed. 21441da177e4SLinus Torvalds */ 21451da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 21461da177e4SLinus Torvalds { 21471da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21481da177e4SLinus Torvalds sector_t iblock, lblock; 21491da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 21501da177e4SLinus Torvalds unsigned int blocksize; 21511da177e4SLinus Torvalds int nr, i; 21521da177e4SLinus Torvalds int fully_mapped = 1; 21531da177e4SLinus Torvalds 2154cd7619d6SMatt Mackall BUG_ON(!PageLocked(page)); 21551da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 21561da177e4SLinus Torvalds if (!page_has_buffers(page)) 21571da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 21581da177e4SLinus Torvalds head = page_buffers(page); 21591da177e4SLinus Torvalds 21601da177e4SLinus Torvalds iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 21611da177e4SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; 21621da177e4SLinus Torvalds bh = head; 21631da177e4SLinus Torvalds nr = 0; 21641da177e4SLinus Torvalds i = 0; 21651da177e4SLinus Torvalds 21661da177e4SLinus Torvalds do { 21671da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21681da177e4SLinus Torvalds continue; 21691da177e4SLinus Torvalds 21701da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2171c64610baSAndrew Morton int err = 0; 2172c64610baSAndrew Morton 21731da177e4SLinus Torvalds fully_mapped = 0; 21741da177e4SLinus Torvalds if (iblock < lblock) { 2175b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2176c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2177c64610baSAndrew Morton if (err) 21781da177e4SLinus Torvalds SetPageError(page); 21791da177e4SLinus Torvalds } 21801da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2181eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2182c64610baSAndrew Morton if (!err) 21831da177e4SLinus Torvalds set_buffer_uptodate(bh); 21841da177e4SLinus Torvalds continue; 21851da177e4SLinus Torvalds } 21861da177e4SLinus Torvalds /* 21871da177e4SLinus Torvalds * get_block() might have updated the buffer 21881da177e4SLinus Torvalds * synchronously 21891da177e4SLinus Torvalds */ 21901da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21911da177e4SLinus Torvalds continue; 21921da177e4SLinus Torvalds } 21931da177e4SLinus Torvalds arr[nr++] = bh; 21941da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 21951da177e4SLinus Torvalds 21961da177e4SLinus Torvalds if (fully_mapped) 21971da177e4SLinus Torvalds SetPageMappedToDisk(page); 21981da177e4SLinus Torvalds 21991da177e4SLinus Torvalds if (!nr) { 22001da177e4SLinus Torvalds /* 22011da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 22021da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 22031da177e4SLinus Torvalds */ 22041da177e4SLinus Torvalds if (!PageError(page)) 22051da177e4SLinus Torvalds SetPageUptodate(page); 22061da177e4SLinus Torvalds unlock_page(page); 22071da177e4SLinus Torvalds return 0; 22081da177e4SLinus Torvalds } 22091da177e4SLinus Torvalds 22101da177e4SLinus Torvalds /* Stage two: lock the buffers */ 22111da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22121da177e4SLinus Torvalds bh = arr[i]; 22131da177e4SLinus Torvalds lock_buffer(bh); 22141da177e4SLinus Torvalds mark_buffer_async_read(bh); 22151da177e4SLinus Torvalds } 22161da177e4SLinus Torvalds 22171da177e4SLinus Torvalds /* 22181da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 22191da177e4SLinus Torvalds * inside the buffer lock in case another process reading 22201da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 22211da177e4SLinus Torvalds */ 22221da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22231da177e4SLinus Torvalds bh = arr[i]; 22241da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22251da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 22261da177e4SLinus Torvalds else 22271da177e4SLinus Torvalds submit_bh(READ, bh); 22281da177e4SLinus Torvalds } 22291da177e4SLinus Torvalds return 0; 22301da177e4SLinus Torvalds } 22311fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 22321da177e4SLinus Torvalds 22331da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 223489e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 22351da177e4SLinus Torvalds * deal with the hole. 22361da177e4SLinus Torvalds */ 223789e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 22381da177e4SLinus Torvalds { 22391da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 22401da177e4SLinus Torvalds struct page *page; 224189e10787SNick Piggin void *fsdata; 22421da177e4SLinus Torvalds int err; 22431da177e4SLinus Torvalds 2244c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2245c08d3b0eSnpiggin@suse.de if (err) 22461da177e4SLinus Torvalds goto out; 22471da177e4SLinus Torvalds 224889e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 224989e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, 225089e10787SNick Piggin &page, &fsdata); 225189e10787SNick Piggin if (err) 225205eb0b51SOGAWA Hirofumi goto out; 225305eb0b51SOGAWA Hirofumi 225489e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 225589e10787SNick Piggin BUG_ON(err > 0); 225605eb0b51SOGAWA Hirofumi 225705eb0b51SOGAWA Hirofumi out: 225805eb0b51SOGAWA Hirofumi return err; 225905eb0b51SOGAWA Hirofumi } 22601fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 226105eb0b51SOGAWA Hirofumi 2262f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 226389e10787SNick Piggin loff_t pos, loff_t *bytes) 226405eb0b51SOGAWA Hirofumi { 226589e10787SNick Piggin struct inode *inode = mapping->host; 226689e10787SNick Piggin unsigned blocksize = 1 << inode->i_blkbits; 226789e10787SNick Piggin struct page *page; 226889e10787SNick Piggin void *fsdata; 226989e10787SNick Piggin pgoff_t index, curidx; 227089e10787SNick Piggin loff_t curpos; 227189e10787SNick Piggin unsigned zerofrom, offset, len; 227289e10787SNick Piggin int err = 0; 227305eb0b51SOGAWA Hirofumi 227489e10787SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 227589e10787SNick Piggin offset = pos & ~PAGE_CACHE_MASK; 227689e10787SNick Piggin 227789e10787SNick Piggin while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { 227889e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 227989e10787SNick Piggin if (zerofrom & (blocksize-1)) { 228089e10787SNick Piggin *bytes |= (blocksize-1); 228189e10787SNick Piggin (*bytes)++; 228289e10787SNick Piggin } 228389e10787SNick Piggin len = PAGE_CACHE_SIZE - zerofrom; 228489e10787SNick Piggin 228589e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 228689e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 228789e10787SNick Piggin &page, &fsdata); 228889e10787SNick Piggin if (err) 228989e10787SNick Piggin goto out; 2290eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 229189e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 229289e10787SNick Piggin page, fsdata); 229389e10787SNick Piggin if (err < 0) 229489e10787SNick Piggin goto out; 229589e10787SNick Piggin BUG_ON(err != len); 229689e10787SNick Piggin err = 0; 2297061e9746SOGAWA Hirofumi 2298061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 229989e10787SNick Piggin } 230089e10787SNick Piggin 230189e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 230289e10787SNick Piggin if (index == curidx) { 230389e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 230489e10787SNick Piggin /* if we will expand the thing last block will be filled */ 230589e10787SNick Piggin if (offset <= zerofrom) { 230689e10787SNick Piggin goto out; 230789e10787SNick Piggin } 230889e10787SNick Piggin if (zerofrom & (blocksize-1)) { 230989e10787SNick Piggin *bytes |= (blocksize-1); 231089e10787SNick Piggin (*bytes)++; 231189e10787SNick Piggin } 231289e10787SNick Piggin len = offset - zerofrom; 231389e10787SNick Piggin 231489e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 231589e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 231689e10787SNick Piggin &page, &fsdata); 231789e10787SNick Piggin if (err) 231889e10787SNick Piggin goto out; 2319eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 232089e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 232189e10787SNick Piggin page, fsdata); 232289e10787SNick Piggin if (err < 0) 232389e10787SNick Piggin goto out; 232489e10787SNick Piggin BUG_ON(err != len); 232589e10787SNick Piggin err = 0; 232689e10787SNick Piggin } 232789e10787SNick Piggin out: 232889e10787SNick Piggin return err; 23291da177e4SLinus Torvalds } 23301da177e4SLinus Torvalds 23311da177e4SLinus Torvalds /* 23321da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 23331da177e4SLinus Torvalds * We may have to extend the file. 23341da177e4SLinus Torvalds */ 233589e10787SNick Piggin int cont_write_begin(struct file *file, struct address_space *mapping, 233689e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 233789e10787SNick Piggin struct page **pagep, void **fsdata, 233889e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 23391da177e4SLinus Torvalds { 23401da177e4SLinus Torvalds struct inode *inode = mapping->host; 23411da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 234289e10787SNick Piggin unsigned zerofrom; 234389e10787SNick Piggin int err; 23441da177e4SLinus Torvalds 234589e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 234689e10787SNick Piggin if (err) 23471da177e4SLinus Torvalds goto out; 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 235089e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 23511da177e4SLinus Torvalds *bytes |= (blocksize-1); 23521da177e4SLinus Torvalds (*bytes)++; 23531da177e4SLinus Torvalds } 23541da177e4SLinus Torvalds 235589e10787SNick Piggin *pagep = NULL; 235689e10787SNick Piggin err = block_write_begin(file, mapping, pos, len, 235789e10787SNick Piggin flags, pagep, fsdata, get_block); 23581da177e4SLinus Torvalds out: 235989e10787SNick Piggin return err; 23601da177e4SLinus Torvalds } 23611fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 23621da177e4SLinus Torvalds 23631da177e4SLinus Torvalds int block_prepare_write(struct page *page, unsigned from, unsigned to, 23641da177e4SLinus Torvalds get_block_t *get_block) 23651da177e4SLinus Torvalds { 23661da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23671da177e4SLinus Torvalds int err = __block_prepare_write(inode, page, from, to, get_block); 23681da177e4SLinus Torvalds if (err) 23691da177e4SLinus Torvalds ClearPageUptodate(page); 23701da177e4SLinus Torvalds return err; 23711da177e4SLinus Torvalds } 23721fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_prepare_write); 23731da177e4SLinus Torvalds 23741da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 23751da177e4SLinus Torvalds { 23761da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23771da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 23781da177e4SLinus Torvalds return 0; 23791da177e4SLinus Torvalds } 23801fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 23811da177e4SLinus Torvalds 238254171690SDavid Chinner /* 238354171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 238454171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 238554171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 238654171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 238754171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 238854171690SDavid Chinner * support these features. 238954171690SDavid Chinner * 239054171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 239154171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 239254171690SDavid Chinner * vmtruncate() writes the inode size before removing pages, once we have the 239354171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 239454171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 239554171690SDavid Chinner * unlock the page. 239654171690SDavid Chinner */ 239754171690SDavid Chinner int 2398c2ec175cSNick Piggin block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 239954171690SDavid Chinner get_block_t get_block) 240054171690SDavid Chinner { 2401c2ec175cSNick Piggin struct page *page = vmf->page; 240254171690SDavid Chinner struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 240354171690SDavid Chinner unsigned long end; 240454171690SDavid Chinner loff_t size; 240556a76f82SNick Piggin int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ 240654171690SDavid Chinner 240754171690SDavid Chinner lock_page(page); 240854171690SDavid Chinner size = i_size_read(inode); 240954171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 241018336338SNick Piggin (page_offset(page) > size)) { 241154171690SDavid Chinner /* page got truncated out from underneath us */ 2412b827e496SNick Piggin unlock_page(page); 2413b827e496SNick Piggin goto out; 241454171690SDavid Chinner } 241554171690SDavid Chinner 241654171690SDavid Chinner /* page is wholly or partially inside EOF */ 241754171690SDavid Chinner if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) 241854171690SDavid Chinner end = size & ~PAGE_CACHE_MASK; 241954171690SDavid Chinner else 242054171690SDavid Chinner end = PAGE_CACHE_SIZE; 242154171690SDavid Chinner 242254171690SDavid Chinner ret = block_prepare_write(page, 0, end, get_block); 242354171690SDavid Chinner if (!ret) 242454171690SDavid Chinner ret = block_commit_write(page, 0, end); 242554171690SDavid Chinner 242656a76f82SNick Piggin if (unlikely(ret)) { 2427b827e496SNick Piggin unlock_page(page); 242856a76f82SNick Piggin if (ret == -ENOMEM) 242956a76f82SNick Piggin ret = VM_FAULT_OOM; 243056a76f82SNick Piggin else /* -ENOSPC, -EIO, etc */ 2431c2ec175cSNick Piggin ret = VM_FAULT_SIGBUS; 2432b827e496SNick Piggin } else 2433b827e496SNick Piggin ret = VM_FAULT_LOCKED; 2434c2ec175cSNick Piggin 2435b827e496SNick Piggin out: 243654171690SDavid Chinner return ret; 243754171690SDavid Chinner } 24381fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 24391da177e4SLinus Torvalds 24401da177e4SLinus Torvalds /* 244103158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 24421da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 24431da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 24441da177e4SLinus Torvalds */ 24451da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 24461da177e4SLinus Torvalds { 244768671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 24481da177e4SLinus Torvalds } 24491da177e4SLinus Torvalds 24501da177e4SLinus Torvalds /* 245103158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 245203158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 245303158cd7SNick Piggin * dirty races). 245403158cd7SNick Piggin */ 245503158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 245603158cd7SNick Piggin { 245703158cd7SNick Piggin struct buffer_head *bh; 245803158cd7SNick Piggin 245903158cd7SNick Piggin BUG_ON(!PageLocked(page)); 246003158cd7SNick Piggin 246103158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 246203158cd7SNick Piggin bh = head; 246303158cd7SNick Piggin do { 246403158cd7SNick Piggin if (PageDirty(page)) 246503158cd7SNick Piggin set_buffer_dirty(bh); 246603158cd7SNick Piggin if (!bh->b_this_page) 246703158cd7SNick Piggin bh->b_this_page = head; 246803158cd7SNick Piggin bh = bh->b_this_page; 246903158cd7SNick Piggin } while (bh != head); 247003158cd7SNick Piggin attach_page_buffers(page, head); 247103158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 247203158cd7SNick Piggin } 247303158cd7SNick Piggin 247403158cd7SNick Piggin /* 24751da177e4SLinus Torvalds * On entry, the page is fully not uptodate. 24761da177e4SLinus Torvalds * On exit the page is fully uptodate in the areas outside (from,to) 24771da177e4SLinus Torvalds */ 247803158cd7SNick Piggin int nobh_write_begin(struct file *file, struct address_space *mapping, 247903158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 248003158cd7SNick Piggin struct page **pagep, void **fsdata, 24811da177e4SLinus Torvalds get_block_t *get_block) 24821da177e4SLinus Torvalds { 248303158cd7SNick Piggin struct inode *inode = mapping->host; 24841da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 24851da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2486a4b0672dSNick Piggin struct buffer_head *head, *bh; 248703158cd7SNick Piggin struct page *page; 248803158cd7SNick Piggin pgoff_t index; 248903158cd7SNick Piggin unsigned from, to; 24901da177e4SLinus Torvalds unsigned block_in_page; 2491a4b0672dSNick Piggin unsigned block_start, block_end; 24921da177e4SLinus Torvalds sector_t block_in_file; 24931da177e4SLinus Torvalds int nr_reads = 0; 24941da177e4SLinus Torvalds int ret = 0; 24951da177e4SLinus Torvalds int is_mapped_to_disk = 1; 24961da177e4SLinus Torvalds 249703158cd7SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 249803158cd7SNick Piggin from = pos & (PAGE_CACHE_SIZE - 1); 249903158cd7SNick Piggin to = from + len; 250003158cd7SNick Piggin 250154566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 250203158cd7SNick Piggin if (!page) 250303158cd7SNick Piggin return -ENOMEM; 250403158cd7SNick Piggin *pagep = page; 250503158cd7SNick Piggin *fsdata = NULL; 250603158cd7SNick Piggin 250703158cd7SNick Piggin if (page_has_buffers(page)) { 250803158cd7SNick Piggin unlock_page(page); 250903158cd7SNick Piggin page_cache_release(page); 251003158cd7SNick Piggin *pagep = NULL; 251103158cd7SNick Piggin return block_write_begin(file, mapping, pos, len, flags, pagep, 251203158cd7SNick Piggin fsdata, get_block); 251303158cd7SNick Piggin } 2514a4b0672dSNick Piggin 25151da177e4SLinus Torvalds if (PageMappedToDisk(page)) 25161da177e4SLinus Torvalds return 0; 25171da177e4SLinus Torvalds 2518a4b0672dSNick Piggin /* 2519a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2520a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2521a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2522a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2523a4b0672dSNick Piggin * 2524a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2525a4b0672dSNick Piggin * than the circular one we're used to. 2526a4b0672dSNick Piggin */ 2527a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 252803158cd7SNick Piggin if (!head) { 252903158cd7SNick Piggin ret = -ENOMEM; 253003158cd7SNick Piggin goto out_release; 253103158cd7SNick Piggin } 2532a4b0672dSNick Piggin 25331da177e4SLinus Torvalds block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); 25341da177e4SLinus Torvalds 25351da177e4SLinus Torvalds /* 25361da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 25371da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 25381da177e4SLinus Torvalds * page is fully mapped-to-disk. 25391da177e4SLinus Torvalds */ 2540a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 25411da177e4SLinus Torvalds block_start < PAGE_CACHE_SIZE; 2542a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 25431da177e4SLinus Torvalds int create; 25441da177e4SLinus Torvalds 2545a4b0672dSNick Piggin block_end = block_start + blocksize; 2546a4b0672dSNick Piggin bh->b_state = 0; 25471da177e4SLinus Torvalds create = 1; 25481da177e4SLinus Torvalds if (block_start >= to) 25491da177e4SLinus Torvalds create = 0; 25501da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2551a4b0672dSNick Piggin bh, create); 25521da177e4SLinus Torvalds if (ret) 25531da177e4SLinus Torvalds goto failed; 2554a4b0672dSNick Piggin if (!buffer_mapped(bh)) 25551da177e4SLinus Torvalds is_mapped_to_disk = 0; 2556a4b0672dSNick Piggin if (buffer_new(bh)) 2557a4b0672dSNick Piggin unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 2558a4b0672dSNick Piggin if (PageUptodate(page)) { 2559a4b0672dSNick Piggin set_buffer_uptodate(bh); 25601da177e4SLinus Torvalds continue; 2561a4b0672dSNick Piggin } 2562a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2563eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2564eebd2aa3SChristoph Lameter to, block_end); 25651da177e4SLinus Torvalds continue; 25661da177e4SLinus Torvalds } 2567a4b0672dSNick Piggin if (buffer_uptodate(bh)) 25681da177e4SLinus Torvalds continue; /* reiserfs does this */ 25691da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2570a4b0672dSNick Piggin lock_buffer(bh); 2571a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 2572a4b0672dSNick Piggin submit_bh(READ, bh); 2573a4b0672dSNick Piggin nr_reads++; 25741da177e4SLinus Torvalds } 25751da177e4SLinus Torvalds } 25761da177e4SLinus Torvalds 25771da177e4SLinus Torvalds if (nr_reads) { 25781da177e4SLinus Torvalds /* 25791da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 25801da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 25811da177e4SLinus Torvalds * for the buffer_head refcounts. 25821da177e4SLinus Torvalds */ 2583a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 25841da177e4SLinus Torvalds wait_on_buffer(bh); 25851da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 25861da177e4SLinus Torvalds ret = -EIO; 25871da177e4SLinus Torvalds } 25881da177e4SLinus Torvalds if (ret) 25891da177e4SLinus Torvalds goto failed; 25901da177e4SLinus Torvalds } 25911da177e4SLinus Torvalds 25921da177e4SLinus Torvalds if (is_mapped_to_disk) 25931da177e4SLinus Torvalds SetPageMappedToDisk(page); 25941da177e4SLinus Torvalds 259503158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2596a4b0672dSNick Piggin 25971da177e4SLinus Torvalds return 0; 25981da177e4SLinus Torvalds 25991da177e4SLinus Torvalds failed: 260003158cd7SNick Piggin BUG_ON(!ret); 26011da177e4SLinus Torvalds /* 2602a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2603a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2604a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2605a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2606a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 26071da177e4SLinus Torvalds */ 260803158cd7SNick Piggin attach_nobh_buffers(page, head); 260903158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2610a4b0672dSNick Piggin 261103158cd7SNick Piggin out_release: 261203158cd7SNick Piggin unlock_page(page); 261303158cd7SNick Piggin page_cache_release(page); 261403158cd7SNick Piggin *pagep = NULL; 2615a4b0672dSNick Piggin 261603158cd7SNick Piggin if (pos + len > inode->i_size) 261703158cd7SNick Piggin vmtruncate(inode, inode->i_size); 2618a4b0672dSNick Piggin 26191da177e4SLinus Torvalds return ret; 26201da177e4SLinus Torvalds } 262103158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 26221da177e4SLinus Torvalds 262303158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 262403158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 262503158cd7SNick Piggin struct page *page, void *fsdata) 26261da177e4SLinus Torvalds { 26271da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2628efdc3131SNick Piggin struct buffer_head *head = fsdata; 262903158cd7SNick Piggin struct buffer_head *bh; 26305b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 26311da177e4SLinus Torvalds 2632d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 263303158cd7SNick Piggin attach_nobh_buffers(page, head); 2634a4b0672dSNick Piggin if (page_has_buffers(page)) 263503158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 263603158cd7SNick Piggin copied, page, fsdata); 2637a4b0672dSNick Piggin 263822c8ca78SNick Piggin SetPageUptodate(page); 26391da177e4SLinus Torvalds set_page_dirty(page); 264003158cd7SNick Piggin if (pos+copied > inode->i_size) { 264103158cd7SNick Piggin i_size_write(inode, pos+copied); 26421da177e4SLinus Torvalds mark_inode_dirty(inode); 26431da177e4SLinus Torvalds } 264403158cd7SNick Piggin 264503158cd7SNick Piggin unlock_page(page); 264603158cd7SNick Piggin page_cache_release(page); 264703158cd7SNick Piggin 264803158cd7SNick Piggin while (head) { 264903158cd7SNick Piggin bh = head; 265003158cd7SNick Piggin head = head->b_this_page; 265103158cd7SNick Piggin free_buffer_head(bh); 26521da177e4SLinus Torvalds } 265303158cd7SNick Piggin 265403158cd7SNick Piggin return copied; 265503158cd7SNick Piggin } 265603158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 26571da177e4SLinus Torvalds 26581da177e4SLinus Torvalds /* 26591da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 26601da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 26611da177e4SLinus Torvalds * the page. 26621da177e4SLinus Torvalds */ 26631da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 26641da177e4SLinus Torvalds struct writeback_control *wbc) 26651da177e4SLinus Torvalds { 26661da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 26671da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 26681da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 26691da177e4SLinus Torvalds unsigned offset; 26701da177e4SLinus Torvalds int ret; 26711da177e4SLinus Torvalds 26721da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 26731da177e4SLinus Torvalds if (page->index < end_index) 26741da177e4SLinus Torvalds goto out; 26751da177e4SLinus Torvalds 26761da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 26771da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 26781da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 26791da177e4SLinus Torvalds /* 26801da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 26811da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 26821da177e4SLinus Torvalds * freeable here, so the page does not leak. 26831da177e4SLinus Torvalds */ 26841da177e4SLinus Torvalds #if 0 26851da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 26861da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 26871da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 26881da177e4SLinus Torvalds #endif 26891da177e4SLinus Torvalds unlock_page(page); 26901da177e4SLinus Torvalds return 0; /* don't care */ 26911da177e4SLinus Torvalds } 26921da177e4SLinus Torvalds 26931da177e4SLinus Torvalds /* 26941da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 26951da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 26961da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 26971da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 26981da177e4SLinus Torvalds * writes to that region are not written out to the file." 26991da177e4SLinus Torvalds */ 2700eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 27011da177e4SLinus Torvalds out: 27021da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 27031da177e4SLinus Torvalds if (ret == -EAGAIN) 270435c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 270535c80d5fSChris Mason end_buffer_async_write); 27061da177e4SLinus Torvalds return ret; 27071da177e4SLinus Torvalds } 27081da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27091da177e4SLinus Torvalds 271003158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 271103158cd7SNick Piggin loff_t from, get_block_t *get_block) 27121da177e4SLinus Torvalds { 27131da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 27141da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 271503158cd7SNick Piggin unsigned blocksize; 271603158cd7SNick Piggin sector_t iblock; 271703158cd7SNick Piggin unsigned length, pos; 271803158cd7SNick Piggin struct inode *inode = mapping->host; 27191da177e4SLinus Torvalds struct page *page; 272003158cd7SNick Piggin struct buffer_head map_bh; 272103158cd7SNick Piggin int err; 27221da177e4SLinus Torvalds 272303158cd7SNick Piggin blocksize = 1 << inode->i_blkbits; 272403158cd7SNick Piggin length = offset & (blocksize - 1); 27251da177e4SLinus Torvalds 272603158cd7SNick Piggin /* Block boundary? Nothing to do */ 272703158cd7SNick Piggin if (!length) 272803158cd7SNick Piggin return 0; 272903158cd7SNick Piggin 273003158cd7SNick Piggin length = blocksize - length; 273103158cd7SNick Piggin iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 273203158cd7SNick Piggin 27331da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 273403158cd7SNick Piggin err = -ENOMEM; 27351da177e4SLinus Torvalds if (!page) 27361da177e4SLinus Torvalds goto out; 27371da177e4SLinus Torvalds 273803158cd7SNick Piggin if (page_has_buffers(page)) { 273903158cd7SNick Piggin has_buffers: 274003158cd7SNick Piggin unlock_page(page); 274103158cd7SNick Piggin page_cache_release(page); 274203158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 27431da177e4SLinus Torvalds } 274403158cd7SNick Piggin 274503158cd7SNick Piggin /* Find the buffer that contains "offset" */ 274603158cd7SNick Piggin pos = blocksize; 274703158cd7SNick Piggin while (offset >= pos) { 274803158cd7SNick Piggin iblock++; 274903158cd7SNick Piggin pos += blocksize; 275003158cd7SNick Piggin } 275103158cd7SNick Piggin 2752460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2753460bcf57STheodore Ts'o map_bh.b_state = 0; 275403158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 275503158cd7SNick Piggin if (err) 275603158cd7SNick Piggin goto unlock; 275703158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 275803158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 275903158cd7SNick Piggin goto unlock; 276003158cd7SNick Piggin 276103158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 276203158cd7SNick Piggin if (!PageUptodate(page)) { 276303158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 276403158cd7SNick Piggin if (err) { 276503158cd7SNick Piggin page_cache_release(page); 276603158cd7SNick Piggin goto out; 276703158cd7SNick Piggin } 276803158cd7SNick Piggin lock_page(page); 276903158cd7SNick Piggin if (!PageUptodate(page)) { 277003158cd7SNick Piggin err = -EIO; 277103158cd7SNick Piggin goto unlock; 277203158cd7SNick Piggin } 277303158cd7SNick Piggin if (page_has_buffers(page)) 277403158cd7SNick Piggin goto has_buffers; 277503158cd7SNick Piggin } 2776eebd2aa3SChristoph Lameter zero_user(page, offset, length); 277703158cd7SNick Piggin set_page_dirty(page); 277803158cd7SNick Piggin err = 0; 277903158cd7SNick Piggin 278003158cd7SNick Piggin unlock: 27811da177e4SLinus Torvalds unlock_page(page); 27821da177e4SLinus Torvalds page_cache_release(page); 27831da177e4SLinus Torvalds out: 278403158cd7SNick Piggin return err; 27851da177e4SLinus Torvalds } 27861da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 27871da177e4SLinus Torvalds 27881da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 27891da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 27901da177e4SLinus Torvalds { 27911da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 27921da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 27931da177e4SLinus Torvalds unsigned blocksize; 279454b21a79SAndrew Morton sector_t iblock; 27951da177e4SLinus Torvalds unsigned length, pos; 27961da177e4SLinus Torvalds struct inode *inode = mapping->host; 27971da177e4SLinus Torvalds struct page *page; 27981da177e4SLinus Torvalds struct buffer_head *bh; 27991da177e4SLinus Torvalds int err; 28001da177e4SLinus Torvalds 28011da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 28021da177e4SLinus Torvalds length = offset & (blocksize - 1); 28031da177e4SLinus Torvalds 28041da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 28051da177e4SLinus Torvalds if (!length) 28061da177e4SLinus Torvalds return 0; 28071da177e4SLinus Torvalds 28081da177e4SLinus Torvalds length = blocksize - length; 280954b21a79SAndrew Morton iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 28101da177e4SLinus Torvalds 28111da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 28121da177e4SLinus Torvalds err = -ENOMEM; 28131da177e4SLinus Torvalds if (!page) 28141da177e4SLinus Torvalds goto out; 28151da177e4SLinus Torvalds 28161da177e4SLinus Torvalds if (!page_has_buffers(page)) 28171da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 28181da177e4SLinus Torvalds 28191da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 28201da177e4SLinus Torvalds bh = page_buffers(page); 28211da177e4SLinus Torvalds pos = blocksize; 28221da177e4SLinus Torvalds while (offset >= pos) { 28231da177e4SLinus Torvalds bh = bh->b_this_page; 28241da177e4SLinus Torvalds iblock++; 28251da177e4SLinus Torvalds pos += blocksize; 28261da177e4SLinus Torvalds } 28271da177e4SLinus Torvalds 28281da177e4SLinus Torvalds err = 0; 28291da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2830b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 28311da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 28321da177e4SLinus Torvalds if (err) 28331da177e4SLinus Torvalds goto unlock; 28341da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 28351da177e4SLinus Torvalds if (!buffer_mapped(bh)) 28361da177e4SLinus Torvalds goto unlock; 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds 28391da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 28401da177e4SLinus Torvalds if (PageUptodate(page)) 28411da177e4SLinus Torvalds set_buffer_uptodate(bh); 28421da177e4SLinus Torvalds 284333a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 28441da177e4SLinus Torvalds err = -EIO; 28451da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 28461da177e4SLinus Torvalds wait_on_buffer(bh); 28471da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 28481da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 28491da177e4SLinus Torvalds goto unlock; 28501da177e4SLinus Torvalds } 28511da177e4SLinus Torvalds 2852eebd2aa3SChristoph Lameter zero_user(page, offset, length); 28531da177e4SLinus Torvalds mark_buffer_dirty(bh); 28541da177e4SLinus Torvalds err = 0; 28551da177e4SLinus Torvalds 28561da177e4SLinus Torvalds unlock: 28571da177e4SLinus Torvalds unlock_page(page); 28581da177e4SLinus Torvalds page_cache_release(page); 28591da177e4SLinus Torvalds out: 28601da177e4SLinus Torvalds return err; 28611da177e4SLinus Torvalds } 28621fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 28631da177e4SLinus Torvalds 28641da177e4SLinus Torvalds /* 28651da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 286635c80d5fSChris Mason * this form passes in the end_io handler used to finish the IO. 28671da177e4SLinus Torvalds */ 286835c80d5fSChris Mason int block_write_full_page_endio(struct page *page, get_block_t *get_block, 286935c80d5fSChris Mason struct writeback_control *wbc, bh_end_io_t *handler) 28701da177e4SLinus Torvalds { 28711da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 28721da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 28731da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 28741da177e4SLinus Torvalds unsigned offset; 28751da177e4SLinus Torvalds 28761da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 28771da177e4SLinus Torvalds if (page->index < end_index) 287835c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 287935c80d5fSChris Mason handler); 28801da177e4SLinus Torvalds 28811da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 28821da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 28831da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 28841da177e4SLinus Torvalds /* 28851da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 28861da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 28871da177e4SLinus Torvalds * freeable here, so the page does not leak. 28881da177e4SLinus Torvalds */ 2889aaa4059bSJan Kara do_invalidatepage(page, 0); 28901da177e4SLinus Torvalds unlock_page(page); 28911da177e4SLinus Torvalds return 0; /* don't care */ 28921da177e4SLinus Torvalds } 28931da177e4SLinus Torvalds 28941da177e4SLinus Torvalds /* 28951da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 28961da177e4SLinus Torvalds * writepage invokation because it may be mmapped. "A file is mapped 28971da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 28981da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 28991da177e4SLinus Torvalds * writes to that region are not written out to the file." 29001da177e4SLinus Torvalds */ 2901eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 290235c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, handler); 29031da177e4SLinus Torvalds } 29041fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page_endio); 29051da177e4SLinus Torvalds 290635c80d5fSChris Mason /* 290735c80d5fSChris Mason * The generic ->writepage function for buffer-backed address_spaces 290835c80d5fSChris Mason */ 290935c80d5fSChris Mason int block_write_full_page(struct page *page, get_block_t *get_block, 291035c80d5fSChris Mason struct writeback_control *wbc) 291135c80d5fSChris Mason { 291235c80d5fSChris Mason return block_write_full_page_endio(page, get_block, wbc, 291335c80d5fSChris Mason end_buffer_async_write); 291435c80d5fSChris Mason } 29151fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 291635c80d5fSChris Mason 29171da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29181da177e4SLinus Torvalds get_block_t *get_block) 29191da177e4SLinus Torvalds { 29201da177e4SLinus Torvalds struct buffer_head tmp; 29211da177e4SLinus Torvalds struct inode *inode = mapping->host; 29221da177e4SLinus Torvalds tmp.b_state = 0; 29231da177e4SLinus Torvalds tmp.b_blocknr = 0; 2924b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 29251da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 29261da177e4SLinus Torvalds return tmp.b_blocknr; 29271da177e4SLinus Torvalds } 29281fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 29291da177e4SLinus Torvalds 29306712ecf8SNeilBrown static void end_bio_bh_io_sync(struct bio *bio, int err) 29311da177e4SLinus Torvalds { 29321da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 29331da177e4SLinus Torvalds 29341da177e4SLinus Torvalds if (err == -EOPNOTSUPP) { 29351da177e4SLinus Torvalds set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); 29361da177e4SLinus Torvalds set_bit(BH_Eopnotsupp, &bh->b_state); 29371da177e4SLinus Torvalds } 29381da177e4SLinus Torvalds 293908bafc03SKeith Mannthey if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) 294008bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 294108bafc03SKeith Mannthey 29421da177e4SLinus Torvalds bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); 29431da177e4SLinus Torvalds bio_put(bio); 29441da177e4SLinus Torvalds } 29451da177e4SLinus Torvalds 29461da177e4SLinus Torvalds int submit_bh(int rw, struct buffer_head * bh) 29471da177e4SLinus Torvalds { 29481da177e4SLinus Torvalds struct bio *bio; 29491da177e4SLinus Torvalds int ret = 0; 29501da177e4SLinus Torvalds 29511da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 29521da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 29531da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 29548fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 29558fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 29561da177e4SLinus Torvalds 295748fd4f93SJens Axboe /* 295848fd4f93SJens Axboe * Mask in barrier bit for a write (could be either a WRITE or a 295948fd4f93SJens Axboe * WRITE_SYNC 296048fd4f93SJens Axboe */ 296148fd4f93SJens Axboe if (buffer_ordered(bh) && (rw & WRITE)) 296248fd4f93SJens Axboe rw |= WRITE_BARRIER; 29631da177e4SLinus Torvalds 29641da177e4SLinus Torvalds /* 296548fd4f93SJens Axboe * Only clear out a write error when rewriting 29661da177e4SLinus Torvalds */ 296748fd4f93SJens Axboe if (test_set_buffer_req(bh) && (rw & WRITE)) 29681da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 29691da177e4SLinus Torvalds 29701da177e4SLinus Torvalds /* 29711da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 29721da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 29731da177e4SLinus Torvalds */ 29741da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 29751da177e4SLinus Torvalds 29761da177e4SLinus Torvalds bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 29771da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 29781da177e4SLinus Torvalds bio->bi_io_vec[0].bv_page = bh->b_page; 29791da177e4SLinus Torvalds bio->bi_io_vec[0].bv_len = bh->b_size; 29801da177e4SLinus Torvalds bio->bi_io_vec[0].bv_offset = bh_offset(bh); 29811da177e4SLinus Torvalds 29821da177e4SLinus Torvalds bio->bi_vcnt = 1; 29831da177e4SLinus Torvalds bio->bi_idx = 0; 29841da177e4SLinus Torvalds bio->bi_size = bh->b_size; 29851da177e4SLinus Torvalds 29861da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 29871da177e4SLinus Torvalds bio->bi_private = bh; 29881da177e4SLinus Torvalds 29891da177e4SLinus Torvalds bio_get(bio); 29901da177e4SLinus Torvalds submit_bio(rw, bio); 29911da177e4SLinus Torvalds 29921da177e4SLinus Torvalds if (bio_flagged(bio, BIO_EOPNOTSUPP)) 29931da177e4SLinus Torvalds ret = -EOPNOTSUPP; 29941da177e4SLinus Torvalds 29951da177e4SLinus Torvalds bio_put(bio); 29961da177e4SLinus Torvalds return ret; 29971da177e4SLinus Torvalds } 29981fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 29991da177e4SLinus Torvalds 30001da177e4SLinus Torvalds /** 30011da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 3002a7662236SJan Kara * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) 30031da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 30041da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 30051da177e4SLinus Torvalds * 3006a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 3007a7662236SJan Kara * requests an I/O operation on them, either a %READ or a %WRITE. The third 3008a7662236SJan Kara * %SWRITE is like %WRITE only we make sure that the *current* data in buffers 3009a7662236SJan Kara * are sent to disk. The fourth %READA option is described in the documentation 3010a7662236SJan Kara * for generic_make_request() which ll_rw_block() calls. 30111da177e4SLinus Torvalds * 30121da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 3013a7662236SJan Kara * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be 3014a7662236SJan Kara * clean when doing a write request, and any buffer that appears to be 3015a7662236SJan Kara * up-to-date when doing read request. Further it marks as clean buffers that 3016a7662236SJan Kara * are processed for writing (the buffer cache won't assume that they are 3017a7662236SJan Kara * actually clean until the buffer gets unlocked). 30181da177e4SLinus Torvalds * 30191da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 30201da177e4SLinus Torvalds * the buffer up-to-date (if approriate), unlocks the buffer and wakes 30211da177e4SLinus Torvalds * any waiters. 30221da177e4SLinus Torvalds * 30231da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 30241da177e4SLinus Torvalds * multiple of the current approved size for the device. 30251da177e4SLinus Torvalds */ 30261da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 30271da177e4SLinus Torvalds { 30281da177e4SLinus Torvalds int i; 30291da177e4SLinus Torvalds 30301da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 30311da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 30321da177e4SLinus Torvalds 30339cf6b720SJens Axboe if (rw == SWRITE || rw == SWRITE_SYNC || rw == SWRITE_SYNC_PLUG) 3034a7662236SJan Kara lock_buffer(bh); 3035ca5de404SNick Piggin else if (!trylock_buffer(bh)) 30361da177e4SLinus Torvalds continue; 30371da177e4SLinus Torvalds 30389cf6b720SJens Axboe if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC || 30399cf6b720SJens Axboe rw == SWRITE_SYNC_PLUG) { 30401da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 304176c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3042e60e5c50SOGAWA Hirofumi get_bh(bh); 304318ce3751SJens Axboe if (rw == SWRITE_SYNC) 304418ce3751SJens Axboe submit_bh(WRITE_SYNC, bh); 304518ce3751SJens Axboe else 30461da177e4SLinus Torvalds submit_bh(WRITE, bh); 30471da177e4SLinus Torvalds continue; 30481da177e4SLinus Torvalds } 30491da177e4SLinus Torvalds } else { 30501da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 305176c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3052e60e5c50SOGAWA Hirofumi get_bh(bh); 30531da177e4SLinus Torvalds submit_bh(rw, bh); 30541da177e4SLinus Torvalds continue; 30551da177e4SLinus Torvalds } 30561da177e4SLinus Torvalds } 30571da177e4SLinus Torvalds unlock_buffer(bh); 30581da177e4SLinus Torvalds } 30591da177e4SLinus Torvalds } 30601fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 30611da177e4SLinus Torvalds 30621da177e4SLinus Torvalds /* 30631da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 30641da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 30651da177e4SLinus Torvalds * the buffer_head. 30661da177e4SLinus Torvalds */ 30671da177e4SLinus Torvalds int sync_dirty_buffer(struct buffer_head *bh) 30681da177e4SLinus Torvalds { 30691da177e4SLinus Torvalds int ret = 0; 30701da177e4SLinus Torvalds 30711da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 30721da177e4SLinus Torvalds lock_buffer(bh); 30731da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 30741da177e4SLinus Torvalds get_bh(bh); 30751da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 30761aa2a7ccSJens Axboe ret = submit_bh(WRITE_SYNC, bh); 30771da177e4SLinus Torvalds wait_on_buffer(bh); 30781da177e4SLinus Torvalds if (buffer_eopnotsupp(bh)) { 30791da177e4SLinus Torvalds clear_buffer_eopnotsupp(bh); 30801da177e4SLinus Torvalds ret = -EOPNOTSUPP; 30811da177e4SLinus Torvalds } 30821da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 30831da177e4SLinus Torvalds ret = -EIO; 30841da177e4SLinus Torvalds } else { 30851da177e4SLinus Torvalds unlock_buffer(bh); 30861da177e4SLinus Torvalds } 30871da177e4SLinus Torvalds return ret; 30881da177e4SLinus Torvalds } 30891fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 30901da177e4SLinus Torvalds 30911da177e4SLinus Torvalds /* 30921da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 30931da177e4SLinus Torvalds * are unused, and releases them if so. 30941da177e4SLinus Torvalds * 30951da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 30961da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 30971da177e4SLinus Torvalds * 30981da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 30991da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 31001da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 31011da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 31021da177e4SLinus Torvalds * filesystem data on the same device. 31031da177e4SLinus Torvalds * 31041da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 31051da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 31061da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 31071da177e4SLinus Torvalds * private_lock. 31081da177e4SLinus Torvalds * 31091da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 31101da177e4SLinus Torvalds */ 31111da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 31121da177e4SLinus Torvalds { 31131da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 31141da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 31151da177e4SLinus Torvalds } 31161da177e4SLinus Torvalds 31171da177e4SLinus Torvalds static int 31181da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 31191da177e4SLinus Torvalds { 31201da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 31211da177e4SLinus Torvalds struct buffer_head *bh; 31221da177e4SLinus Torvalds 31231da177e4SLinus Torvalds bh = head; 31241da177e4SLinus Torvalds do { 3125de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 31261da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 31271da177e4SLinus Torvalds if (buffer_busy(bh)) 31281da177e4SLinus Torvalds goto failed; 31291da177e4SLinus Torvalds bh = bh->b_this_page; 31301da177e4SLinus Torvalds } while (bh != head); 31311da177e4SLinus Torvalds 31321da177e4SLinus Torvalds do { 31331da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 31341da177e4SLinus Torvalds 3135535ee2fbSJan Kara if (bh->b_assoc_map) 31361da177e4SLinus Torvalds __remove_assoc_queue(bh); 31371da177e4SLinus Torvalds bh = next; 31381da177e4SLinus Torvalds } while (bh != head); 31391da177e4SLinus Torvalds *buffers_to_free = head; 31401da177e4SLinus Torvalds __clear_page_buffers(page); 31411da177e4SLinus Torvalds return 1; 31421da177e4SLinus Torvalds failed: 31431da177e4SLinus Torvalds return 0; 31441da177e4SLinus Torvalds } 31451da177e4SLinus Torvalds 31461da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 31471da177e4SLinus Torvalds { 31481da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 31491da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 31501da177e4SLinus Torvalds int ret = 0; 31511da177e4SLinus Torvalds 31521da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3153ecdfc978SLinus Torvalds if (PageWriteback(page)) 31541da177e4SLinus Torvalds return 0; 31551da177e4SLinus Torvalds 31561da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 31571da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 31581da177e4SLinus Torvalds goto out; 31591da177e4SLinus Torvalds } 31601da177e4SLinus Torvalds 31611da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 31621da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3163ecdfc978SLinus Torvalds 3164ecdfc978SLinus Torvalds /* 3165ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3166ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3167ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3168ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3169ecdfc978SLinus Torvalds * 3170ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3171ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3172ecdfc978SLinus Torvalds * the page also. 317387df7241SNick Piggin * 317487df7241SNick Piggin * private_lock must be held over this entire operation in order 317587df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 317687df7241SNick Piggin * dirty bit from being lost. 3177ecdfc978SLinus Torvalds */ 3178ecdfc978SLinus Torvalds if (ret) 3179ecdfc978SLinus Torvalds cancel_dirty_page(page, PAGE_CACHE_SIZE); 318087df7241SNick Piggin spin_unlock(&mapping->private_lock); 31811da177e4SLinus Torvalds out: 31821da177e4SLinus Torvalds if (buffers_to_free) { 31831da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 31841da177e4SLinus Torvalds 31851da177e4SLinus Torvalds do { 31861da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 31871da177e4SLinus Torvalds free_buffer_head(bh); 31881da177e4SLinus Torvalds bh = next; 31891da177e4SLinus Torvalds } while (bh != buffers_to_free); 31901da177e4SLinus Torvalds } 31911da177e4SLinus Torvalds return ret; 31921da177e4SLinus Torvalds } 31931da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 31941da177e4SLinus Torvalds 31953978d717SNeilBrown void block_sync_page(struct page *page) 31961da177e4SLinus Torvalds { 31971da177e4SLinus Torvalds struct address_space *mapping; 31981da177e4SLinus Torvalds 31991da177e4SLinus Torvalds smp_mb(); 32001da177e4SLinus Torvalds mapping = page_mapping(page); 32011da177e4SLinus Torvalds if (mapping) 32021da177e4SLinus Torvalds blk_run_backing_dev(mapping->backing_dev_info, page); 32031da177e4SLinus Torvalds } 32041fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_sync_page); 32051da177e4SLinus Torvalds 32061da177e4SLinus Torvalds /* 32071da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 32081da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 32091da177e4SLinus Torvalds * 32101da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 32115b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 32121da177e4SLinus Torvalds */ 3213bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 32141da177e4SLinus Torvalds { 32151da177e4SLinus Torvalds static int msg_count; 32161da177e4SLinus Torvalds 32171da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 32181da177e4SLinus Torvalds return -EPERM; 32191da177e4SLinus Torvalds 32201da177e4SLinus Torvalds if (msg_count < 5) { 32211da177e4SLinus Torvalds msg_count++; 32221da177e4SLinus Torvalds printk(KERN_INFO 32231da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 32241da177e4SLinus Torvalds " system call\n", current->comm); 32251da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 32261da177e4SLinus Torvalds } 32271da177e4SLinus Torvalds 32281da177e4SLinus Torvalds if (func == 1) 32291da177e4SLinus Torvalds do_exit(0); 32301da177e4SLinus Torvalds return 0; 32311da177e4SLinus Torvalds } 32321da177e4SLinus Torvalds 32331da177e4SLinus Torvalds /* 32341da177e4SLinus Torvalds * Buffer-head allocation 32351da177e4SLinus Torvalds */ 3236e18b890bSChristoph Lameter static struct kmem_cache *bh_cachep; 32371da177e4SLinus Torvalds 32381da177e4SLinus Torvalds /* 32391da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 32401da177e4SLinus Torvalds * stripping them in writeback. 32411da177e4SLinus Torvalds */ 32421da177e4SLinus Torvalds static int max_buffer_heads; 32431da177e4SLinus Torvalds 32441da177e4SLinus Torvalds int buffer_heads_over_limit; 32451da177e4SLinus Torvalds 32461da177e4SLinus Torvalds struct bh_accounting { 32471da177e4SLinus Torvalds int nr; /* Number of live bh's */ 32481da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 32491da177e4SLinus Torvalds }; 32501da177e4SLinus Torvalds 32511da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 32521da177e4SLinus Torvalds 32531da177e4SLinus Torvalds static void recalc_bh_state(void) 32541da177e4SLinus Torvalds { 32551da177e4SLinus Torvalds int i; 32561da177e4SLinus Torvalds int tot = 0; 32571da177e4SLinus Torvalds 32581da177e4SLinus Torvalds if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) 32591da177e4SLinus Torvalds return; 32601da177e4SLinus Torvalds __get_cpu_var(bh_accounting).ratelimit = 0; 32618a143426SEric Dumazet for_each_online_cpu(i) 32621da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 32631da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 32641da177e4SLinus Torvalds } 32651da177e4SLinus Torvalds 3266dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 32671da177e4SLinus Torvalds { 3268*019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 32691da177e4SLinus Torvalds if (ret) { 3270a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3271736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr++; 32721da177e4SLinus Torvalds recalc_bh_state(); 3273736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 32741da177e4SLinus Torvalds } 32751da177e4SLinus Torvalds return ret; 32761da177e4SLinus Torvalds } 32771da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 32781da177e4SLinus Torvalds 32791da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 32801da177e4SLinus Torvalds { 32811da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 32821da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3283736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr--; 32841da177e4SLinus Torvalds recalc_bh_state(); 3285736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 32861da177e4SLinus Torvalds } 32871da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 32881da177e4SLinus Torvalds 32891da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 32901da177e4SLinus Torvalds { 32911da177e4SLinus Torvalds int i; 32921da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 32931da177e4SLinus Torvalds 32941da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 32951da177e4SLinus Torvalds brelse(b->bhs[i]); 32961da177e4SLinus Torvalds b->bhs[i] = NULL; 32971da177e4SLinus Torvalds } 32988a143426SEric Dumazet get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; 32998a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 33008a143426SEric Dumazet put_cpu_var(bh_accounting); 33011da177e4SLinus Torvalds } 33021da177e4SLinus Torvalds 33031da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 33041da177e4SLinus Torvalds unsigned long action, void *hcpu) 33051da177e4SLinus Torvalds { 33068bb78442SRafael J. Wysocki if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) 33071da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 33081da177e4SLinus Torvalds return NOTIFY_OK; 33091da177e4SLinus Torvalds } 33101da177e4SLinus Torvalds 3311389d1b08SAneesh Kumar K.V /** 3312a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3313389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3314389d1b08SAneesh Kumar K.V * 3315389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3316389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3317389d1b08SAneesh Kumar K.V */ 3318389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3319389d1b08SAneesh Kumar K.V { 3320389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3321389d1b08SAneesh Kumar K.V lock_buffer(bh); 3322389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3323389d1b08SAneesh Kumar K.V return 0; 3324389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3325389d1b08SAneesh Kumar K.V } 3326389d1b08SAneesh Kumar K.V return 1; 3327389d1b08SAneesh Kumar K.V } 3328389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3329389d1b08SAneesh Kumar K.V 3330389d1b08SAneesh Kumar K.V /** 3331a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3332389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3333389d1b08SAneesh Kumar K.V * 3334389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3335389d1b08SAneesh Kumar K.V */ 3336389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3337389d1b08SAneesh Kumar K.V { 3338389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3339389d1b08SAneesh Kumar K.V 3340389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3341389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3342389d1b08SAneesh Kumar K.V return 0; 3343389d1b08SAneesh Kumar K.V } 3344389d1b08SAneesh Kumar K.V 3345389d1b08SAneesh Kumar K.V get_bh(bh); 3346389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 3347389d1b08SAneesh Kumar K.V submit_bh(READ, bh); 3348389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3349389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3350389d1b08SAneesh Kumar K.V return 0; 3351389d1b08SAneesh Kumar K.V return -EIO; 3352389d1b08SAneesh Kumar K.V } 3353389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3354389d1b08SAneesh Kumar K.V 33551da177e4SLinus Torvalds void __init buffer_init(void) 33561da177e4SLinus Torvalds { 33571da177e4SLinus Torvalds int nrpages; 33581da177e4SLinus Torvalds 3359b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3360b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3361b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3362b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3363*019b4d12SRichard Kennedy NULL); 33641da177e4SLinus Torvalds 33651da177e4SLinus Torvalds /* 33661da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 33671da177e4SLinus Torvalds */ 33681da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 33691da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 33701da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 33711da177e4SLinus Torvalds } 3372