diff options
Diffstat (limited to 'fs/buffer.c')
| -rw-r--r-- | fs/buffer.c | 928 |
1 files changed, 469 insertions, 459 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 2379564e5aea..838c0c571022 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -55,7 +55,7 @@ static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh, - struct writeback_control *wbc); + enum rw_hint hint, struct writeback_control *wbc); #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) @@ -157,8 +157,8 @@ static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) */ void end_buffer_read_sync(struct buffer_head *bh, int uptodate) { - __end_buffer_read_notouch(bh, uptodate); put_bh(bh); + __end_buffer_read_notouch(bh, uptodate); } EXPORT_SYMBOL(end_buffer_read_sync); @@ -176,21 +176,11 @@ void end_buffer_write_sync(struct buffer_head *bh, int uptodate) } EXPORT_SYMBOL(end_buffer_write_sync); -/* - * Various filesystems appear to want __find_get_block to be non-blocking. - * But it's the page lock which protects the buffers. To get around this, - * we get exclusion from try_to_free_buffers with the blockdev mapping's - * private_lock. - * - * Hack idea: for the blockdev mapping, private_lock contention - * may be quite high. This code could TryLock the page, and if that - * succeeds, there is no need to take private_lock. - */ static struct buffer_head * -__find_get_block_slow(struct block_device *bdev, sector_t block) +__find_get_block_slow(struct block_device *bdev, sector_t block, bool atomic) { - struct inode *bd_inode = bdev->bd_inode; - struct address_space *bd_mapping = bd_inode->i_mapping; + struct address_space *bd_mapping = bdev->bd_mapping; + const int blkbits = bd_mapping->host->i_blkbits; struct buffer_head *ret = NULL; pgoff_t index; struct buffer_head *bh; @@ -199,15 +189,33 @@ __find_get_block_slow(struct block_device *bdev, sector_t block) int all_mapped = 1; static DEFINE_RATELIMIT_STATE(last_warned, HZ, 1); - index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); + index = ((loff_t)block << blkbits) / PAGE_SIZE; folio = __filemap_get_folio(bd_mapping, index, FGP_ACCESSED, 0); if (IS_ERR(folio)) goto out; - spin_lock(&bd_mapping->private_lock); + /* + * Folio lock protects the buffers. Callers that cannot block + * will fallback to serializing vs try_to_free_buffers() via + * the i_private_lock. + */ + if (atomic) + spin_lock(&bd_mapping->i_private_lock); + else + folio_lock(folio); + head = folio_buffers(folio); if (!head) goto out_unlock; + /* + * Upon a noref migration, the folio lock serializes here; + * otherwise bail. + */ + if (test_bit_acquire(BH_Migrate, &head->b_state)) { + WARN_ON(!atomic); + goto out_unlock; + } + bh = head; do { if (!buffer_mapped(bh)) @@ -233,10 +241,13 @@ __find_get_block_slow(struct block_device *bdev, sector_t block) (unsigned long long)block, (unsigned long long)bh->b_blocknr, bh->b_state, bh->b_size, bdev, - 1 << bd_inode->i_blkbits); + 1 << blkbits); } out_unlock: - spin_unlock(&bd_mapping->private_lock); + if (atomic) + spin_unlock(&bd_mapping->i_private_lock); + else + folio_unlock(folio); folio_put(folio); out: return ret; @@ -258,7 +269,6 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate) } else { clear_buffer_uptodate(bh); buffer_io_error(bh, ", async page read"); - folio_set_error(folio); } /* @@ -282,18 +292,11 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate) } while (tmp != bh); spin_unlock_irqrestore(&first->b_uptodate_lock, flags); - /* - * If all of the buffers are uptodate then we can set the page - * uptodate. - */ - if (folio_uptodate) - folio_mark_uptodate(folio); - folio_unlock(folio); + folio_end_read(folio, folio_uptodate); return; still_busy: spin_unlock_irqrestore(&first->b_uptodate_lock, flags); - return; } struct postprocess_bh_ctx { @@ -378,10 +381,10 @@ static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate) } /* - * Completion handler for block_write_full_page() - pages which are unlocked - * during I/O, and which have PageWriteback cleared upon I/O completion. + * Completion handler for block_write_full_folio() - folios which are unlocked + * during I/O, and which have the writeback flag cleared upon I/O completion. */ -void end_buffer_async_write(struct buffer_head *bh, int uptodate) +static void end_buffer_async_write(struct buffer_head *bh, int uptodate) { unsigned long flags; struct buffer_head *first; @@ -397,7 +400,6 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate) buffer_io_error(bh, ", lost async page write"); mark_buffer_write_io_error(bh); clear_buffer_uptodate(bh); - folio_set_error(folio); } first = folio_buffers(folio); @@ -419,9 +421,7 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate) still_busy: spin_unlock_irqrestore(&first->b_uptodate_lock, flags); - return; } -EXPORT_SYMBOL(end_buffer_async_write); /* * If a page's buffers are under async readin (end_buffer_async_read @@ -471,27 +471,27 @@ EXPORT_SYMBOL(mark_buffer_async_write); * a successful fsync(). For example, ext2 indirect blocks need to be * written back and waited upon before fsync() returns. * - * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), + * The functions mark_buffer_dirty_inode(), fsync_inode_buffers(), * inode_has_buffers() and invalidate_inode_buffers() are provided for the - * management of a list of dependent buffers at ->i_mapping->private_list. + * management of a list of dependent buffers at ->i_mapping->i_private_list. * * Locking is a little subtle: try_to_free_buffers() will remove buffers * from their controlling inode's queue when they are being freed. But * try_to_free_buffers() will be operating against the *blockdev* mapping * at the time, not against the S_ISREG file which depends on those buffers. - * So the locking for private_list is via the private_lock in the address_space + * So the locking for i_private_list is via the i_private_lock in the address_space * which backs the buffers. Which is different from the address_space * against which the buffers are listed. So for a particular address_space, - * mapping->private_lock does *not* protect mapping->private_list! In fact, - * mapping->private_list will always be protected by the backing blockdev's - * ->private_lock. + * mapping->i_private_lock does *not* protect mapping->i_private_list! In fact, + * mapping->i_private_list will always be protected by the backing blockdev's + * ->i_private_lock. * * Which introduces a requirement: all buffers on an address_space's - * ->private_list must be from the same address_space: the blockdev's. + * ->i_private_list must be from the same address_space: the blockdev's. * - * address_spaces which do not place buffers at ->private_list via these - * utility functions are free to use private_lock and private_list for - * whatever they want. The only requirement is that list_empty(private_list) + * address_spaces which do not place buffers at ->i_private_list via these + * utility functions are free to use i_private_lock and i_private_list for + * whatever they want. The only requirement is that list_empty(i_private_list) * be true at clear_inode() time. * * FIXME: clear_inode should not call invalidate_inode_buffers(). The @@ -514,7 +514,7 @@ EXPORT_SYMBOL(mark_buffer_async_write); */ /* - * The buffer's backing address_space's private_lock must be held + * The buffer's backing address_space's i_private_lock must be held */ static void __remove_assoc_queue(struct buffer_head *bh) { @@ -525,7 +525,7 @@ static void __remove_assoc_queue(struct buffer_head *bh) int inode_has_buffers(struct inode *inode) { - return !list_empty(&inode->i_data.private_list); + return !list_empty(&inode->i_data.i_private_list); } /* @@ -567,7 +567,7 @@ repeat: * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers * @mapping: the mapping which wants those buffers written * - * Starts I/O against the buffers at mapping->private_list, and waits upon + * Starts I/O against the buffers at mapping->i_private_list, and waits upon * that I/O. * * Basically, this is a convenience function for fsync(). @@ -576,13 +576,13 @@ repeat: */ int sync_mapping_buffers(struct address_space *mapping) { - struct address_space *buffer_mapping = mapping->private_data; + struct address_space *buffer_mapping = mapping->i_private_data; - if (buffer_mapping == NULL || list_empty(&mapping->private_list)) + if (buffer_mapping == NULL || list_empty(&mapping->i_private_list)) return 0; - return fsync_buffers_list(&buffer_mapping->private_lock, - &mapping->private_list); + return fsync_buffers_list(&buffer_mapping->i_private_lock, + &mapping->i_private_list); } EXPORT_SYMBOL(sync_mapping_buffers); @@ -611,9 +611,9 @@ int generic_buffers_fsync_noflush(struct file *file, loff_t start, loff_t end, return err; ret = sync_mapping_buffers(inode->i_mapping); - if (!(inode->i_state & I_DIRTY_ALL)) + if (!(inode_state_read_once(inode) & I_DIRTY_ALL)) goto out; - if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) + if (datasync && !(inode_state_read_once(inode) & I_DIRTY_DATASYNC)) goto out; err = sync_inode_metadata(inode, 1); @@ -665,7 +665,9 @@ EXPORT_SYMBOL(generic_buffers_fsync); void write_boundary_block(struct block_device *bdev, sector_t bblock, unsigned blocksize) { - struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); + struct buffer_head *bh; + + bh = __find_get_block_nonatomic(bdev, bblock + 1, blocksize); if (bh) { if (buffer_dirty(bh)) write_dirty_buffer(bh, 0); @@ -679,52 +681,59 @@ void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) struct address_space *buffer_mapping = bh->b_folio->mapping; mark_buffer_dirty(bh); - if (!mapping->private_data) { - mapping->private_data = buffer_mapping; + if (!mapping->i_private_data) { + mapping->i_private_data = buffer_mapping; } else { - BUG_ON(mapping->private_data != buffer_mapping); + BUG_ON(mapping->i_private_data != buffer_mapping); } if (!bh->b_assoc_map) { - spin_lock(&buffer_mapping->private_lock); + spin_lock(&buffer_mapping->i_private_lock); list_move_tail(&bh->b_assoc_buffers, - &mapping->private_list); + &mapping->i_private_list); bh->b_assoc_map = mapping; - spin_unlock(&buffer_mapping->private_lock); + spin_unlock(&buffer_mapping->i_private_lock); } } EXPORT_SYMBOL(mark_buffer_dirty_inode); -/* - * Add a page to the dirty page list. - * - * It is a sad fact of life that this function is called from several places - * deeply under spinlocking. It may not sleep. - * - * If the page has buffers, the uptodate buffers are set dirty, to preserve - * dirty-state coherency between the page and the buffers. It the page does - * not have buffers then when they are later attached they will all be set - * dirty. - * - * The buffers are dirtied before the page is dirtied. There's a small race - * window in which a writepage caller may see the page cleanness but not the - * buffer dirtiness. That's fine. If this code were to set the page dirty - * before the buffers, a concurrent writepage caller could clear the page dirty - * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean - * page on the dirty page list. - * - * We use private_lock to lock against try_to_free_buffers while using the - * page's buffer list. Also use this to protect against clean buffers being - * added to the page after it was set dirty. - * - * FIXME: may need to call ->reservepage here as well. That's rather up to the - * address_space though. +/** + * block_dirty_folio - Mark a folio as dirty. + * @mapping: The address space containing this folio. + * @folio: The folio to mark dirty. + * + * Filesystems which use buffer_heads can use this function as their + * ->dirty_folio implementation. Some filesystems need to do a little + * work before calling this function. Filesystems which do not use + * buffer_heads should call filemap_dirty_folio() instead. + * + * If the folio has buffers, the uptodate buffers are set dirty, to + * preserve dirty-state coherency between the folio and the buffers. + * Buffers added to a dirty folio are created dirty. + * + * The buffers are dirtied before the folio is dirtied. There's a small + * race window in which writeback may see the folio cleanness but not the + * buffer dirtiness. That's fine. If this code were to set the folio + * dirty before the buffers, writeback could clear the folio dirty flag, + * see a bunch of clean buffers and we'd end up with dirty buffers/clean + * folio on the dirty folio list. + * + * We use i_private_lock to lock against try_to_free_buffers() while + * using the folio's buffer list. This also prevents clean buffers + * being added to the folio after it was set dirty. + * + * Context: May only be called from process context. Does not sleep. + * Caller must ensure that @folio cannot be truncated during this call, + * typically by holding the folio lock or having a page in the folio + * mapped and holding the page table lock. + * + * Return: True if the folio was dirtied; false if it was already dirtied. */ bool block_dirty_folio(struct address_space *mapping, struct folio *folio) { struct buffer_head *head; bool newly_dirty; - spin_lock(&mapping->private_lock); + spin_lock(&mapping->i_private_lock); head = folio_buffers(folio); if (head) { struct buffer_head *bh = head; @@ -738,15 +747,12 @@ bool block_dirty_folio(struct address_space *mapping, struct folio *folio) * Lock out page's memcg migration to keep PageDirty * synchronized with per-memcg dirty page counters. */ - folio_memcg_lock(folio); newly_dirty = !folio_test_set_dirty(folio); - spin_unlock(&mapping->private_lock); + spin_unlock(&mapping->i_private_lock); if (newly_dirty) __folio_mark_dirty(folio, mapping, 1); - folio_memcg_unlock(folio); - if (newly_dirty) __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); @@ -776,12 +782,11 @@ EXPORT_SYMBOL(block_dirty_folio); static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) { struct buffer_head *bh; - struct list_head tmp; struct address_space *mapping; int err = 0, err2; struct blk_plug plug; + LIST_HEAD(tmp); - INIT_LIST_HEAD(&tmp); blk_start_plug(&plug); spin_lock(lock); @@ -833,7 +838,7 @@ static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) smp_mb(); if (buffer_dirty(bh)) { list_add(&bh->b_assoc_buffers, - &mapping->private_list); + &mapping->i_private_list); bh->b_assoc_map = mapping; } spin_unlock(lock); @@ -857,21 +862,20 @@ static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) * probably unmounting the fs, but that doesn't mean we have already * done a sync(). Just drop the buffers from the inode list. * - * NOTE: we take the inode's blockdev's mapping's private_lock. Which - * assumes that all the buffers are against the blockdev. Not true - * for reiserfs. + * NOTE: we take the inode's blockdev's mapping's i_private_lock. Which + * assumes that all the buffers are against the blockdev. */ void invalidate_inode_buffers(struct inode *inode) { if (inode_has_buffers(inode)) { struct address_space *mapping = &inode->i_data; - struct list_head *list = &mapping->private_list; - struct address_space *buffer_mapping = mapping->private_data; + struct list_head *list = &mapping->i_private_list; + struct address_space *buffer_mapping = mapping->i_private_data; - spin_lock(&buffer_mapping->private_lock); + spin_lock(&buffer_mapping->i_private_lock); while (!list_empty(list)) __remove_assoc_queue(BH_ENTRY(list->next)); - spin_unlock(&buffer_mapping->private_lock); + spin_unlock(&buffer_mapping->i_private_lock); } } EXPORT_SYMBOL(invalidate_inode_buffers); @@ -888,10 +892,10 @@ int remove_inode_buffers(struct inode *inode) if (inode_has_buffers(inode)) { struct address_space *mapping = &inode->i_data; - struct list_head *list = &mapping->private_list; - struct address_space *buffer_mapping = mapping->private_data; + struct list_head *list = &mapping->i_private_list; + struct address_space *buffer_mapping = mapping->i_private_data; - spin_lock(&buffer_mapping->private_lock); + spin_lock(&buffer_mapping->i_private_lock); while (!list_empty(list)) { struct buffer_head *bh = BH_ENTRY(list->next); if (buffer_dirty(bh)) { @@ -900,7 +904,7 @@ int remove_inode_buffers(struct inode *inode) } __remove_assoc_queue(bh); } - spin_unlock(&buffer_mapping->private_lock); + spin_unlock(&buffer_mapping->i_private_lock); } return ret; } @@ -915,16 +919,12 @@ int remove_inode_buffers(struct inode *inode) * which may not fail from ordinary buffer allocations. */ struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size, - bool retry) + gfp_t gfp) { struct buffer_head *bh, *head; - gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT; long offset; struct mem_cgroup *memcg, *old_memcg; - if (retry) - gfp |= __GFP_NOFAIL; - /* The folio lock pins the memcg */ memcg = folio_memcg(folio); old_memcg = set_active_memcg(memcg); @@ -964,10 +964,11 @@ no_grow: } EXPORT_SYMBOL_GPL(folio_alloc_buffers); -struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, - bool retry) +struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size) { - return folio_alloc_buffers(page_folio(page), size, retry); + gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT; + + return folio_alloc_buffers(page_folio(page), size, gfp); } EXPORT_SYMBOL_GPL(alloc_page_buffers); @@ -1001,11 +1002,12 @@ static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) * Initialise the state of a blockdev folio's buffers. */ static sector_t folio_init_buffers(struct folio *folio, - struct block_device *bdev, sector_t block, int size) + struct block_device *bdev, unsigned size) { struct buffer_head *head = folio_buffers(folio); struct buffer_head *bh = head; bool uptodate = folio_test_uptodate(folio); + sector_t block = div_u64(folio_pos(folio), size); sector_t end_block = blkdev_max_block(bdev, size); do { @@ -1030,121 +1032,114 @@ static sector_t folio_init_buffers(struct folio *folio, } /* - * Create the page-cache page that contains the requested block. + * Create the page-cache folio that contains the requested block. * * This is used purely for blockdev mappings. + * + * Returns false if we have a failure which cannot be cured by retrying + * without sleeping. Returns true if we succeeded, or the caller should retry. */ -static int -grow_dev_page(struct block_device *bdev, sector_t block, - pgoff_t index, int size, int sizebits, gfp_t gfp) +static bool grow_dev_folio(struct block_device *bdev, sector_t block, + pgoff_t index, unsigned size, gfp_t gfp) { - struct inode *inode = bdev->bd_inode; + struct address_space *mapping = bdev->bd_mapping; struct folio *folio; struct buffer_head *bh; - sector_t end_block; - int ret = 0; - gfp_t gfp_mask; - - gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; + sector_t end_block = 0; - /* - * XXX: __getblk_slow() can not really deal with failure and - * will endlessly loop on improvised global reclaim. Prefer - * looping in the allocator rather than here, at least that - * code knows what it's doing. - */ - gfp_mask |= __GFP_NOFAIL; - - folio = __filemap_get_folio(inode->i_mapping, index, - FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp_mask); + folio = __filemap_get_folio(mapping, index, + FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp); + if (IS_ERR(folio)) + return false; bh = folio_buffers(folio); if (bh) { if (bh->b_size == size) { - end_block = folio_init_buffers(folio, bdev, - (sector_t)index << sizebits, size); - goto done; + end_block = folio_init_buffers(folio, bdev, size); + goto unlock; + } + + /* + * Retrying may succeed; for example the folio may finish + * writeback, or buffers may be cleaned. This should not + * happen very often; maybe we have old buffers attached to + * this blockdev's page cache and we're trying to change + * the block size? + */ + if (!try_to_free_buffers(folio)) { + end_block = ~0ULL; + goto unlock; } - if (!try_to_free_buffers(folio)) - goto failed; } - bh = folio_alloc_buffers(folio, size, true); + bh = folio_alloc_buffers(folio, size, gfp | __GFP_ACCOUNT); + if (!bh) + goto unlock; /* * Link the folio to the buffers and initialise them. Take the * lock to be atomic wrt __find_get_block(), which does not * run under the folio lock. */ - spin_lock(&inode->i_mapping->private_lock); + spin_lock(&mapping->i_private_lock); link_dev_buffers(folio, bh); - end_block = folio_init_buffers(folio, bdev, - (sector_t)index << sizebits, size); - spin_unlock(&inode->i_mapping->private_lock); -done: - ret = (block < end_block) ? 1 : -ENXIO; -failed: + end_block = folio_init_buffers(folio, bdev, size); + spin_unlock(&mapping->i_private_lock); +unlock: folio_unlock(folio); folio_put(folio); - return ret; + return block < end_block; } /* - * Create buffers for the specified block device block's page. If - * that page was dirty, the buffers are set dirty also. + * Create buffers for the specified block device block's folio. If + * that folio was dirty, the buffers are set dirty also. Returns false + * if we've hit a permanent error. */ -static int -grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) +static bool grow_buffers(struct block_device *bdev, sector_t block, + unsigned size, gfp_t gfp) { - pgoff_t index; - int sizebits; - - sizebits = PAGE_SHIFT - __ffs(size); - index = block >> sizebits; + loff_t pos; /* - * Check for a block which wants to lie outside our maximum possible - * pagecache index. (this comparison is done using sector_t types). + * Check for a block which lies outside our maximum possible + * pagecache index. */ - if (unlikely(index != block >> sizebits)) { - printk(KERN_ERR "%s: requested out-of-range block %llu for " - "device %pg\n", + if (check_mul_overflow(block, (sector_t)size, &pos) || pos > MAX_LFS_FILESIZE) { + printk(KERN_ERR "%s: requested out-of-range block %llu for device %pg\n", __func__, (unsigned long long)block, bdev); - return -EIO; + return false; } - /* Create a page with the proper size buffers.. */ - return grow_dev_page(bdev, block, index, size, sizebits, gfp); + /* Create a folio with the proper size buffers */ + return grow_dev_folio(bdev, block, pos / PAGE_SIZE, size, gfp); } static struct buffer_head * __getblk_slow(struct block_device *bdev, sector_t block, unsigned size, gfp_t gfp) { - /* Size must be multiple of hard sectorsize */ - if (unlikely(size & (bdev_logical_block_size(bdev)-1) || - (size < 512 || size > PAGE_SIZE))) { - printk(KERN_ERR "getblk(): invalid block size %d requested\n", - size); - printk(KERN_ERR "logical block size: %d\n", - bdev_logical_block_size(bdev)); + bool blocking = gfpflags_allow_blocking(gfp); - dump_stack(); + if (WARN_ON_ONCE(!IS_ALIGNED(size, bdev_logical_block_size(bdev)))) { + printk(KERN_ERR "getblk(): block size %d not aligned to logical block size %d\n", + size, bdev_logical_block_size(bdev)); return NULL; } for (;;) { struct buffer_head *bh; - int ret; - bh = __find_get_block(bdev, block, size); + if (!grow_buffers(bdev, block, size, gfp)) + return NULL; + + if (blocking) + bh = __find_get_block_nonatomic(bdev, block, size); + else + bh = __find_get_block(bdev, block, size); if (bh) return bh; - - ret = grow_buffers(bdev, block, size, gfp); - if (ret < 0) - return NULL; } } @@ -1180,7 +1175,7 @@ __getblk_slow(struct block_device *bdev, sector_t block, * and then attach the address_space's inode to its superblock's dirty * inode list. * - * mark_buffer_dirty() is atomic. It takes bh->b_folio->mapping->private_lock, + * mark_buffer_dirty() is atomic. It takes bh->b_folio->mapping->i_private_lock, * i_pages lock and mapping->host->i_lock. */ void mark_buffer_dirty(struct buffer_head *bh) @@ -1205,13 +1200,11 @@ void mark_buffer_dirty(struct buffer_head *bh) struct folio *folio = bh->b_folio; struct address_space *mapping = NULL; - folio_memcg_lock(folio); if (!folio_test_set_dirty(folio)) { mapping = folio->mapping; if (mapping) __folio_mark_dirty(folio, mapping, 0); } - folio_memcg_unlock(folio); if (mapping) __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); } @@ -1224,33 +1217,33 @@ void mark_buffer_write_io_error(struct buffer_head *bh) /* FIXME: do we need to set this in both places? */ if (bh->b_folio && bh->b_folio->mapping) mapping_set_error(bh->b_folio->mapping, -EIO); - if (bh->b_assoc_map) { + if (bh->b_assoc_map) mapping_set_error(bh->b_assoc_map, -EIO); - errseq_set(&bh->b_assoc_map->host->i_sb->s_wb_err, -EIO); - } } EXPORT_SYMBOL(mark_buffer_write_io_error); -/* - * Decrement a buffer_head's reference count. If all buffers against a page - * have zero reference count, are clean and unlocked, and if the page is clean - * and unlocked then try_to_free_buffers() may strip the buffers from the page - * in preparation for freeing it (sometimes, rarely, buffers are removed from - * a page but it ends up not being freed, and buffers may later be reattached). +/** + * __brelse - Release a buffer. + * @bh: The buffer to release. + * + * This variant of brelse() can be called if @bh is guaranteed to not be NULL. */ -void __brelse(struct buffer_head * buf) +void __brelse(struct buffer_head *bh) { - if (atomic_read(&buf->b_count)) { - put_bh(buf); + if (atomic_read(&bh->b_count)) { + put_bh(bh); return; } WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); } EXPORT_SYMBOL(__brelse); -/* - * bforget() is like brelse(), except it discards any - * potentially dirty data. +/** + * __bforget - Discard any dirty data in a buffer. + * @bh: The buffer to forget. + * + * This variant of bforget() can be called if @bh is guaranteed to not + * be NULL. */ void __bforget(struct buffer_head *bh) { @@ -1258,10 +1251,10 @@ void __bforget(struct buffer_head *bh) if (bh->b_assoc_map) { struct address_space *buffer_mapping = bh->b_folio->mapping; - spin_lock(&buffer_mapping->private_lock); + spin_lock(&buffer_mapping->i_private_lock); list_del_init(&bh->b_assoc_buffers); bh->b_assoc_map = NULL; - spin_unlock(&buffer_mapping->private_lock); + spin_unlock(&buffer_mapping->i_private_lock); } __brelse(bh); } @@ -1401,16 +1394,18 @@ lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) /* * Perform a pagecache lookup for the matching buffer. If it's there, refresh * it in the LRU and mark it as accessed. If it is not present then return - * NULL + * NULL. Atomic context callers may also return NULL if the buffer is being + * migrated; similarly the page is not marked accessed either. */ -struct buffer_head * -__find_get_block(struct block_device *bdev, sector_t block, unsigned size) +static struct buffer_head * +find_get_block_common(struct block_device *bdev, sector_t block, + unsigned size, bool atomic) { struct buffer_head *bh = lookup_bh_lru(bdev, block, size); if (bh == NULL) { /* __find_get_block_slow will mark the page accessed */ - bh = __find_get_block_slow(bdev, block); + bh = __find_get_block_slow(bdev, block, atomic); if (bh) bh_lru_install(bh); } else @@ -1418,35 +1413,63 @@ __find_get_block(struct block_device *bdev, sector_t block, unsigned size) return bh; } + +struct buffer_head * +__find_get_block(struct block_device *bdev, sector_t block, unsigned size) +{ + return find_get_block_common(bdev, block, size, true); +} EXPORT_SYMBOL(__find_get_block); -/* - * __getblk_gfp() will locate (and, if necessary, create) the buffer_head - * which corresponds to the passed block_device, block and size. The - * returned buffer has its reference count incremented. - * - * __getblk_gfp() will lock up the machine if grow_dev_page's - * try_to_free_buffers() attempt is failing. FIXME, perhaps? - */ +/* same as __find_get_block() but allows sleeping contexts */ struct buffer_head * -__getblk_gfp(struct block_device *bdev, sector_t block, - unsigned size, gfp_t gfp) +__find_get_block_nonatomic(struct block_device *bdev, sector_t block, + unsigned size) +{ + return find_get_block_common(bdev, block, size, false); +} +EXPORT_SYMBOL(__find_get_block_nonatomic); + +/** + * bdev_getblk - Get a buffer_head in a block device's buffer cache. + * @bdev: The block device. + * @block: The block number. + * @size: The size of buffer_heads for this @bdev. + * @gfp: The memory allocation flags to use. + * + * The returned buffer head has its reference count incremented, but is + * not locked. The caller should call brelse() when it has finished + * with the buffer. The buffer may not be uptodate. If needed, the + * caller can bring it uptodate either by reading it or overwriting it. + * + * Return: The buffer head, or NULL if memory could not be allocated. + */ +struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block, + unsigned size, gfp_t gfp) { - struct buffer_head *bh = __find_get_block(bdev, block, size); + struct buffer_head *bh; - might_sleep(); - if (bh == NULL) - bh = __getblk_slow(bdev, block, size, gfp); - return bh; + if (gfpflags_allow_blocking(gfp)) + bh = __find_get_block_nonatomic(bdev, block, size); + else + bh = __find_get_block(bdev, block, size); + + might_alloc(gfp); + if (bh) + return bh; + + return __getblk_slow(bdev, block, size, gfp); } -EXPORT_SYMBOL(__getblk_gfp); +EXPORT_SYMBOL(bdev_getblk); /* * Do async read-ahead on a buffer.. */ void __breadahead(struct block_device *bdev, sector_t block, unsigned size) { - struct buffer_head *bh = __getblk(bdev, block, size); + struct buffer_head *bh = bdev_getblk(bdev, block, size, + GFP_NOWAIT | __GFP_MOVABLE); + if (likely(bh)) { bh_readahead(bh, REQ_RAHEAD); brelse(bh); @@ -1455,22 +1478,41 @@ void __breadahead(struct block_device *bdev, sector_t block, unsigned size) EXPORT_SYMBOL(__breadahead); /** - * __bread_gfp() - reads a specified block and returns the bh - * @bdev: the block_device to read from - * @block: number of block - * @size: size (in bytes) to read - * @gfp: page allocation flag - * - * Reads a specified block, and returns buffer head that contains it. - * The page cache can be allocated from non-movable area - * not to prevent page migration if you set gfp to zero. - * It returns NULL if the block was unreadable. + * __bread_gfp() - Read a block. + * @bdev: The block device to read from. + * @block: Block number in units of block size. + * @size: The block size of this device in bytes. + * @gfp: Not page allocation flags; see below. + * + * You are not expected to call this function. You should use one of + * sb_bread(), sb_bread_unmovable() or __bread(). + * + * Read a specified block, and return the buffer head that refers to it. + * If @gfp is 0, the memory will be allocated using the block device's + * default GFP flags. If @gfp is __GFP_MOVABLE, the memory may be + * allocated from a movable area. Do not pass in a complete set of + * GFP flags. + * + * The returned buffer head has its refcount increased. The caller should + * call brelse() when it has finished with the buffer. + * + * Context: May sleep waiting for I/O. + * Return: NULL if the block was unreadable. */ -struct buffer_head * -__bread_gfp(struct block_device *bdev, sector_t block, - unsigned size, gfp_t gfp) +struct buffer_head *__bread_gfp(struct block_device *bdev, sector_t block, + unsigned size, gfp_t gfp) { - struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); + struct buffer_head *bh; + + gfp |= mapping_gfp_constraint(bdev->bd_mapping, ~__GFP_FS); + + /* + * Prefer looping in the allocator rather than here, at least that + * code knows what it's doing. + */ + gfp |= __GFP_NOFAIL; + + bh = bdev_getblk(bdev, block, size, gfp); if (likely(bh) && !buffer_uptodate(bh)) bh = __bread_slow(bh); @@ -1566,8 +1608,8 @@ static void discard_buffer(struct buffer_head * bh) bh->b_bdev = NULL; b_state = READ_ONCE(bh->b_state); do { - } while (!try_cmpxchg(&bh->b_state, &b_state, - b_state & ~BUFFER_FLAGS_DISCARD)); + } while (!try_cmpxchg_relaxed(&bh->b_state, &b_state, + b_state & ~BUFFER_FLAGS_DISCARD)); unlock_buffer(bh); } @@ -1631,21 +1673,22 @@ void block_invalidate_folio(struct folio *folio, size_t offset, size_t length) if (length == folio_size(folio)) filemap_release_folio(folio, 0); out: - return; + folio_clear_mappedtodisk(folio); } EXPORT_SYMBOL(block_invalidate_folio); /* * We attach and possibly dirty the buffers atomically wrt - * block_dirty_folio() via private_lock. try_to_free_buffers + * block_dirty_folio() via i_private_lock. try_to_free_buffers * is already excluded via the folio lock. */ -void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize, - unsigned long b_state) +struct buffer_head *create_empty_buffers(struct folio *folio, + unsigned long blocksize, unsigned long b_state) { struct buffer_head *bh, *head, *tail; + gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT | __GFP_NOFAIL; - head = folio_alloc_buffers(folio, blocksize, true); + head = folio_alloc_buffers(folio, blocksize, gfp); bh = head; do { bh->b_state |= b_state; @@ -1654,7 +1697,7 @@ void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize, } while (bh); tail->b_this_page = head; - spin_lock(&folio->mapping->private_lock); + spin_lock(&folio->mapping->i_private_lock); if (folio_test_uptodate(folio) || folio_test_dirty(folio)) { bh = head; do { @@ -1666,14 +1709,9 @@ void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize, } while (bh != head); } folio_attach_private(folio, head); - spin_unlock(&folio->mapping->private_lock); -} -EXPORT_SYMBOL(folio_create_empty_buffers); + spin_unlock(&folio->mapping->i_private_lock); -void create_empty_buffers(struct page *page, - unsigned long blocksize, unsigned long b_state) -{ - folio_create_empty_buffers(page_folio(page), blocksize, b_state); + return head; } EXPORT_SYMBOL(create_empty_buffers); @@ -1699,16 +1737,16 @@ EXPORT_SYMBOL(create_empty_buffers); */ void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) { - struct inode *bd_inode = bdev->bd_inode; - struct address_space *bd_mapping = bd_inode->i_mapping; + struct address_space *bd_mapping = bdev->bd_mapping; + const int blkbits = bd_mapping->host->i_blkbits; struct folio_batch fbatch; - pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); + pgoff_t index = ((loff_t)block << blkbits) / PAGE_SIZE; pgoff_t end; int i, count; struct buffer_head *bh; struct buffer_head *head; - end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); + end = ((loff_t)(block + len - 1) << blkbits) / PAGE_SIZE; folio_batch_init(&fbatch); while (filemap_get_folios(bd_mapping, &index, end, &fbatch)) { count = folio_batch_count(&fbatch); @@ -1718,7 +1756,7 @@ void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) if (!folio_buffers(folio)) continue; /* - * We use folio lock instead of bd_mapping->private_lock + * We use folio lock instead of bd_mapping->i_private_lock * to pin buffers here since we can afford to sleep and * it scales better than a global spinlock lock. */ @@ -1751,30 +1789,19 @@ unlock_page: } EXPORT_SYMBOL(clean_bdev_aliases); -/* - * Size is a power-of-two in the range 512..PAGE_SIZE, - * and the case we care about most is PAGE_SIZE. - * - * So this *could* possibly be written with those - * constraints in mind (relevant mostly if some - * architecture has a slow bit-scan instruction) - */ -static inline int block_size_bits(unsigned int blocksize) -{ - return ilog2(blocksize); -} - static struct buffer_head *folio_create_buffers(struct folio *folio, struct inode *inode, unsigned int b_state) { + struct buffer_head *bh; + BUG_ON(!folio_test_locked(folio)); - if (!folio_buffers(folio)) - folio_create_empty_buffers(folio, - 1 << READ_ONCE(inode->i_blkbits), - b_state); - return folio_buffers(folio); + bh = folio_buffers(folio); + if (!bh) + bh = create_empty_buffers(folio, + 1 << READ_ONCE(inode->i_blkbits), b_state); + return bh; } /* @@ -1791,30 +1818,29 @@ static struct buffer_head *folio_create_buffers(struct folio *folio, */ /* - * While block_write_full_page is writing back the dirty buffers under + * While block_write_full_folio is writing back the dirty buffers under * the page lock, whoever dirtied the buffers may decide to clean them * again at any time. We handle that by only looking at the buffer * state inside lock_buffer(). * - * If block_write_full_page() is called for regular writeback + * If block_write_full_folio() is called for regular writeback * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a * locked buffer. This only can happen if someone has written the buffer * directly, with submit_bh(). At the address_space level PageWriteback * prevents this contention from occurring. * - * If block_write_full_page() is called with wbc->sync_mode == + * If block_write_full_folio() is called with wbc->sync_mode == * WB_SYNC_ALL, the writes are posted using REQ_SYNC; this * causes the writes to be flagged as synchronous writes. */ int __block_write_full_folio(struct inode *inode, struct folio *folio, - get_block_t *get_block, struct writeback_control *wbc, - bh_end_io_t *handler) + get_block_t *get_block, struct writeback_control *wbc) { int err; sector_t block; sector_t last_block; struct buffer_head *bh, *head; - unsigned int blocksize, bbits; + size_t blocksize; int nr_underway = 0; blk_opf_t write_flags = wbc_to_write_flags(wbc); @@ -1833,10 +1859,9 @@ int __block_write_full_folio(struct inode *inode, struct folio *folio, bh = head; blocksize = bh->b_size; - bbits = block_size_bits(blocksize); - block = (sector_t)folio->index << (PAGE_SHIFT - bbits); - last_block = (i_size_read(inode) - 1) >> bbits; + block = div_u64(folio_pos(folio), blocksize); + last_block = div_u64(i_size_read(inode) - 1, blocksize); /* * Get all the dirty buffers mapped to disk addresses and @@ -1850,7 +1875,7 @@ int __block_write_full_folio(struct inode *inode, struct folio *folio, * truncate in progress. */ /* - * The buffer was zeroed by block_write_full_page() + * The buffer was zeroed by block_write_full_folio() */ clear_buffer_dirty(bh); set_buffer_uptodate(bh); @@ -1888,7 +1913,8 @@ int __block_write_full_folio(struct inode *inode, struct folio *folio, continue; } if (test_clear_buffer_dirty(bh)) { - mark_buffer_async_write_endio(bh, handler); + mark_buffer_async_write_endio(bh, + end_buffer_async_write); } else { unlock_buffer(bh); } @@ -1904,7 +1930,8 @@ int __block_write_full_folio(struct inode *inode, struct folio *folio, do { struct buffer_head *next = bh->b_this_page; if (buffer_async_write(bh)) { - submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, wbc); + submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, + inode->i_write_hint, wbc); nr_underway++; } bh = next; @@ -1941,7 +1968,8 @@ recover: if (buffer_mapped(bh) && buffer_dirty(bh) && !buffer_delay(bh)) { lock_buffer(bh); - mark_buffer_async_write_endio(bh, handler); + mark_buffer_async_write_endio(bh, + end_buffer_async_write); } else { /* * The buffer may have been set dirty during @@ -1950,7 +1978,6 @@ recover: clear_buffer_dirty(bh); } } while ((bh = bh->b_this_page) != head); - folio_set_error(folio); BUG_ON(folio_test_writeback(folio)); mapping_set_error(folio->mapping, err); folio_start_writeback(folio); @@ -1958,7 +1985,8 @@ recover: struct buffer_head *next = bh->b_this_page; if (buffer_async_write(bh)) { clear_buffer_dirty(bh); - submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, wbc); + submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, + inode->i_write_hint, wbc); nr_underway++; } bh = next; @@ -2011,11 +2039,11 @@ void folio_zero_new_buffers(struct folio *folio, size_t from, size_t to) } EXPORT_SYMBOL(folio_zero_new_buffers); -static void +static int iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, const struct iomap *iomap) { - loff_t offset = block << inode->i_blkbits; + loff_t offset = (loff_t)block << inode->i_blkbits; bh->b_bdev = iomap->bdev; @@ -2025,7 +2053,8 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, * current block, then do not map the buffer and let the caller * handle it. */ - BUG_ON(offset >= iomap->offset + iomap->length); + if (offset >= iomap->offset + iomap->length) + return -EIO; switch (iomap->type) { case IOMAP_HOLE: @@ -2037,7 +2066,7 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, if (!buffer_uptodate(bh) || (offset >= i_size_read(inode))) set_buffer_new(bh); - break; + return 0; case IOMAP_DELALLOC: if (!buffer_uptodate(bh) || (offset >= i_size_read(inode))) @@ -2045,7 +2074,7 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, set_buffer_uptodate(bh); set_buffer_mapped(bh); set_buffer_delay(bh); - break; + return 0; case IOMAP_UNWRITTEN: /* * For unwritten regions, we always need to ensure that regions @@ -2057,39 +2086,48 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, fallthrough; case IOMAP_MAPPED: if ((iomap->flags & IOMAP_F_NEW) || - offset >= i_size_read(inode)) + offset >= i_size_read(inode)) { + /* + * This can happen if truncating the block device races + * with the check in the caller as i_size updates on + * block devices aren't synchronized by i_rwsem for + * block devices. + */ + if (S_ISBLK(inode->i_mode)) + return -EIO; set_buffer_new(bh); + } bh->b_blocknr = (iomap->addr + offset - iomap->offset) >> inode->i_blkbits; set_buffer_mapped(bh); - break; + return 0; + default: + WARN_ON_ONCE(1); + return -EIO; } } int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len, get_block_t *get_block, const struct iomap *iomap) { - unsigned from = pos & (PAGE_SIZE - 1); - unsigned to = from + len; + size_t from = offset_in_folio(folio, pos); + size_t to = from + len; struct inode *inode = folio->mapping->host; - unsigned block_start, block_end; + size_t block_start, block_end; sector_t block; int err = 0; - unsigned blocksize, bbits; + size_t blocksize; struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; BUG_ON(!folio_test_locked(folio)); - BUG_ON(from > PAGE_SIZE); - BUG_ON(to > PAGE_SIZE); + BUG_ON(to > folio_size(folio)); BUG_ON(from > to); head = folio_create_buffers(folio, inode, 0); blocksize = head->b_size; - bbits = block_size_bits(blocksize); + block = div_u64(folio_pos(folio), blocksize); - block = (sector_t)folio->index << (PAGE_SHIFT - bbits); - - for(bh = head, block_start = 0; bh != head || !block_start; + for (bh = head, block_start = 0; bh != head || !block_start; block++, block_start=block_end, bh = bh->b_this_page) { block_end = block_start + blocksize; if (block_end <= from || block_start >= to) { @@ -2103,13 +2141,12 @@ int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len, clear_buffer_new(bh); if (!buffer_mapped(bh)) { WARN_ON(bh->b_size != blocksize); - if (get_block) { + if (get_block) err = get_block(inode, block, bh, 1); - if (err) - break; - } else { - iomap_to_bh(inode, block, bh, iomap); - } + else + err = iomap_to_bh(inode, block, bh, iomap); + if (err) + break; if (buffer_new(bh)) { clean_bdev_bh_alias(bh); @@ -2151,15 +2188,14 @@ int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len, return err; } -int __block_write_begin(struct page *page, loff_t pos, unsigned len, +int __block_write_begin(struct folio *folio, loff_t pos, unsigned len, get_block_t *get_block) { - return __block_write_begin_int(page_folio(page), pos, len, get_block, - NULL); + return __block_write_begin_int(folio, pos, len, get_block, NULL); } EXPORT_SYMBOL(__block_write_begin); -static void __block_commit_write(struct folio *folio, size_t from, size_t to) +void block_commit_write(struct folio *folio, size_t from, size_t to) { size_t block_start, block_end; bool partial = false; @@ -2167,6 +2203,8 @@ static void __block_commit_write(struct folio *folio, size_t from, size_t to) struct buffer_head *bh, *head; bh = head = folio_buffers(folio); + if (!bh) + return; blocksize = bh->b_size; block_start = 0; @@ -2195,6 +2233,7 @@ static void __block_commit_write(struct folio *folio, size_t from, size_t to) if (!partial) folio_mark_uptodate(folio); } +EXPORT_SYMBOL(block_commit_write); /* * block_write_begin takes care of the basic task of block allocation and @@ -2203,33 +2242,32 @@ static void __block_commit_write(struct folio *folio, size_t from, size_t to) * The filesystem needs to handle block truncation upon failure. */ int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, - struct page **pagep, get_block_t *get_block) + struct folio **foliop, get_block_t *get_block) { pgoff_t index = pos >> PAGE_SHIFT; - struct page *page; + struct folio *folio; int status; - page = grab_cache_page_write_begin(mapping, index); - if (!page) - return -ENOMEM; + folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN, + mapping_gfp_mask(mapping)); + if (IS_ERR(folio)) + return PTR_ERR(folio); - status = __block_write_begin(page, pos, len, get_block); + status = __block_write_begin_int(folio, pos, len, get_block, NULL); if (unlikely(status)) { - unlock_page(page); - put_page(page); - page = NULL; + folio_unlock(folio); + folio_put(folio); + folio = NULL; } - *pagep = page; + *foliop = folio; return status; } EXPORT_SYMBOL(block_write_begin); -int block_write_end(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned copied, - struct page *page, void *fsdata) +int block_write_end(loff_t pos, unsigned len, unsigned copied, + struct folio *folio) { - struct folio *folio = page_folio(page); size_t start = pos - folio_pos(folio); if (unlikely(copied < len)) { @@ -2253,27 +2291,27 @@ int block_write_end(struct file *file, struct address_space *mapping, flush_dcache_folio(folio); /* This could be a short (even 0-length) commit */ - __block_commit_write(folio, start, start + copied); + block_commit_write(folio, start, start + copied); return copied; } EXPORT_SYMBOL(block_write_end); -int generic_write_end(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned copied, - struct page *page, void *fsdata) +int generic_write_end(const struct kiocb *iocb, struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct folio *folio, void *fsdata) { struct inode *inode = mapping->host; loff_t old_size = inode->i_size; bool i_size_changed = false; - copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); + copied = block_write_end(pos, len, copied, folio); /* * No need to use i_size_read() here, the i_size cannot change under us * because we hold i_rwsem. * - * But it's important to update i_size while still holding page lock: + * But it's important to update i_size while still holding folio lock: * page writeout could otherwise come in and zero beyond i_size. */ if (pos + copied > inode->i_size) { @@ -2281,8 +2319,8 @@ int generic_write_end(struct file *file, struct address_space *mapping, i_size_changed = true; } - unlock_page(page); - put_page(page); + folio_unlock(folio); + folio_put(folio); if (old_size < pos) pagecache_isize_extended(inode, old_size, pos); @@ -2352,9 +2390,8 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) { struct inode *inode = folio->mapping->host; sector_t iblock, lblock; - struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; - unsigned int blocksize, bbits; - int nr, i; + struct buffer_head *bh, *head, *prev = NULL; + size_t blocksize; int fully_mapped = 1; bool page_error = false; loff_t limit = i_size_read(inode); @@ -2363,17 +2400,12 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode)) limit = inode->i_sb->s_maxbytes; - VM_BUG_ON_FOLIO(folio_test_large(folio), folio); - head = folio_create_buffers(folio, inode, 0); blocksize = head->b_size; - bbits = block_size_bits(blocksize); - iblock = (sector_t)folio->index << (PAGE_SHIFT - bbits); - lblock = (limit+blocksize-1) >> bbits; + iblock = div_u64(folio_pos(folio), blocksize); + lblock = div_u64(limit + blocksize - 1, blocksize); bh = head; - nr = 0; - i = 0; do { if (buffer_uptodate(bh)) @@ -2386,13 +2418,11 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) if (iblock < lblock) { WARN_ON(bh->b_size != blocksize); err = get_block(inode, iblock, bh, 0); - if (err) { - folio_set_error(folio); + if (err) page_error = true; - } } if (!buffer_mapped(bh)) { - folio_zero_range(folio, i * blocksize, + folio_zero_range(folio, bh_offset(bh), blocksize); if (!err) set_buffer_uptodate(bh); @@ -2405,42 +2435,33 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) if (buffer_uptodate(bh)) continue; } - arr[nr++] = bh; - } while (i++, iblock++, (bh = bh->b_this_page) != head); - - if (fully_mapped) - folio_set_mappedtodisk(folio); - if (!nr) { - /* - * All buffers are uptodate - we can set the folio uptodate - * as well. But not if get_block() returned an error. - */ - if (!page_error) - folio_mark_uptodate(folio); - folio_unlock(folio); - return 0; - } - - /* Stage two: lock the buffers */ - for (i = 0; i < nr; i++) { - bh = arr[i]; lock_buffer(bh); + if (buffer_uptodate(bh)) { + unlock_buffer(bh); + continue; + } + mark_buffer_async_read(bh); - } + if (prev) + submit_bh(REQ_OP_READ, prev); + prev = bh; + } while (iblock++, (bh = bh->b_this_page) != head); + + if (fully_mapped) + folio_set_mappedtodisk(folio); /* - * Stage 3: start the IO. Check for uptodateness - * inside the buffer lock in case another process reading - * the underlying blockdev brought it uptodate (the sct fix). + * All buffers are uptodate or get_block() returned an error + * when trying to map them - we must finish the read because + * end_buffer_async_read() will never be called on any buffer + * in this folio. */ - for (i = 0; i < nr; i++) { - bh = arr[i]; - if (buffer_uptodate(bh)) - end_buffer_async_read(bh, 1); - else - submit_bh(REQ_OP_READ, bh); - } + if (prev) + submit_bh(REQ_OP_READ, prev); + else + folio_end_read(folio, !page_error); + return 0; } EXPORT_SYMBOL(block_read_full_folio); @@ -2453,7 +2474,7 @@ int generic_cont_expand_simple(struct inode *inode, loff_t size) { struct address_space *mapping = inode->i_mapping; const struct address_space_operations *aops = mapping->a_ops; - struct page *page; + struct folio *folio; void *fsdata = NULL; int err; @@ -2461,11 +2482,11 @@ int generic_cont_expand_simple(struct inode *inode, loff_t size) if (err) goto out; - err = aops->write_begin(NULL, mapping, size, 0, &page, &fsdata); + err = aops->write_begin(NULL, mapping, size, 0, &folio, &fsdata); if (err) goto out; - err = aops->write_end(NULL, mapping, size, 0, 0, page, fsdata); + err = aops->write_end(NULL, mapping, size, 0, 0, folio, fsdata); BUG_ON(err > 0); out: @@ -2473,13 +2494,14 @@ out: } EXPORT_SYMBOL(generic_cont_expand_simple); -static int cont_expand_zero(struct file *file, struct address_space *mapping, +static int cont_expand_zero(const struct kiocb *iocb, + struct address_space *mapping, loff_t pos, loff_t *bytes) { struct inode *inode = mapping->host; const struct address_space_operations *aops = mapping->a_ops; unsigned int blocksize = i_blocksize(inode); - struct page *page; + struct folio *folio; void *fsdata = NULL; pgoff_t index, curidx; loff_t curpos; @@ -2497,13 +2519,13 @@ static int cont_expand_zero(struct file *file, struct address_space *mapping, } len = PAGE_SIZE - zerofrom; - err = aops->write_begin(file, mapping, curpos, len, - &page, &fsdata); + err = aops->write_begin(iocb, mapping, curpos, len, + &folio, &fsdata); if (err) goto out; - zero_user(page, zerofrom, len); - err = aops->write_end(file, mapping, curpos, len, len, - page, fsdata); + folio_zero_range(folio, offset_in_folio(folio, curpos), len); + err = aops->write_end(iocb, mapping, curpos, len, len, + folio, fsdata); if (err < 0) goto out; BUG_ON(err != len); @@ -2530,13 +2552,13 @@ static int cont_expand_zero(struct file *file, struct address_space *mapping, } len = offset - zerofrom; - err = aops->write_begin(file, mapping, curpos, len, - &page, &fsdata); + err = aops->write_begin(iocb, mapping, curpos, len, + &folio, &fsdata); if (err) goto out; - zero_user(page, zerofrom, len); - err = aops->write_end(file, mapping, curpos, len, len, - page, fsdata); + folio_zero_range(folio, offset_in_folio(folio, curpos), len); + err = aops->write_end(iocb, mapping, curpos, len, len, + folio, fsdata); if (err < 0) goto out; BUG_ON(err != len); @@ -2550,17 +2572,16 @@ out: * For moronic filesystems that do not allow holes in file. * We may have to extend the file. */ -int cont_write_begin(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, - struct page **pagep, void **fsdata, - get_block_t *get_block, loff_t *bytes) +int cont_write_begin(const struct kiocb *iocb, struct address_space *mapping, + loff_t pos, unsigned len, struct folio **foliop, + void **fsdata, get_block_t *get_block, loff_t *bytes) { struct inode *inode = mapping->host; unsigned int blocksize = i_blocksize(inode); unsigned int zerofrom; int err; - err = cont_expand_zero(file, mapping, pos, bytes); + err = cont_expand_zero(iocb, mapping, pos, bytes); if (err) return err; @@ -2570,17 +2591,10 @@ int cont_write_begin(struct file *file, struct address_space *mapping, (*bytes)++; } - return block_write_begin(mapping, pos, len, pagep, get_block); + return block_write_begin(mapping, pos, len, foliop, get_block); } EXPORT_SYMBOL(cont_write_begin); -void block_commit_write(struct page *page, unsigned from, unsigned to) -{ - struct folio *folio = page_folio(page); - __block_commit_write(folio, from, to); -} -EXPORT_SYMBOL(block_commit_write); - /* * block_page_mkwrite() is not allowed to change the file size as it gets * called from a page fault handler when a page is first dirtied. Hence we must @@ -2589,7 +2603,7 @@ EXPORT_SYMBOL(block_commit_write); * holes and correct delalloc and unwritten extent mapping on filesystems that * support these features. * - * We are not allowed to take the i_mutex here so we have to play games to + * We are not allowed to take the i_rwsem here so we have to play games to * protect against truncate races as the page could now be beyond EOF. Because * truncate writes the inode size before removing pages, once we have the * page lock we can determine safely if the page is beyond EOF. If it is not @@ -2626,7 +2640,7 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, if (unlikely(ret)) goto out_unlock; - __block_commit_write(folio, 0, end); + block_commit_write(folio, 0, end); folio_mark_dirty(folio); folio_wait_stable(folio); @@ -2657,17 +2671,15 @@ int block_truncate_page(struct address_space *mapping, return 0; length = blocksize - length; - iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); - + iblock = ((loff_t)index * PAGE_SIZE) >> inode->i_blkbits; + folio = filemap_grab_folio(mapping, index); if (IS_ERR(folio)) return PTR_ERR(folio); bh = folio_buffers(folio); - if (!bh) { - folio_create_empty_buffers(folio, blocksize, 0); - bh = folio_buffers(folio); - } + if (!bh) + bh = create_empty_buffers(folio, blocksize, 0); /* Find the buffer that contains "offset" */ offset = offset_in_folio(folio, from); @@ -2711,19 +2723,17 @@ unlock: EXPORT_SYMBOL(block_truncate_page); /* - * The generic ->writepage function for buffer-backed address_spaces + * The generic write folio function for buffer-backed address_spaces */ -int block_write_full_page(struct page *page, get_block_t *get_block, - struct writeback_control *wbc) +int block_write_full_folio(struct folio *folio, struct writeback_control *wbc, + void *get_block) { - struct folio *folio = page_folio(page); struct inode * const inode = folio->mapping->host; loff_t i_size = i_size_read(inode); /* Is the folio fully inside i_size? */ - if (folio_pos(folio) + folio_size(folio) <= i_size) - return __block_write_full_folio(inode, folio, get_block, wbc, - end_buffer_async_write); + if (folio_next_pos(folio) <= i_size) + return __block_write_full_folio(inode, folio, get_block, wbc); /* Is the folio fully outside i_size? (truncate in progress) */ if (folio_pos(folio) >= i_size) { @@ -2733,17 +2743,15 @@ int block_write_full_page(struct page *page, get_block_t *get_block, /* * The folio straddles i_size. It must be zeroed out on each and every - * writepage invocation because it may be mmapped. "A file is mapped + * writeback invocation because it may be mmapped. "A file is mapped * in multiples of the page size. For a file that is not a multiple of * the page size, the remaining memory is zeroed when mapped, and * writes to that region are not written out to the file." */ folio_zero_segment(folio, offset_in_folio(folio, i_size), folio_size(folio)); - return __block_write_full_folio(inode, folio, get_block, wbc, - end_buffer_async_write); + return __block_write_full_folio(inode, folio, get_block, wbc); } -EXPORT_SYMBOL(block_write_full_page); sector_t generic_block_bmap(struct address_space *mapping, sector_t block, get_block_t *get_block) @@ -2770,6 +2778,7 @@ static void end_bio_bh_io_sync(struct bio *bio) } static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh, + enum rw_hint write_hint, struct writeback_control *wbc) { const enum req_op op = opf & REQ_OP_MASK; @@ -2797,8 +2806,9 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh, fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO); bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); + bio->bi_write_hint = write_hint; - __bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); + bio_add_folio_nofail(bio, bh->b_folio, bh->b_size, bh_offset(bh)); bio->bi_end_io = end_bio_bh_io_sync; bio->bi_private = bh; @@ -2808,7 +2818,7 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh, if (wbc) { wbc_init_bio(wbc, bio); - wbc_account_cgroup_owner(wbc, bh->b_page, bh->b_size); + wbc_account_cgroup_owner(wbc, bh->b_folio, bh->b_size); } submit_bio(bio); @@ -2816,7 +2826,7 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh, void submit_bh(blk_opf_t opf, struct buffer_head *bh) { - submit_bh_wbc(opf, bh, NULL); + submit_bh_wbc(opf, bh, WRITE_LIFE_NOT_SET, NULL); } EXPORT_SYMBOL(submit_bh); @@ -2871,26 +2881,6 @@ int sync_dirty_buffer(struct buffer_head *bh) } EXPORT_SYMBOL(sync_dirty_buffer); -/* - * try_to_free_buffers() checks if all the buffers on this particular folio - * are unused, and releases them if so. - * - * Exclusion against try_to_free_buffers may be obtained by either - * locking the folio or by holding its mapping's private_lock. - * - * If the folio is dirty but all the buffers are clean then we need to - * be sure to mark the folio clean as well. This is because the folio - * may be against a block device, and a later reattachment of buffers - * to a dirty folio will set *all* buffers dirty. Which would corrupt - * filesystem data on the same device. - * - * The same applies to regular filesystem folios: if all the buffers are - * clean then we set the folio clean and proceed. To do that, we require - * total exclusion from block_dirty_folio(). That is obtained with - * private_lock. - * - * try_to_free_buffers() is non-blocking. - */ static inline int buffer_busy(struct buffer_head *bh) { return atomic_read(&bh->b_count) | @@ -2924,6 +2914,30 @@ failed: return false; } +/** + * try_to_free_buffers - Release buffers attached to this folio. + * @folio: The folio. + * + * If any buffers are in use (dirty, under writeback, elevated refcount), + * no buffers will be freed. + * + * If the folio is dirty but all the buffers are clean then we need to + * be sure to mark the folio clean as well. This is because the folio + * may be against a block device, and a later reattachment of buffers + * to a dirty folio will set *all* buffers dirty. Which would corrupt + * filesystem data on the same device. + * + * The same applies to regular filesystem folios: if all the buffers are + * clean then we set the folio clean and proceed. To do that, we require + * total exclusion from block_dirty_folio(). That is obtained with + * i_private_lock. + * + * Exclusion against try_to_free_buffers may be obtained by either + * locking the folio or by holding its mapping's i_private_lock. + * + * Context: Process context. @folio must be locked. Will not sleep. + * Return: true if all buffers attached to this folio were freed. + */ bool try_to_free_buffers(struct folio *folio) { struct address_space * const mapping = folio->mapping; @@ -2939,7 +2953,7 @@ bool try_to_free_buffers(struct folio *folio) goto out; } - spin_lock(&mapping->private_lock); + spin_lock(&mapping->i_private_lock); ret = drop_buffers(folio, &buffers_to_free); /* @@ -2952,13 +2966,13 @@ bool try_to_free_buffers(struct folio *folio) * the folio's buffers clean. We discover that here and clean * the folio also. * - * private_lock must be held over this entire operation in order + * i_private_lock must be held over this entire operation in order * to synchronise against block_dirty_folio and prevent the * dirty bit from being lost. */ if (ret) folio_cancel_dirty(folio); - spin_unlock(&mapping->private_lock); + spin_unlock(&mapping->i_private_lock); out: if (buffers_to_free) { struct buffer_head *bh = buffers_to_free; @@ -2976,13 +2990,13 @@ EXPORT_SYMBOL(try_to_free_buffers); /* * Buffer-head allocation */ -static struct kmem_cache *bh_cachep __read_mostly; +static struct kmem_cache *bh_cachep __ro_after_init; /* * Once the number of bh's in the machine exceeds this level, we start * stripping them in writeback. */ -static unsigned long max_buffer_heads; +static unsigned long max_buffer_heads __ro_after_init; int buffer_heads_over_limit; @@ -3135,12 +3149,8 @@ void __init buffer_init(void) unsigned long nrpages; int ret; - bh_cachep = kmem_cache_create("buffer_head", - sizeof(struct buffer_head), 0, - (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| - SLAB_MEM_SPREAD), - NULL); - + bh_cachep = KMEM_CACHE(buffer_head, + SLAB_RECLAIM_ACCOUNT|SLAB_PANIC); /* * Limit the bh occupancy to 10% of ZONE_NORMAL */ |