From 58f74b2203d786da37128cbf786873996145bfdc Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 22 Dec 2020 13:59:24 +0800 Subject: [PATCH] btrfs: refactor btrfs_dec_test_* functions for ordered extents The refactoring involves the following modifications: - Return bool instead of int - Parameter update for @cached of btrfs_dec_test_first_ordered_pending() For btrfs_dec_test_first_ordered_pending(), @cached is only used to return the finished ordered extent. Rename it to @finished_ret. - Comment updates * Change one stale comment Which still refers to btrfs_dec_test_ordered_pending(), but the context is calling btrfs_dec_test_first_ordered_pending(). * Follow the common comment style for both functions Add more detailed descriptions for parameters and the return value * Move the reason why test_and_set_bit() is used into the call sites - Change how the return value is calculated The most anti-human part of the return value is: if (...) ret = 1; ... return ret == 0; This means, when we set ret to 1, the function returns 0. Change the local variable name to @finished, and directly return the value of it. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 6 +-- fs/btrfs/ordered-data.c | 104 ++++++++++++++++++++++------------------ fs/btrfs/ordered-data.h | 10 ++-- 3 files changed, 65 insertions(+), 55 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 4056fc3b39cf..ef6cb7b620d0 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7797,10 +7797,8 @@ static void __endio_write_update_ordered(struct btrfs_inode *inode, NULL); btrfs_queue_work(wq, &ordered->work); } - /* - * If btrfs_dec_test_ordered_pending does not find any ordered - * extent in the range, we can exit. - */ + + /* No ordered extent found in the range, exit */ if (ordered_offset == last_offset) return; /* diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 79d366a36223..d5d326c674b1 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -297,26 +297,33 @@ void btrfs_add_ordered_sum(struct btrfs_ordered_extent *entry, } /* - * this is used to account for finished IO across a given range - * of the file. The IO may span ordered extents. If - * a given ordered_extent is completely done, 1 is returned, otherwise - * 0. + * Finish IO for one ordered extent across a given range. The range can + * contain several ordered extents. * - * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used - * to make sure this function only returns 1 once for a given ordered extent. + * @found_ret: Return the finished ordered extent + * @file_offset: File offset for the finished IO + * Will also be updated to one byte past the range that is + * recordered as finished. This allows caller to walk forward. + * @io_size: Length of the finish IO range + * @uptodate: If the IO finished without problem * - * file_offset is updated to one byte past the range that is recorded as - * complete. This allows you to walk forward in the file. + * Return true if any ordered extent is finished in the range, and update + * @found_ret and @file_offset. + * Return false otherwise. + * + * NOTE: Although The range can cross multiple ordered extents, only one + * ordered extent will be updated during one call. The caller is responsible to + * iterate all ordered extents in the range. */ -int btrfs_dec_test_first_ordered_pending(struct btrfs_inode *inode, - struct btrfs_ordered_extent **cached, +bool btrfs_dec_test_first_ordered_pending(struct btrfs_inode *inode, + struct btrfs_ordered_extent **finished_ret, u64 *file_offset, u64 io_size, int uptodate) { struct btrfs_fs_info *fs_info = inode->root->fs_info; struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree; struct rb_node *node; struct btrfs_ordered_extent *entry = NULL; - int ret; + bool finished = false; unsigned long flags; u64 dec_end; u64 dec_start; @@ -324,16 +331,12 @@ int btrfs_dec_test_first_ordered_pending(struct btrfs_inode *inode, spin_lock_irqsave(&tree->lock, flags); node = tree_search(tree, *file_offset); - if (!node) { - ret = 1; + if (!node) goto out; - } entry = rb_entry(node, struct btrfs_ordered_extent, rb_node); - if (!offset_in_entry(entry, *file_offset)) { - ret = 1; + if (!offset_in_entry(entry, *file_offset)) goto out; - } dec_start = max(*file_offset, entry->file_offset); dec_end = min(*file_offset + io_size, @@ -354,39 +357,50 @@ int btrfs_dec_test_first_ordered_pending(struct btrfs_inode *inode, set_bit(BTRFS_ORDERED_IOERR, &entry->flags); if (entry->bytes_left == 0) { - ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags); + /* + * Ensure only one caller can set the flag and finished_ret + * accordingly + */ + finished = !test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags); /* test_and_set_bit implies a barrier */ cond_wake_up_nomb(&entry->wait); - } else { - ret = 1; } out: - if (!ret && cached && entry) { - *cached = entry; + if (finished && finished_ret && entry) { + *finished_ret = entry; refcount_inc(&entry->refs); } spin_unlock_irqrestore(&tree->lock, flags); - return ret == 0; + return finished; } /* - * this is used to account for finished IO across a given range - * of the file. The IO should not span ordered extents. If - * a given ordered_extent is completely done, 1 is returned, otherwise - * 0. + * Finish IO for one ordered extent across a given range. The range can only + * contain one ordered extent. * - * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used - * to make sure this function only returns 1 once for a given ordered extent. + * @cached: The cached ordered extent. If not NULL, we can skip the tree + * search and use the ordered extent directly. + * Will be also used to store the finished ordered extent. + * @file_offset: File offset for the finished IO + * @io_size: Length of the finish IO range + * @uptodate: If the IO finishes without problem + * + * Return true if the ordered extent is finished in the range, and update + * @cached. + * Return false otherwise. + * + * NOTE: The range can NOT cross multiple ordered extents. + * Thus caller should ensure the range doesn't cross ordered extents. */ -int btrfs_dec_test_ordered_pending(struct btrfs_inode *inode, - struct btrfs_ordered_extent **cached, - u64 file_offset, u64 io_size, int uptodate) +bool btrfs_dec_test_ordered_pending(struct btrfs_inode *inode, + struct btrfs_ordered_extent **cached, + u64 file_offset, u64 io_size, int uptodate) { struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree; struct rb_node *node; struct btrfs_ordered_extent *entry = NULL; unsigned long flags; - int ret; + bool finished = false; spin_lock_irqsave(&tree->lock, flags); if (cached && *cached) { @@ -395,41 +409,39 @@ int btrfs_dec_test_ordered_pending(struct btrfs_inode *inode, } node = tree_search(tree, file_offset); - if (!node) { - ret = 1; + if (!node) goto out; - } entry = rb_entry(node, struct btrfs_ordered_extent, rb_node); have_entry: - if (!offset_in_entry(entry, file_offset)) { - ret = 1; + if (!offset_in_entry(entry, file_offset)) goto out; - } - if (io_size > entry->bytes_left) { + if (io_size > entry->bytes_left) btrfs_crit(inode->root->fs_info, "bad ordered accounting left %llu size %llu", entry->bytes_left, io_size); - } + entry->bytes_left -= io_size; if (!uptodate) set_bit(BTRFS_ORDERED_IOERR, &entry->flags); if (entry->bytes_left == 0) { - ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags); + /* + * Ensure only one caller can set the flag and finished_ret + * accordingly + */ + finished = !test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags); /* test_and_set_bit implies a barrier */ cond_wake_up_nomb(&entry->wait); - } else { - ret = 1; } out: - if (!ret && cached && entry) { + if (finished && cached && entry) { *cached = entry; refcount_inc(&entry->refs); } spin_unlock_irqrestore(&tree->lock, flags); - return ret == 0; + return finished; } /* diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h index 0bfa82b58e23..46194c2c05d4 100644 --- a/fs/btrfs/ordered-data.h +++ b/fs/btrfs/ordered-data.h @@ -152,11 +152,11 @@ btrfs_ordered_inode_tree_init(struct btrfs_ordered_inode_tree *t) void btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry); void btrfs_remove_ordered_extent(struct btrfs_inode *btrfs_inode, struct btrfs_ordered_extent *entry); -int btrfs_dec_test_ordered_pending(struct btrfs_inode *inode, - struct btrfs_ordered_extent **cached, - u64 file_offset, u64 io_size, int uptodate); -int btrfs_dec_test_first_ordered_pending(struct btrfs_inode *inode, - struct btrfs_ordered_extent **cached, +bool btrfs_dec_test_ordered_pending(struct btrfs_inode *inode, + struct btrfs_ordered_extent **cached, + u64 file_offset, u64 io_size, int uptodate); +bool btrfs_dec_test_first_ordered_pending(struct btrfs_inode *inode, + struct btrfs_ordered_extent **finished_ret, u64 *file_offset, u64 io_size, int uptodate); int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,