btrfs: move extent locking outside of btrfs_truncate_inode_items

Currently we are locking the extent and dropping the extent cache for
any inodes we truncate, unless they're in the tree log.  We call this
helper from:

- truncate
- evict
- tree log
- free space cache truncation

For evict we've already dropped all of the extent cache for this inode
once we've gotten here, and we're the only one accessing this inode, so
this step is unnecessary.

For the tree log code we already skip this part.

Pull this work into the truncate path and the free space cache
truncation path.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c29e7c87ff27..9f9cd6c598fe 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8583,10 +8583,28 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
 	trans->block_rsv = rsv;
 
 	while (1) {
+		struct extent_state *cached_state = NULL;
+		const u64 new_size = inode->i_size;
+		const u64 lock_start = ALIGN_DOWN(new_size, fs_info->sectorsize);
+
+		lock_extent_bits(&BTRFS_I(inode)->io_tree, lock_start, (u64)-1,
+				 &cached_state);
+		/*
+		 * We want to drop from the next block forward in case this new
+		 * size is not block aligned since we will be keeping the last
+		 * block of the extent just the way it is.
+		 */
+		btrfs_drop_extent_cache(BTRFS_I(inode),
+					ALIGN(new_size, fs_info->sectorsize),
+					(u64)-1, 0);
+
 		ret = btrfs_truncate_inode_items(trans, root, BTRFS_I(inode),
 						 inode->i_size,
 						 BTRFS_EXTENT_DATA_KEY,
 						 &extents_found);
+		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lock_start,
+				     (u64)-1, &cached_state);
+
 		trans->block_rsv = &fs_info->trans_block_rsv;
 		if (ret != -ENOSPC && ret != -EAGAIN)
 			break;