[PATCH v13 31/42] btrfs: wait existing extents before truncating

[Naohiro Aota <naohiro.aota@wdc.com>]

When truncating a file, file buffers which have already been allocated but
not yet written may be truncated.  Truncating these buffers could cause
breakage of a sequential write pattern in a block group if the truncated
blocks are for example followed by blocks allocated to another file. To
avoid this problem, always wait for write out of all unwritten buffers
before proceeding with the truncate execution.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/inode.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a5503af5369b..06d15d77f170 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5169,6 +5169,16 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr)
 		btrfs_drew_write_unlock(&root->snapshot_lock);
 		btrfs_end_transaction(trans);
 	} else {
+		struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+		if (btrfs_is_zoned(fs_info)) {
+			ret = btrfs_wait_ordered_range(
+				inode,
+				ALIGN(newsize, fs_info->sectorsize),
+				(u64)-1);
+			if (ret)
+				return ret;
+		}
 
 		/*
 		 * We're truncating a file that used to have good data down to
-- 
2.27.0