[PATCH v6 19/28] btrfs: wait existing extents before truncating

Naohiro Aota
2019-12-13T04:11:22Z

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>
---
fs/btrfs/inode.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 44658590c6e8..e7fc217be095 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5323,6 +5323,16 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr)
btrfs_end_write_no_snapshotting(root);
btrfs_end_transaction(trans);
} else {
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+ if (btrfs_fs_incompat(fs_info, HMZONED)) {
+ 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
--
2.24.0