From: Omar Sandoval <osandov@xxxxxx>
Jun Wu at Facebook reported that an internal service was seeing a return
value of 1 from ftruncate() on Btrfs in some cases. This is coming from
the NEED_TRUNCATE_BLOCK return value from btrfs_truncate_inode_items().
btrfs_truncate() uses two variables for error handling, ret and err.
When btrfs_truncate_inode_items() returns non-zero, we set err to the
return value. However, NEED_TRUNCATE_BLOCK is not an error. Make sure we
only set err if ret is an error (i.e., negative).
Fixes: ddfae63cc8e0 ("btrfs: move btrfs_truncate_block out of trans handle")
Reported-by: Jun Wu <quark@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
---
This version makes the minimal fix which should be good for v4.17 and
stable. I'll submit a cleanup separately.
fs/btrfs/inode.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d241285a0d2a..f276da70f659 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9117,7 +9117,8 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
BTRFS_EXTENT_DATA_KEY);
trans->block_rsv = &fs_info->trans_block_rsv;
if (ret != -ENOSPC && ret != -EAGAIN) {
- err = ret;
+ if (ret < 0)
+ err = ret;
break;
}
--
2.17.0
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