On 2023/4/18 09:17, Dominique Martinet wrote:
From: Dominique Martinet dominique.martinet@atmark-techno.com
btfs_file_read's truncate path has a comment noting '>0 means no extent' and bailing out immediately, but the buffer has not been written so probably needs zeroing out.
This is a theorical fix only and hasn't been tested on a file that actually runs this code path.
IIRC there is a memset() at the very beginning of btrfs_file_read() to set the whole dest memory to zero.
This is to handle cases like NO_HOLE cases, which we can skip hole extents.
Thanks, Qu
Signed-off-by: Dominique Martinet dominique.martinet@atmark-techno.com
fs/btrfs/inode.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index efffec0f2e68..23c006c98c3b 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -756,9 +756,12 @@ int btrfs_file_read(struct btrfs_root *root, u64 ino, u64 file_offset, u64 len, btrfs_release_path(&path); ret = lookup_data_extent(root, &path, ino, cur, &next_offset);
/* <0 is error, >0 means no extent */if (ret)
/* <0 is error, >0 means no extent: zero end of buffer */if (ret) {if (ret > 0)memset(dest + cur, 0, end - cur); goto out;}