On 2023/4/18 09:17, Dominique Martinet wrote:
From: Dominique Martinet <dominique.marti...@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.marti...@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;
+ }
fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
struct btrfs_file_extent_item);
ret = read_and_truncate_page(&path, fi, cur,
