[PATCH 2/5] xfs: fallocate() should call file_modified()

Dave Chinner
2022-01-31T23:39:28Z

In XFS, we always update the inode change and modification time when
any fallocate() operation succeeds. Furthermore, as various
fallocate modes can change the file contents (extending EOF,
punching holes, zeroing things, shifting extents), we should drop
file privileges like suid just like we do for a regular write().
There's already a VFS helper that figures all this out for us, so
use that.

The net effect of this is that we no longer drop suid/sgid if the
caller is root, but we also now drop file capabilities.

We also move the xfs_update_prealloc_flags() function so that it now
is only called by the scope that needs to set the the prealloc flag.

Based on a patch from Darrick Wong.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/xfs_file.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index ed375b3d0614..7846d55cba01 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -953,6 +953,10 @@ xfs_file_fallocate(
goto out_unlock;
}

+ error = file_modified(file);
+ if (error)
+ goto out_unlock;
+
if (mode & FALLOC_FL_PUNCH_HOLE) {
error = xfs_free_file_space(ip, offset, len);
if (error)
@@ -1053,11 +1057,12 @@ xfs_file_fallocate(
if (error)
goto out_unlock;
}
- }

- error = xfs_update_prealloc_flags(ip, flags);
- if (error)
- goto out_unlock;
+ error = xfs_update_prealloc_flags(ip, XFS_PREALLOC_SET);
+ if (error)
+ goto out_unlock;
+
+ }

/* Change file size if needed */
if (new_size) {
--
2.33.0