fs: Simplify getattr interface function checking AT_GETATTR_NOSEC flag

Commit 8a924db2d7b5 ("fs: Pass AT_GETATTR_NOSEC flag to getattr interface
function")' introduced the AT_GETATTR_NOSEC flag to ensure that the
call paths only call vfs_getattr_nosec if it is set instead of vfs_getattr.
Now, simplify the getattr interface functions of filesystems where the flag
AT_GETATTR_NOSEC is checked.

There is only a single caller of inode_operations getattr function and it
is located in fs/stat.c in vfs_getattr_nosec. The caller there is the only
one from which the AT_GETATTR_NOSEC flag is passed from.

Two filesystems are checking this flag in .getattr and the flag is always
passed to them unconditionally from only vfs_getattr_nosec:

- ecryptfs:  Simplify by always calling vfs_getattr_nosec in
             ecryptfs_getattr. From there the flag is passed to no other
             function and this function is not called otherwise.

- overlayfs: Simplify by always calling vfs_getattr_nosec in
             ovl_getattr. From there the flag is passed to no other
             function and this function is not called otherwise.

The query_flags in vfs_getattr_nosec will mask-out AT_GETATTR_NOSEC from
any caller using AT_STATX_SYNC_TYPE as mask so that the flag is not
important inside this function. Also, since no filesystem is checking the
flag anymore, remove the flag entirely now, including the BUG_ON check that
never triggered.

The net change of the changes here combined with the original commit is
that ecryptfs and overlayfs do not call vfs_getattr but only
vfs_getattr_nosec.

Fixes: 8a924db2d7b5 ("fs: Pass AT_GETATTR_NOSEC flag to getattr interface function")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Closes: https://lore.kernel.org/linux-fsdevel/20241101011724.GN1350452@ZenIV/T/#u
Cc: Tyler Hicks <code@tyhicks.com>
Cc: ecryptfs@vger.kernel.org
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: linux-unionfs@vger.kernel.org
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 10 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 5ed1e4cf6c0b..644e973d5a77 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -1008,14 +1008,6 @@ static int ecryptfs_getattr_link(struct mnt_idmap *idmap,
 	return rc;
 }
 
-static int ecryptfs_do_getattr(const struct path *path, struct kstat *stat,
-			       u32 request_mask, unsigned int flags)
-{
-	if (flags & AT_GETATTR_NOSEC)
-		return vfs_getattr_nosec(path, stat, request_mask, flags);
-	return vfs_getattr(path, stat, request_mask, flags);
-}
-
 static int ecryptfs_getattr(struct mnt_idmap *idmap,
 			    const struct path *path, struct kstat *stat,
 			    u32 request_mask, unsigned int flags)
@@ -1024,8 +1016,8 @@ static int ecryptfs_getattr(struct mnt_idmap *idmap,
 	struct kstat lower_stat;
 	int rc;
 
-	rc = ecryptfs_do_getattr(ecryptfs_dentry_to_lower_path(dentry),
-				 &lower_stat, request_mask, flags);
+	rc = vfs_getattr_nosec(ecryptfs_dentry_to_lower_path(dentry),
+			       &lower_stat, request_mask, flags);
 	if (!rc) {
 		fsstack_copy_attr_all(d_inode(dentry),
 				      ecryptfs_inode_to_lower(d_inode(dentry)));