vfs: export check_sticky()

It's already duplicated in btrfs and about to be used in overlayfs too.

Move the sticky bit check to an inline helper and call the out-of-line
helper only in the unlikly case of the sticky bit being set.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 1 insertions, 19 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8d2b76e..4399f0c 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -765,23 +765,6 @@ out:
 	return ret;
 }
 
-/*  copy of check_sticky in fs/namei.c()
-* It's inline, so penalty for filesystems that don't use sticky bit is
-* minimal.
-*/
-static inline int btrfs_check_sticky(struct inode *dir, struct inode *inode)
-{
-	kuid_t fsuid = current_fsuid();
-
-	if (!(dir->i_mode & S_ISVTX))
-		return 0;
-	if (uid_eq(inode->i_uid, fsuid))
-		return 0;
-	if (uid_eq(dir->i_uid, fsuid))
-		return 0;
-	return !capable(CAP_FOWNER);
-}
-
 /*  copy of may_delete in fs/namei.c()
  *	Check whether we can remove a link victim from directory dir, check
  *  whether the type of victim is right.
@@ -817,8 +800,7 @@ static int btrfs_may_delete(struct inode *dir, struct dentry *victim, int isdir)
 		return error;
 	if (IS_APPEND(dir))
 		return -EPERM;
-	if (btrfs_check_sticky(dir, victim->d_inode)||
-		IS_APPEND(victim->d_inode)||
+	if (check_sticky(dir, victim->d_inode) || IS_APPEND(victim->d_inode) ||
 	    IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
 		return -EPERM;
 	if (isdir) {