don't unlink an active swapfile

Peter Cordes is sorry that he rm'ed his swapfiles while they were in use,
he then had no pathname to swapoff.  It's a curious little oversight, but
not one worth a lot of hackery.  Kudos to Willy Tarreau for turning this
around from a discussion of synthetic pathnames to how to prevent unlink.
Mimic immutable: prohibit unlinking an active swapfile in may_delete()
(and don't worry my little head over the tiny race window).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Willy Tarreau <w@1wt.eu>
Acked-by: Christoph Hellwig <hch@infradead.org>
Cc: Peter Cordes <peter@cordes.ca>
Cc: Bodo Eggert <7eggert@gmx.de>
Cc: David Newall <davidn@davidnewall.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 09ce58e49e72..d34e0f9681c6 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1378,7 +1378,7 @@ static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
         if (IS_APPEND(dir))
                 return -EPERM;
         if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
-            IS_IMMUTABLE(victim->d_inode))
+            IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
                 return -EPERM;
         if (isdir) {
                 if (!S_ISDIR(victim->d_inode->i_mode))