enforce ->sync_fs is only called for rw superblock

Make sure a superblock really is writeable by checking MS_RDONLY
under s_umount.  sync_filesystems needed some re-arragement for
that, but all but one sync_filesystem caller had the correct locking
already so that we could add that check there.  cachefiles grew
s_umount locking.

I've also added a WARN_ON to sync_filesystem to assert this for
future callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig
2009-05-05 15:41:25 +02:00
committed by Al Viro
parent e500475338
commit 5af7926ff3
5 changed files with 27 additions and 25 deletions

View File

@ -354,7 +354,9 @@ static void cachefiles_sync_cache(struct fscache_cache *_cache)
/* make sure all pages pinned by operations on behalf of the netfs are
* written to disc */
cachefiles_begin_secure(cache, &saved_cred);
down_read(&cache->mnt->mnt_sb->s_umount);
ret = sync_filesystem(cache->mnt->mnt_sb);
up_read(&cache->mnt->mnt_sb->s_umount);
cachefiles_end_secure(cache, saved_cred);
if (ret == -EIO)