diff options
| author | Christoph Hellwig <hch@lst.de> | 2009-05-05 15:41:25 +0200 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-06-11 21:36:06 -0400 |
| commit | 5af7926ff33b68b3ba46531471c6e0564b285efc (patch) | |
| tree | a25266f9db482ce9dd8e663148ffb0f1a524bd83 /fs/sync.c | |
| parent | e5004753388dcf5e1b8a52ac0ab807d232340fbb (diff) | |
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>
Diffstat (limited to 'fs/sync.c')
| -rw-r--r-- | fs/sync.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/fs/sync.c b/fs/sync.c index 4487b5560dc..89c37f732af 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -51,6 +51,18 @@ int sync_filesystem(struct super_block *sb) { int ret; + /* + * We need to be protected against the filesystem going from + * r/o to r/w or vice versa. + */ + WARN_ON(!rwsem_is_locked(&sb->s_umount)); + + /* + * No point in syncing out anything if the filesystem is read-only. + */ + if (sb->s_flags & MS_RDONLY) + return 0; + ret = __sync_filesystem(sb, 0); if (ret < 0) return ret; @@ -79,25 +91,22 @@ static void sync_filesystems(int wait) mutex_lock(&mutex); /* Could be down_interruptible */ spin_lock(&sb_lock); - list_for_each_entry(sb, &super_blocks, s_list) { - if (sb->s_flags & MS_RDONLY) - continue; + list_for_each_entry(sb, &super_blocks, s_list) sb->s_need_sync = 1; - } restart: list_for_each_entry(sb, &super_blocks, s_list) { if (!sb->s_need_sync) continue; sb->s_need_sync = 0; - if (sb->s_flags & MS_RDONLY) - continue; /* hm. Was remounted r/o meanwhile */ sb->s_count++; spin_unlock(&sb_lock); + down_read(&sb->s_umount); - if (sb->s_root) + if (!(sb->s_flags & MS_RDONLY) && sb->s_root) __sync_filesystem(sb, wait); up_read(&sb->s_umount); + /* restart only when sb is no longer on the list */ spin_lock(&sb_lock); if (__put_super_and_need_restart(sb)) |