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enforce ->sync_fs is only called for rw superblock

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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
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3
fs/btrfs/super.c
View File

@ -394,9 +394,6 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
struct btrfs_root *root = btrfs_sb(sb);
int ret;
if (sb->s_flags & MS_RDONLY)
return 0;
if (!wait) {
filemap_flush(root->fs_info->btree_inode->i_mapping);
return 0;

2
fs/cachefiles/interface.c
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)

21
fs/reiserfs/super.c
View File

@ -64,18 +64,15 @@ static int reiserfs_statfs(struct dentry *dentry, struct kstatfs *buf);
static int reiserfs_sync_fs(struct super_block *s, int wait)
{
if (!(s->s_flags & MS_RDONLY)) {
struct reiserfs_transaction_handle th;
reiserfs_write_lock(s);
if (!journal_begin(&th, s, 1))
if (!journal_end_sync(&th, s, 1))
reiserfs_flush_old_commits(s);
s->s_dirt = 0; /* Even if it's not true.
* We'll loop forever in sync_supers otherwise */
reiserfs_write_unlock(s);
} else {
s->s_dirt = 0;
}
struct reiserfs_transaction_handle th;
reiserfs_write_lock(s);
if (!journal_begin(&th, s, 1))
if (!journal_end_sync(&th, s, 1))
reiserfs_flush_old_commits(s);
s->s_dirt = 0; /* Even if it's not true.
* We'll loop forever in sync_supers otherwise */
reiserfs_write_unlock(s);
return 0;
}

23
fs/sync.c
View File

@ -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))

3
fs/ubifs/super.c
View File

@ -447,9 +447,6 @@ static int ubifs_sync_fs(struct super_block *sb, int wait)
if (!wait)
return 0;
if (sb->s_flags & MS_RDONLY)
return 0;
/*
* VFS calls '->sync_fs()' before synchronizing all dirty inodes and
* pages, so synchronize them first, then commit the journal. Strictly