Commit 5af7926f authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e5004753

fs/btrfs/super.c

+0 −3
Original line number Diff line number Diff line
@@ -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;

fs/cachefiles/interface.c

+2 −0
Original line number Diff line number Diff line
@@ -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)

fs/reiserfs/super.c

+9 −12
Original line number Diff line number Diff line
@@ -64,8 +64,8 @@ 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))
@@ -73,9 +73,6 @@ static int reiserfs_sync_fs(struct super_block *s, int wait) 
	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;

	}

	return 0;

}

fs/sync.c

+16 −7
Original line number Diff line number Diff line
@@ -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))

fs/ubifs/super.c

+0 −3
Original line number Diff line number Diff line
@@ -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

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