From 5af7926ff33b68b3ba46531471c6e0564b285efc Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 5 May 2009 15:41:25 +0200 Subject: [PATCH] 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 Signed-off-by: Al Viro --- fs/btrfs/super.c | 3 --- fs/cachefiles/interface.c | 2 ++ fs/reiserfs/super.c | 21 +++++++++------------ fs/sync.c | 23 ++++++++++++++++------- fs/ubifs/super.c | 3 --- 5 files changed, 27 insertions(+), 25 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 52d84522c2c2..9f179d4832d5 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -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; diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index dafd484d7bda..431accd475a7 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -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) diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c index 1b52daa351c5..3da0401c0a96 100644 --- a/fs/reiserfs/super.c +++ b/fs/reiserfs/super.c @@ -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; } diff --git a/fs/sync.c b/fs/sync.c index 4487b5560dc8..89c37f732afa 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)) diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index e9f7a754c4f7..84f3c7fd1552 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -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 -- GitLab