fs: Assign bdi in super_block

We do this automatically in get_sb_bdev() from the set_bdev_super()
callback. Filesystems that have their own private backing_dev_info
must assign that in ->fill_super().

Note that ->s_bdi assignment is required for proper writeback!

Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

7 files changed, 21 insertions, 1 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 15831d5c7367..8b8192790011 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1600,6 +1600,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 
         sb->s_blocksize = 4096;
         sb->s_blocksize_bits = blksize_bits(4096);
+        sb->s_bdi = &fs_info->bdi;
 
         /*
          * we set the i_size on the btree inode to the max possible int.
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 4567db6f9430..e5dbecd87b0f 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -894,6 +894,8 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
         if (err)
                 goto err_put_conn;
 
+        sb->s_bdi = &fc->bdi;
+
         /* Handle umasking inside the fuse code */
         if (sb->s_flags & MS_POSIXACL)
                 fc->dont_mask = 1;
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 867f70504531..de935692d40d 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1918,6 +1918,8 @@ static inline void nfs_initialise_sb(struct super_block *sb)
         if (server->flags & NFS_MOUNT_NOAC)
                 sb->s_flags |= MS_SYNCHRONOUS;
 
+        sb->s_bdi = &server->backing_dev_info;
+
         nfs_super_set_maxbytes(sb, server->maxfilesize);
 }
 
diff --git a/fs/super.c b/fs/super.c
index 9cda337ddae2..b03fea8fbfb6 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -707,6 +707,12 @@ static int set_bdev_super(struct super_block *s, void *data)
 {
         s->s_bdev = data;
         s->s_dev = s->s_bdev->bd_dev;
+
+        /*
+         * We set the bdi here to the queue backing, file systems can
+         * overwrite this in ->fill_super()
+         */
+        s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
         return 0;
 }
 
diff --git a/fs/sync.c b/fs/sync.c
index 192340930bb4..c08467a5d7cb 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -27,6 +27,13 @@
  */
 static int __sync_filesystem(struct super_block *sb, int wait)
 {
+        /*
+         * This should be safe, as we require bdi backing to actually
+         * write out data in the first place
+         */
+        if (!sb->s_bdi)
+                return 0;
+
         /* Avoid doing twice syncing and cache pruning for quota sync */
         if (!wait) {
                 writeout_quota_sb(sb, -1);
@@ -101,7 +108,7 @@ restart:
                 spin_unlock(&sb_lock);
 
                 down_read(&sb->s_umount);
-                if (!(sb->s_flags & MS_RDONLY) && sb->s_root)
+                if (!(sb->s_flags & MS_RDONLY) && sb->s_root && sb->s_bdi)
                         __sync_filesystem(sb, wait);
                 up_read(&sb->s_umount);
 
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 51763aa8f4de..c4af069df1ad 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1980,6 +1980,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
         if (err)
                 goto out_bdi;
 
+        sb->s_bdi = &c->bdi;
         sb->s_fs_info = c;
         sb->s_magic = UBIFS_SUPER_MAGIC;
         sb->s_blocksize = UBIFS_BLOCK_SIZE;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index db29588874ac..90162fb3bf04 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1342,6 +1342,7 @@ struct super_block {
         int                     s_nr_dentry_unused;     /* # of dentry on lru */
 
         struct block_device     *s_bdev;
+        struct backing_dev_info *s_bdi;
         struct mtd_info         *s_mtd;
         struct list_head        s_instances;
         struct quota_info       s_dquot;        /* Diskquota specific options */