mm: bdi: expose the BDI object in sysfs for FUSE

Register FUSE's backing_dev_info under sysfs with the name "fuse-MAJOR:MINOR"

Make the fuse control filesystem use s_dev instead of a fuse specific ID.
This makes it easier to match directories under /sys/fs/fuse/connections/ with
directories under /sys/class/bdi, and with actual mounts.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 18 insertions, 18 deletions

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index 105d4a271e07..4f3cab321415 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -117,7 +117,7 @@ int fuse_ctl_add_conn(struct fuse_conn *fc)
 
         parent = fuse_control_sb->s_root;
         inc_nlink(parent->d_inode);
-        sprintf(name, "%llu", (unsigned long long) fc->id);
+        sprintf(name, "%u", fc->dev);
         parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
                                      &simple_dir_inode_operations,
                                      &simple_dir_operations);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 67aaf6ee38ea..c0481e48d161 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -390,8 +390,8 @@ struct fuse_conn {
         /** Entry on the fuse_conn_list */
         struct list_head entry;
 
-        /** Unique ID */
-        u64 id;
+        /** Device ID from super block */
+        dev_t dev;
 
         /** Dentries in the control filesystem */
         struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 4df34da2284a..c4fcfd59cd80 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -447,7 +447,7 @@ static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
         return 0;
 }
 
-static struct fuse_conn *new_conn(void)
+static struct fuse_conn *new_conn(struct super_block *sb)
 {
         struct fuse_conn *fc;
         int err;
@@ -468,19 +468,26 @@ static struct fuse_conn *new_conn(void)
                 atomic_set(&fc->num_waiting, 0);
                 fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
                 fc->bdi.unplug_io_fn = default_unplug_io_fn;
+                fc->dev = sb->s_dev;
                 err = bdi_init(&fc->bdi);
-                if (err) {
-                        kfree(fc);
-                        fc = NULL;
-                        goto out;
-                }
+                if (err)
+                        goto error_kfree;
+                err = bdi_register_dev(&fc->bdi, fc->dev);
+                if (err)
+                        goto error_bdi_destroy;
                 fc->reqctr = 0;
                 fc->blocked = 1;
                 fc->attr_version = 1;
                 get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
         }
-out:
         return fc;
+
+error_bdi_destroy:
+        bdi_destroy(&fc->bdi);
+error_kfree:
+        mutex_destroy(&fc->inst_mutex);
+        kfree(fc);
+        return NULL;
 }
 
 void fuse_conn_put(struct fuse_conn *fc)
@@ -578,12 +585,6 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
         request_send_background(fc, req);
 }
 
-static u64 conn_id(void)
-{
-        static u64 ctr = 1;
-        return ctr++;
-}
-
 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 {
         struct fuse_conn *fc;
@@ -621,7 +622,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
         if (file->f_op != &fuse_dev_operations)
                 return -EINVAL;
 
-        fc = new_conn();
+        fc = new_conn(sb);
         if (!fc)
                 return -ENOMEM;
 
@@ -659,7 +660,6 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
         if (file->private_data)
                 goto err_unlock;
 
-        fc->id = conn_id();
         err = fuse_ctl_add_conn(fc);
         if (err)
                 goto err_unlock;