Ensure that our per-subvolume anonymous dev_t gets published to userspace,
instead of the global device in struct super_block. We do this by embedding a
struct fs_view in btrfs_root. The anonymous device number is placed in
view->v_dev. Each inode is then pointed to the view embedded in their owning 
root.

Signed-off-by: Mark Fasheh <mfas...@suse.de>
---
 fs/btrfs/ctree.h     |  7 ++-----
 fs/btrfs/disk-io.c   | 14 ++++++++------
 fs/btrfs/disk-io.h   |  2 +-
 fs/btrfs/inode.c     |  5 +++--
 fs/btrfs/root-tree.c |  2 +-
 5 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a3cca35642e2..cffd3aa51e93 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1216,11 +1216,6 @@ struct btrfs_root {
         * protected by inode_lock
         */
        struct radix_tree_root delayed_nodes_tree;
-       /*
-        * right now this just gets used so that a root has its own devid
-        * for stat.  It may be used for more later
-        */
-       dev_t anon_dev;
 
        spinlock_t root_item_lock;
        refcount_t refs;
@@ -1262,6 +1257,8 @@ struct btrfs_root {
 
        /* For qgroup metadata space reserve */
        atomic64_t qgroup_meta_rsv;
+
+       struct fs_view view; /* fill in and link to inodes for vfs usage */
 };
 
 struct btrfs_file_private {
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 334234da997c..c50af14b5856 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1191,7 +1191,8 @@ static void __setup_root(struct btrfs_root *root, struct 
btrfs_fs_info *fs_info,
        else
                root->defrag_trans_start = 0;
        root->root_key.objectid = objectid;
-       root->anon_dev = 0;
+       memset(&root->view, 0, sizeof(struct fs_view));
+       root->view.v_sb = fs_info->sb;
 
        spin_lock_init(&root->root_item_lock);
 }
@@ -1463,7 +1464,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_root 
*tree_root,
        return root;
 }
 
-int btrfs_init_fs_root(struct btrfs_root *root)
+int btrfs_init_fs_root(struct btrfs_root *root, struct super_block *sb)
 {
        int ret;
        struct btrfs_subvolume_writers *writers;
@@ -1487,7 +1488,8 @@ int btrfs_init_fs_root(struct btrfs_root *root)
        spin_lock_init(&root->ino_cache_lock);
        init_waitqueue_head(&root->ino_cache_wait);
 
-       ret = get_anon_bdev(&root->anon_dev);
+       root->view.v_sb = sb;
+       ret = get_anon_bdev(&root->view.v_dev);
        if (ret)
                goto fail;
 
@@ -1587,7 +1589,7 @@ struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info 
*fs_info,
                goto fail;
        }
 
-       ret = btrfs_init_fs_root(root);
+       ret = btrfs_init_fs_root(root, fs_info->sb);
        if (ret)
                goto fail;
 
@@ -3603,8 +3605,8 @@ static void free_fs_root(struct btrfs_root *root)
        WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
        btrfs_free_block_rsv(root->fs_info, root->orphan_block_rsv);
        root->orphan_block_rsv = NULL;
-       if (root->anon_dev)
-               free_anon_bdev(root->anon_dev);
+       if (root->view.v_dev)
+               free_anon_bdev(root->view.v_dev);
        if (root->subv_writers)
                btrfs_free_subvolume_writers(root->subv_writers);
        free_extent_buffer(root->node);
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 301151a50ac1..af60e7d76449 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -72,7 +72,7 @@ int btrfs_read_dev_one_super(struct block_device *bdev, int 
copy_num,
 int btrfs_commit_super(struct btrfs_fs_info *fs_info);
 struct btrfs_root *btrfs_read_fs_root(struct btrfs_root *tree_root,
                                      struct btrfs_key *location);
-int btrfs_init_fs_root(struct btrfs_root *root);
+int btrfs_init_fs_root(struct btrfs_root *root, struct super_block *sb);
 struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
                                        u64 root_id);
 int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1d4a28a4763a..17e93fb6d871 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5705,6 +5705,7 @@ static int btrfs_init_locked_inode(struct inode *inode, 
void *p)
        memcpy(&BTRFS_I(inode)->location, args->location,
               sizeof(*args->location));
        BTRFS_I(inode)->root = args->root;
+       inode->i_view = &args->root->view;
        return 0;
 }
 
@@ -6346,6 +6347,7 @@ static struct inode *btrfs_new_inode(struct 
btrfs_trans_handle *trans,
        BTRFS_I(inode)->root = root;
        BTRFS_I(inode)->generation = trans->transid;
        inode->i_generation = BTRFS_I(inode)->generation;
+       inode->i_view = &root->view;
 
        /*
         * We could have gotten an inode number from somebody who was fsynced
@@ -9528,8 +9530,7 @@ static int btrfs_getattr(const struct path *path, struct 
kstat *stat,
                                  STATX_ATTR_NODUMP);
 
        generic_fillattr(inode, stat);
-       stat->dev = BTRFS_I(inode)->root->anon_dev;
-
+       stat->dev = inode->i_view->v_dev;
        spin_lock(&BTRFS_I(inode)->lock);
        delalloc_bytes = BTRFS_I(inode)->new_delalloc_bytes;
        spin_unlock(&BTRFS_I(inode)->lock);
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index aab0194efe46..1e6f820c0974 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -308,7 +308,7 @@ int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
                        continue;
                }
 
-               err = btrfs_init_fs_root(root);
+               err = btrfs_init_fs_root(root, fs_info->sb);
                if (err) {
                        btrfs_free_fs_root(root);
                        break;
-- 
2.15.1

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