Btrfs: Fix NFS exporting of subvol roots.

Date: Tue, 19 Aug 2008 22:20:17 +0100
btrfs_lookup_fs_root() only finds subvol roots which have already been
seen and put into the cache. For btrfs_get_dentry() we actually have to
go to the medium -- so use btrfs_read_fs_root_no_name() instead.

In btrfs_get_parent(), notice when we've hit the root of the
subvolume and return the real root instead.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index a913b9befe682c1294ae6e86d8726c3d7c01fb4d..36cbc6872fd0e5f7ce9f900d580e4def20763270 100644 (file)
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -71,11 +71,18 @@ static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
        struct dentry *result;
        struct btrfs_key key;
 
+       key.objectid = root_objectid;
+       btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+       key.offset = (u64)-1;
+
+       root = btrfs_read_fs_root_no_name(btrfs_sb(sb)->fs_info, &key);
+       if (IS_ERR(root))
+               return ERR_CAST(root);
+
        key.objectid = objectid;
        btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
        key.offset = 0;
 
-       root = btrfs_lookup_fs_root(btrfs_sb(sb)->fs_info, root_objectid);
        inode = btrfs_iget(sb, &key, root, NULL);
        if (IS_ERR(inode))
                return (void *)inode;
@@ -178,6 +185,10 @@ static struct dentry *btrfs_get_parent(struct dentry *child)
 
        objectid = key.offset;
 
+       /* If we are already at the root of a subvol, return the real root */
+       if (objectid == dir->i_ino)
+               return dget(dir->i_sb->s_root);
+
        /* Build a new key for the inode item */
        key.objectid = objectid;
        btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);