btrfs: Introduce new mount option usebackuproot to replace recovery

Current "recovery" mount option will only try to use backup root.
However the word "recovery" is too generic and may be confusing for some
users.

Here introduce a new and more specific mount option, "usebackuproot" to
replace "recovery" mount option.
"Recovery" will be kept for compatibility reason, but will be
deprecated.

Also, since "usebackuproot" will only affect mount behavior and after
open_ctree() it has nothing to do with the filesystem, so clear the flag
after mount succeeded.

This provides the basis for later unified "norecovery" mount option.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[ dropped usebackuproot from show_mount, added note about 'recovery' to
  docs ]
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4545e2e2ad45..c0363626c5da 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3146,6 +3146,12 @@ retry_root_backup:
 
         fs_info->open = 1;
 
+        /*
+         * backuproot only affect mount behavior, and if open_ctree succeeded,
+         * no need to keep the flag
+         */
+        btrfs_clear_opt(fs_info->mount_opt, USEBACKUPROOT);
+
         return 0;
 
 fail_qgroup:
@@ -3200,7 +3206,7 @@ fail:
         return err;
 
 recovery_tree_root:
-        if (!btrfs_test_opt(tree_root, RECOVERY))
+        if (!btrfs_test_opt(tree_root, USEBACKUPROOT))
                 goto fail_tree_roots;
 
         free_root_pointers(fs_info, 0);