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>

3 files changed, 17 insertions, 8 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index bfe4a33..e39eeb9 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2241,7 +2241,7 @@ struct btrfs_ioctl_defrag_range_args {
 #define BTRFS_MOUNT_ENOSPC_DEBUG	 (1 << 15)
 #define BTRFS_MOUNT_AUTO_DEFRAG		(1 << 16)
 #define BTRFS_MOUNT_INODE_MAP_CACHE	(1 << 17)
-#define BTRFS_MOUNT_RECOVERY		(1 << 18)
+#define BTRFS_MOUNT_USEBACKUPROOT	(1 << 18)
 #define BTRFS_MOUNT_SKIP_BALANCE	(1 << 19)
 #define BTRFS_MOUNT_CHECK_INTEGRITY	(1 << 20)
 #define BTRFS_MOUNT_CHECK_INTEGRITY_INCLUDING_EXTENT_DATA (1 << 21)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4545e2e..c036362 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);
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index d41e09f..7ed3863 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -303,7 +303,7 @@ enum {
 	Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
 	Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
 	Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
-	Opt_datasum, Opt_treelog, Opt_noinode_cache,
+	Opt_datasum, Opt_treelog, Opt_noinode_cache, Opt_usebackuproot,
 #ifdef CONFIG_BTRFS_DEBUG
 	Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 #endif
@@ -352,7 +352,8 @@ static const match_table_t tokens = {
 	{Opt_inode_cache, "inode_cache"},
 	{Opt_noinode_cache, "noinode_cache"},
 	{Opt_no_space_cache, "nospace_cache"},
-	{Opt_recovery, "recovery"},
+	{Opt_recovery, "recovery"}, /* deprecated */
+	{Opt_usebackuproot, "usebackuproot"},
 	{Opt_skip_balance, "skip_balance"},
 	{Opt_check_integrity, "check_int"},
 	{Opt_check_integrity_including_extent_data, "check_int_data"},
@@ -696,8 +697,12 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 					     "disabling auto defrag");
 			break;
 		case Opt_recovery:
-			btrfs_info(root->fs_info, "enabling auto recovery");
-			btrfs_set_opt(info->mount_opt, RECOVERY);
+			btrfs_warn(root->fs_info,
+				   "'recovery' is deprecated, use 'usebackuproot' instead");
+		case Opt_usebackuproot:
+			btrfs_info(root->fs_info,
+				   "trying to use backup root at mount time");
+			btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 			break;
 		case Opt_skip_balance:
 			btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
@@ -1228,8 +1233,6 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 		seq_puts(seq, ",inode_cache");
 	if (btrfs_test_opt(root, SKIP_BALANCE))
 		seq_puts(seq, ",skip_balance");
-	if (btrfs_test_opt(root, RECOVERY))
-		seq_puts(seq, ",recovery");
 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 	if (btrfs_test_opt(root, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
 		seq_puts(seq, ",check_int_data");