This patch introduces a new "rescue=" mount option for all those mount
options for data recovery.

Different rescue sub options are seperated by ':'. E.g
"ro,rescue=no_log_replay:use_backup_root".
(The original plan is to use ';', but ';' needs to be escaped/quoted,
or it will be interpreted by bash)

The following mount options are converted to "rescue=", old mount
options are deprecated but still available for compatibility purpose:

- usebackuproot
  Now it's "rescue=use_backup_root"

- nologreplay
  Now it's "rescue=no_log_replay"

The new underscore is here to make the option more readable and make
spell check happier.

Signed-off-by: Qu Wenruo <[email protected]>
---
 fs/btrfs/super.c | 65 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 62 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 64f20725615a..4512f25dcf69 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -310,7 +310,6 @@ enum {
        Opt_datasum, Opt_nodatasum,
        Opt_defrag, Opt_nodefrag,
        Opt_discard, Opt_nodiscard,
-       Opt_nologreplay,
        Opt_ratio,
        Opt_rescan_uuid_tree,
        Opt_skip_balance,
@@ -323,7 +322,6 @@ enum {
        Opt_subvolid,
        Opt_thread_pool,
        Opt_treelog, Opt_notreelog,
-       Opt_usebackuproot,
        Opt_user_subvol_rm_allowed,
 
        /* Deprecated options */
@@ -341,6 +339,8 @@ enum {
 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
        Opt_ref_verify,
 #endif
+       /* Rescue options */
+       Opt_rescue, Opt_usebackuproot, Opt_nologreplay,
        Opt_err,
 };
 
@@ -401,6 +401,7 @@ static const match_table_t tokens = {
        {Opt_check_integrity_print_mask, "check_int_print_mask=%u"},
        {Opt_enospc_debug, "enospc_debug"},
        {Opt_noenospc_debug, "noenospc_debug"},
+       {Opt_rescue, "rescue=%s"},
 #ifdef CONFIG_BTRFS_DEBUG
        {Opt_fragment_data, "fragment=data"},
        {Opt_fragment_metadata, "fragment=metadata"},
@@ -412,6 +413,55 @@ static const match_table_t tokens = {
        {Opt_err, NULL},
 };
 
+static const match_table_t rescue_tokens = {
+       {Opt_usebackuproot, "use_backup_root"},
+       {Opt_nologreplay, "no_log_replay"},
+       {Opt_err, NULL},
+};
+
+static int parse_rescue_options(struct btrfs_fs_info *info, const char 
*options)
+{
+       char *opts;
+       char *orig;
+       char *p;
+       substring_t args[MAX_OPT_ARGS];
+       int ret = 0;
+
+       opts = kstrdup(options, GFP_KERNEL);
+       if (!opts)
+               return -ENOMEM;
+       orig = opts;
+
+       while ((p = strsep(&opts, ":")) != NULL) {
+               int token;
+
+               if (!*p)
+                       continue;
+               token = match_token(p, rescue_tokens, args);
+               switch (token){
+               case Opt_usebackuproot:
+                       btrfs_info(info,
+                                  "trying to use backup root at mount time");
+                       btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
+                       break;
+               case Opt_nologreplay:
+                       btrfs_set_and_info(info, NOLOGREPLAY,
+                                          "disabling log replay at mount 
time");
+                       break;
+               case Opt_err:
+                       btrfs_info(info, "unrecognized rescue option '%s'", p);
+                       ret = -EINVAL;
+                       goto out;
+               default:
+                       break;
+               }
+
+       }
+out:
+       kfree(orig);
+       return ret;
+}
+
 /*
  * Regular mount options parser.  Everything that is needed only when
  * reading in a new superblock is parsed here.
@@ -667,6 +717,8 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char 
*options,
                                             "enabling tree log");
                        break;
                case Opt_nologreplay:
+                       btrfs_warn(info,
+       "'nologreplay' is deprecated, use 'rescue=no_log_replay' instead");
                        btrfs_set_and_info(info, NOLOGREPLAY,
                                           "disabling log replay at mount 
time");
                        break;
@@ -755,6 +807,8 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char 
*options,
                                             "disabling auto defrag");
                        break;
                case Opt_usebackuproot:
+                       btrfs_warn(info,
+       "'usebackuproot' is deprecated, use 'rescue=use_backup_root' instead");
                        btrfs_info(info,
                                   "trying to use backup root at mount time");
                        btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
@@ -841,6 +895,11 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char 
*options,
                        btrfs_set_opt(info->mount_opt, REF_VERIFY);
                        break;
 #endif
+               case Opt_rescue:
+                       ret = parse_rescue_options(info, args[0].from);
+                       if (ret < 0)
+                               goto out;
+                       break;
                case Opt_err:
                        btrfs_info(info, "unrecognized mount option '%s'", p);
                        ret = -EINVAL;
@@ -1307,7 +1366,7 @@ static int btrfs_show_options(struct seq_file *seq, 
struct dentry *dentry)
        if (btrfs_test_opt(info, NOTREELOG))
                seq_puts(seq, ",notreelog");
        if (btrfs_test_opt(info, NOLOGREPLAY))
-               seq_puts(seq, ",nologreplay");
+               seq_puts(seq, ",rescue=no_log_replay");
        if (btrfs_test_opt(info, FLUSHONCOMMIT))
                seq_puts(seq, ",flushoncommit");
        if (btrfs_test_opt(info, DISCARD))
-- 
2.22.0

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