[PATCH v5 1/2] btrfs: Introduce "rescue=" mount option

Qu Wenruo
2019-10-29T05:02:58Z

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

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

And obviously, user can specify rescue options one by one like:
"ro,rescue=nologreplay,rescue=usebackuproot"

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

- usebackuproot
Now it's "rescue=usebackuproot"

- nologreplay
Now it's "rescue=nologreplay"

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/super.c | 79 +++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 71 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 1b151af25772..4cc88173e26d 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -313,7 +313,6 @@ enum {
Opt_datasum, Opt_nodatasum,
Opt_defrag, Opt_nodefrag,
Opt_discard, Opt_nodiscard,
- Opt_nologreplay,
Opt_norecovery,
Opt_ratio,
Opt_rescan_uuid_tree,
@@ -327,9 +326,13 @@ enum {
Opt_subvolid,
Opt_thread_pool,
Opt_treelog, Opt_notreelog,
- Opt_usebackuproot,
Opt_user_subvol_rm_allowed,

+ /* Rescue options */
+ Opt_rescue,
+ Opt_usebackuproot,
+ Opt_nologreplay,
+
/* Deprecated options */
Opt_alloc_start,
Opt_recovery,
@@ -376,7 +379,6 @@ static const match_table_t tokens = {
{Opt_nodefrag, "noautodefrag"},
{Opt_discard, "discard"},
{Opt_nodiscard, "nodiscard"},
- {Opt_nologreplay, "nologreplay"},
{Opt_norecovery, "norecovery"},
{Opt_ratio, "metadata_ratio=%u"},
{Opt_rescan_uuid_tree, "rescan_uuid_tree"},
@@ -394,9 +396,13 @@ static const match_table_t tokens = {
{Opt_thread_pool, "thread_pool=%u"},
{Opt_treelog, "treelog"},
{Opt_notreelog, "notreelog"},
- {Opt_usebackuproot, "usebackuproot"},
{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},

+ /* Recovery options */
+ {Opt_rescue, "rescue=%s"},
+ {Opt_nologreplay, "nologreplay"},
+ {Opt_usebackuproot, "usebackuproot"},
+
/* Deprecated options */
{Opt_alloc_start, "alloc_start=%s"},
{Opt_recovery, "recovery"},
@@ -419,6 +425,55 @@ static const match_table_t tokens = {
{Opt_err, NULL},
};

+static const match_table_t rescue_tokens = {
+ {Opt_usebackuproot, "usebackuproot"},
+ {Opt_nologreplay, "nologreplay"},
+ {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.
@@ -675,6 +730,8 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
break;
case Opt_norecovery:
case Opt_nologreplay:
+ btrfs_warn(info,
+ "'nologreplay' is deprecated, use 'rescue=nologreplay' instead");
btrfs_set_and_info(info, NOLOGREPLAY,
"disabling log replay at mount time");
break;
@@ -763,10 +820,11 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
"disabling auto defrag");
break;
case Opt_recovery:
- btrfs_warn(info,
- "'recovery' is deprecated, use 'usebackuproot' instead");
- /* fall through */
case Opt_usebackuproot:
+ btrfs_warn(info,
+ "'%s' is deprecated, use 'rescue=usebackuproot' instead",
+ token == Opt_recovery ? "recovery" :
+ "usebackuproot");
btrfs_info(info,
"trying to use backup root at mount time");
btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
@@ -853,6 +911,11 @@ 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;
@@ -1319,7 +1382,7 @@ 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))
--
2.23.0