nilfs2: add norecovery mount option

This adds "norecovery" mount option which disables temporal write
access to read-only mounts or snapshots during mount/recovery.
Without this option, write access will be even performed for those
types of mounts; the temporal write access is needed to mount root
file system read-only after an unclean shutdown.

This option will be helpful when user wants to prevent any write
access to the device.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Eric Sandeen <sandeen@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 990ead43a833..5403b3ef3a42 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -479,6 +479,8 @@ static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
                 seq_printf(seq, ",errors=panic");
         if (nilfs_test_opt(sbi, STRICT_ORDER))
                 seq_printf(seq, ",order=strict");
+        if (nilfs_test_opt(sbi, NORECOVERY))
+                seq_printf(seq, ",norecovery");
 
         return 0;
 }
@@ -547,7 +549,7 @@ static const struct export_operations nilfs_export_ops = {
 
 enum {
         Opt_err_cont, Opt_err_panic, Opt_err_ro,
-        Opt_nobarrier, Opt_snapshot, Opt_order,
+        Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
         Opt_err,
 };
 
@@ -558,6 +560,7 @@ static match_table_t tokens = {
         {Opt_nobarrier, "nobarrier"},
         {Opt_snapshot, "cp=%u"},
         {Opt_order, "order=%s"},
+        {Opt_norecovery, "norecovery"},
         {Opt_err, NULL}
 };
 
@@ -608,6 +611,9 @@ static int parse_options(char *options, struct super_block *sb)
                         sbi->s_snapshot_cno = option;
                         nilfs_set_opt(sbi, SNAPSHOT);
                         break;
+                case Opt_norecovery:
+                        nilfs_set_opt(sbi, NORECOVERY);
+                        break;
                 default:
                         printk(KERN_ERR
                                "NILFS: Unrecognized mount option \"%s\"\n", p);
@@ -863,6 +869,14 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
                 goto restore_opts;
         }
 
+        if (!nilfs_valid_fs(nilfs)) {
+                printk(KERN_WARNING "NILFS (device %s): couldn't "
+                       "remount because the filesystem is in an "
+                       "incomplete recovery state.\n", sb->s_id);
+                err = -EINVAL;
+                goto restore_opts;
+        }
+
         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
                 goto out;
         if (*flags & MS_RDONLY) {