1 files changed, 26 insertions, 23 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 6a11243ebc51..952f4ccb18de 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -621,7 +621,7 @@ static match_table_t tokens = {
         {Opt_err, NULL}
 };
 
-static int parse_options(char *options, struct super_block *sb)
+static int parse_options(char *options, struct super_block *sb, int is_remount)
 {
         struct nilfs_sb_info *sbi = NILFS_SB(sb);
         char *p;
@@ -666,8 +666,26 @@ static int parse_options(char *options, struct super_block *sb)
                 case Opt_snapshot:
                         if (match_int(&args[0], &option) || option <= 0)
                                 return 0;
-                        if (!(sb->s_flags & MS_RDONLY))
+                        if (is_remount) {
+                                if (!nilfs_test_opt(sbi, SNAPSHOT)) {
+                                        printk(KERN_ERR
+                                               "NILFS: cannot change regular "
+                                               "mount to snapshot.\n");
+                                        return 0;
+                                } else if (option != sbi->s_snapshot_cno) {
+                                        printk(KERN_ERR
+                                               "NILFS: cannot remount to a "
+                                               "different snapshot.\n");
+                                        return 0;
+                                }
+                                break;
+                        }
+                        if (!(sb->s_flags & MS_RDONLY)) {
+                                printk(KERN_ERR "NILFS: cannot mount snapshot "
+                                       "read/write.  A read-only option is "
+                                       "required.\n");
                                 return 0;
+                        }
                         sbi->s_snapshot_cno = option;
                         nilfs_set_opt(sbi, SNAPSHOT);
                         break;
@@ -767,7 +785,7 @@ int nilfs_store_magic_and_option(struct super_block *sb,
         sbi->s_interval = le32_to_cpu(sbp->s_c_interval);
         sbi->s_watermark = le32_to_cpu(sbp->s_c_block_max);
 
-        return !parse_options(data, sb) ? -EINVAL : 0 ;
+        return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
 }
 
 /**
@@ -929,32 +947,17 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
         old_opts.snapshot_cno = sbi->s_snapshot_cno;
         was_snapshot = nilfs_test_opt(sbi, SNAPSHOT);
 
-        if (!parse_options(data, sb)) {
+        if (!parse_options(data, sb, 1)) {
                 err = -EINVAL;
                 goto restore_opts;
         }
         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
 
         err = -EINVAL;
-        if (was_snapshot) {
-                if (!(*flags & MS_RDONLY)) {
-                        printk(KERN_ERR "NILFS (device %s): cannot remount "
-                               "snapshot read/write.\n",
-                               sb->s_id);
-                        goto restore_opts;
-                } else if (sbi->s_snapshot_cno != old_opts.snapshot_cno) {
-                        printk(KERN_ERR "NILFS (device %s): cannot "
-                               "remount to a different snapshot.\n",
-                               sb->s_id);
-                        goto restore_opts;
-                }
-        } else {
-                if (nilfs_test_opt(sbi, SNAPSHOT)) {
-                        printk(KERN_ERR "NILFS (device %s): cannot change "
-                               "a regular mount to a snapshot.\n",
-                               sb->s_id);
-                        goto restore_opts;
-                }
+        if (was_snapshot && !(*flags & MS_RDONLY)) {
+                printk(KERN_ERR "NILFS (device %s): cannot remount snapshot "
+                       "read/write.\n", sb->s_id);
+                goto restore_opts;
         }
 
         if (!nilfs_valid_fs(nilfs)) {