nilfs2: pass remount flag to parse_options

This adds is_remount argument to the parse_options() function that
obtains mount options from strings.

Previously, parse_options did not distinguish context whether it's
called for a new mount or remount, so the caller needed additional
verifications outside the function.

This allows parse_options to verify options and print messages
depending on the context.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 6a11243ebc51f8cce33670f95e21e7e26d1a7cd2..952f4ccb18de4b0d6b23d3e21bbb23597e07c4e4 100644 (file)
--- 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)) {