nilfs2: refactor parser of snapshot mount option

Move parser of snapshot mount option to a separate function
nilfs_parse_snapshot_option(), replace simple_strtoull() with
kstrtoull() to avoid checkpatch.pl warning "WARNING: simple_strtoull is
obsolete, use kstrtoull instead", and refine the error message of the
parser.

Link: http://lkml.kernel.org/r/1464875891-5443-9-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 35 insertions, 18 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 33ba6f78de69..c95d369e90aa 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -1205,6 +1205,38 @@ struct nilfs_super_data {
         int flags;
 };
 
+static int nilfs_parse_snapshot_option(const char *option,
+                                       const substring_t *arg,
+                                       struct nilfs_super_data *sd)
+{
+        unsigned long long val;
+        const char *msg = NULL;
+        int err;
+
+        if (!(sd->flags & MS_RDONLY)) {
+                msg = "read-only option is not specified";
+                goto parse_error;
+        }
+
+        err = kstrtoull(arg->from, 0, &val);
+        if (err) {
+                if (err == -ERANGE)
+                        msg = "too large checkpoint number";
+                else
+                        msg = "malformed argument";
+                goto parse_error;
+        } else if (val == 0) {
+                msg = "invalid checkpoint number 0";
+                goto parse_error;
+        }
+        sd->cno = val;
+        return 0;
+
+parse_error:
+        nilfs_msg(NULL, KERN_ERR, "invalid option \"%s\": %s", option, msg);
+        return 1;
+}
+
 /**
  * nilfs_identify - pre-read mount options needed to identify mount instance
  * @data: mount options
@@ -1221,24 +1253,9 @@ static int nilfs_identify(char *data, struct nilfs_super_data *sd)
                 p = strsep(&options, ",");
                 if (p != NULL && *p) {
                         token = match_token(p, tokens, args);
-                        if (token == Opt_snapshot) {
-                                if (!(sd->flags & MS_RDONLY)) {
-                                        ret++;
-                                } else {
-                                        sd->cno = simple_strtoull(args[0].from,
-                                                                  NULL, 0);
-                                        /*
-                                         * No need to see the end pointer;
-                                         * match_token() has done syntax
-                                         * checking.
-                                         */
-                                        if (sd->cno == 0)
-                                                ret++;
-                                }
-                        }
-                        if (ret)
-                                nilfs_msg(NULL, KERN_ERR,
-                                          "invalid mount option: %s", p);
+                        if (token == Opt_snapshot)
+                                ret = nilfs_parse_snapshot_option(p, &args[0],
+                                                                  sd);
                 }
                 if (!options)
                         break;