Update CHANGELOG, coding style cleanup.

[pandora-u-boot.git] / fs / ubifs / sb.c

diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 9708fda..00c9cd3 100644 (file)
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -235,17 +235,39 @@ int ubifs_read_superblock(struct ubifs_info *c)
        if (IS_ERR(sup))
                return PTR_ERR(sup);
 
+       c->fmt_version = le32_to_cpu(sup->fmt_version);
+       c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
+
        /*
         * The software supports all previous versions but not future versions,
         * due to the unavailability of time-travelling equipment.
         */
-       c->fmt_version = le32_to_cpu(sup->fmt_version);
        if (c->fmt_version > UBIFS_FORMAT_VERSION) {
-               ubifs_err("on-flash format version is %d, but software only "
-                         "supports up to version %d", c->fmt_version,
-                         UBIFS_FORMAT_VERSION);
-               err = -EINVAL;
-               goto out;
+               struct super_block *sb = c->vfs_sb;
+               int mounting_ro = sb->s_flags & MS_RDONLY;
+
+               ubifs_assert(!c->ro_media || mounting_ro);
+               if (!mounting_ro ||
+                   c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
+                       ubifs_err("on-flash format version is w%d/r%d, but "
+                                 "software only supports up to version "
+                                 "w%d/r%d", c->fmt_version,
+                                 c->ro_compat_version, UBIFS_FORMAT_VERSION,
+                                 UBIFS_RO_COMPAT_VERSION);
+                       if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
+                               ubifs_msg("only R/O mounting is possible");
+                               err = -EROFS;
+                       } else
+                               err = -EINVAL;
+                       goto out;
+               }
+
+               /*
+                * The FS is mounted R/O, and the media format is
+                * R/O-compatible with the UBIFS implementation, so we can
+                * mount.
+                */
+               c->rw_incompat = 1;
        }
 
        if (c->fmt_version < 3) {