Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc

[pandora-kernel.git] / fs / ubifs / sb.c

diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index e070c64..57085e4 100644 (file)
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -193,6 +193,7 @@ static int create_default_filesystem(struct ubifs_info *c)
        if (tmp64 > DEFAULT_MAX_RP_SIZE)
                tmp64 = DEFAULT_MAX_RP_SIZE;
        sup->rp_size = cpu_to_le64(tmp64);
+       sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
 
        err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0, UBI_LONGTERM);
        kfree(sup);
@@ -532,17 +533,39 @@ 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) {
@@ -623,7 +646,6 @@ int ubifs_read_superblock(struct ubifs_info *c)
        c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
        c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
        c->main_first = c->leb_cnt - c->main_lebs;
-       c->report_rp_size = ubifs_reported_space(c, c->rp_size);
 
        err = validate_sb(c, sup);
 out: