diff options
Diffstat (limited to 'fs/ubifs/sb.c')
| -rw-r--r-- | fs/ubifs/sb.c | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c index 9708fda95..00c9cd31a 100644 --- 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) { |