diff options
| -rw-r--r-- | fs/ubifs/sb.c | 35 | ||||
| -rw-r--r-- | fs/ubifs/super.c | 14 | ||||
| -rw-r--r-- | fs/ubifs/ubifs-media.h | 30 | ||||
| -rw-r--r-- | fs/ubifs/ubifs.h | 4 |
4 files changed, 72 insertions, 11 deletions
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c index 0dec47c87c6..57085e43320 100644 --- 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) { diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index 372c7fb6653..302a2056422 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -1351,8 +1351,9 @@ static int mount_ubifs(struct ubifs_info *c) x = (long long)c->log_lebs * c->leb_size + c->max_bud_bytes; ubifs_msg("journal size: %lld bytes (%lld KiB, %lld MiB, %d " "LEBs)", x, x >> 10, x >> 20, c->log_lebs + c->max_bud_cnt); - ubifs_msg("media format: %d (latest is %d)", - c->fmt_version, UBIFS_FORMAT_VERSION); + ubifs_msg("media format: w%d/r%d (latest is w%d/r%d)", + c->fmt_version, c->ro_compat_version, + UBIFS_FORMAT_VERSION, UBIFS_RO_COMPAT_VERSION); ubifs_msg("default compressor: %s", ubifs_compr_name(c->default_compr)); ubifs_msg("reserved for root: %llu bytes (%llu KiB)", c->report_rp_size, c->report_rp_size >> 10); @@ -1492,6 +1493,15 @@ static int ubifs_remount_rw(struct ubifs_info *c) { int err, lnum; + if (c->rw_incompat) { + ubifs_err("the file-system is not R/W-compatible"); + ubifs_msg("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); + return -EROFS; + } + mutex_lock(&c->umount_mutex); dbg_save_space_info(c); c->remounting_rw = 1; diff --git a/fs/ubifs/ubifs-media.h b/fs/ubifs/ubifs-media.h index b25fc36cf72..3eee07e0c49 100644 --- a/fs/ubifs/ubifs-media.h +++ b/fs/ubifs/ubifs-media.h @@ -36,9 +36,31 @@ /* UBIFS node magic number (must not have the padding byte first or last) */ #define UBIFS_NODE_MAGIC 0x06101831 -/* UBIFS on-flash format version */ +/* + * UBIFS on-flash format version. This version is increased when the on-flash + * format is changing. If this happens, UBIFS is will support older versions as + * well. But older UBIFS code will not support newer formats. Format changes + * will be rare and only when absolutely necessary, e.g. to fix a bug or to add + * a new feature. + * + * UBIFS went into mainline kernel with format version 4. The older formats + * were development formats. + */ #define UBIFS_FORMAT_VERSION 4 +/* + * Read-only compatibility version. If the UBIFS format is changed, older UBIFS + * implementations will not be able to mount newer formats in read-write mode. + * However, depending on the change, it may be possible to mount newer formats + * in R/O mode. This is indicated by the R/O compatibility version which is + * stored in the super-block. + * + * This is needed to support boot-loaders which only need R/O mounting. With + * this flag it is possible to do UBIFS format changes without a need to update + * boot-loaders. + */ +#define UBIFS_RO_COMPAT_VERSION 0 + /* Minimum logical eraseblock size in bytes */ #define UBIFS_MIN_LEB_SZ (15*1024) @@ -53,7 +75,7 @@ /* * If compressed data length is less than %UBIFS_MIN_COMPRESS_DIFF bytes - * shorter than uncompressed data length, UBIFS preferes to leave this data + * shorter than uncompressed data length, UBIFS prefers to leave this data * node uncompress, because it'll be read faster. */ #define UBIFS_MIN_COMPRESS_DIFF 64 @@ -586,6 +608,7 @@ struct ubifs_pad_node { * @padding2: reserved for future, zeroes * @time_gran: time granularity in nanoseconds * @uuid: UUID generated when the file system image was created + * @ro_compat_version: UBIFS R/O compatibility version */ struct ubifs_sb_node { struct ubifs_ch ch; @@ -612,7 +635,8 @@ struct ubifs_sb_node { __le64 rp_size; __le32 time_gran; __u8 uuid[16]; - __u8 padding2[3972]; + __le32 ro_compat_version; + __u8 padding2[3968]; } __attribute__ ((packed)); /** diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h index a53b9a6df2b..0a8341e1408 100644 --- a/fs/ubifs/ubifs.h +++ b/fs/ubifs/ubifs.h @@ -934,6 +934,7 @@ struct ubifs_debug_info; * by @commit_sem * @cnt_lock: protects @highest_inum and @max_sqnum counters * @fmt_version: UBIFS on-flash format version + * @ro_compat_version: R/O compatibility version * @uuid: UUID from super block * * @lhead_lnum: log head logical eraseblock number @@ -966,6 +967,7 @@ struct ubifs_debug_info; * recovery) * @bulk_read: enable bulk-reads * @default_compr: default compression algorithm (%UBIFS_COMPR_LZO, etc) + * @rw_incompat: the media is not R/W compatible * * @tnc_mutex: protects the Tree Node Cache (TNC), @zroot, @cnext, @enext, and * @calc_idx_sz @@ -1179,6 +1181,7 @@ struct ubifs_info { unsigned long long cmt_no; spinlock_t cnt_lock; int fmt_version; + int ro_compat_version; unsigned char uuid[16]; int lhead_lnum; @@ -1207,6 +1210,7 @@ struct ubifs_info { unsigned int no_chk_data_crc:1; unsigned int bulk_read:1; unsigned int default_compr:2; + unsigned int rw_incompat:1; struct mutex tnc_mutex; struct ubifs_zbranch zroot; |