partitions: dos: parse extended partition
DOS MBRs might contain an extended partition that holds several logical partitions. Add these to the partitions of the block device. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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@ -116,12 +116,64 @@ static int dos_get_disk_signature(struct param_d *p, void *_priv)
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return 0;
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}
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static void dos_extended_partition(struct block_device *blk, struct partition_desc *pd,
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struct partition *partition)
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{
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uint8_t *buf = dma_alloc(SECTOR_SIZE);
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uint32_t ebr_sector = partition->first_sec;
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struct partition_entry *table = (struct partition_entry *)&buf[0x1be];
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while (pd->used_entries < ARRAY_SIZE(pd->parts)) {
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int rc, i;
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int n = pd->used_entries;
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dev_dbg(blk->dev, "expect EBR in sector %x\n", ebr_sector);
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rc = block_read(blk, buf, ebr_sector, 1);
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if (rc != 0) {
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dev_err(blk->dev, "Cannot read EBR partition table\n");
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goto out;
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}
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/* sanity checks */
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if (buf[0x1fe] != 0x55 || buf[0x1ff] != 0xaa) {
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dev_err(blk->dev, "sector %x doesn't contain an EBR signature\n", ebr_sector);
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goto out;
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}
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for (i = 0x1de; i < 0x1fe; ++i)
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if (buf[i]) {
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dev_err(blk->dev, "EBR's third or fourth partition non-empty\n");
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goto out;
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}
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/* /sanity checks */
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/* the first entry defines the extended partition */
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pd->parts[n].first_sec = ebr_sector +
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get_unaligned_le32(&table[0].partition_start);
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pd->parts[n].size = get_unaligned_le32(&table[0].partition_size);
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pd->parts[n].dos_partition_type = table[0].type;
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pd->used_entries++;
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/* the second entry defines the start of the next ebr if != 0 */
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if (get_unaligned_le32(&table[1].partition_start))
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ebr_sector = partition->first_sec +
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get_unaligned_le32(&table[1].partition_start);
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else
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break;
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}
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out:
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dma_free(buf);
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return;
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}
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/**
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* Check if a DOS like partition describes this block device
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* @param blk Block device to register to
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* @param pd Where to store the partition information
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*
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* It seems at least on ARM this routine canot use temp. stack space for the
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* It seems at least on ARM this routine cannot use temp. stack space for the
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* sector. So, keep the malloc/free.
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*/
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static void dos_partition(void *buf, struct block_device *blk,
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@ -129,6 +181,7 @@ static void dos_partition(void *buf, struct block_device *blk,
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{
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struct partition_entry *table;
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struct partition pentry;
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struct partition *extended_partition = NULL;
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uint8_t *buffer = buf;
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int i;
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struct disk_signature_priv *dsp;
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@ -150,11 +203,32 @@ static void dos_partition(void *buf, struct block_device *blk,
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pd->parts[n].size = pentry.size;
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pd->parts[n].dos_partition_type = pentry.dos_partition_type;
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pd->used_entries++;
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/*
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* Partitions of type 0x05 and 0x0f (and some more)
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* contain extended partitions. Only check for type 0x0f
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* here as this is the easiest to parse and common
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* enough.
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*/
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if (pentry.dos_partition_type == 0x0f) {
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if (!extended_partition)
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extended_partition = &pd->parts[n];
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else
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/*
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* An DOS MBR must only contain a single
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* extended partition. Just ignore all
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* but the first.
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*/
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dev_warn(blk->dev, "Skipping additional extended partition\n");
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}
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} else {
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dev_dbg(blk->dev, "Skipping empty partition %d\n", i);
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}
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}
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if (extended_partition)
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dos_extended_partition(blk, pd, extended_partition);
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dsp = xzalloc(sizeof(*dsp));
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dsp->blk = blk;
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