[PATCH 1/7] block: refactor rescan_partitions

Christoph Hellwig
2019-11-14T14:34:46Z

Split out a helper that adds one single partition, and another one
calling that dealing with the parsed_partitions state. This makes
it much more obvious how we clean up all state and start again when
using the rescan label.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
block/partition-generic.c | 172 +++++++++++++++++++++-----------------
1 file changed, 94 insertions(+), 78 deletions(-)

diff --git a/block/partition-generic.c b/block/partition-generic.c
index 31bff3fb28af..0909f66aab9d 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -459,128 +459,144 @@ static int drop_partitions(struct gendisk *disk, struct block_device *bdev)
return 0;
}

-int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
+static bool blk_add_partition(struct gendisk *disk, struct block_device *bdev,
+ struct parsed_partitions *state, int p)
{
- struct parsed_partitions *state = NULL;
+ sector_t size = state->parts[p].size;
+ sector_t from = state->parts[p].from;
struct hd_struct *part;
- int p, highest, res;
-rescan:
- if (state && !IS_ERR(state)) {
- free_partitions(state);
- state = NULL;
+
+ if (!size)
+ return true;
+
+ if (from >= get_capacity(disk)) {
+ printk(KERN_WARNING
+ "%s: p%d start %llu is beyond EOD, ",
+ disk->disk_name, p, (unsigned long long) from);
+ if (disk_unlock_native_capacity(disk))
+ return false;
+ return true;
}

- res = drop_partitions(disk, bdev);
- if (res)
- return res;
+ if (from + size > get_capacity(disk)) {
+ printk(KERN_WARNING
+ "%s: p%d size %llu extends beyond EOD, ",
+ disk->disk_name, p, (unsigned long long) size);

- if (disk->fops->revalidate_disk)
- disk->fops->revalidate_disk(disk);
- check_disk_size_change(disk, bdev, true);
- bdev->bd_invalidated = 0;
- if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
+ if (disk_unlock_native_capacity(disk))
+ return false;
+
+ /*
+ * We can not ignore partitions of broken tables created by for
+ * example camera firmware, but we limit them to the end of the
+ * disk to avoid creating invalid block devices.
+ */
+ size = get_capacity(disk) - from;
+ }
+
+ part = add_partition(disk, p, from, size, state->parts[p].flags,
+ &state->parts[p].info);
+ if (IS_ERR(part)) {
+ printk(KERN_ERR " %s: p%d could not be added: %ld\n",
+ disk->disk_name, p, -PTR_ERR(part));
+ return true;
+ }
+
+#ifdef CONFIG_BLK_DEV_MD
+ if (state->parts[p].flags & ADDPART_FLAG_RAID)
+ md_autodetect_dev(part_to_dev(part)->devt);
+#endif
+ return true;
+}
+
+static int blk_add_partitions(struct gendisk *disk, struct block_device *bdev)
+{
+ struct parsed_partitions *state;
+ int ret = -EAGAIN, p, highest;
+
+ state = check_partition(disk, bdev);
+ if (!state)
return 0;
if (IS_ERR(state)) {
/*
- * I/O error reading the partition table. If any
- * partition code tried to read beyond EOD, retry
- * after unlocking native capacity.
+ * I/O error reading the partition table. If we tried to read
+ * beyond EOD, retry after unlocking the native capacity.
*/
if (PTR_ERR(state) == -ENOSPC) {
printk(KERN_WARNING "%s: partition table beyond EOD, ",
disk->disk_name);
if (disk_unlock_native_capacity(disk))
- goto rescan;
+ return -EAGAIN;
}
return -EIO;
}

- /* Partitions are not supported on zoned block devices */
+ /*
+ * Partitions are not supported on zoned block devices.
+ */
if (bdev_is_zoned(bdev)) {
pr_warn("%s: ignoring partition table on zoned block device\n",
disk->disk_name);
- goto out;
+ ret = 0;
+ goto out_free_state;
}

/*
- * If any partition code tried to read beyond EOD, try
- * unlocking native capacity even if partition table is
- * successfully read as we could be missing some partitions.
+ * If we read beyond EOD, try unlocking native capacity even if the
+ * partition table was successfully read as we could be missing some
+ * partitions.
*/
if (state->access_beyond_eod) {
printk(KERN_WARNING
"%s: partition table partially beyond EOD, ",
disk->disk_name);
if (disk_unlock_native_capacity(disk))
- goto rescan;
+ goto out_free_state;
}

/* tell userspace that the media / partition table may have changed */
kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);

- /* Detect the highest partition number and preallocate
- * disk->part_tbl. This is an optimization and not strictly
- * necessary.
+ /*
+ * Detect the highest partition number and preallocate disk->part_tbl.
+ * This is an optimization and not strictly necessary.
*/
for (p = 1, highest = 0; p < state->limit; p++)
if (state->parts[p].size)
highest = p;
-
disk_expand_part_tbl(disk, highest);

- /* add partitions */
- for (p = 1; p < state->limit; p++) {
- sector_t size, from;
+ for (p = 1; p < state->limit; p++)
+ if (!blk_add_partition(disk, bdev, state, p))
+ goto out_free_state;

- size = state->parts[p].size;
- if (!size)
- continue;
+ ret = 0;
+out_free_state:
+ free_partitions(state);
+ return ret;
+}

- from = state->parts[p].from;
- if (from >= get_capacity(disk)) {
- printk(KERN_WARNING
- "%s: p%d start %llu is beyond EOD, ",
- disk->disk_name, p, (unsigned long long) from);
- if (disk_unlock_native_capacity(disk))
- goto rescan;
- continue;
- }
+int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
+{
+ int ret;

- if (from + size > get_capacity(disk)) {
- printk(KERN_WARNING
- "%s: p%d size %llu extends beyond EOD, ",
- disk->disk_name, p, (unsigned long long) size);
-
- if (disk_unlock_native_capacity(disk)) {
- /* free state and restart */
- goto rescan;
- } else {
- /*
- * we can not ignore partitions of broken tables
- * created by for example camera firmware, but
- * we limit them to the end of the disk to avoid
- * creating invalid block devices
- */
- size = get_capacity(disk) - from;
- }
- }
+rescan:
+ ret = drop_partitions(disk, bdev);
+ if (ret)
+ return ret;

- part = add_partition(disk, p, from, size,
- state->parts[p].flags,
- &state->parts[p].info);
- if (IS_ERR(part)) {
- printk(KERN_ERR " %s: p%d could not be added: %ld\n",
- disk->disk_name, p, -PTR_ERR(part));
- continue;
- }
-#ifdef CONFIG_BLK_DEV_MD
- if (state->parts[p].flags & ADDPART_FLAG_RAID)
- md_autodetect_dev(part_to_dev(part)->devt);
-#endif
- }
-out:
- free_partitions(state);
- return 0;
+ if (disk->fops->revalidate_disk)
+ disk->fops->revalidate_disk(disk);
+ check_disk_size_change(disk, bdev, true);
+ bdev->bd_invalidated = 0;
+
+ if (!get_capacity(disk))
+ return 0;
+
+ ret = blk_add_partitions(disk, bdev);
+ if (ret == -EAGAIN)
+ goto rescan;
+ return ret;
}

int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
--
2.20.1