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block: split __blkdev_get 

Split __blkdev_get into one helper for the whole device, and one for
opening partitions.  This removes the (bounded) recursion when opening
a partition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210525061301.2242282-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-05-25 08:12:54 +02:00 committed by Jens Axboe
parent da7ba72960
commit 362529d928
1 changed files with 61 additions and 65 deletions
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126
fs/block_dev.c
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@ -1290,78 +1290,68 @@ int bdev_disk_changed(struct block_device *bdev, bool invalidate)
*/
EXPORT_SYMBOL_GPL(bdev_disk_changed);
/*
* bd_mutex locking:
*
* mutex_lock(part->bd_mutex)
* mutex_lock_nested(whole->bd_mutex, 1)
*/
static int __blkdev_get(struct block_device *bdev, fmode_t mode)
static int blkdev_get_whole(struct block_device *bdev, fmode_t mode)
{
struct gendisk *disk = bdev->bd_disk;
int ret = 0;
if (!(disk->flags & GENHD_FL_UP))
return -ENXIO;
if (!bdev->bd_openers) {
if (!bdev_is_partition(bdev)) {
ret = 0;
if (disk->fops->open)
ret = disk->fops->open(bdev, mode);
if (!ret)
set_init_blocksize(bdev);
/*
* If the device is invalidated, rescan partition
* if open succeeded or failed with -ENOMEDIUM.
* The latter is necessary to prevent ghost
* partitions on a removed medium.
*/
if (test_bit(GD_NEED_PART_SCAN, &disk->state) &&
(!ret || ret == -ENOMEDIUM))
bdev_disk_changed(bdev, ret == -ENOMEDIUM);
if (ret)
return ret;
} else {
struct block_device *whole = bdgrab(disk->part0);
mutex_lock_nested(&whole->bd_mutex, 1);
ret = __blkdev_get(whole, mode);
if (ret) {
mutex_unlock(&whole->bd_mutex);
bdput(whole);
return ret;
}
whole->bd_part_count++;
mutex_unlock(&whole->bd_mutex);
if (!bdev_nr_sectors(bdev)) {
__blkdev_put(whole, mode, 1);
bdput(whole);
return -ENXIO;
}
set_init_blocksize(bdev);
}
if (bdev->bd_bdi == &noop_backing_dev_info)
bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
} else {
if (!bdev_is_partition(bdev)) {
if (bdev->bd_disk->fops->open)
ret = bdev->bd_disk->fops->open(bdev, mode);
/* the same as first opener case, read comment there */
if (test_bit(GD_NEED_PART_SCAN, &disk->state) &&
(!ret || ret == -ENOMEDIUM))
bdev_disk_changed(bdev, ret == -ENOMEDIUM);
if (ret)
return ret;
if (disk->fops->open) {
ret = disk->fops->open(bdev, mode);
if (ret) {
/* avoid ghost partitions on a removed medium */
if (ret == -ENOMEDIUM &&
test_bit(GD_NEED_PART_SCAN, &disk->state))
bdev_disk_changed(bdev, true);
return ret;
}
}
if (!bdev->bd_openers) {
set_init_blocksize(bdev);
if (bdev->bd_bdi == &noop_backing_dev_info)
bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
}
if (test_bit(GD_NEED_PART_SCAN, &disk->state))
bdev_disk_changed(bdev, false);
bdev->bd_openers++;
return 0;;
}
static int blkdev_get_part(struct block_device *part, fmode_t mode)
{
struct gendisk *disk = part->bd_disk;
struct block_device *whole;
int ret;
if (part->bd_openers)
goto done;
whole = bdgrab(disk->part0);
mutex_lock_nested(&whole->bd_mutex, 1);
ret = blkdev_get_whole(whole, mode);
if (ret) {
mutex_unlock(&whole->bd_mutex);
goto out_put_whole;
}
whole->bd_part_count++;
mutex_unlock(&whole->bd_mutex);
ret = -ENXIO;
if (!bdev_nr_sectors(part))
goto out_blkdev_put;
set_init_blocksize(part);
if (part->bd_bdi == &noop_backing_dev_info)
part->bd_bdi = bdi_get(disk->queue->backing_dev_info);
done:
part->bd_openers++;
return 0;
out_blkdev_put:
__blkdev_put(whole, mode, 1);
out_put_whole:
bdput(whole);
return ret;
}
struct block_device *blkdev_get_no_open(dev_t dev)
@ -1448,7 +1438,13 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
disk_block_events(disk);
mutex_lock(&bdev->bd_mutex);
ret =__blkdev_get(bdev, mode);
ret = -ENXIO;
if (!(disk->flags & GENHD_FL_UP))
goto abort_claiming;
if (bdev_is_partition(bdev))
ret = blkdev_get_part(bdev, mode);
else
ret = blkdev_get_whole(bdev, mode);
if (ret)
goto abort_claiming;
if (mode & FMODE_EXCL) {