From 362529d9280af4b08d2c25a4b39b8e5ae7658f9a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 25 May 2021 08:12:54 +0200 Subject: [PATCH] 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 Reviewed-by: Ming Lei Reviewed-by: Hannes Reinecke Link: https://lore.kernel.org/r/20210525061301.2242282-2-hch@lst.de Signed-off-by: Jens Axboe --- fs/block_dev.c | 118 ++++++++++++++++++++++++++++----------------------------- 1 file changed, 57 insertions(+), 61 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 6cc4d4c..2b5073e 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1290,78 +1290,68 @@ rescan: */ 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 (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) { - if (!bdev_is_partition(bdev)) { - ret = 0; - if (disk->fops->open) - ret = disk->fops->open(bdev, mode); + 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;; +} - if (!ret) - set_init_blocksize(bdev); +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 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 (part->bd_openers) + goto done; - 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); + 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); - if (!bdev_nr_sectors(bdev)) { - __blkdev_put(whole, mode, 1); - bdput(whole); - return -ENXIO; - } - set_init_blocksize(bdev); - } + ret = -ENXIO; + if (!bdev_nr_sectors(part)) + goto out_blkdev_put; - 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; - } - } - bdev->bd_openers++; + 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) { -- 2.7.4