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| author | Christoph Hellwig <hch@lst.de> | 2021-05-14 15:18:41 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-05-20 07:59:35 -0600 |
| commit | 6c60ff048ca1e0739f39aa25996543c6e662a46c (patch) | |
| tree | 2cbd9f0a9f9c0e49600c999500d7c388e6c8ec4e /fs/block_dev.c | |
| parent | 9a66e6bd7e9ba51d83854aaf7670014e9538e462 (diff) | |
| download | lwn-6c60ff048ca1e0739f39aa25996543c6e662a46c.tar.gz lwn-6c60ff048ca1e0739f39aa25996543c6e662a46c.zip | |
block: prevent block device lookups at the beginning of del_gendisk
As an artifact of how gendisk lookup used to work in earlier kernels,
GENHD_FL_UP is only cleared very late in del_gendisk, and a global lock
is used to prevent opens from succeeding while del_gendisk is tearing
down the gendisk. Switch to clearing the flag early and under bd_mutex
so that callers can use bd_mutex to stabilize the flag, which removes
the need for the global mutex.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210514131842.1600568-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/block_dev.c')
| -rw-r--r-- | fs/block_dev.c | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index eb265d72fce8..580bae995b87 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1298,6 +1298,9 @@ static int __blkdev_get(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; @@ -1332,8 +1335,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode) whole->bd_part_count++; mutex_unlock(&whole->bd_mutex); - if (!(disk->flags & GENHD_FL_UP) || - !bdev_nr_sectors(bdev)) { + if (!bdev_nr_sectors(bdev)) { __blkdev_put(whole, mode, 1); bdput(whole); return -ENXIO; @@ -1364,16 +1366,12 @@ struct block_device *blkdev_get_no_open(dev_t dev) struct block_device *bdev; struct gendisk *disk; - down_read(&bdev_lookup_sem); bdev = bdget(dev); if (!bdev) { - up_read(&bdev_lookup_sem); blk_request_module(dev); - down_read(&bdev_lookup_sem); - bdev = bdget(dev); if (!bdev) - goto unlock; + return NULL; } disk = bdev->bd_disk; @@ -1383,14 +1381,11 @@ struct block_device *blkdev_get_no_open(dev_t dev) goto put_disk; if (!try_module_get(bdev->bd_disk->fops->owner)) goto put_disk; - up_read(&bdev_lookup_sem); return bdev; put_disk: put_disk(disk); bdput: bdput(bdev); -unlock: - up_read(&bdev_lookup_sem); return NULL; } |