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authorChristoph Hellwig <hch@lst.de>2021-05-14 15:18:41 +0200
committerJens Axboe <axboe@kernel.dk>2021-05-20 07:59:35 -0600
commit6c60ff048ca1e0739f39aa25996543c6e662a46c (patch)
tree2cbd9f0a9f9c0e49600c999500d7c388e6c8ec4e /fs/block_dev.c
parent9a66e6bd7e9ba51d83854aaf7670014e9538e462 (diff)
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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.c15
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;
}