diff options
| 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 | |
| parent | 9a66e6bd7e9ba51d83854aaf7670014e9538e462 (diff) | |
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>
| -rw-r--r-- | block/genhd.c | 11 | ||||
| -rw-r--r-- | fs/block_dev.c | 15 | ||||
| -rw-r--r-- | include/linux/genhd.h | 2 |
3 files changed, 6 insertions, 22 deletions
diff --git a/block/genhd.c b/block/genhd.c index 39ca97b0edc6..9f8cb7beaad1 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -29,8 +29,6 @@ static struct kobject *block_depr; -DECLARE_RWSEM(bdev_lookup_sem); - /* for extended dynamic devt allocation, currently only one major is used */ #define NR_EXT_DEVT (1 << MINORBITS) static DEFINE_IDA(ext_devt_ida); @@ -609,13 +607,8 @@ void del_gendisk(struct gendisk *disk) blk_integrity_del(disk); disk_del_events(disk); - /* - * Block lookups of the disk until all bdevs are unhashed and the - * disk is marked as dead (GENHD_FL_UP cleared). - */ - down_write(&bdev_lookup_sem); - mutex_lock(&disk->part0->bd_mutex); + disk->flags &= ~GENHD_FL_UP; blk_drop_partitions(disk); mutex_unlock(&disk->part0->bd_mutex); @@ -629,8 +622,6 @@ void del_gendisk(struct gendisk *disk) remove_inode_hash(disk->part0->bd_inode); set_capacity(disk, 0); - disk->flags &= ~GENHD_FL_UP; - up_write(&bdev_lookup_sem); if (!(disk->flags & GENHD_FL_HIDDEN)) { sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi"); 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; } diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 7e9660ea967d..6fc26f7bdf71 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -306,8 +306,6 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev, } #endif /* CONFIG_SYSFS */ -extern struct rw_semaphore bdev_lookup_sem; - dev_t blk_lookup_devt(const char *name, int partno); void blk_request_module(dev_t devt); #ifdef CONFIG_BLOCK |