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. Fix DM core device cleanup regression -- due to a latent race that was

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exposed by the bdi changes that were introduced during the 4.0 merge.
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Merge tag 'dm-4.0-fix-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fix from Mike Snitzer:
 "Fix DM core device cleanup regression -- due to a latent race that was
  exposed by the bdi changes that were introduced during the 4.0 merge"

* tag 'dm-4.0-fix-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: fix add_disk() NULL pointer due to race with free_dev()
This commit is contained in:
Linus Torvalds 2015-03-26 14:53:47 -07:00
commit be8a9bc633
1 changed files with 16 additions and 10 deletions
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26
drivers/md/dm.c
View file

@ -433,7 +433,6 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode)
dm_get(md);
atomic_inc(&md->open_count);
out:
spin_unlock(&_minor_lock);
@ -442,16 +441,20 @@ out:
static void dm_blk_close(struct gendisk *disk, fmode_t mode)
{
struct mapped_device *md = disk->private_data;
struct mapped_device *md;
spin_lock(&_minor_lock);
md = disk->private_data;
if (WARN_ON(!md))
goto out;
if (atomic_dec_and_test(&md->open_count) &&
(test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
queue_work(deferred_remove_workqueue, &deferred_remove_work);
dm_put(md);
out:
spin_unlock(&_minor_lock);
}
@ -2241,7 +2244,6 @@ static void free_dev(struct mapped_device *md)
int minor = MINOR(disk_devt(md->disk));
unlock_fs(md);
bdput(md->bdev);
destroy_workqueue(md->wq);
if (md->kworker_task)
@ -2252,19 +2254,22 @@ static void free_dev(struct mapped_device *md)
mempool_destroy(md->rq_pool);
if (md->bs)
bioset_free(md->bs);
blk_integrity_unregister(md->disk);
del_gendisk(md->disk);
cleanup_srcu_struct(&md->io_barrier);
free_table_devices(&md->table_devices);
free_minor(minor);
dm_stats_cleanup(&md->stats);
spin_lock(&_minor_lock);
md->disk->private_data = NULL;
spin_unlock(&_minor_lock);
if (blk_get_integrity(md->disk))
blk_integrity_unregister(md->disk);
del_gendisk(md->disk);
put_disk(md->disk);
blk_cleanup_queue(md->queue);
dm_stats_cleanup(&md->stats);
bdput(md->bdev);
free_minor(minor);
module_put(THIS_MODULE);
kfree(md);
}
@ -2642,8 +2647,9 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
might_sleep();
spin_lock(&_minor_lock);
map = dm_get_live_table(md, &srcu_idx);
spin_lock(&_minor_lock);
idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
set_bit(DMF_FREEING, &md->flags);
spin_unlock(&_minor_lock);