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loop: fix LO_FLAGS_PARTSCAN hang 

loop_reread_partitions() needs to do I/O, but we just froze the queue,
so we end up waiting forever. This can easily be reproduced with losetup
-P. Fix it by moving the reread to after we unfreeze the queue.

Fixes: ecdd09597a ("block/loop: fix race between I/O and set_status")
Reported-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Omar Sandoval 2017-03-01 10:42:38 -08:00 committed by Jens Axboe
parent 302ad8cc09
commit e02898b423
1 changed files with 8 additions and 7 deletions
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15
drivers/block/loop.c
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@ -1142,13 +1142,6 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
(info->lo_flags & LO_FLAGS_AUTOCLEAR)) (info->lo_flags & LO_FLAGS_AUTOCLEAR))
lo->lo_flags ^= LO_FLAGS_AUTOCLEAR; lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
!(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
lo->lo_flags |= LO_FLAGS_PARTSCAN;
lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
loop_reread_partitions(lo, lo->lo_device);
}
lo->lo_encrypt_key_size = info->lo_encrypt_key_size; lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
lo->lo_init[0] = info->lo_init[0]; lo->lo_init[0] = info->lo_init[0];
lo->lo_init[1] = info->lo_init[1]; lo->lo_init[1] = info->lo_init[1];
@ -1163,6 +1156,14 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
exit: exit:
blk_mq_unfreeze_queue(lo->lo_queue); blk_mq_unfreeze_queue(lo->lo_queue);
if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) &&
!(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
lo->lo_flags |= LO_FLAGS_PARTSCAN;
lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
loop_reread_partitions(lo, lo->lo_device);
}
return err; return err;
} }