diff options
| author | NeilBrown <neilb@suse.de> | 2015-04-27 14:12:22 +1000 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-04-27 10:27:20 -0600 |
| commit | 6cd18e711dd8075da9d78cfc1239f912ff28968a (patch) | |
| tree | 4383aaa3187800278a5f0f50e3c4c33cec926952 /drivers/md | |
| parent | 393a33970540ac6a2c894b0d6ef3f5d485860884 (diff) | |
block: destroy bdi before blockdev is unregistered.
Because of the peculiar way that md devices are created (automatically
when the device node is opened), a new device can be created and
registered immediately after the
blk_unregister_region(disk_devt(disk), disk->minors);
call in del_gendisk().
Therefore it is important that all visible artifacts of the previous
device are removed before this call. In particular, the 'bdi'.
Since:
commit c4db59d31e39ea067c32163ac961e9c80198fd37
Author: Christoph Hellwig <hch@lst.de>
fs: don't reassign dirty inodes to default_backing_dev_info
moved the
device_unregister(bdi->dev);
call from bdi_unregister() to bdi_destroy() it has been quite easy to
lose a race and have a new (e.g.) "md127" be created after the
blk_unregister_region() call and before bdi_destroy() is ultimately
called by the final 'put_disk', which must come after del_gendisk().
The new device finds that the bdi name is already registered in sysfs
and complains
> [ 9627.630029] WARNING: CPU: 18 PID: 3330 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x5a/0x70()
> [ 9627.630032] sysfs: cannot create duplicate filename '/devices/virtual/bdi/9:127'
We can fix this by moving the bdi_destroy() call out of
blk_release_queue() (which can happen very late when a refcount
reaches zero) and into blk_cleanup_queue() - which happens exactly when the md
device driver calls it.
Then it is only necessary for md to call blk_cleanup_queue() before
del_gendisk(). As loop.c devices are also created on demand by
opening the device node, we make the same change there.
Fixes: c4db59d31e39ea067c32163ac961e9c80198fd37
Reported-by: Azat Khuzhin <a3at.mail@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org (v4.0)
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/md.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index e6178787ce3d..e47d1dd046da 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4754,12 +4754,12 @@ static void md_free(struct kobject *ko) if (mddev->sysfs_state) sysfs_put(mddev->sysfs_state); + if (mddev->queue) + blk_cleanup_queue(mddev->queue); if (mddev->gendisk) { del_gendisk(mddev->gendisk); put_disk(mddev->gendisk); } - if (mddev->queue) - blk_cleanup_queue(mddev->queue); kfree(mddev); } |