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dm: only initialize the request_queue once 

Commit bfebd1cdb4 ("dm: add full blk-mq support to request-based DM")
didn't properly account for the need to short-circuit re-initializing
DM's blk-mq request_queue if it was already initialized.

Otherwise, reloading a blk-mq request-based DM table (either manually
or via multipathd) resulted in errors, see:
 https://www.redhat.com/archives/dm-devel/2015-April/msg00132.html

Fix is to only initialize the request_queue on the initial table load
(when the mapped_device type is assigned).

This is better than having dm_init_request_based_blk_mq_queue() return
early if the queue was already initialized because it elevates the
constraint to a more meaningful location in DM core.  As such the
pre-existing early return in dm_init_request_based_queue() can now be
removed.

Fixes: bfebd1cdb4 ("dm: add full blk-mq support to request-based DM")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Christoph Hellwig 2015-04-30 10:10:36 -04:00 committed by Mike Snitzer
parent b787f68c36
commit 3e6180f0c8
2 changed files with 9 additions and 11 deletions
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17
drivers/md/dm-ioctl.c
View File

@ -1298,21 +1298,22 @@ static int table_load(struct dm_ioctl *param, size_t param_size)
goto err_unlock_md_type; goto err_unlock_md_type;
} }
if (dm_get_md_type(md) == DM_TYPE_NONE) if (dm_get_md_type(md) == DM_TYPE_NONE) {
/* Initial table load: acquire type of table. */ /* Initial table load: acquire type of table. */
dm_set_md_type(md, dm_table_get_type(t)); dm_set_md_type(md, dm_table_get_type(t));
else if (dm_get_md_type(md) != dm_table_get_type(t)) {
/* setup md->queue to reflect md's type (may block) */
r = dm_setup_md_queue(md);
if (r) {
DMWARN("unable to set up device queue for new table.");
goto err_unlock_md_type;
}
} else if (dm_get_md_type(md) != dm_table_get_type(t)) {
DMWARN("can't change device type after initial table load."); DMWARN("can't change device type after initial table load.");
r = -EINVAL; r = -EINVAL;
goto err_unlock_md_type; goto err_unlock_md_type;
} }
/* setup md->queue to reflect md's type (may block) */
r = dm_setup_md_queue(md);
if (r) {
DMWARN("unable to set up device queue for new table.");
goto err_unlock_md_type;
}
dm_unlock_md_type(md); dm_unlock_md_type(md);
/* stage inactive table */ /* stage inactive table */

3
drivers/md/dm.c
View File

@ -2662,9 +2662,6 @@ static int dm_init_request_based_queue(struct mapped_device *md)
{ {
struct request_queue *q = NULL; struct request_queue *q = NULL;
if (md->queue->elevator)
return 0;
/* Fully initialize the queue */ /* Fully initialize the queue */
q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL); q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
if (!q) if (!q)