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author | Mike Snitzer <snitzer@redhat.com> | 2010-08-12 04:14:02 +0100 |
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committer | Alasdair G Kergon <agk@redhat.com> | 2010-08-12 04:14:02 +0100 |
commit | 4a0b4ddf261fc89c050fe0a10ec57a61251d7ac0 (patch) | |
tree | 23854bb6d42e7cedec9100fcdd63c307ee5d1332 /drivers/md/dm-ioctl.c | |
parent | a5664dad7e1a278d2915c2bf79cf42250e12d7db (diff) | |
download | op-kernel-dev-4a0b4ddf261fc89c050fe0a10ec57a61251d7ac0.zip op-kernel-dev-4a0b4ddf261fc89c050fe0a10ec57a61251d7ac0.tar.gz |
dm: do not initialise full request queue when bio based
Change bio-based mapped devices no longer to have a fully initialized
request_queue (request_fn, elevator, etc). This means bio-based DM
devices no longer register elevator sysfs attributes ('iosched/' tree
or 'scheduler' other than "none").
In contrast, a request-based DM device will continue to have a full
request_queue and will register elevator sysfs attributes. Therefore
a user can determine a DM device's type by checking if elevator sysfs
attributes exist.
First allocate a minimalist request_queue structure for a DM device
(needed for both bio and request-based DM).
Initialization of a full request_queue is deferred until it is known
that the DM device is request-based, at the end of the table load
sequence.
Factor DM device's request_queue initialization:
- common to both request-based and bio-based into dm_init_md_queue().
- specific to request-based into dm_init_request_based_queue().
The md->type_lock mutex is used to protect md->queue, in addition to
md->type, during table_load().
A DM device's first table_load will establish the immutable md->type.
But md->queue initialization, based on md->type, may fail at that time
(because blk_init_allocated_queue cannot allocate memory). Therefore
any subsequent table_load must (re)try dm_setup_md_queue independently of
establishing md->type.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-ioctl.c')
-rw-r--r-- | drivers/md/dm-ioctl.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 4702f38..ed85859 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1189,7 +1189,7 @@ static int table_load(struct dm_ioctl *param, size_t param_size) goto out; } - /* Protect md->type against concurrent table loads. */ + /* Protect md->type and md->queue against concurrent table loads. */ dm_lock_md_type(md); if (dm_get_md_type(md) == DM_TYPE_NONE) /* Initial table load: acquire type of table. */ @@ -1201,6 +1201,15 @@ static int table_load(struct dm_ioctl *param, size_t param_size) r = -EINVAL; goto out; } + + /* 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."); + dm_table_destroy(t); + dm_unlock_md_type(md); + goto out; + } dm_unlock_md_type(md); /* stage inactive table */ |