dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Kiyoshi Ueda
Alasdair G Kergon
parent
cec47e3d4a
commit
e6ee8c0b76
4 changed files with 285 additions and 26 deletions
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@ -1050,6 +1050,12 @@ static int populate_table(struct dm_table *table,
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next = spec->next;
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}
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r = dm_table_set_type(table);
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if (r) {
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DMWARN("unable to set table type");
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return r;
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}
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return dm_table_complete(table);
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}
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@ -1095,6 +1101,13 @@ static int table_load(struct dm_ioctl *param, size_t param_size)
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goto out;
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}
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r = dm_table_alloc_md_mempools(t);
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if (r) {
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DMWARN("unable to allocate mempools for this table");
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dm_table_destroy(t);
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goto out;
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}
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down_write(&_hash_lock);
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hc = dm_get_mdptr(md);
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if (!hc || hc->md != md) {
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@ -41,6 +41,7 @@
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struct dm_table {
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struct mapped_device *md;
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atomic_t holders;
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unsigned type;
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/* btree table */
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unsigned int depth;
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@ -65,6 +66,8 @@ struct dm_table {
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/* events get handed up using this callback */
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void (*event_fn)(void *);
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void *event_context;
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struct dm_md_mempools *mempools;
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};
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/*
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@ -258,6 +261,8 @@ void dm_table_destroy(struct dm_table *t)
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if (t->devices.next != &t->devices)
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free_devices(&t->devices);
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dm_free_md_mempools(t->mempools);
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kfree(t);
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}
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@ -764,6 +769,99 @@ int dm_table_add_target(struct dm_table *t, const char *type,
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return r;
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}
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int dm_table_set_type(struct dm_table *t)
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{
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unsigned i;
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unsigned bio_based = 0, request_based = 0;
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struct dm_target *tgt;
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struct dm_dev_internal *dd;
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struct list_head *devices;
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for (i = 0; i < t->num_targets; i++) {
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tgt = t->targets + i;
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if (dm_target_request_based(tgt))
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request_based = 1;
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else
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bio_based = 1;
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if (bio_based && request_based) {
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DMWARN("Inconsistent table: different target types"
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" can't be mixed up");
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return -EINVAL;
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}
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}
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if (bio_based) {
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/* We must use this table as bio-based */
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t->type = DM_TYPE_BIO_BASED;
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return 0;
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}
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BUG_ON(!request_based); /* No targets in this table */
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/* Non-request-stackable devices can't be used for request-based dm */
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devices = dm_table_get_devices(t);
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list_for_each_entry(dd, devices, list) {
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if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev.bdev))) {
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DMWARN("table load rejected: including"
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" non-request-stackable devices");
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return -EINVAL;
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}
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}
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/*
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* Request-based dm supports only tables that have a single target now.
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* To support multiple targets, request splitting support is needed,
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* and that needs lots of changes in the block-layer.
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* (e.g. request completion process for partial completion.)
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*/
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if (t->num_targets > 1) {
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DMWARN("Request-based dm doesn't support multiple targets yet");
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return -EINVAL;
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}
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t->type = DM_TYPE_REQUEST_BASED;
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return 0;
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}
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unsigned dm_table_get_type(struct dm_table *t)
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{
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return t->type;
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}
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bool dm_table_request_based(struct dm_table *t)
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{
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return dm_table_get_type(t) == DM_TYPE_REQUEST_BASED;
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}
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int dm_table_alloc_md_mempools(struct dm_table *t)
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{
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unsigned type = dm_table_get_type(t);
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if (unlikely(type == DM_TYPE_NONE)) {
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DMWARN("no table type is set, can't allocate mempools");
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return -EINVAL;
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}
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t->mempools = dm_alloc_md_mempools(type);
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if (!t->mempools)
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return -ENOMEM;
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return 0;
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}
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void dm_table_free_md_mempools(struct dm_table *t)
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{
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dm_free_md_mempools(t->mempools);
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t->mempools = NULL;
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}
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struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t)
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{
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return t->mempools;
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}
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static int setup_indexes(struct dm_table *t)
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{
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int i;
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@ -985,6 +1083,19 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
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queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, q);
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dm_table_set_integrity(t);
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/*
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* QUEUE_FLAG_STACKABLE must be set after all queue settings are
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* visible to other CPUs because, once the flag is set, incoming bios
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* are processed by request-based dm, which refers to the queue
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* settings.
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* Until the flag set, bios are passed to bio-based dm and queued to
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* md->deferred where queue settings are not needed yet.
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* Those bios are passed to request-based dm at the resume time.
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*/
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smp_mb();
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if (dm_table_request_based(t))
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queue_flag_set_unlocked(QUEUE_FLAG_STACKABLE, q);
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}
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unsigned int dm_table_get_num_targets(struct dm_table *t)
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162
drivers/md/dm.c
162
drivers/md/dm.c
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@ -190,6 +190,15 @@ struct mapped_device {
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struct bio barrier_bio;
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};
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/*
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* For mempools pre-allocation at the table loading time.
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*/
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struct dm_md_mempools {
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mempool_t *io_pool;
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mempool_t *tio_pool;
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struct bio_set *bs;
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};
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#define MIN_IOS 256
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static struct kmem_cache *_io_cache;
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static struct kmem_cache *_tio_cache;
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@ -1739,10 +1748,22 @@ static struct mapped_device *alloc_dev(int minor)
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INIT_LIST_HEAD(&md->uevent_list);
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spin_lock_init(&md->uevent_lock);
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md->queue = blk_alloc_queue(GFP_KERNEL);
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md->queue = blk_init_queue(dm_request_fn, NULL);
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if (!md->queue)
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goto bad_queue;
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/*
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* Request-based dm devices cannot be stacked on top of bio-based dm
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* devices. The type of this dm device has not been decided yet,
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* although we initialized the queue using blk_init_queue().
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* The type is decided at the first table loading time.
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* To prevent problematic device stacking, clear the queue flag
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* for request stacking support until then.
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*
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* This queue is new, so no concurrency on the queue_flags.
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*/
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queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
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md->saved_make_request_fn = md->queue->make_request_fn;
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md->queue->queuedata = md;
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md->queue->backing_dev_info.congested_fn = dm_any_congested;
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md->queue->backing_dev_info.congested_data = md;
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@ -1751,18 +1772,9 @@ static struct mapped_device *alloc_dev(int minor)
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blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
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md->queue->unplug_fn = dm_unplug_all;
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blk_queue_merge_bvec(md->queue, dm_merge_bvec);
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md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
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if (!md->io_pool)
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goto bad_io_pool;
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md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache);
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if (!md->tio_pool)
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goto bad_tio_pool;
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md->bs = bioset_create(16, 0);
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if (!md->bs)
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goto bad_no_bioset;
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blk_queue_softirq_done(md->queue, dm_softirq_done);
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blk_queue_prep_rq(md->queue, dm_prep_fn);
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blk_queue_lld_busy(md->queue, dm_lld_busy);
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md->disk = alloc_disk(1);
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if (!md->disk)
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@ -1804,12 +1816,6 @@ static struct mapped_device *alloc_dev(int minor)
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bad_thread:
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put_disk(md->disk);
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bad_disk:
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bioset_free(md->bs);
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bad_no_bioset:
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mempool_destroy(md->tio_pool);
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bad_tio_pool:
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mempool_destroy(md->io_pool);
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bad_io_pool:
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blk_cleanup_queue(md->queue);
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bad_queue:
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free_minor(minor);
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@ -1829,9 +1835,12 @@ static void free_dev(struct mapped_device *md)
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unlock_fs(md);
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bdput(md->bdev);
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destroy_workqueue(md->wq);
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mempool_destroy(md->tio_pool);
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mempool_destroy(md->io_pool);
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bioset_free(md->bs);
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if (md->tio_pool)
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mempool_destroy(md->tio_pool);
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if (md->io_pool)
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mempool_destroy(md->io_pool);
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if (md->bs)
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bioset_free(md->bs);
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blk_integrity_unregister(md->disk);
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del_gendisk(md->disk);
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free_minor(minor);
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@ -1846,6 +1855,29 @@ static void free_dev(struct mapped_device *md)
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kfree(md);
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}
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static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
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{
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struct dm_md_mempools *p;
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if (md->io_pool && md->tio_pool && md->bs)
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/* the md already has necessary mempools */
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goto out;
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p = dm_table_get_md_mempools(t);
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BUG_ON(!p || md->io_pool || md->tio_pool || md->bs);
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md->io_pool = p->io_pool;
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p->io_pool = NULL;
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md->tio_pool = p->tio_pool;
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p->tio_pool = NULL;
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md->bs = p->bs;
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p->bs = NULL;
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out:
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/* mempool bind completed, now no need any mempools in the table */
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dm_table_free_md_mempools(t);
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}
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/*
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* Bind a table to the device.
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*/
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@ -1897,6 +1929,18 @@ static int __bind(struct mapped_device *md, struct dm_table *t,
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dm_table_event_callback(t, event_callback, md);
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/*
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* The queue hasn't been stopped yet, if the old table type wasn't
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* for request-based during suspension. So stop it to prevent
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* I/O mapping before resume.
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* This must be done before setting the queue restrictions,
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* because request-based dm may be run just after the setting.
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*/
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if (dm_table_request_based(t) && !blk_queue_stopped(q))
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stop_queue(q);
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__bind_mempools(md, t);
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write_lock(&md->map_lock);
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md->map = t;
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dm_table_set_restrictions(t, q, limits);
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@ -2110,10 +2154,14 @@ static void dm_wq_work(struct work_struct *work)
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up_write(&md->io_lock);
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if (bio_barrier(c))
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process_barrier(md, c);
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else
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__split_and_process_bio(md, c);
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if (dm_request_based(md))
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generic_make_request(c);
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else {
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if (bio_barrier(c))
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process_barrier(md, c);
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else
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__split_and_process_bio(md, c);
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}
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down_write(&md->io_lock);
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}
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@ -2146,6 +2194,13 @@ int dm_swap_table(struct mapped_device *md, struct dm_table *table)
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if (r)
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goto out;
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/* cannot change the device type, once a table is bound */
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if (md->map &&
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(dm_table_get_type(md->map) != dm_table_get_type(table))) {
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DMWARN("can't change the device type after a table is bound");
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goto out;
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}
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__unbind(md);
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r = __bind(md, table, &limits);
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@ -2542,6 +2597,61 @@ int dm_noflush_suspending(struct dm_target *ti)
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}
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EXPORT_SYMBOL_GPL(dm_noflush_suspending);
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struct dm_md_mempools *dm_alloc_md_mempools(unsigned type)
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{
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struct dm_md_mempools *pools = kmalloc(sizeof(*pools), GFP_KERNEL);
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if (!pools)
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return NULL;
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pools->io_pool = (type == DM_TYPE_BIO_BASED) ?
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mempool_create_slab_pool(MIN_IOS, _io_cache) :
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mempool_create_slab_pool(MIN_IOS, _rq_bio_info_cache);
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if (!pools->io_pool)
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goto free_pools_and_out;
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pools->tio_pool = (type == DM_TYPE_BIO_BASED) ?
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mempool_create_slab_pool(MIN_IOS, _tio_cache) :
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mempool_create_slab_pool(MIN_IOS, _rq_tio_cache);
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if (!pools->tio_pool)
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goto free_io_pool_and_out;
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pools->bs = (type == DM_TYPE_BIO_BASED) ?
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bioset_create(16, 0) : bioset_create(MIN_IOS, 0);
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if (!pools->bs)
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goto free_tio_pool_and_out;
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return pools;
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free_tio_pool_and_out:
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mempool_destroy(pools->tio_pool);
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free_io_pool_and_out:
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mempool_destroy(pools->io_pool);
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free_pools_and_out:
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kfree(pools);
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return NULL;
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}
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void dm_free_md_mempools(struct dm_md_mempools *pools)
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{
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if (!pools)
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return;
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if (pools->io_pool)
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mempool_destroy(pools->io_pool);
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if (pools->tio_pool)
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mempool_destroy(pools->tio_pool);
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if (pools->bs)
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bioset_free(pools->bs);
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kfree(pools);
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}
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static struct block_device_operations dm_blk_dops = {
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.open = dm_blk_open,
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.release = dm_blk_close,
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@ -22,6 +22,13 @@
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#define DM_SUSPEND_LOCKFS_FLAG (1 << 0)
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#define DM_SUSPEND_NOFLUSH_FLAG (1 << 1)
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/*
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* Type of table and mapped_device's mempool
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*/
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#define DM_TYPE_NONE 0
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#define DM_TYPE_BIO_BASED 1
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#define DM_TYPE_REQUEST_BASED 2
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/*
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* List of devices that a metadevice uses and should open/close.
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*/
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@ -32,6 +39,7 @@ struct dm_dev_internal {
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};
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struct dm_table;
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struct dm_md_mempools;
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/*-----------------------------------------------------------------
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* Internal table functions.
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@ -51,12 +59,23 @@ void dm_table_postsuspend_targets(struct dm_table *t);
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int dm_table_resume_targets(struct dm_table *t);
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int dm_table_any_congested(struct dm_table *t, int bdi_bits);
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int dm_table_any_busy_target(struct dm_table *t);
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int dm_table_set_type(struct dm_table *t);
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unsigned dm_table_get_type(struct dm_table *t);
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bool dm_table_request_based(struct dm_table *t);
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int dm_table_alloc_md_mempools(struct dm_table *t);
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||||
void dm_table_free_md_mempools(struct dm_table *t);
|
||||
struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
|
||||
|
||||
/*
|
||||
* To check the return value from dm_table_find_target().
|
||||
*/
|
||||
#define dm_target_is_valid(t) ((t)->table)
|
||||
|
||||
/*
|
||||
* To check whether the target type is request-based or not (bio-based).
|
||||
*/
|
||||
#define dm_target_request_based(t) ((t)->type->map_rq != NULL)
|
||||
|
||||
/*-----------------------------------------------------------------
|
||||
* A registry of target types.
|
||||
*---------------------------------------------------------------*/
|
||||
|
|
@ -102,4 +121,10 @@ void dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
|
|||
int dm_kcopyd_init(void);
|
||||
void dm_kcopyd_exit(void);
|
||||
|
||||
/*
|
||||
* Mempool operations
|
||||
*/
|
||||
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type);
|
||||
void dm_free_md_mempools(struct dm_md_mempools *pools);
|
||||
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Reference in a new issue