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synced 2024-11-16 16:54:20 +08:00
dm thin: prepare to support discard
This patch contains the ground work needed for dm-thin to support discard.
- Adds endio function that replaces shared_read_endio.
- Introduce an explicit 'quiesced' flag into the new_mapping structure.
Before, this was implicitly indicated by m->list being empty.
- The map_info->ptr remains constant for the duration of a bio's trip
through the thin target. Make it easier to reason about it.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Joe Thornber
Alasdair G Kergon
parent
6efd6e8309
commit
eb2aa48d4e
@ -523,7 +523,7 @@ struct pool {
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struct bio_list retry_on_resume_list;
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struct deferred_set ds; /* FIXME: move to thin_c */
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struct deferred_set shared_read_ds;
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struct new_mapping *next_mapping;
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mempool_t *mapping_pool;
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@ -618,6 +618,12 @@ static struct pool *__pool_table_lookup_metadata_dev(struct block_device *md_dev
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/*----------------------------------------------------------------*/
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struct endio_hook {
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struct thin_c *tc;
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struct deferred_entry *shared_read_entry;
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struct new_mapping *overwrite_mapping;
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};
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static void __requeue_bio_list(struct thin_c *tc, struct bio_list *master)
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{
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struct bio *bio;
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@ -628,7 +634,8 @@ static void __requeue_bio_list(struct thin_c *tc, struct bio_list *master)
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bio_list_init(master);
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while ((bio = bio_list_pop(&bios))) {
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if (dm_get_mapinfo(bio)->ptr == tc)
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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if (h->tc == tc)
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bio_endio(bio, DM_ENDIO_REQUEUE);
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else
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bio_list_add(master, bio);
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@ -716,16 +723,11 @@ static void wake_worker(struct pool *pool)
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/*
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* Bio endio functions.
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*/
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struct endio_hook {
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struct thin_c *tc;
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bio_end_io_t *saved_bi_end_io;
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struct deferred_entry *entry;
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};
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struct new_mapping {
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struct list_head list;
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int prepared;
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unsigned quiesced:1;
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unsigned prepared:1;
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struct thin_c *tc;
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dm_block_t virt_block;
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@ -747,7 +749,7 @@ static void __maybe_add_mapping(struct new_mapping *m)
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{
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struct pool *pool = m->tc->pool;
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if (list_empty(&m->list) && m->prepared) {
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if (m->quiesced && m->prepared) {
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list_add(&m->list, &pool->prepared_mappings);
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wake_worker(pool);
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}
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@ -770,7 +772,8 @@ static void copy_complete(int read_err, unsigned long write_err, void *context)
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static void overwrite_endio(struct bio *bio, int err)
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{
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unsigned long flags;
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struct new_mapping *m = dm_get_mapinfo(bio)->ptr;
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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struct new_mapping *m = h->overwrite_mapping;
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struct pool *pool = m->tc->pool;
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m->err = err;
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@ -781,31 +784,6 @@ static void overwrite_endio(struct bio *bio, int err)
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spin_unlock_irqrestore(&pool->lock, flags);
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}
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static void shared_read_endio(struct bio *bio, int err)
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{
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struct list_head mappings;
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struct new_mapping *m, *tmp;
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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unsigned long flags;
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struct pool *pool = h->tc->pool;
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bio->bi_end_io = h->saved_bi_end_io;
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bio_endio(bio, err);
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INIT_LIST_HEAD(&mappings);
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ds_dec(h->entry, &mappings);
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spin_lock_irqsave(&pool->lock, flags);
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list_for_each_entry_safe(m, tmp, &mappings, list) {
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list_del(&m->list);
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INIT_LIST_HEAD(&m->list);
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__maybe_add_mapping(m);
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}
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spin_unlock_irqrestore(&pool->lock, flags);
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mempool_free(h, pool->endio_hook_pool);
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}
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/*----------------------------------------------------------------*/
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/*
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@ -957,6 +935,7 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
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struct new_mapping *m = get_next_mapping(pool);
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INIT_LIST_HEAD(&m->list);
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m->quiesced = 0;
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m->prepared = 0;
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m->tc = tc;
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m->virt_block = virt_block;
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@ -965,7 +944,8 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
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m->err = 0;
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m->bio = NULL;
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ds_add_work(&pool->ds, &m->list);
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if (!ds_add_work(&pool->shared_read_ds, &m->list))
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m->quiesced = 1;
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/*
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* IO to pool_dev remaps to the pool target's data_dev.
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@ -974,9 +954,10 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
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* bio immediately. Otherwise we use kcopyd to clone the data first.
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*/
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if (io_overwrites_block(pool, bio)) {
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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h->overwrite_mapping = m;
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m->bio = bio;
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save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
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dm_get_mapinfo(bio)->ptr = m;
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remap_and_issue(tc, bio, data_dest);
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} else {
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struct dm_io_region from, to;
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@ -1023,6 +1004,7 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
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struct new_mapping *m = get_next_mapping(pool);
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INIT_LIST_HEAD(&m->list);
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m->quiesced = 1;
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m->prepared = 0;
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m->tc = tc;
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m->virt_block = virt_block;
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@ -1040,9 +1022,10 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
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process_prepared_mapping(m);
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else if (io_overwrites_block(pool, bio)) {
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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h->overwrite_mapping = m;
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m->bio = bio;
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save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
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dm_get_mapinfo(bio)->ptr = m;
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remap_and_issue(tc, bio, data_block);
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} else {
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@ -1129,7 +1112,8 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
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*/
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static void retry_on_resume(struct bio *bio)
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{
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struct thin_c *tc = dm_get_mapinfo(bio)->ptr;
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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struct thin_c *tc = h->tc;
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struct pool *pool = tc->pool;
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unsigned long flags;
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@ -1195,13 +1179,9 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
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if (bio_data_dir(bio) == WRITE)
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break_sharing(tc, bio, block, &key, lookup_result, cell);
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else {
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struct endio_hook *h;
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h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO);
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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h->tc = tc;
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h->entry = ds_inc(&pool->ds);
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save_and_set_endio(bio, &h->saved_bi_end_io, shared_read_endio);
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dm_get_mapinfo(bio)->ptr = h;
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h->shared_read_entry = ds_inc(&pool->shared_read_ds);
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cell_release_singleton(cell, bio);
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remap_and_issue(tc, bio, lookup_result->block);
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@ -1325,7 +1305,9 @@ static void process_deferred_bios(struct pool *pool)
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spin_unlock_irqrestore(&pool->lock, flags);
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while ((bio = bio_list_pop(&bios))) {
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struct thin_c *tc = dm_get_mapinfo(bio)->ptr;
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struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
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struct thin_c *tc = h->tc;
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/*
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* If we've got no free new_mapping structs, and processing
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* this bio might require one, we pause until there are some
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@ -1408,6 +1390,18 @@ static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
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wake_worker(pool);
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}
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static struct endio_hook *thin_hook_bio(struct thin_c *tc, struct bio *bio)
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{
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struct pool *pool = tc->pool;
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struct endio_hook *h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO);
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h->tc = tc;
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h->shared_read_entry = NULL;
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h->overwrite_mapping = NULL;
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return h;
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}
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/*
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* Non-blocking function called from the thin target's map function.
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*/
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@ -1420,11 +1414,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio,
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struct dm_thin_device *td = tc->td;
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struct dm_thin_lookup_result result;
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/*
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* Save the thin context for easy access from the deferred bio later.
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*/
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map_context->ptr = tc;
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map_context->ptr = thin_hook_bio(tc, bio);
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if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
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thin_defer_bio(tc, bio);
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return DM_MAPIO_SUBMITTED;
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@ -1604,7 +1594,7 @@ static struct pool *pool_create(struct mapped_device *pool_md,
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pool->low_water_triggered = 0;
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pool->no_free_space = 0;
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bio_list_init(&pool->retry_on_resume_list);
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ds_init(&pool->ds);
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ds_init(&pool->shared_read_ds);
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pool->next_mapping = NULL;
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pool->mapping_pool =
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@ -2394,6 +2384,34 @@ static int thin_map(struct dm_target *ti, struct bio *bio,
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return thin_bio_map(ti, bio, map_context);
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}
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static int thin_endio(struct dm_target *ti,
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struct bio *bio, int err,
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union map_info *map_context)
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{
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unsigned long flags;
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struct endio_hook *h = map_context->ptr;
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struct list_head work;
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struct new_mapping *m, *tmp;
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struct pool *pool = h->tc->pool;
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if (h->shared_read_entry) {
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INIT_LIST_HEAD(&work);
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ds_dec(h->shared_read_entry, &work);
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spin_lock_irqsave(&pool->lock, flags);
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list_for_each_entry_safe(m, tmp, &work, list) {
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list_del(&m->list);
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m->quiesced = 1;
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__maybe_add_mapping(m);
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}
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spin_unlock_irqrestore(&pool->lock, flags);
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}
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mempool_free(h, pool->endio_hook_pool);
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return 0;
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}
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static void thin_postsuspend(struct dm_target *ti)
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{
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if (dm_noflush_suspending(ti))
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@ -2481,6 +2499,7 @@ static struct target_type thin_target = {
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.ctr = thin_ctr,
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.dtr = thin_dtr,
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.map = thin_map,
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.end_io = thin_endio,
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.postsuspend = thin_postsuspend,
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.status = thin_status,
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.iterate_devices = thin_iterate_devices,
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