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authorJoe Thornber <ejt@redhat.com>2014-10-15 14:46:58 +0100
committerMike Snitzer <snitzer@redhat.com>2014-11-10 15:25:28 -0500
commit23ca2bb6c6104db9d4cff4e33cbabee303c49d4d (patch)
tree8864d046b4f97795c263705b8795d756c3a50131 /drivers/md/dm-thin.c
parent2d759a46b4d65e1392843cf9df7101897af87008 (diff)
downloadlinux-23ca2bb6c6104db9d4cff4e33cbabee303c49d4d.tar.gz
dm thin: direct dispatch when breaking sharing
This use of direct submission in process_shared_bio() reduces latency for submitting bios in the shared cell by avoiding adding those bios to the deferred list and waiting for the next iteration of the worker. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-thin.c')
-rw-r--r--drivers/md/dm-thin.c70
1 files changed, 57 insertions, 13 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 5036d4b3f368..3f3a66124d46 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1390,11 +1390,53 @@ static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
}
}
+static void __remap_and_issue_shared_cell(void *context,
+ struct dm_bio_prison_cell *cell)
+{
+ struct remap_info *info = context;
+ struct bio *bio;
+
+ while ((bio = bio_list_pop(&cell->bios))) {
+ if ((bio_data_dir(bio) == WRITE) ||
+ (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA)))
+ bio_list_add(&info->defer_bios, bio);
+ else {
+ struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));;
+
+ h->shared_read_entry = dm_deferred_entry_inc(info->tc->pool->shared_read_ds);
+ inc_all_io_entry(info->tc->pool, bio);
+ bio_list_add(&info->issue_bios, bio);
+ }
+ }
+}
+
+static void remap_and_issue_shared_cell(struct thin_c *tc,
+ struct dm_bio_prison_cell *cell,
+ dm_block_t block)
+{
+ struct bio *bio;
+ struct remap_info info;
+
+ info.tc = tc;
+ bio_list_init(&info.defer_bios);
+ bio_list_init(&info.issue_bios);
+
+ cell_visit_release(tc->pool, __remap_and_issue_shared_cell,
+ &info, cell);
+
+ while ((bio = bio_list_pop(&info.defer_bios)))
+ thin_defer_bio(tc, bio);
+
+ while ((bio = bio_list_pop(&info.issue_bios)))
+ remap_and_issue(tc, bio, block);
+}
+
static void process_shared_bio(struct thin_c *tc, struct bio *bio,
dm_block_t block,
- struct dm_thin_lookup_result *lookup_result)
+ struct dm_thin_lookup_result *lookup_result,
+ struct dm_bio_prison_cell *virt_cell)
{
- struct dm_bio_prison_cell *cell;
+ struct dm_bio_prison_cell *data_cell;
struct pool *pool = tc->pool;
struct dm_cell_key key;
@@ -1403,19 +1445,23 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
* of being broken so we have nothing further to do here.
*/
build_data_key(tc->td, lookup_result->block, &key);
- if (bio_detain(pool, &key, bio, &cell))
+ if (bio_detain(pool, &key, bio, &data_cell)) {
+ cell_defer_no_holder(tc, virt_cell);
return;
+ }
- if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size)
- break_sharing(tc, bio, block, &key, lookup_result, cell);
- else {
+ if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size) {
+ break_sharing(tc, bio, block, &key, lookup_result, data_cell);
+ cell_defer_no_holder(tc, virt_cell);
+ } else {
struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
inc_all_io_entry(pool, bio);
- cell_defer_no_holder(tc, cell);
-
remap_and_issue(tc, bio, lookup_result->block);
+
+ remap_and_issue_shared_cell(tc, data_cell, lookup_result->block);
+ remap_and_issue_shared_cell(tc, virt_cell, lookup_result->block);
}
}
@@ -1484,11 +1530,9 @@ static void process_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
switch (r) {
case 0:
- if (lookup_result.shared) {
- process_shared_bio(tc, bio, block, &lookup_result);
- // FIXME: we can't remap because we're waiting on a commit
- cell_defer_no_holder(tc, cell); /* FIXME: pass this cell into process_shared? */
- } else {
+ if (lookup_result.shared)
+ process_shared_bio(tc, bio, block, &lookup_result, cell);
+ else {
inc_all_io_entry(pool, bio);
remap_and_issue(tc, bio, lookup_result.block);
inc_remap_and_issue_cell(tc, cell, lookup_result.block);