[dm-devel] [for-3.19 PATCH 14/17] dm thin: defer whole cells rather than individual bios
Mike Snitzer
snitzer at redhat.com
Fri Oct 17 06:07:04 UTC 2014
From: Joe Thornber <ejt at redhat.com>
This avoids dropping the cell, so increases the probability that other
bios will collect within the cell, rather than being passed individually
to the worker.
Also add required process_cell and process_discard_cell error handling
wrappers and set associated pool-mode function pointers accordingly.
Signed-off-by: Joe Thornber <ejt at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm-bio-prison.h | 1 +
drivers/md/dm-thin.c | 233 +++++++++++++++++++++++++++++++++++----------
2 files changed, 183 insertions(+), 51 deletions(-)
diff --git a/drivers/md/dm-bio-prison.h b/drivers/md/dm-bio-prison.h
index 997a439..c0cddb1 100644
--- a/drivers/md/dm-bio-prison.h
+++ b/drivers/md/dm-bio-prison.h
@@ -35,6 +35,7 @@ struct dm_cell_key {
* themselves.
*/
struct dm_bio_prison_cell {
+ struct list_head user_list; /* for client use */
struct rb_node node;
struct dm_cell_key key;
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 176362e..507e674 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -202,6 +202,7 @@ struct pool_features {
struct thin_c;
typedef void (*process_bio_fn)(struct thin_c *tc, struct bio *bio);
+typedef void (*process_cell_fn)(struct thin_c *tc, struct dm_bio_prison_cell *cell);
typedef void (*process_mapping_fn)(struct dm_thin_new_mapping *m);
struct pool {
@@ -246,6 +247,9 @@ struct pool {
process_bio_fn process_bio;
process_bio_fn process_discard;
+ process_cell_fn process_cell;
+ process_cell_fn process_discard_cell;
+
process_mapping_fn process_prepared_mapping;
process_mapping_fn process_prepared_discard;
};
@@ -282,6 +286,7 @@ struct thin_c {
struct dm_thin_device *td;
bool requeue_mode:1;
spinlock_t lock;
+ struct list_head deferred_cells;
struct bio_list deferred_bio_list;
struct bio_list retry_on_resume_list;
struct rb_root sort_bio_list; /* sorted list of deferred bios */
@@ -346,19 +351,6 @@ static void cell_release_no_holder(struct pool *pool,
dm_bio_prison_free_cell(pool->prison, cell);
}
-static void cell_defer_no_holder_no_free(struct thin_c *tc,
- struct dm_bio_prison_cell *cell)
-{
- struct pool *pool = tc->pool;
- unsigned long flags;
-
- spin_lock_irqsave(&tc->lock, flags);
- dm_cell_release_no_holder(pool->prison, cell, &tc->deferred_bio_list);
- spin_unlock_irqrestore(&tc->lock, flags);
-
- wake_worker(pool);
-}
-
static void cell_error_with_code(struct pool *pool,
struct dm_bio_prison_cell *cell, int error_code)
{
@@ -371,6 +363,11 @@ static void cell_error(struct pool *pool, struct dm_bio_prison_cell *cell)
cell_error_with_code(pool, cell, -EIO);
}
+static void cell_success(struct pool *pool, struct dm_bio_prison_cell *cell)
+{
+ cell_error_with_code(pool, cell, 0);
+}
+
/*----------------------------------------------------------------*/
/*
@@ -706,6 +703,28 @@ static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *c
wake_worker(pool);
}
+static void thin_defer_bio(struct thin_c *tc, struct bio *bio);
+
+static void inc_remap_and_issue_cell(struct thin_c *tc,
+ struct dm_bio_prison_cell *cell,
+ dm_block_t block)
+{
+ struct bio *bio;
+ struct bio_list bios;
+
+ bio_list_init(&bios);
+ cell_release_no_holder(tc->pool, cell, &bios);
+
+ while ((bio = bio_list_pop(&bios))) {
+ if (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA))
+ thin_defer_bio(tc, bio);
+ else {
+ inc_all_io_entry(tc->pool, bio);
+ remap_and_issue(tc, bio, block);
+ }
+ }
+}
+
static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
{
if (m->bio) {
@@ -1193,20 +1212,17 @@ static void retry_bios_on_resume(struct pool *pool, struct dm_bio_prison_cell *c
retry_on_resume(bio);
}
-static void process_discard(struct thin_c *tc, struct bio *bio)
+static void process_discard_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
{
int r;
+ struct bio *bio = cell->holder;
struct pool *pool = tc->pool;
- struct dm_bio_prison_cell *cell, *cell2;
- struct dm_cell_key key, key2;
+ struct dm_bio_prison_cell *cell2;
+ struct dm_cell_key key2;
dm_block_t block = get_bio_block(tc, bio);
struct dm_thin_lookup_result lookup_result;
struct dm_thin_new_mapping *m;
- build_virtual_key(tc->td, block, &key);
- if (bio_detain(tc->pool, &key, bio, &cell))
- return;
-
r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
switch (r) {
case 0:
@@ -1273,6 +1289,19 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
}
}
+static void process_discard_bio(struct thin_c *tc, struct bio *bio)
+{
+ struct dm_bio_prison_cell *cell;
+ struct dm_cell_key key;
+ dm_block_t block = get_bio_block(tc, bio);
+
+ build_virtual_key(tc->td, block, &key);
+ if (bio_detain(tc->pool, &key, bio, &cell))
+ return;
+
+ process_discard_cell(tc, cell);
+}
+
static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
struct dm_cell_key *key,
struct dm_thin_lookup_result *lookup_result,
@@ -1379,34 +1408,25 @@ static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block
}
}
-static void process_bio(struct thin_c *tc, struct bio *bio)
+static void process_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
{
int r;
struct pool *pool = tc->pool;
+ struct bio *bio = cell->holder;
dm_block_t block = get_bio_block(tc, bio);
- struct dm_bio_prison_cell *cell;
- struct dm_cell_key key;
struct dm_thin_lookup_result lookup_result;
- /*
- * If cell is already occupied, then the block is already
- * being provisioned so we have nothing further to do here.
- */
- build_virtual_key(tc->td, block, &key);
- if (bio_detain(pool, &key, bio, &cell))
- return;
-
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 {
inc_all_io_entry(pool, bio);
- cell_defer_no_holder(tc, cell);
-
remap_and_issue(tc, bio, lookup_result.block);
+ inc_remap_and_issue_cell(tc, cell, lookup_result.block);
}
break;
@@ -1440,7 +1460,26 @@ static void process_bio(struct thin_c *tc, struct bio *bio)
}
}
-static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
+static void process_bio(struct thin_c *tc, struct bio *bio)
+{
+ struct pool *pool = tc->pool;
+ dm_block_t block = get_bio_block(tc, bio);
+ struct dm_bio_prison_cell *cell;
+ struct dm_cell_key key;
+
+ /*
+ * If cell is already occupied, then the block is already
+ * being provisioned so we have nothing further to do here.
+ */
+ build_virtual_key(tc->td, block, &key);
+ if (bio_detain(pool, &key, bio, &cell))
+ return;
+
+ process_cell(tc, cell);
+}
+
+static void __process_bio_read_only(struct thin_c *tc, struct bio *bio,
+ struct dm_bio_prison_cell *cell)
{
int r;
int rw = bio_data_dir(bio);
@@ -1450,15 +1489,21 @@ static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
switch (r) {
case 0:
- if (lookup_result.shared && (rw == WRITE) && bio->bi_iter.bi_size)
+ if (lookup_result.shared && (rw == WRITE) && bio->bi_iter.bi_size) {
handle_unserviceable_bio(tc->pool, bio);
- else {
+ if (cell)
+ cell_defer_no_holder(tc, cell);
+ } else {
inc_all_io_entry(tc->pool, bio);
remap_and_issue(tc, bio, lookup_result.block);
+ if (cell)
+ inc_remap_and_issue_cell(tc, cell, lookup_result.block);
}
break;
case -ENODATA:
+ if (cell)
+ cell_defer_no_holder(tc, cell);
if (rw != READ) {
handle_unserviceable_bio(tc->pool, bio);
break;
@@ -1477,11 +1522,23 @@ static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
default:
DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
__func__, r);
+ if (cell)
+ cell_defer_no_holder(tc, cell);
bio_io_error(bio);
break;
}
}
+static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
+{
+ __process_bio_read_only(tc, bio, NULL);
+}
+
+static void process_cell_read_only(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+ __process_bio_read_only(tc, cell->holder, cell);
+}
+
static void process_bio_success(struct thin_c *tc, struct bio *bio)
{
bio_endio(bio, 0);
@@ -1492,6 +1549,16 @@ static void process_bio_fail(struct thin_c *tc, struct bio *bio)
bio_io_error(bio);
}
+static void process_cell_success(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+ cell_success(tc->pool, cell);
+}
+
+static void process_cell_fail(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+ cell_error(tc->pool, cell);
+}
+
/*
* FIXME: should we also commit due to size of transaction, measured in
* metadata blocks?
@@ -1624,6 +1691,51 @@ static void process_thin_deferred_bios(struct thin_c *tc)
blk_finish_plug(&plug);
}
+static void process_thin_deferred_cells(struct thin_c *tc)
+{
+ struct pool *pool = tc->pool;
+ unsigned long flags;
+ struct list_head cells;
+ struct dm_bio_prison_cell *cell, *tmp;
+
+ // FIXME: push down into per cell processing
+ if (tc->requeue_mode) {
+ requeue_bio_list(tc, &tc->deferred_bio_list);
+ return;
+ }
+
+ INIT_LIST_HEAD(&cells);
+
+ spin_lock_irqsave(&tc->lock, flags);
+ list_splice_init(&tc->deferred_cells, &cells);
+ spin_unlock_irqrestore(&tc->lock, flags);
+
+ if (list_empty(&cells))
+ return;
+
+ list_for_each_entry_safe(cell, tmp, &cells, user_list) {
+ BUG_ON(!cell->holder);
+
+ /*
+ * If we've got no free new_mapping structs, and processing
+ * this bio might require one, we pause until there are some
+ * prepared mappings to process.
+ */
+ if (ensure_next_mapping(pool)) {
+ spin_lock_irqsave(&tc->lock, flags);
+ list_add(&cell->user_list, &tc->deferred_cells);
+ list_splice(&cells, &tc->deferred_cells);
+ spin_unlock_irqrestore(&tc->lock, flags);
+ break;
+ }
+
+ if (cell->holder->bi_rw & REQ_DISCARD)
+ pool->process_discard_cell(tc, cell);
+ else
+ pool->process_cell(tc, cell);
+ }
+}
+
static void thin_get(struct thin_c *tc);
static void thin_put(struct thin_c *tc);
@@ -1672,6 +1784,7 @@ static void process_deferred_bios(struct pool *pool)
tc = get_first_thin(pool);
while (tc) {
+ process_thin_deferred_cells(tc);
process_thin_deferred_bios(tc);
tc = get_next_thin(pool, tc);
}
@@ -1850,6 +1963,8 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
dm_pool_metadata_read_only(pool->pmd);
pool->process_bio = process_bio_fail;
pool->process_discard = process_bio_fail;
+ pool->process_cell = process_cell_fail;
+ pool->process_discard_cell = process_cell_fail;
pool->process_prepared_mapping = process_prepared_mapping_fail;
pool->process_prepared_discard = process_prepared_discard_fail;
@@ -1862,6 +1977,8 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
dm_pool_metadata_read_only(pool->pmd);
pool->process_bio = process_bio_read_only;
pool->process_discard = process_bio_success;
+ pool->process_cell = process_cell_read_only;
+ pool->process_discard_cell = process_cell_success;
pool->process_prepared_mapping = process_prepared_mapping_fail;
pool->process_prepared_discard = process_prepared_discard_passdown;
@@ -1880,7 +1997,9 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
if (old_mode != new_mode)
notify_of_pool_mode_change(pool, "out-of-data-space");
pool->process_bio = process_bio_read_only;
- pool->process_discard = process_discard;
+ pool->process_discard = process_discard_bio;
+ pool->process_cell = process_cell_read_only;
+ pool->process_discard_cell = process_discard_cell;
pool->process_prepared_mapping = process_prepared_mapping;
pool->process_prepared_discard = process_prepared_discard_passdown;
@@ -1893,7 +2012,9 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
notify_of_pool_mode_change(pool, "write");
dm_pool_metadata_read_write(pool->pmd);
pool->process_bio = process_bio;
- pool->process_discard = process_discard;
+ pool->process_discard = process_discard_bio;
+ pool->process_cell = process_cell;
+ pool->process_discard_cell = process_discard_cell;
pool->process_prepared_mapping = process_prepared_mapping;
pool->process_prepared_discard = process_prepared_discard;
break;
@@ -1955,6 +2076,18 @@ static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
wake_worker(pool);
}
+static void thin_defer_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+ unsigned long flags;
+ struct pool *pool = tc->pool;
+
+ spin_lock_irqsave(&tc->lock, flags);
+ list_add_tail(&cell->user_list, &tc->deferred_cells);
+ spin_unlock_irqrestore(&tc->lock, flags);
+
+ wake_worker(pool);
+}
+
static void thin_hook_bio(struct thin_c *tc, struct bio *bio)
{
struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
@@ -1975,8 +2108,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
dm_block_t block = get_bio_block(tc, bio);
struct dm_thin_device *td = tc->td;
struct dm_thin_lookup_result result;
- struct dm_bio_prison_cell cell1, cell2;
- struct dm_bio_prison_cell *cell_result;
+ struct dm_bio_prison_cell *virt_cell, *data_cell;
struct dm_cell_key key;
thin_hook_bio(tc, bio);
@@ -2001,7 +2133,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* there's a race with discard.
*/
build_virtual_key(tc->td, block, &key);
- if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1, &cell_result))
+ if (bio_detain(tc->pool, &key, bio, &virt_cell))
return DM_MAPIO_SUBMITTED;
r = dm_thin_find_block(td, block, 0, &result);
@@ -2026,20 +2158,19 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* More distant ancestors are irrelevant. The
* shared flag will be set in their case.
*/
- thin_defer_bio(tc, bio);
- cell_defer_no_holder_no_free(tc, &cell1);
+ thin_defer_cell(tc, virt_cell);
return DM_MAPIO_SUBMITTED;
}
build_data_key(tc->td, result.block, &key);
- if (dm_bio_detain(tc->pool->prison, &key, bio, &cell2, &cell_result)) {
- cell_defer_no_holder_no_free(tc, &cell1);
+ if (bio_detain(tc->pool, &key, bio, &data_cell)) {
+ cell_defer_no_holder(tc, virt_cell);
return DM_MAPIO_SUBMITTED;
}
inc_all_io_entry(tc->pool, bio);
- cell_defer_no_holder_no_free(tc, &cell2);
- cell_defer_no_holder_no_free(tc, &cell1);
+ cell_defer_no_holder(tc, data_cell);
+ cell_defer_no_holder(tc, virt_cell);
remap(tc, bio, result.block);
return DM_MAPIO_REMAPPED;
@@ -2051,14 +2182,13 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* of doing so.
*/
handle_unserviceable_bio(tc->pool, bio);
- cell_defer_no_holder_no_free(tc, &cell1);
+ cell_defer_no_holder(tc, virt_cell);
return DM_MAPIO_SUBMITTED;
}
/* fall through */
case -EWOULDBLOCK:
- thin_defer_bio(tc, bio);
- cell_defer_no_holder_no_free(tc, &cell1);
+ thin_defer_cell(tc, virt_cell);
return DM_MAPIO_SUBMITTED;
default:
@@ -2068,7 +2198,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* pool is switched to fail-io mode.
*/
bio_io_error(bio);
- cell_defer_no_holder_no_free(tc, &cell1);
+ cell_defer_no_holder(tc, virt_cell);
return DM_MAPIO_SUBMITTED;
}
}
@@ -3381,6 +3511,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
goto out_unlock;
}
spin_lock_init(&tc->lock);
+ INIT_LIST_HEAD(&tc->deferred_cells);
bio_list_init(&tc->deferred_bio_list);
bio_list_init(&tc->retry_on_resume_list);
tc->sort_bio_list = RB_ROOT;
--
1.9.3
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