From: Joe Thornber <ejt@xxxxxxxxxx>
In every case dm_cell_release_singleton is called the bio in question
is the holder. If there are no non-holder entries in the cell then
cell_defer_no_holder (renamed from cell_defer_except) behaves
identically to dm_cell_release_singleton. If there *are* non-holder
entries then dm_cell_release_singleton is the wrong thing to call
because those entries must be deferred.
This patch offers no functional change but is a pre-requisite for
"dm thin: eliminate race when io and discards are issued
simultaneously the same block".
Signed-off-by: Joe Thornber <ejt@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/md/dm-thin.c | 38 +++++++++++++++++++-------------------
1 files changed, 19 insertions(+), 19 deletions(-)
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index ceb17be..2fadaef 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -513,10 +513,10 @@ static void cell_defer(struct thin_c *tc, struct dm_bio_prison_cell *cell,
}
/*
- * Same as cell_defer above, except it omits one particular detainee,
- * a write bio that covers the block and has already been processed.
+ * Same as cell_defer except it omits the original holder of the cell.
*/
-static void cell_defer_except(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+static void cell_defer_no_holder(struct thin_c *tc,
+ struct dm_bio_prison_cell *cell)
{
struct bio_list bios;
struct pool *pool = tc->pool;
@@ -573,7 +573,7 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
* the bios in the cell.
*/
if (bio) {
- cell_defer_except(tc, m->cell);
+ cell_defer_no_holder(tc, m->cell);
bio_endio(bio, 0);
} else
cell_defer(tc, m->cell, m->data_block);
@@ -588,8 +588,8 @@ static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)
struct thin_c *tc = m->tc;
bio_io_error(m->bio);
- cell_defer_except(tc, m->cell);
- cell_defer_except(tc, m->cell2);
+ cell_defer_no_holder(tc, m->cell);
+ cell_defer_no_holder(tc, m->cell2);
mempool_free(m, tc->pool->mapping_pool);
}
@@ -602,8 +602,8 @@ static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m)
else
bio_endio(m->bio, 0);
- cell_defer_except(tc, m->cell);
- cell_defer_except(tc, m->cell2);
+ cell_defer_no_holder(tc, m->cell);
+ cell_defer_no_holder(tc, m->cell2);
mempool_free(m, tc->pool->mapping_pool);
}
@@ -936,7 +936,7 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
*/
build_data_key(tc->td, lookup_result.block, &key2);
if (dm_bio_detain(tc->pool->prison, &key2, bio, &cell2)) {
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
break;
}
@@ -967,8 +967,8 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
* a block boundary. So we submit the discard of a
* partial block appropriately.
*/
- dm_cell_release_singleton(cell, bio);
- dm_cell_release_singleton(cell2, bio);
+ cell_defer_no_holder(tc, cell);
+ cell_defer_no_holder(tc, cell2);
if ((!lookup_result.shared) && pool->pf.discard_passdown)
remap_and_issue(tc, bio, lookup_result.block);
else
@@ -980,14 +980,14 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
/*
* It isn't provisioned, just forget it.
*/
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
bio_endio(bio, 0);
break;
default:
DMERR_LIMIT("%s: dm_thin_find_block() failed, error = %d",
__func__, r);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
bio_io_error(bio);
break;
}
@@ -1043,7 +1043,7 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
remap_and_issue(tc, bio, lookup_result->block);
}
}
@@ -1058,7 +1058,7 @@ static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block
* Remap empty bios (flushes) immediately, without provisioning.
*/
if (!bio->bi_size) {
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
remap_and_issue(tc, bio, 0);
return;
}
@@ -1068,7 +1068,7 @@ static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block
*/
if (bio_data_dir(bio) == READ) {
zero_fill_bio(bio);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
bio_endio(bio, 0);
return;
}
@@ -1123,7 +1123,7 @@ static void process_bio(struct thin_c *tc, struct bio *bio)
* TODO: this will probably have to change when discard goes
* back in.
*/
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
if (lookup_result.shared)
process_shared_bio(tc, bio, block, &lookup_result);
@@ -1133,7 +1133,7 @@ static void process_bio(struct thin_c *tc, struct bio *bio)
case -ENODATA:
if (bio_data_dir(bio) == READ && tc->origin_dev) {
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
remap_to_origin_and_issue(tc, bio);
} else
provision_block(tc, bio, block, cell);
@@ -1142,7 +1142,7 @@ static void process_bio(struct thin_c *tc, struct bio *bio)
default:
DMERR_LIMIT("%s: dm_thin_find_block() failed, error = %d",
__func__, r);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_no_holder(tc, cell);
bio_io_error(bio);
break;
}
--
1.7.1
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