dm thin: replace dm_cell_release_singleton with cell_defer_except
Change existing users of the function dm_cell_release_singleton to share
cell_defer_except instead, and then remove the now-unused function.
Everywhere that calls dm_cell_release_singleton, the bio in question
is the holder of the cell.
If there are no non-holder entries in the cell then cell_defer_except
behaves exactly like dm_cell_release_singleton. Conversely, if there
*are* non-holder entries then dm_cell_release_singleton must not be used
because those entries would need to be deferred.
Consequently, it is safe to replace use of dm_cell_release_singleton
with cell_defer_except.
This patch is a pre-requisite for "dm thin: fix race between
simultaneous io and discards to same block".
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 058acf3..25dfd23 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -513,8 +513,7 @@
}
/*
- * 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)
{
@@ -936,7 +935,7 @@
*/
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_except(tc, cell);
break;
}
@@ -967,8 +966,8 @@
* 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_except(tc, cell);
+ cell_defer_except(tc, cell2);
if ((!lookup_result.shared) && pool->pf.discard_passdown)
remap_and_issue(tc, bio, lookup_result.block);
else
@@ -980,13 +979,13 @@
/*
* It isn't provisioned, just forget it.
*/
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
bio_endio(bio, 0);
break;
default:
DMERR("discard: find block unexpectedly returned %d", r);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
bio_io_error(bio);
break;
}
@@ -1041,7 +1040,7 @@
h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
remap_and_issue(tc, bio, lookup_result->block);
}
}
@@ -1056,7 +1055,7 @@
* Remap empty bios (flushes) immediately, without provisioning.
*/
if (!bio->bi_size) {
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
remap_and_issue(tc, bio, 0);
return;
}
@@ -1066,7 +1065,7 @@
*/
if (bio_data_dir(bio) == READ) {
zero_fill_bio(bio);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
bio_endio(bio, 0);
return;
}
@@ -1120,7 +1119,7 @@
* TODO: this will probably have to change when discard goes
* back in.
*/
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
if (lookup_result.shared)
process_shared_bio(tc, bio, block, &lookup_result);
@@ -1130,7 +1129,7 @@
case -ENODATA:
if (bio_data_dir(bio) == READ && tc->origin_dev) {
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
remap_to_origin_and_issue(tc, bio);
} else
provision_block(tc, bio, block, cell);
@@ -1138,7 +1137,7 @@
default:
DMERR("dm_thin_find_block() failed, error = %d", r);
- dm_cell_release_singleton(cell, bio);
+ cell_defer_except(tc, cell);
bio_io_error(bio);
break;
}