dm bio prison: pass cell memory in
Change the dm_bio_prison interface so that instead of allocating memory
internally, dm_bio_detain is supplied with a pre-allocated cell each
time it is called.
This enables a subsequent patch to move the allocation of the struct
dm_bio_prison_cell outside the thin target's mapping function so it can
no longer block there.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 35d9d03..5304e3a 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -229,6 +229,54 @@
/*----------------------------------------------------------------*/
+static int bio_detain(struct pool *pool, struct dm_cell_key *key, struct bio *bio,
+ struct dm_bio_prison_cell **cell_result)
+{
+ int r;
+ struct dm_bio_prison_cell *cell_prealloc;
+
+ /*
+ * Allocate a cell from the prison's mempool.
+ * This might block but it can't fail.
+ */
+ cell_prealloc = dm_bio_prison_alloc_cell(pool->prison, GFP_NOIO);
+
+ r = dm_bio_detain(pool->prison, key, bio, cell_prealloc, cell_result);
+ if (r)
+ /*
+ * We reused an old cell; we can get rid of
+ * the new one.
+ */
+ dm_bio_prison_free_cell(pool->prison, cell_prealloc);
+
+ return r;
+}
+
+static void cell_release(struct pool *pool,
+ struct dm_bio_prison_cell *cell,
+ struct bio_list *bios)
+{
+ dm_cell_release(pool->prison, cell, bios);
+ dm_bio_prison_free_cell(pool->prison, cell);
+}
+
+static void cell_release_no_holder(struct pool *pool,
+ struct dm_bio_prison_cell *cell,
+ struct bio_list *bios)
+{
+ dm_cell_release_no_holder(pool->prison, cell, bios);
+ dm_bio_prison_free_cell(pool->prison, cell);
+}
+
+static void cell_error(struct pool *pool,
+ struct dm_bio_prison_cell *cell)
+{
+ dm_cell_error(pool->prison, cell);
+ dm_bio_prison_free_cell(pool->prison, cell);
+}
+
+/*----------------------------------------------------------------*/
+
/*
* A global list of pools that uses a struct mapped_device as a key.
*/
@@ -524,14 +572,14 @@
unsigned long flags;
spin_lock_irqsave(&pool->lock, flags);
- dm_cell_release(cell, &pool->deferred_bios);
+ cell_release(pool, cell, &pool->deferred_bios);
spin_unlock_irqrestore(&tc->pool->lock, flags);
wake_worker(pool);
}
/*
- * Same as cell_defer except it omits the original holder of the cell.
+ * Same as cell_defer above, except it omits the original holder of the cell.
*/
static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *cell)
{
@@ -539,7 +587,7 @@
unsigned long flags;
spin_lock_irqsave(&pool->lock, flags);
- dm_cell_release_no_holder(cell, &pool->deferred_bios);
+ cell_release_no_holder(pool, cell, &pool->deferred_bios);
spin_unlock_irqrestore(&pool->lock, flags);
wake_worker(pool);
@@ -549,13 +597,14 @@
{
if (m->bio)
m->bio->bi_end_io = m->saved_bi_end_io;
- dm_cell_error(m->cell);
+ cell_error(m->tc->pool, m->cell);
list_del(&m->list);
mempool_free(m, m->tc->pool->mapping_pool);
}
static void process_prepared_mapping(struct dm_thin_new_mapping *m)
{
struct thin_c *tc = m->tc;
+ struct pool *pool = tc->pool;
struct bio *bio;
int r;
@@ -564,7 +613,7 @@
bio->bi_end_io = m->saved_bi_end_io;
if (m->err) {
- dm_cell_error(m->cell);
+ cell_error(pool, m->cell);
goto out;
}
@@ -576,7 +625,7 @@
r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
if (r) {
DMERR_LIMIT("dm_thin_insert_block() failed");
- dm_cell_error(m->cell);
+ cell_error(pool, m->cell);
goto out;
}
@@ -594,7 +643,7 @@
out:
list_del(&m->list);
- mempool_free(m, tc->pool->mapping_pool);
+ mempool_free(m, pool->mapping_pool);
}
static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)
@@ -745,7 +794,7 @@
if (r < 0) {
mempool_free(m, pool->mapping_pool);
DMERR_LIMIT("dm_kcopyd_copy() failed");
- dm_cell_error(cell);
+ cell_error(pool, cell);
}
}
}
@@ -811,7 +860,7 @@
if (r < 0) {
mempool_free(m, pool->mapping_pool);
DMERR_LIMIT("dm_kcopyd_zero() failed");
- dm_cell_error(cell);
+ cell_error(pool, cell);
}
}
}
@@ -917,13 +966,13 @@
spin_unlock_irqrestore(&pool->lock, flags);
}
-static void no_space(struct dm_bio_prison_cell *cell)
+static void no_space(struct pool *pool, struct dm_bio_prison_cell *cell)
{
struct bio *bio;
struct bio_list bios;
bio_list_init(&bios);
- dm_cell_release(cell, &bios);
+ cell_release(pool, cell, &bios);
while ((bio = bio_list_pop(&bios)))
retry_on_resume(bio);
@@ -941,7 +990,7 @@
struct dm_thin_new_mapping *m;
build_virtual_key(tc->td, block, &key);
- if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))
+ if (bio_detain(tc->pool, &key, bio, &cell))
return;
r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
@@ -953,7 +1002,7 @@
* on this block.
*/
build_data_key(tc->td, lookup_result.block, &key2);
- if (dm_bio_detain(tc->pool->prison, &key2, bio, &cell2)) {
+ if (bio_detain(tc->pool, &key2, bio, &cell2)) {
cell_defer_no_holder(tc, cell);
break;
}
@@ -1029,13 +1078,13 @@
break;
case -ENOSPC:
- no_space(cell);
+ no_space(tc->pool, cell);
break;
default:
DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
__func__, r);
- dm_cell_error(cell);
+ cell_error(tc->pool, cell);
break;
}
}
@@ -1053,7 +1102,7 @@
* of being broken so we have nothing further to do here.
*/
build_data_key(tc->td, lookup_result->block, &key);
- if (dm_bio_detain(pool->prison, &key, bio, &cell))
+ if (bio_detain(pool, &key, bio, &cell))
return;
if (bio_data_dir(bio) == WRITE && bio->bi_size)
@@ -1074,12 +1123,13 @@
{
int r;
dm_block_t data_block;
+ struct pool *pool = tc->pool;
/*
* Remap empty bios (flushes) immediately, without provisioning.
*/
if (!bio->bi_size) {
- inc_all_io_entry(tc->pool, bio);
+ inc_all_io_entry(pool, bio);
cell_defer_no_holder(tc, cell);
remap_and_issue(tc, bio, 0);
@@ -1106,14 +1156,14 @@
break;
case -ENOSPC:
- no_space(cell);
+ no_space(pool, cell);
break;
default:
DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
__func__, r);
- set_pool_mode(tc->pool, PM_READ_ONLY);
- dm_cell_error(cell);
+ set_pool_mode(pool, PM_READ_ONLY);
+ cell_error(pool, cell);
break;
}
}
@@ -1121,6 +1171,7 @@
static void process_bio(struct thin_c *tc, struct bio *bio)
{
int r;
+ 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;
@@ -1131,7 +1182,7 @@
* being provisioned so we have nothing further to do here.
*/
build_virtual_key(tc->td, block, &key);
- if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))
+ if (bio_detain(pool, &key, bio, &cell))
return;
r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
@@ -1139,9 +1190,9 @@
case 0:
if (lookup_result.shared) {
process_shared_bio(tc, bio, block, &lookup_result);
- cell_defer_no_holder(tc, cell);
+ cell_defer_no_holder(tc, cell); /* FIXME: pass this cell into process_shared? */
} else {
- inc_all_io_entry(tc->pool, bio);
+ inc_all_io_entry(pool, bio);
cell_defer_no_holder(tc, cell);
remap_and_issue(tc, bio, lookup_result.block);
@@ -1150,7 +1201,7 @@
case -ENODATA:
if (bio_data_dir(bio) == READ && tc->origin_dev) {
- inc_all_io_entry(tc->pool, bio);
+ inc_all_io_entry(pool, bio);
cell_defer_no_holder(tc, cell);
remap_to_origin_and_issue(tc, bio);
@@ -1429,11 +1480,11 @@
}
build_virtual_key(tc->td, block, &key);
- if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1))
+ if (bio_detain(tc->pool, &key, bio, &cell1))
return DM_MAPIO_SUBMITTED;
build_data_key(tc->td, result.block, &key);
- if (dm_bio_detain(tc->pool->prison, &key, bio, &cell2)) {
+ if (bio_detain(tc->pool, &key, bio, &cell2)) {
cell_defer_no_holder(tc, cell1);
return DM_MAPIO_SUBMITTED;
}