[Devel] [PATCH VZ10 02/10] drivers/md/dm-qcow2: generalize COW index update machinery
Andrey Zhadchenko
andrey.zhadchenko at virtuozzo.com
Wed Aug 12 21:56:30 MSK 2026
The two-stage L1/L2 entry update pipeline is not COW-specific:
backward merge already uses it to zero L2 entries, and upcoming
discard support will be the third user. Rename it to reflect
what it does.
No functional changes.
Feature: dm-qcow2: block device over QCOW2 files driver
https://virtuozzo.atlassian.net/browse/VSTOR-139406
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
---
drivers/md/dm-qcow2-map.c | 100 +++++++++++++++++++-------------------
drivers/md/dm-qcow2.h | 10 ++--
2 files changed, 55 insertions(+), 55 deletions(-)
diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c
index 2cd8e174049f8..08d46eb177dd1 100644
--- a/drivers/md/dm-qcow2-map.c
+++ b/drivers/md/dm-qcow2-map.c
@@ -2579,10 +2579,10 @@ static int prepare_l1l2_allocation(struct qcow2 *qcow2, struct qio *qio,
* we have to wait all previous READs. We do that around
* index wb. See md->wpc_noread_count update details.
*/
-static int prepare_l_entry_cow(struct qcow2 *qcow2, struct qcow2_map *map,
- struct qio *qio, struct md_page *md,
- u32 index_in_page, loff_t cow_clu_pos,
- loff_t cow_clu_end, u8 cow_level)
+static int prepare_l_entry_replace(struct qcow2 *qcow2, struct qcow2_map *map,
+ struct qio *qio, struct md_page *md,
+ u32 index_in_page, loff_t unuse_clu_pos,
+ loff_t unuse_clu_end, u8 lx_level)
{
struct lock_desc *lockd = NULL;
struct qio_ext *ext;
@@ -2591,9 +2591,9 @@ static int prepare_l_entry_cow(struct qcow2 *qcow2, struct qcow2_map *map,
return -ENOMEM;
ext = qio->ext;
- ext->cow_clu_pos = cow_clu_pos;
- ext->cow_clu_end = cow_clu_end;
- ext->cow_level = cow_level;
+ ext->unuse_clu_pos = unuse_clu_pos;
+ ext->unuse_clu_end = unuse_clu_end;
+ ext->lx_level = lx_level;
spin_lock_irq(&qcow2->md_pages_lock);
if (!md->lockd) {
@@ -2614,23 +2614,23 @@ static int prepare_l_entry_cow(struct qcow2 *qcow2, struct qcow2_map *map,
return 1;
}
-static int prepare_l1l2_cow(struct qcow2 *qcow2, struct qio *qio,
- struct qcow2_map *map)
+static int prepare_l1l2_replace(struct qcow2 *qcow2, struct qio *qio,
+ struct qcow2_map *map)
{
if (WARN_ON_ONCE(!(map->level & L1_LEVEL)))
return -EIO; /* Sanity check: L1 must be cached */
if (!(map->level & L2_LEVEL)) {
- return prepare_l_entry_cow(qcow2, map, qio, map->l1.md,
- map->l1.index_in_page,
- map->cow_clu_pos,
- map->cow_clu_end, L1_LEVEL);
+ return prepare_l_entry_replace(qcow2, map, qio, map->l1.md,
+ map->l1.index_in_page,
+ map->cow_clu_pos,
+ map->cow_clu_end, L1_LEVEL);
}
- return prepare_l_entry_cow(qcow2, map, qio, map->l2.md,
- map->l2.index_in_page,
- map->cow_clu_pos,
- map->cow_clu_end, L2_LEVEL);
+ return prepare_l_entry_replace(qcow2, map, qio, map->l2.md,
+ map->l2.index_in_page,
+ map->cow_clu_pos,
+ map->cow_clu_end, L2_LEVEL);
}
static void backward_merge_write_complete(struct qcow2_target *tgt, struct qio *unused,
@@ -2648,7 +2648,7 @@ static void backward_merge_write_complete(struct qcow2_target *tgt, struct qio *
WARN_ON_ONCE(qio->flags & QIO_IS_DISCARD_FL);
qio->flags |= QIO_IS_DISCARD_FL;
- qio->queue_list_id = QLIST_COW_INDEXES;
+ qio->queue_list_id = QLIST_INDEXES_WRITE;
qcow2_dispatch_qios(qcow2, qio, NULL);
}
@@ -2704,7 +2704,7 @@ static int prepare_backward_merge(struct qcow2 *qcow2, struct qio **qio,
if (!op_is_write((*qio)->bi_op)) {
/*
* READ qio may data may be contained in several deltas.
- * We can't read lower delta after prepare_l1l2_cow()
+ * We can't read lower delta after prepare_l1l2_replace()
* prepares us.
*/
aux_qio = qcow2_alloc_qio(qcow2->tgt->qio_pool, true);
@@ -2725,10 +2725,10 @@ static int prepare_backward_merge(struct qcow2 *qcow2, struct qio **qio,
}
/*
- * Mark as COW, as this completely defers any parallel qios.
- * @qio is COW status holder.
+ * Lock the entry, as this completely defers any parallel qios.
+ * @qio is the lock holder.
*/
- ret = prepare_l1l2_cow(qcow2, *qio, map);
+ ret = prepare_l1l2_replace(qcow2, *qio, map);
if (ret < 0) {
(*qio)->bi_status = errno_to_blk_status(ret);
goto endio;
@@ -2736,13 +2736,13 @@ static int prepare_backward_merge(struct qcow2 *qcow2, struct qio **qio,
if (!map->clu_is_cow) {
/* Forced set these to unuse them after discard */
- (*qio)->ext->cow_clu_pos = map->data_clu_pos;
- (*qio)->ext->cow_clu_end = map->data_clu_pos + qcow2->clu_size;
+ (*qio)->ext->unuse_clu_pos = map->data_clu_pos;
+ (*qio)->ext->unuse_clu_end = map->data_clu_pos + qcow2->clu_size;
}
return 1;
endio:
- qio_endio(*qio); /* Breaks COW set in prepare_l1l2_cow() */
+ qio_endio(*qio); /* Releases the lock set in prepare_l1l2_replace() */
return 0;
}
@@ -3348,7 +3348,7 @@ static int handle_metadata(struct qcow2 *qcow2, struct qio **qio,
(!qio_is_fully_alloced(qcow2, *qio, map) || map->clu_is_cow)) {
if (map->clu_is_cow) {
/* COW to compressed or shared with snapshot cluster */
- ret = prepare_l1l2_cow(qcow2, *qio, map);
+ ret = prepare_l1l2_replace(qcow2, *qio, map);
} else if ((map->level & L2_LEVEL) &&
qio_border_is_inside_unmapped_unit(qcow2, *qio, map) &&
maybe_mapped_in_lower_delta(qcow2, *qio)) {
@@ -3358,7 +3358,7 @@ static int handle_metadata(struct qcow2 *qcow2, struct qio **qio,
* snapshots). Here is data COW on L2_LEVEL.
*/
map->backing_file_cow = true;
- ret = prepare_l1l2_cow(qcow2, *qio, map);
+ ret = prepare_l1l2_replace(qcow2, *qio, map);
} else if (unlikely(op_is_discard((*qio)->bi_op) &&
(map->level & L2_LEVEL))) {
if (!map->data_clu_alloced) {
@@ -3837,7 +3837,7 @@ static void cow_data_write_endio(struct qcow2_target *tgt, struct qio *unused,
qio->bi_status = bi_status;
qio_endio(qio);
} else {
- qio->queue_list_id = QLIST_COW_INDEXES;
+ qio->queue_list_id = QLIST_INDEXES_WRITE;
qcow2_dispatch_qios(qcow2, qio, NULL);
}
}
@@ -3885,7 +3885,7 @@ static void sliced_cow_data_write_complete(struct qcow2_target *tgt, struct qio
qio->bi_status = bi_status;
qio_endio(qio);
} else {
- qio->queue_list_id = QLIST_COW_INDEXES;
+ qio->queue_list_id = QLIST_INDEXES_WRITE;
qcow2_dispatch_qios(qcow2, qio, NULL);
}
}
@@ -3919,7 +3919,7 @@ static void process_cow_data_write(struct qcow2 *qcow2, struct list_head *cow_li
ext = qio->ext;
if (ext->only_set_ext_l2) {
- WARN_ON_ONCE(ext->cow_level != L2_LEVEL);
+ WARN_ON_ONCE(ext->lx_level != L2_LEVEL);
pos = ext->allocated_clu_pos;
goto submit;
}
@@ -3938,14 +3938,14 @@ static void process_cow_data_write(struct qcow2 *qcow2, struct list_head *cow_li
ext->allocated_clu_pos = pos;
ext->cleanup_mask |= FREE_ALLOCATED_CLU;
submit:
- if (ext->cow_level == L2_LEVEL)
+ if (ext->lx_level == L2_LEVEL)
submit_sliced_cow_data_write(qcow2, qio, pos);
else
submit_cow_data_write(qcow2, qio, pos);
}
}
-static void process_cow_indexes_write(struct qcow2 *qcow2,
+static void process_indexes_write(struct qcow2 *qcow2,
struct list_head *qio_list)
{
struct qcow2_bvec *qvec;
@@ -3965,7 +3965,7 @@ static void process_cow_indexes_write(struct qcow2 *qcow2,
lx_md = ext->lx_md;
/* Return back to the same stage in case of writeback */
- qio->queue_list_id = QLIST_COW_INDEXES;
+ qio->queue_list_id = QLIST_INDEXES_WRITE;
if (delay_if_writeback(qcow2, lx_md, -1, &qio, true))
continue;
@@ -3974,7 +3974,7 @@ static void process_cow_indexes_write(struct qcow2 *qcow2,
arg_mask = (discard ? 0 : LU_SET_ONE_MASK) | LU_WANTS_PE_PAGE;
if (ext->only_set_ext_l2) {
- WARN_ON_ONCE(ext->cow_level != L2_LEVEL);
+ WARN_ON_ONCE(ext->lx_level != L2_LEVEL);
goto set_ext_l2;
}
@@ -3982,14 +3982,14 @@ static void process_cow_indexes_write(struct qcow2 *qcow2,
ret = prepare_l_entry_update(qcow2, qio, lx_md,
ext->lx_index_in_page,
&ext->allocated_clu_pos,
- arg_mask, ext->cow_level);
+ arg_mask, ext->lx_level);
if (ret < 0) {
qio->bi_status = errno_to_blk_status(ret);
qio_endio(qio);
continue;
}
set_ext_l2:
- if (qcow2->ext_l2 && ext->cow_level == L2_LEVEL) {
+ if (qcow2->ext_l2 && ext->lx_level == L2_LEVEL) {
arg_mask &= ~LU_SET_ONE_MASK;
ret = prepare_l_entry_update(qcow2, qio, lx_md,
ext->lx_index_in_page + 1,
@@ -3999,7 +3999,7 @@ static void process_cow_indexes_write(struct qcow2 *qcow2,
}
/* Next stage */
- qio->queue_list_id = QLIST_COW_END;
+ qio->queue_list_id = QLIST_INDEXES_END;
spin_lock_irq(&qcow2->md_pages_lock);
/*
@@ -4015,8 +4015,8 @@ static void process_cow_indexes_write(struct qcow2 *qcow2,
}
}
-/* Finalize successful COW */
-static void process_cow_end(struct qcow2 *qcow2, struct list_head *qio_list)
+/* Finalize successful L1/L2 entry replace */
+static void process_indexes_end(struct qcow2 *qcow2, struct list_head *qio_list)
{
struct dm_target *ti = qcow2->tgt->ti;
u32 mask, clu_size = qcow2->clu_size;
@@ -4036,7 +4036,7 @@ next: qio = qio_list_pop(qio_list);
ext->cleanup_mask &= ~FREE_ALLOCATED_CLU;
/* Should be already set... */
- qio->queue_list_id = QLIST_COW_END;
+ qio->queue_list_id = QLIST_INDEXES_END;
/*
* Wait last user before we (possible) mark clusters
* unused. In real only compressed COW requires this.
@@ -4044,8 +4044,8 @@ next: qio = qio_list_pop(qio_list);
if (delay_if_has_wpc_readers(qcow2, ext->lx_md, &qio))
goto next;
- pos = ext->cow_clu_pos;
- for (; pos < ext->cow_clu_end; pos += clu_size) {
+ pos = ext->unuse_clu_pos;
+ for (; pos < ext->unuse_clu_end; pos += clu_size) {
ret = __handle_r1r2_maps(qcow2, pos, &qio, &r1, &r2);
if (ret == 0) /* We never shrink md pages, impossible */
goto next;
@@ -4053,7 +4053,7 @@ next: qio = qio_list_pop(qio_list);
QC_ERR(ti, "clu at %lld leaked", pos);
else
dec_cluster_usage(qcow2, r2.md, r2.index_in_page, pos);
- ext->cow_clu_pos += clu_size;
+ ext->unuse_clu_pos += clu_size;
}
mask = MD_INDEX_SET_UNLOCKED|DEC_WPC_NOREAD_COUNT;
@@ -4061,7 +4061,7 @@ next: qio = qio_list_pop(qio_list);
mask |= FREE_QIO_DATA_QVEC;
WARN_ON_ONCE(ext->cleanup_mask != mask); /* Sanity check */
- if (ext->cow_level == L1_LEVEL) {
+ if (ext->lx_level == L1_LEVEL) {
finalize_qio_ext(qio);
/* COW on L1 completed, it's time for COW on L2 */
qio->queue_list_id = QLIST_DEFERRED;
@@ -4101,8 +4101,8 @@ void do_qcow2_work(struct work_struct *ws)
LIST_HEAD(zread_qios);
LIST_HEAD(bwrite_qios);
LIST_HEAD(cow_data_qios);
- LIST_HEAD(cow_indexes_qios);
- LIST_HEAD(cow_end_qios);
+ LIST_HEAD(indexes_write_qios);
+ LIST_HEAD(indexes_end_qios);
LIST_HEAD(resubmit_qios);
LIST_HEAD(seek_qios);
unsigned int pflags = current->flags;
@@ -4114,8 +4114,8 @@ void do_qcow2_work(struct work_struct *ws)
list_splice_init(&qcow2->qios[QLIST_ZREAD], &zread_qios);
list_splice_init(&qcow2->qios[QLIST_BMERGE_WRITE], &bwrite_qios);
list_splice_init(&qcow2->qios[QLIST_COW_DATA], &cow_data_qios);
- list_splice_init(&qcow2->qios[QLIST_COW_INDEXES], &cow_indexes_qios);
- list_splice_init(&qcow2->qios[QLIST_COW_END], &cow_end_qios);
+ list_splice_init(&qcow2->qios[QLIST_INDEXES_WRITE], &indexes_write_qios);
+ list_splice_init(&qcow2->qios[QLIST_INDEXES_END], &indexes_end_qios);
list_splice_init(&qcow2->resubmit_qios, &resubmit_qios);
list_splice_init(&qcow2->qios[QLIST_SEEK], &seek_qios);
spin_unlock_irq(&qcow2->deferred_lock);
@@ -4125,8 +4125,8 @@ void do_qcow2_work(struct work_struct *ws)
process_compressed_read(&zread_qios, &cow_data_qios);
process_backward_merge_write(qcow2, &bwrite_qios);
process_cow_data_write(qcow2, &cow_data_qios);
- process_cow_indexes_write(qcow2, &cow_indexes_qios);
- process_cow_end(qcow2, &cow_end_qios);
+ process_indexes_write(qcow2, &indexes_write_qios);
+ process_indexes_end(qcow2, &indexes_end_qios);
process_resubmit_qios(qcow2, &resubmit_qios);
process_seek_qios(qcow2, &seek_qios);
diff --git a/drivers/md/dm-qcow2.h b/drivers/md/dm-qcow2.h
index aa3487007523f..230e7a4a34e76 100644
--- a/drivers/md/dm-qcow2.h
+++ b/drivers/md/dm-qcow2.h
@@ -228,8 +228,8 @@ enum {
QLIST_ZREAD,
QLIST_BMERGE_WRITE,
QLIST_COW_DATA,
- QLIST_COW_INDEXES,
- QLIST_COW_END,
+ QLIST_INDEXES_WRITE,
+ QLIST_INDEXES_END,
QLIST_SEEK,
QLIST_COUNT,
@@ -307,13 +307,13 @@ struct qio_ext {
u32 lx_index_in_page, r2_index_in_page;
u64 allocated_clu_pos;
- loff_t cow_clu_pos;
- loff_t cow_clu_end;
+ loff_t unuse_clu_pos;
+ loff_t unuse_clu_end;
u64 new_ext_l2;
u32 cow_mask;
bool only_set_ext_l2:1;
- u8 cow_level;
+ u8 lx_level;
#define MD_INDEX_SET_UNLOCKED (1ULL << 0)
#define DEC_WPC_NOREAD_COUNT (1ULL << 1)
--
2.43.5
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