* FAILED: patch "[PATCH] dm-writecache: fix REQ_FUA processing" failed to apply to 5.15-stable tree
@ 2026-11-07 11:01 Sasha Levin
2026-11-11 1:46 ` [PATCH 5.15.y] dm-writecache: fix REQ_FUA processing Sasha Levin
0 siblings, 1 reply; 2+ messages in thread
From: Sasha Levin @ 2026-11-07 11:01 UTC (permalink / raw)
To: mpatocka; +Cc: stable
The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x c0df022cb0fa2bbee74bd9b90c66790bcd4e3050
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107060120-failed-5.15-c0df022cb0fa@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'
Thanks,
Sasha
------------------ original commit in Linus's tree ------------------
From c0df022cb0fa2bbee74bd9b90c66790bcd4e3050 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Wed, 30 Sep 2026 21:43:26 +0200
Subject: [PATCH] dm-writecache: fix REQ_FUA processing
REQ_FUA did not flush metadata in SSD mode, this commit fixes it.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Fixes: c1005322ff02 ("dm writecache: handle REQ_FUA")
Assisted-by: Claude:claude-opus-5
Assisted-by: Codex:gpt-6-sol
---
drivers/md/dm-writecache.c | 45 +++++++++++++++++++++++++++++---------
1 file changed, 35 insertions(+), 10 deletions(-)
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index a38780a7b1be9..6f977fb8c9397 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -188,6 +188,7 @@ struct dm_writecache {
struct task_struct *endio_thread;
struct task_struct *flush_thread;
+ spinlock_t flush_list_lock;
struct bio_list flush_list;
struct dm_kcopyd_client *dm_kcopyd;
@@ -1289,9 +1290,11 @@ static int writecache_flush_thread(void *data)
struct bio *bio;
wc_lock(wc);
+ spin_lock_irq(&wc->flush_list_lock);
bio = bio_list_pop(&wc->flush_list);
if (!bio) {
set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&wc->flush_list_lock);
wc_unlock(wc);
if (unlikely(kthread_should_stop())) {
@@ -1302,6 +1305,7 @@ static int writecache_flush_thread(void *data)
schedule();
continue;
}
+ spin_unlock_irq(&wc->flush_list_lock);
if (bio_op(bio) == REQ_OP_DISCARD) {
writecache_discard(wc, bio->bi_iter.bi_sector,
@@ -1323,9 +1327,12 @@ static int writecache_flush_thread(void *data)
static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
{
+ unsigned long flags;
+ spin_lock_irqsave(&wc->flush_list_lock, flags);
if (bio_list_empty(&wc->flush_list))
wake_up_process(wc->flush_thread);
bio_list_add(&wc->flush_list, bio);
+ spin_unlock_irqrestore(&wc->flush_list_lock, flags);
}
enum wc_map_op {
@@ -1437,6 +1444,8 @@ static void writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio)
{
struct wc_entry *e;
+ enum wc_map_op ret = WC_MAP_SUBMIT;
+ bool need_flush = false;
do {
bool found_entry = false;
@@ -1473,7 +1482,8 @@ static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio
writecache_map_remap_origin(wc, bio, e);
wc->stats.writes_around += bio->bi_iter.bi_size >> wc->block_size_bits;
wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
- return WC_MAP_REMAP_ORIGIN;
+ ret = WC_MAP_REMAP_ORIGIN;
+ goto flush_pmem_and_ret;
}
wc->stats.writes_blocked_on_freelist++;
writecache_wait_on_freelist(wc);
@@ -1487,21 +1497,25 @@ static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio
if (WC_MODE_PMEM(wc)) {
bio_copy_block(wc, bio, memory_data(wc, e));
wc->stats.writes++;
+ need_flush = true;
} else {
writecache_bio_copy_ssd(wc, bio, e, search_used);
return WC_MAP_REMAP;
}
} while (bio->bi_iter.bi_size);
- if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks)) {
- writecache_flush(wc);
- if (writecache_has_error(wc))
- bio->bi_status = BLK_STS_IOERR;
- } else {
- writecache_schedule_autocommit(wc);
+flush_pmem_and_ret:
+ if (need_flush) {
+ if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks)) {
+ writecache_flush(wc);
+ if (writecache_has_error(wc))
+ ret = WC_MAP_ERROR;
+ } else {
+ writecache_schedule_autocommit(wc);
+ }
}
- return WC_MAP_SUBMIT;
+ return ret;
}
static enum wc_map_op writecache_map_flush(struct dm_writecache *wc, struct bio *bio)
@@ -1591,7 +1605,10 @@ static int writecache_map(struct dm_target *ti, struct bio *bio)
case WC_MAP_REMAP:
/* make sure that writecache_end_io decrements bio_in_progress: */
- bio->bi_private = (void *)1;
+ if (unlikely(bio->bi_opf & REQ_FUA) && bio_op(bio) == REQ_OP_WRITE)
+ bio->bi_private = (void *)3;
+ else
+ bio->bi_private = (void *)1;
atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
wc_unlock(wc);
return DM_MAPIO_REMAPPED;
@@ -1621,12 +1638,19 @@ static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t
{
struct dm_writecache *wc = ti->private;
- if (bio->bi_private == (void *)1) {
+ if (bio->bi_private == (void *)1 || bio->bi_private == (void *)3) {
int dir = bio_data_dir(bio);
+ bool fua = bio->bi_private == (void *)3;
if (atomic_dec_and_test(&wc->bio_in_progress[dir]))
if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
wake_up(&wc->bio_in_progress_wait[dir]);
+
+ if (fua && likely(*status == BLK_STS_OK)) {
+ bio->bi_private = NULL;
+ writecache_offload_bio(wc, bio);
+ return DM_ENDIO_INCOMPLETE;
+ }
} else if (bio->bi_private == (void *)2) {
dm_iot_io_end(&wc->iot, 1);
}
@@ -2519,6 +2543,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned int argc, char **argv)
wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
+ spin_lock_init(&wc->flush_list_lock);
bio_list_init(&wc->flush_list);
wc->flush_thread = kthread_run(writecache_flush_thread, wc, "dm_writecache_flush");
if (IS_ERR(wc->flush_thread)) {
--
2.53.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 5.15.y] dm-writecache: fix REQ_FUA processing
2026-11-07 11:01 FAILED: patch "[PATCH] dm-writecache: fix REQ_FUA processing" failed to apply to 5.15-stable tree Sasha Levin
@ 2026-11-11 1:46 ` Sasha Levin
0 siblings, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2026-11-11 1:46 UTC (permalink / raw)
To: stable; +Cc: Mikulas Patocka, Sasha Levin
From: Mikulas Patocka <mpatocka@redhat.com>
[ Upstream commit c0df022cb0fa2bbee74bd9b90c66790bcd4e3050 ]
REQ_FUA did not flush metadata in SSD mode, this commit fixes it.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Fixes: c1005322ff02 ("dm writecache: handle REQ_FUA")
Assisted-by: Claude:claude-opus-5
Assisted-by: Codex:gpt-6-sol
[ sashal: added a blank line after the bool fua declaration in writecache_end_io() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm-writecache.c | 46 +++++++++++++++++++++++++++++---------
1 file changed, 36 insertions(+), 10 deletions(-)
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index b0d827b84cdb5..7c1825de25f8d 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -198,6 +198,7 @@ struct dm_writecache {
struct task_struct *endio_thread;
struct task_struct *flush_thread;
+ spinlock_t flush_list_lock;
struct bio_list flush_list;
struct dm_kcopyd_client *dm_kcopyd;
@@ -1279,9 +1280,11 @@ static int writecache_flush_thread(void *data)
struct bio *bio;
wc_lock(wc);
+ spin_lock_irq(&wc->flush_list_lock);
bio = bio_list_pop(&wc->flush_list);
if (!bio) {
set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&wc->flush_list_lock);
wc_unlock(wc);
if (unlikely(kthread_should_stop())) {
@@ -1292,6 +1295,7 @@ static int writecache_flush_thread(void *data)
schedule();
continue;
}
+ spin_unlock_irq(&wc->flush_list_lock);
if (bio_op(bio) == REQ_OP_DISCARD) {
writecache_discard(wc, bio->bi_iter.bi_sector,
@@ -1313,9 +1317,12 @@ static int writecache_flush_thread(void *data)
static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
{
+ unsigned long flags;
+ spin_lock_irqsave(&wc->flush_list_lock, flags);
if (bio_list_empty(&wc->flush_list))
wake_up_process(wc->flush_thread);
bio_list_add(&wc->flush_list, bio);
+ spin_unlock_irqrestore(&wc->flush_list_lock, flags);
}
enum wc_map_op {
@@ -1425,6 +1432,8 @@ static void writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio)
{
struct wc_entry *e;
+ enum wc_map_op ret = WC_MAP_SUBMIT;
+ bool need_flush = false;
do {
bool found_entry = false;
@@ -1460,7 +1469,8 @@ static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio
writecache_map_remap_origin(wc, bio, e);
wc->stats.writes_around += bio->bi_iter.bi_size >> wc->block_size_bits;
wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
- return WC_MAP_REMAP_ORIGIN;
+ ret = WC_MAP_REMAP_ORIGIN;
+ goto flush_pmem_and_ret;
}
wc->stats.writes_blocked_on_freelist++;
writecache_wait_on_freelist(wc);
@@ -1474,21 +1484,25 @@ static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio
if (WC_MODE_PMEM(wc)) {
bio_copy_block(wc, bio, memory_data(wc, e));
wc->stats.writes++;
+ need_flush = true;
} else {
writecache_bio_copy_ssd(wc, bio, e, search_used);
return WC_MAP_REMAP;
}
} while (bio->bi_iter.bi_size);
- if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks)) {
- writecache_flush(wc);
- if (writecache_has_error(wc))
- bio->bi_status = BLK_STS_IOERR;
- } else {
- writecache_schedule_autocommit(wc);
+flush_pmem_and_ret:
+ if (need_flush) {
+ if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks)) {
+ writecache_flush(wc);
+ if (writecache_has_error(wc))
+ ret = WC_MAP_ERROR;
+ } else {
+ writecache_schedule_autocommit(wc);
+ }
}
- return WC_MAP_SUBMIT;
+ return ret;
}
static enum wc_map_op writecache_map_flush(struct dm_writecache *wc, struct bio *bio)
@@ -1578,7 +1592,10 @@ static int writecache_map(struct dm_target *ti, struct bio *bio)
case WC_MAP_REMAP:
/* make sure that writecache_end_io decrements bio_in_progress: */
- bio->bi_private = (void *)1;
+ if (unlikely(bio->bi_opf & REQ_FUA) && bio_op(bio) == REQ_OP_WRITE)
+ bio->bi_private = (void *)3;
+ else
+ bio->bi_private = (void *)1;
atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
wc_unlock(wc);
return DM_MAPIO_REMAPPED;
@@ -1607,11 +1624,19 @@ static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t
{
struct dm_writecache *wc = ti->private;
- if (bio->bi_private == (void *)1) {
+ if (bio->bi_private == (void *)1 || bio->bi_private == (void *)3) {
int dir = bio_data_dir(bio);
+ bool fua = bio->bi_private == (void *)3;
+
if (atomic_dec_and_test(&wc->bio_in_progress[dir]))
if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
wake_up(&wc->bio_in_progress_wait[dir]);
+
+ if (fua && likely(*status == BLK_STS_OK)) {
+ bio->bi_private = NULL;
+ writecache_offload_bio(wc, bio);
+ return DM_ENDIO_INCOMPLETE;
+ }
} else if (bio->bi_private == (void *)2) {
dm_iot_io_end(&wc->iot, 1);
}
@@ -2506,6 +2531,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
+ spin_lock_init(&wc->flush_list_lock);
bio_list_init(&wc->flush_list);
wc->flush_thread = kthread_create(writecache_flush_thread, wc, "dm_writecache_flush");
if (IS_ERR(wc->flush_thread)) {
--
2.53.0
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