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Message-ID: <20251121051406.1316884-2-yukuai@fnnas.com>
Date: Fri, 21 Nov 2025 13:13:59 +0800
From: Yu Kuai <yukuai@...as.com>
To: song@...nel.org,
yukuai@...as.com
Cc: linux-raid@...r.kernel.org,
linux-kernel@...r.kernel.org,
linan122@...wei.com,
xni@...hat.com
Subject: [PATCH 1/7] md/raid5: use mempool to allocate stripe_request_ctx
On the one hand, stripe_request_ctx is 72 bytes, and it's a bit huge for
a stack variable.
On the other hand, the bitmap sectors_to_do is a fixed size, result in
max_hw_sector_kb of raid5 array is at most 256 * 4k = 1Mb, and this will
make full stripe IO impossible for the array that chunk_size * data_disks
is bigger. Allocate ctx during runtime will make it possible to get rid
of this limit.
Signed-off-by: Yu Kuai <yukuai@...as.com>
---
drivers/md/md.h | 4 +++
drivers/md/raid1-10.c | 5 ----
drivers/md/raid5.c | 58 +++++++++++++++++++++++++++----------------
drivers/md/raid5.h | 2 ++
4 files changed, 42 insertions(+), 27 deletions(-)
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 6985f2829bbd..75fd8c873b6f 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -22,6 +22,10 @@
#include <trace/events/block.h>
#define MaxSector (~(sector_t)0)
+/*
+ * Number of guaranteed raid bios in case of extreme VM load:
+ */
+#define NR_RAID_BIOS 256
enum md_submodule_type {
MD_PERSONALITY = 0,
diff --git a/drivers/md/raid1-10.c b/drivers/md/raid1-10.c
index 521625756128..c33099925f23 100644
--- a/drivers/md/raid1-10.c
+++ b/drivers/md/raid1-10.c
@@ -3,11 +3,6 @@
#define RESYNC_BLOCK_SIZE (64*1024)
#define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
-/*
- * Number of guaranteed raid bios in case of extreme VM load:
- */
-#define NR_RAID_BIOS 256
-
/* when we get a read error on a read-only array, we redirect to another
* device without failing the first device, or trying to over-write to
* correct the read error. To keep track of bad blocks on a per-bio
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index cdbc7eba5c54..0ccb5907cd20 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6079,13 +6079,13 @@ static sector_t raid5_bio_lowest_chunk_sector(struct r5conf *conf,
static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
{
DEFINE_WAIT_FUNC(wait, woken_wake_function);
- bool on_wq;
struct r5conf *conf = mddev->private;
- sector_t logical_sector;
- struct stripe_request_ctx ctx = {};
const int rw = bio_data_dir(bi);
+ struct stripe_request_ctx *ctx;
+ sector_t logical_sector;
enum stripe_result res;
int s, stripe_cnt;
+ bool on_wq;
if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
int ret = log_handle_flush_request(conf, bi);
@@ -6097,11 +6097,6 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
return true;
}
/* ret == -EAGAIN, fallback */
- /*
- * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
- * we need to flush journal device
- */
- ctx.do_flush = bi->bi_opf & REQ_PREFLUSH;
}
md_write_start(mddev, bi);
@@ -6124,16 +6119,24 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
}
logical_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
- ctx.first_sector = logical_sector;
- ctx.last_sector = bio_end_sector(bi);
bi->bi_next = NULL;
- stripe_cnt = DIV_ROUND_UP_SECTOR_T(ctx.last_sector - logical_sector,
+ ctx = mempool_alloc(conf->ctx_pool, GFP_NOIO | __GFP_ZERO);
+ ctx->first_sector = logical_sector;
+ ctx->last_sector = bio_end_sector(bi);
+ /*
+ * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
+ * we need to flush journal device
+ */
+ if (unlikely(bi->bi_opf & REQ_PREFLUSH))
+ ctx->do_flush = true;
+
+ stripe_cnt = DIV_ROUND_UP_SECTOR_T(ctx->last_sector - logical_sector,
RAID5_STRIPE_SECTORS(conf));
- bitmap_set(ctx.sectors_to_do, 0, stripe_cnt);
+ bitmap_set(ctx->sectors_to_do, 0, stripe_cnt);
pr_debug("raid456: %s, logical %llu to %llu\n", __func__,
- bi->bi_iter.bi_sector, ctx.last_sector);
+ bi->bi_iter.bi_sector, ctx->last_sector);
/* Bail out if conflicts with reshape and REQ_NOWAIT is set */
if ((bi->bi_opf & REQ_NOWAIT) &&
@@ -6141,6 +6144,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
bio_wouldblock_error(bi);
if (rw == WRITE)
md_write_end(mddev);
+ mempool_free(ctx, conf->ctx_pool);
return true;
}
md_account_bio(mddev, &bi);
@@ -6159,10 +6163,10 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
add_wait_queue(&conf->wait_for_reshape, &wait);
on_wq = true;
}
- s = (logical_sector - ctx.first_sector) >> RAID5_STRIPE_SHIFT(conf);
+ s = (logical_sector - ctx->first_sector) >> RAID5_STRIPE_SHIFT(conf);
while (1) {
- res = make_stripe_request(mddev, conf, &ctx, logical_sector,
+ res = make_stripe_request(mddev, conf, ctx, logical_sector,
bi);
if (res == STRIPE_FAIL || res == STRIPE_WAIT_RESHAPE)
break;
@@ -6179,9 +6183,9 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
* raid5_activate_delayed() from making progress
* and thus deadlocking.
*/
- if (ctx.batch_last) {
- raid5_release_stripe(ctx.batch_last);
- ctx.batch_last = NULL;
+ if (ctx->batch_last) {
+ raid5_release_stripe(ctx->batch_last);
+ ctx->batch_last = NULL;
}
wait_woken(&wait, TASK_UNINTERRUPTIBLE,
@@ -6189,21 +6193,23 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
continue;
}
- s = find_next_bit_wrap(ctx.sectors_to_do, stripe_cnt, s);
+ s = find_next_bit_wrap(ctx->sectors_to_do, stripe_cnt, s);
if (s == stripe_cnt)
break;
- logical_sector = ctx.first_sector +
+ logical_sector = ctx->first_sector +
(s << RAID5_STRIPE_SHIFT(conf));
}
if (unlikely(on_wq))
remove_wait_queue(&conf->wait_for_reshape, &wait);
- if (ctx.batch_last)
- raid5_release_stripe(ctx.batch_last);
+ if (ctx->batch_last)
+ raid5_release_stripe(ctx->batch_last);
if (rw == WRITE)
md_write_end(mddev);
+
+ mempool_free(ctx, conf->ctx_pool);
if (res == STRIPE_WAIT_RESHAPE) {
md_free_cloned_bio(bi);
return false;
@@ -7370,6 +7376,7 @@ static void free_conf(struct r5conf *conf)
bioset_exit(&conf->bio_split);
kfree(conf->stripe_hashtbl);
kfree(conf->pending_data);
+ mempool_destroy(conf->ctx_pool);
kfree(conf);
}
@@ -8053,6 +8060,13 @@ static int raid5_run(struct mddev *mddev)
goto abort;
}
+ conf->ctx_pool = mempool_create_kmalloc_pool(NR_RAID_BIOS,
+ sizeof(struct stripe_request_ctx));
+ if (!conf->ctx_pool) {
+ ret = -ENOMEM;
+ goto abort;
+ }
+
if (log_init(conf, journal_dev, raid5_has_ppl(conf)))
goto abort;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index eafc6e9ed6ee..6e3f07119fa4 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -690,6 +690,8 @@ struct r5conf {
struct list_head pending_list;
int pending_data_cnt;
struct r5pending_data *next_pending_data;
+
+ mempool_t *ctx_pool;
};
#if PAGE_SIZE == DEFAULT_STRIPE_SIZE
--
2.51.0
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