md/raid1: fix writebehind bio clone
After bio is submitted, we should not clone it as its bi_iter might be
invalid by driver. This is the case of behind_master_bio. In certain
situration, we could dispatch behind_master_bio immediately for the
first disk and then clone it for other disks.
https://bugzilla.kernel.org/show_bug.cgi?id=196383
Reported-and-tested-by: Markus <m4rkusxxl@web.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Fix: 841c1316c7da(md: raid1: improve write behind)
Cc: stable@vger.kernel.org (4.12+)
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 8387eb1..1d235cc 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -484,10 +484,6 @@ static void raid1_end_write_request(struct bio *bio)
}
if (behind) {
- /* we release behind master bio when all write are done */
- if (r1_bio->behind_master_bio == bio)
- to_put = NULL;
-
if (test_bit(WriteMostly, &rdev->flags))
atomic_dec(&r1_bio->behind_remaining);
@@ -1080,7 +1076,7 @@ static void unfreeze_array(struct r1conf *conf)
wake_up(&conf->wait_barrier);
}
-static struct bio *alloc_behind_master_bio(struct r1bio *r1_bio,
+static void alloc_behind_master_bio(struct r1bio *r1_bio,
struct bio *bio)
{
int size = bio->bi_iter.bi_size;
@@ -1090,11 +1086,13 @@ static struct bio *alloc_behind_master_bio(struct r1bio *r1_bio,
behind_bio = bio_alloc_mddev(GFP_NOIO, vcnt, r1_bio->mddev);
if (!behind_bio)
- goto fail;
+ return;
/* discard op, we don't support writezero/writesame yet */
- if (!bio_has_data(bio))
+ if (!bio_has_data(bio)) {
+ behind_bio->bi_iter.bi_size = size;
goto skip_copy;
+ }
while (i < vcnt && size) {
struct page *page;
@@ -1115,14 +1113,13 @@ static struct bio *alloc_behind_master_bio(struct r1bio *r1_bio,
r1_bio->behind_master_bio = behind_bio;;
set_bit(R1BIO_BehindIO, &r1_bio->state);
- return behind_bio;
+ return;
free_pages:
pr_debug("%dB behind alloc failed, doing sync I/O\n",
bio->bi_iter.bi_size);
bio_free_pages(behind_bio);
-fail:
- return behind_bio;
+ bio_put(behind_bio);
}
struct raid1_plug_cb {
@@ -1475,7 +1472,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
(atomic_read(&bitmap->behind_writes)
< mddev->bitmap_info.max_write_behind) &&
!waitqueue_active(&bitmap->behind_wait)) {
- mbio = alloc_behind_master_bio(r1_bio, bio);
+ alloc_behind_master_bio(r1_bio, bio);
}
bitmap_startwrite(bitmap, r1_bio->sector,
@@ -1485,14 +1482,11 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
first_clone = 0;
}
- if (!mbio) {
- if (r1_bio->behind_master_bio)
- mbio = bio_clone_fast(r1_bio->behind_master_bio,
- GFP_NOIO,
- mddev->bio_set);
- else
- mbio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
- }
+ if (r1_bio->behind_master_bio)
+ mbio = bio_clone_fast(r1_bio->behind_master_bio,
+ GFP_NOIO, mddev->bio_set);
+ else
+ mbio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
if (r1_bio->behind_master_bio) {
if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
@@ -2346,8 +2340,6 @@ static int narrow_write_error(struct r1bio *r1_bio, int i)
wbio = bio_clone_fast(r1_bio->behind_master_bio,
GFP_NOIO,
mddev->bio_set);
- /* We really need a _all clone */
- wbio->bi_iter = (struct bvec_iter){ 0 };
} else {
wbio = bio_clone_fast(r1_bio->master_bio, GFP_NOIO,
mddev->bio_set);
