[PATCH 06/17] md: raid1/raid10: borrow .bi_error as pre-allocated page index

Ming Lei
2017-02-16T11:51:01Z

Before bio is submitted, it is safe to borrow .bi_error. This
patch uses .bi_error as index of pre-allocated page in bio, so
that we can avoid to mess .bi_vcnt. Especially the old way
will not work any more when multipage bvec is introduced.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
drivers/md/raid1.c | 12 ++++++++++--
drivers/md/raid10.c | 14 ++++++++++----
2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c4791fbd69ac..8904a9149671 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2811,13 +2811,14 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
len = sync_blocks<<9;
}

+ /* borrow .bi_error as pre-allocated page index */
for (i = 0 ; i < conf->raid_disks * 2; i++) {
bio = r1_bio->bios[i];
if (bio->bi_end_io) {
- page = mdev_get_page_from_bio(bio, bio->bi_vcnt);
+ page = mdev_get_page_from_bio(bio, bio->bi_error++);
if (bio_add_page(bio, page, len, 0) == 0) {
/* stop here */
- mdev_put_page_to_bio(bio, bio->bi_vcnt, page);
+ mdev_put_page_to_bio(bio, --bio->bi_error, page);
while (i > 0) {
i--;
bio = r1_bio->bios[i];
@@ -2836,6 +2837,13 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
sync_blocks -= (len>>9);
} while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
bio_full:
+ /* return .bi_error back to bio */
+ for (i = 0 ; i < conf->raid_disks * 2; i++) {
+ bio = r1_bio->bios[i];
+ if (bio->bi_end_io)
+ bio->bi_error = 0;
+ }
+
r1_bio->sectors = nr_sectors;

if (mddev_is_clustered(mddev) &&
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index b7dfbca869a3..9cfc22cd1330 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3348,7 +3348,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,

bio = r10_bio->devs[i].bio;
bio_reset(bio);
- bio->bi_error = -EIO;
rcu_read_lock();
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev == NULL || test_bit(Faulty, &rdev->flags)) {
@@ -3392,7 +3391,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
/* Need to set up for writing to the replacement */
bio = r10_bio->devs[i].repl_bio;
bio_reset(bio);
- bio->bi_error = -EIO;

sector = r10_bio->devs[i].addr;
bio->bi_next = biolist;
@@ -3435,14 +3433,15 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
len = (max_sector - sector_nr) << 9;
if (len == 0)
break;
+ /* borrow .bi_error as pre-allocated page index */
for (bio= biolist ; bio ; bio=bio->bi_next) {
struct bio *bio2;
- page = mdev_get_page_from_bio(bio, bio->bi_vcnt);
+ page = mdev_get_page_from_bio(bio, bio->bi_error++);
if (bio_add_page(bio, page, len, 0))
continue;

/* stop here */
- mdev_put_page_to_bio(bio, bio->bi_vcnt, page);
+ mdev_put_page_to_bio(bio, --bio->bi_error, page);
for (bio2 = biolist;
bio2 && bio2 != bio;
bio2 = bio2->bi_next) {
@@ -3456,6 +3455,13 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
sector_nr += len>>9;
} while (biolist->bi_vcnt < RESYNC_PAGES);
bio_full:
+ /* return .bi_error back to bio, and set resync's as -EIO */
+ for (bio= biolist ; bio ; bio=bio->bi_next)
+ if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
+ bio->bi_error = -EIO;
+ else
+ bio->bi_error = 0;
+
r10_bio->sectors = nr_sectors;

while (biolist) {
--
2.7.4