Re: [PATCH v2 11/51] md: raid1: initialize bvec table via bio_add_page()

[Guoqing Jiang]

On 06/28/2017 12:22 AM, Ming Lei wrote:

Seems above section is similar as reset_bvec_table introduced in next patch,
why there is difference between raid1 and raid10? Maybe add reset_bvec_table
into md.c, then call it in raid1 or raid10 is better, just my 2 cents.

Hi Guoqing,

I think it is a good idea, and even the two patches can be put into
one, so how about the following patch?

Looks good.

Acked-by: Guoqing Jiang <gqji...@suse.com>

Thanks,
Guoqing

Shaohua, what do you think of this one?

---
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 3d957ac1e109..7ffc622dd7fa 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -9126,6 +9126,24 @@ void md_reload_sb(struct mddev *mddev, int nr)
  }
  EXPORT_SYMBOL(md_reload_sb);

+/* generally called after bio_reset() for reseting bvec */

+void reset_bvec_table(struct bio *bio, struct resync_pages *rp, int size)
+{
+       /* initialize bvec table again */
+       rp->idx = 0;
+       do {
+               struct page *page = resync_fetch_page(rp, rp->idx++);
+               int len = min_t(int, size, PAGE_SIZE);
+
+               /*
+                * won't fail because the vec table is big
+                * enough to hold all these pages
+                */
+               bio_add_page(bio, page, len, 0);
+               size -= len;
+       } while (rp->idx < RESYNC_PAGES && size > 0);
+}
+
  #ifndef MODULE

/*

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 991f0fe2dcc6..f569831b1de9 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -783,4 +783,6 @@ static inline struct page *resync_fetch_page(struct 
resync_pages *rp,
                return NULL;
        return rp->pages[idx];
  }
+
+void reset_bvec_table(struct bio *bio, struct resync_pages *rp, int size);
  #endif /* _MD_MD_H */
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 3febfc8391fb..6ae2665ecd58 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2086,10 +2086,7 @@ static void process_checks(struct r1bio *r1_bio)
        /* Fix variable parts of all bios */
        vcnt = (r1_bio->sectors + PAGE_SIZE / 512 - 1) >> (PAGE_SHIFT - 9);
        for (i = 0; i < conf->raid_disks * 2; i++) {
-               int j;
-               int size;
                blk_status_t status;
-               struct bio_vec *bi;
                struct bio *b = r1_bio->bios[i];
                struct resync_pages *rp = get_resync_pages(b);
                if (b->bi_end_io != end_sync_read)
@@ -2098,8 +2095,6 @@ static void process_checks(struct r1bio *r1_bio)
                status = b->bi_status;
                bio_reset(b);
                b->bi_status = status;
-               b->bi_vcnt = vcnt;
-               b->bi_iter.bi_size = r1_bio->sectors << 9;
                b->bi_iter.bi_sector = r1_bio->sector +
                        conf->mirrors[i].rdev->data_offset;
                b->bi_bdev = conf->mirrors[i].rdev->bdev;
@@ -2107,15 +2102,8 @@ static void process_checks(struct r1bio *r1_bio)
                rp->raid_bio = r1_bio;
                b->bi_private = rp;

- size = b->bi_iter.bi_size;

-               bio_for_each_segment_all(bi, b, j) {
-                       bi->bv_offset = 0;
-                       if (size > PAGE_SIZE)
-                               bi->bv_len = PAGE_SIZE;
-                       else
-                               bi->bv_len = size;
-                       size -= PAGE_SIZE;
-               }
+               /* initialize bvec table again */
+               reset_bvec_table(b, rp, r1_bio->sectors << 9);
        }
        for (primary = 0; primary < conf->raid_disks * 2; primary++)
                if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 5026e7ad51d3..72f4fa07449b 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2087,8 +2087,8 @@ static void sync_request_write(struct mddev *mddev, 
struct r10bio *r10_bio)
                rp = get_resync_pages(tbio);
                bio_reset(tbio);

- tbio->bi_vcnt = vcnt;

-               tbio->bi_iter.bi_size = fbio->bi_iter.bi_size;
+               reset_bvec_table(tbio, rp, fbio->bi_iter.bi_size);
+
                rp->raid_bio = r10_bio;
                tbio->bi_private = rp;
                tbio->bi_iter.bi_sector = r10_bio->devs[i].addr;

Thanks,
Ming