[md PATCH 12/36] md/raid1: store behind-write pages in bi_vecs.

When performing write-behind we allocate pages to store the data
during write.
Previously we just keep a list of pages. Now we keep a list of
bi_vec which includes offset and size.
This means that the r1bio has complete information to create a new
bio which will be needed for retrying after write errors.

Signed-off-by: NeilBrown
---

drivers/md/raid1.c | 33 +++++++++++++++++----------------
drivers/md/raid1.h | 2 +-
2 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 6e605b2..42e815d 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -327,9 +327,9 @@ static void r1_bio_write_done(r1bio_t *r1_bio)
/* free extra copy of the data pages */
int i = r1_bio->behind_page_count;
while (i--)
- safe_put_page(r1_bio->behind_pages[i]);
- kfree(r1_bio->behind_pages);
- r1_bio->behind_pages = NULL;
+ safe_put_page(r1_bio->behind_bvecs[i].bv_page);
+ kfree(r1_bio->behind_bvecs);
+ r1_bio->behind_bvecs = NULL;
}
/* clear the bitmap if all writes complete successfully */
bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
@@ -748,30 +748,31 @@ static void alloc_behind_pages(struct bio *bio, r1bio_t *r1_bio)
{
int i;
struct bio_vec *bvec;
- struct page **pages = kzalloc(bio->bi_vcnt * sizeof(struct page*),
+ struct bio_vec *bvecs = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec),
GFP_NOIO);
- if (unlikely(!pages))
+ if (unlikely(!bvecs))
return;

bio_for_each_segment(bvec, bio, i) {
- pages[i] = alloc_page(GFP_NOIO);
- if (unlikely(!pages[i]))
+ bvecs[i] = *bvec;
+ bvecs[i].bv_page = alloc_page(GFP_NOIO);
+ if (unlikely(!bvecs[i].bv_page))
goto do_sync_io;
- memcpy(kmap(pages[i]) + bvec->bv_offset,
- kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
- kunmap(pages[i]);
+ memcpy(kmap(bvecs[i].bv_page) + bvec->bv_offset,
+ kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
+ kunmap(bvecs[i].bv_page);
kunmap(bvec->bv_page);
}
- r1_bio->behind_pages = pages;
+ r1_bio->behind_bvecs = bvecs;
r1_bio->behind_page_count = bio->bi_vcnt;
set_bit(R1BIO_BehindIO, &r1_bio->state);
return;

do_sync_io:
for (i = 0; i < bio->bi_vcnt; i++)
- if (pages[i])
- put_page(pages[i]);
- kfree(pages);
+ if (bvecs[i].bv_page)
+ put_page(bvecs[i].bv_page);
+ kfree(bvecs);
PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
}

@@ -1059,7 +1060,7 @@ read_again:
&r1_bio->state));
first_clone = 0;
}
- if (r1_bio->behind_pages) {
+ if (r1_bio->behind_bvecs) {
struct bio_vec *bvec;
int j;

@@ -1071,7 +1072,7 @@ read_again:
* them all
*/
__bio_for_each_segment(bvec, mbio, j, 0)
- bvec->bv_page = r1_bio->behind_pages[j];
+ bvec->bv_page = r1_bio->behind_bvecs[j].bv_page;
if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
atomic_inc(&r1_bio->behind_remaining);
}
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index f81360d..b788547 100644
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -101,7 +101,7 @@ struct r1bio_s {

struct list_head retry_list;
/* Next two are only valid when R1BIO_BehindIO is set */
- struct page **behind_pages;
+ struct bio_vec *behind_bvecs;
int behind_page_count;
/*
* if the IO is in WRITE direction, then multiple bios are used.


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