From: Hans Holmberg <hans.holmb...@cnexlabs.com>

Ever since '07173c3ec276 ("block: enable multipage bvecs")' we
need to handle bios with multipage bvecs in pblk.

Currently, a multipage bvec results in a crash[1].
Fix this by using bvec iterators in stead of direct bvec indexing.

Also add a dcache flush, for the same reasons as in:
'6e6e811d747b ("block: Add missing flush_dcache_page() call")'

[1] https://github.com/OpenChannelSSD/linux/issues/61

Reported-by: Klaus Jensen <klaus.jen...@cnexlabs.com>
Signed-off-by: Hans Holmberg <hans.holmb...@cnexlabs.com>
---

It ain't pretty, but let's fix the breakage while waiting for Igor's
partial read cleanup to be ready.

 drivers/lightnvm/pblk-read.c | 50 ++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 22 deletions(-)

diff --git a/drivers/lightnvm/pblk-read.c b/drivers/lightnvm/pblk-read.c
index f08f7d9bd3be..27f8a76d8bd8 100644
--- a/drivers/lightnvm/pblk-read.c
+++ b/drivers/lightnvm/pblk-read.c
@@ -230,14 +230,14 @@ static void pblk_end_partial_read(struct nvm_rq *rqd)
        struct pblk_sec_meta *meta;
        struct bio *new_bio = rqd->bio;
        struct bio *bio = pr_ctx->orig_bio;
-       struct bio_vec src_bv, dst_bv;
        void *meta_list = rqd->meta_list;
-       int bio_init_idx = pr_ctx->bio_init_idx;
        unsigned long *read_bitmap = pr_ctx->bitmap;
+       struct bvec_iter orig_iter = BVEC_ITER_ALL_INIT;
+       struct bvec_iter new_iter = BVEC_ITER_ALL_INIT;
        int nr_secs = pr_ctx->orig_nr_secs;
        int nr_holes = nr_secs - bitmap_weight(read_bitmap, nr_secs);
        void *src_p, *dst_p;
-       int hole, i;
+       int bit, i;
 
        if (unlikely(nr_holes == 1)) {
                struct ppa_addr ppa;
@@ -256,33 +256,39 @@ static void pblk_end_partial_read(struct nvm_rq *rqd)
 
        /* Fill the holes in the original bio */
        i = 0;
-       hole = find_first_zero_bit(read_bitmap, nr_secs);
-       do {
-               struct pblk_line *line;
+       for (bit = 0; bit < nr_secs; bit++) {
+               if (!test_bit(bit, read_bitmap)) {
+                       struct bio_vec dst_bv, src_bv;
+                       struct pblk_line *line;
 
-               line = pblk_ppa_to_line(pblk, rqd->ppa_list[i]);
-               kref_put(&line->ref, pblk_line_put);
+                       line = pblk_ppa_to_line(pblk, rqd->ppa_list[i]);
+                       kref_put(&line->ref, pblk_line_put);
 
-               meta = pblk_get_meta(pblk, meta_list, hole);
-               meta->lba = cpu_to_le64(pr_ctx->lba_list_media[i]);
+                       meta = pblk_get_meta(pblk, meta_list, bit);
+                       meta->lba = cpu_to_le64(pr_ctx->lba_list_media[i]);
 
-               src_bv = new_bio->bi_io_vec[i++];
-               dst_bv = bio->bi_io_vec[bio_init_idx + hole];
+                       dst_bv = bio_iter_iovec(bio, orig_iter);
+                       src_bv = bio_iter_iovec(new_bio, new_iter);
 
-               src_p = kmap_atomic(src_bv.bv_page);
-               dst_p = kmap_atomic(dst_bv.bv_page);
+                       src_p = kmap_atomic(src_bv.bv_page);
+                       dst_p = kmap_atomic(dst_bv.bv_page);
 
-               memcpy(dst_p + dst_bv.bv_offset,
-                       src_p + src_bv.bv_offset,
-                       PBLK_EXPOSED_PAGE_SIZE);
+                       memcpy(dst_p + dst_bv.bv_offset,
+                               src_p + src_bv.bv_offset,
+                               PBLK_EXPOSED_PAGE_SIZE);
 
-               kunmap_atomic(src_p);
-               kunmap_atomic(dst_p);
+                       kunmap_atomic(src_p);
+                       kunmap_atomic(dst_p);
 
-               mempool_free(src_bv.bv_page, &pblk->page_bio_pool);
+                       flush_dcache_page(dst_bv.bv_page);
+                       mempool_free(src_bv.bv_page, &pblk->page_bio_pool);
 
-               hole = find_next_zero_bit(read_bitmap, nr_secs, hole + 1);
-       } while (hole < nr_secs);
+                       bio_advance_iter(new_bio, &new_iter,
+                                       PBLK_EXPOSED_PAGE_SIZE);
+                       i++;
+               }
+               bio_advance_iter(bio, &orig_iter, PBLK_EXPOSED_PAGE_SIZE);
+       }
 
        bio_put(new_bio);
        kfree(pr_ctx);
-- 
2.17.1

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