[PATCH 2/2] block: enable zone-append for iov_iter of bvec type

[Kanchan Joshi]

zone-append with bvec iov_iter gives WARN_ON, and returns -EINVAL.
Add new helper to process such iov_iter and add pages in bio honoring
zone-append specific constraints.

Signed-off-by: Kanchan Joshi <josh...@samsung.com>
Signed-off-by: Selvakumar S <selvakuma...@samsung.com>
Signed-off-by: Nitesh Shetty <nj.she...@samsung.com>
Signed-off-by: Javier Gonzalez <javier.g...@samsung.com>
---
 block/bio.c | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 0cecdbc..ade9da7 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -975,6 +975,30 @@ static int __bio_iov_bvec_add_pages(struct bio *bio, 
struct iov_iter *iter)
        iov_iter_advance(iter, size);
        return 0;
 }
+static int __bio_iov_bvec_append_add_pages(struct bio *bio, struct iov_iter 
*iter)
+{
+       const struct bio_vec *bv = iter->bvec;
+       unsigned int len;
+       size_t size;
+       struct request_queue *q = bio->bi_disk->queue;
+       unsigned int max_append_sectors = queue_max_zone_append_sectors(q);
+       bool same_page = false;
+
+       if (WARN_ON_ONCE(!max_append_sectors))
+               return -EINVAL;
+
+       if (WARN_ON_ONCE(iter->iov_offset > bv->bv_len))
+               return -EINVAL;
+
+       len = min_t(size_t, bv->bv_len - iter->iov_offset, iter->count);
+       size = bio_add_hw_page(q, bio, bv->bv_page, len,
+                               bv->bv_offset + iter->iov_offset,
+                               max_append_sectors, &same_page);
+       if (unlikely(size != len))
+               return -EINVAL;
+       iov_iter_advance(iter, size);
+       return 0;
+}
 
 #define PAGE_PTRS_PER_BVEC     (sizeof(struct bio_vec) / sizeof(struct page *))
 
@@ -1105,9 +1129,10 @@ int bio_iov_iter_get_pages(struct bio *bio, struct 
iov_iter *iter)
 
        do {
                if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
-                       if (WARN_ON_ONCE(is_bvec))
-                               return -EINVAL;
-                       ret = __bio_iov_append_get_pages(bio, iter);
+                       if (is_bvec)
+                               ret = __bio_iov_bvec_append_add_pages(bio, 
iter);
+                       else
+                               ret = __bio_iov_append_get_pages(bio, iter);
                } else {
                        if (is_bvec)
                                ret = __bio_iov_bvec_add_pages(bio, iter);
-- 
2.7.4