block: refactor get_contig_folio_len

Move all of the logic to find the contigous length inside a folio into
get_contig_folio_len instead of keeping some of it in the caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index ac7703e149c6b018816d538b8fde03dd9ec5dbb3..d633e80d821fbb63df20b7875285b35c6970c1db 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1172,33 +1172,35 @@ void bio_iov_bvec_set(struct bio *bio, const struct iov_iter *iter)
        bio_set_flag(bio, BIO_CLONED);
 }
 
-static unsigned int get_contig_folio_len(unsigned int *num_pages,
-                                        struct page **pages, unsigned int i,
-                                        struct folio *folio, size_t left,
+static unsigned int get_contig_folio_len(struct page **pages,
+                                        unsigned int *num_pages, size_t left,
                                         size_t offset)
 {
-       size_t bytes = left;
-       size_t contig_sz = min_t(size_t, PAGE_SIZE - offset, bytes);
-       unsigned int j;
+       struct folio *folio = page_folio(pages[0]);
+       size_t contig_sz = min_t(size_t, PAGE_SIZE - offset, left);
+       unsigned int max_pages, i;
+       size_t folio_offset, len;
+
+       folio_offset = PAGE_SIZE * folio_page_idx(folio, pages[0]) + offset;
+       len = min(folio_size(folio) - folio_offset, left);
 
        /*
-        * We might COW a single page in the middle of
-        * a large folio, so we have to check that all
-        * pages belong to the same folio.
+        * We might COW a single page in the middle of a large folio, so we have
+        * to check that all pages belong to the same folio.
         */
-       bytes -= contig_sz;
-       for (j = i + 1; j < i + *num_pages; j++) {
-               size_t next = min_t(size_t, PAGE_SIZE, bytes);
+       left -= contig_sz;
+       max_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE);
+       for (i = 1; i < max_pages; i++) {
+               size_t next = min_t(size_t, PAGE_SIZE, left);
 
-               if (page_folio(pages[j]) != folio ||
-                   pages[j] != pages[j - 1] + 1) {
+               if (page_folio(pages[i]) != folio ||
+                   pages[i] != pages[i - 1] + 1)
                        break;
-               }
                contig_sz += next;
-               bytes -= next;
+               left -= next;
        }
-       *num_pages = j - i;
 
+       *num_pages = i;
        return contig_sz;
 }
 
@@ -1222,8 +1224,8 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
        struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
        struct page **pages = (struct page **)bv;
        ssize_t size;
-       unsigned int num_pages, i = 0;
-       size_t offset, folio_offset, left, len;
+       unsigned int i = 0;
+       size_t offset, left, len;
        int ret = 0;
 
        /*
@@ -1244,23 +1246,12 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
                return size ? size : -EFAULT;
 
        nr_pages = DIV_ROUND_UP(offset + size, PAGE_SIZE);
-       for (left = size, i = 0; left > 0; left -= len, i += num_pages) {
-               struct page *page = pages[i];
-               struct folio *folio = page_folio(page);
+       for (left = size; left > 0; left -= len) {
                unsigned int old_vcnt = bio->bi_vcnt;
+               unsigned int nr_to_add;
 
-               folio_offset = ((size_t)folio_page_idx(folio, page) <<
-                              PAGE_SHIFT) + offset;
-
-               len = min(folio_size(folio) - folio_offset, left);
-
-               num_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE);
-
-               if (num_pages > 1)
-                       len = get_contig_folio_len(&num_pages, pages, i,
-                                                  folio, left, offset);
-
-               if (!bio_add_folio(bio, folio, len, folio_offset)) {
+               len = get_contig_folio_len(&pages[i], &nr_to_add, left, offset);
+               if (!bio_add_page(bio, pages[i], len, offset)) {
                        WARN_ON_ONCE(1);
                        ret = -EINVAL;
                        goto out;
@@ -1275,8 +1266,9 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
                         * single pin per page.
                         */
                        if (offset && bio->bi_vcnt == old_vcnt)
-                               unpin_user_folio(folio, 1);
+                               unpin_user_folio(page_folio(pages[i]), 1);
                }
+               i += nr_to_add;
                offset = 0;
        }