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block: refactor get_contig_folio_len

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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>
This commit is contained in:
Christoph Hellwig 2026-01-26 06:53:33 +01:00 • committed by Jens Axboe
commit 4d77007d42
1 changed files with 27 additions and 35 deletions
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62
block/bio.c
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@ -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;
}