On Fri, Jul 03, 2020 at 05:32:56AM +0000, Damien Le Moal wrote:
On 2020/07/03 0:42, Kanchan Joshi wrote:
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 <joshi.k@xxxxxxxxxxx>
Signed-off-by: Selvakumar S <selvakuma.s1@xxxxxxxxxxx>
Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
Signed-off-by: Javier Gonzalez <javier.gonz@xxxxxxxxxxx>
---
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);
The only user of this function that issues zone append requests is zonefs. The
issued requests are not using bvec iter but a user direct IO buffer iter. So
this change would have no user at all as far as I can see. Am I missing
something ? What IO path makes this change necessary ?
Yes, zonefs does not use bvec iter. But while enabling io-uring path for
zone-append, I hit into this condition returning -EINVAL.
Reference (from user zone-append series cover letter):
"Append using io_uring fixed-buffer --->
This is flagged as not-supported at the moment. Reason being, for fixed-buffer
io-uring sends iov_iter of bvec type. But current append-infra in block-layer
does not support such iov_iter."
And zone-append doesn't have a problem in using bvec iter as well, so
thought that this may make infra more complete/future-proof?
--
Damien Le Moal
Western Digital Research
