* [PATCH 1/3] block: improve the gap check in __bio_add_pc_page
2019-08-12 15:39 bio_add_pc_page cleanups Christoph Hellwig
@ 2019-08-12 15:39 ` Christoph Hellwig
2019-08-12 15:39 ` [PATCH 2/3] block: create a bio_try_merge_pc_page helper Christoph Hellwig
` (3 subsequent siblings)
4 siblings, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2019-08-12 15:39 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block, Johannes Thumshirn
If we can add more data into an existing segment we do not create a gap
per definition, so move the check for a gap after the attempt to merge
into the segment.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
---
block/bio.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 24a496f5d2e2..9f80bf4531b3 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -710,18 +710,18 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
goto done;
}
- /*
- * If the queue doesn't support SG gaps and adding this
- * offset would create a gap, disallow it.
- */
- if (bvec_gap_to_prev(q, bvec, offset))
- return 0;
-
if (page_is_mergeable(bvec, page, len, offset, &same_page) &&
can_add_page_to_seg(q, bvec, page, len, offset)) {
bvec->bv_len += len;
goto done;
}
+
+ /*
+ * If the queue doesn't support SG gaps and adding this segment
+ * would create a gap, disallow it.
+ */
+ if (bvec_gap_to_prev(q, bvec, offset))
+ return 0;
}
if (bio_full(bio, len))
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH 2/3] block: create a bio_try_merge_pc_page helper
2019-08-12 15:39 bio_add_pc_page cleanups Christoph Hellwig
2019-08-12 15:39 ` [PATCH 1/3] block: improve the gap check in __bio_add_pc_page Christoph Hellwig
@ 2019-08-12 15:39 ` Christoph Hellwig
2019-08-12 15:39 ` [PATCH 3/3] block: move same page handling from __bio_add_pc_page to the callers Christoph Hellwig
` (2 subsequent siblings)
4 siblings, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2019-08-12 15:39 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block
Passsthrough bio handling should be the same as normal bio handling,
except that we need to take hardware limitations into account. Thus
use the common try_merge implementation after checking the hardware
limits. This changes behavior in that we now also check segment
and dma boundary settings for same page merges, which is a little
more work but has no effect as those need to be larger than the
page size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/bio.c | 34 ++++++++++------------------------
1 file changed, 10 insertions(+), 24 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 9f80bf4531b3..6ea4b9257667 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -646,25 +646,20 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
return true;
}
-/*
- * Check if the @page can be added to the current segment(@bv), and make
- * sure to call it only if page_is_mergeable(@bv, @page) is true
- */
-static bool can_add_page_to_seg(struct request_queue *q,
- struct bio_vec *bv, struct page *page, unsigned len,
- unsigned offset)
+static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,
+ struct page *page, unsigned len, unsigned offset,
+ bool *same_page)
{
+ struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
unsigned long mask = queue_segment_boundary(q);
phys_addr_t addr1 = page_to_phys(bv->bv_page) + bv->bv_offset;
phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
if ((addr1 | mask) != (addr2 | mask))
return false;
-
if (bv->bv_len + len > queue_max_segment_size(q))
return false;
-
- return true;
+ return __bio_try_merge_page(bio, page, len, offset, same_page);
}
/**
@@ -700,26 +695,18 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
return 0;
if (bio->bi_vcnt > 0) {
- bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
-
- if (page == bvec->bv_page &&
- offset == bvec->bv_offset + bvec->bv_len) {
- if (put_same_page)
+ if (bio_try_merge_pc_page(q, bio, page, len, offset,
+ &same_page)) {
+ if (put_same_page && same_page)
put_page(page);
- bvec->bv_len += len;
- goto done;
- }
-
- if (page_is_mergeable(bvec, page, len, offset, &same_page) &&
- can_add_page_to_seg(q, bvec, page, len, offset)) {
- bvec->bv_len += len;
- goto done;
+ return len;
}
/*
* If the queue doesn't support SG gaps and adding this segment
* would create a gap, disallow it.
*/
+ bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (bvec_gap_to_prev(q, bvec, offset))
return 0;
}
@@ -735,7 +722,6 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
bvec->bv_len = len;
bvec->bv_offset = offset;
bio->bi_vcnt++;
- done:
bio->bi_iter.bi_size += len;
return len;
}
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH 3/3] block: move same page handling from __bio_add_pc_page to the callers
2019-08-12 15:39 bio_add_pc_page cleanups Christoph Hellwig
2019-08-12 15:39 ` [PATCH 1/3] block: improve the gap check in __bio_add_pc_page Christoph Hellwig
2019-08-12 15:39 ` [PATCH 2/3] block: create a bio_try_merge_pc_page helper Christoph Hellwig
@ 2019-08-12 15:39 ` Christoph Hellwig
2019-08-22 1:00 ` bio_add_pc_page cleanups Christoph Hellwig
2019-08-22 13:15 ` Jens Axboe
4 siblings, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2019-08-12 15:39 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block
Hiding page refcount manipulation inside a low-level bio helper is
somewhat awkward. Instead return the same page information to the
callers, where it fits in much better.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/bio.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 6ea4b9257667..11aa6738ed62 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -669,7 +669,7 @@ static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,
* @page: page to add
* @len: vec entry length
* @offset: vec entry offset
- * @put_same_page: put the page if it is same with last added page
+ * @same_page: return if the merge happen inside the same page
*
* Attempt to add a page to the bio_vec maplist. This can fail for a
* number of reasons, such as the bio being full or target block device
@@ -680,10 +680,9 @@ static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,
*/
static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset,
- bool put_same_page)
+ bool *same_page)
{
struct bio_vec *bvec;
- bool same_page = false;
/*
* cloned bio must not modify vec list
@@ -695,12 +694,8 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
return 0;
if (bio->bi_vcnt > 0) {
- if (bio_try_merge_pc_page(q, bio, page, len, offset,
- &same_page)) {
- if (put_same_page && same_page)
- put_page(page);
+ if (bio_try_merge_pc_page(q, bio, page, len, offset, same_page))
return len;
- }
/*
* If the queue doesn't support SG gaps and adding this segment
@@ -729,7 +724,8 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
int bio_add_pc_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset)
{
- return __bio_add_pc_page(q, bio, page, len, offset, false);
+ bool same_page = false;
+ return __bio_add_pc_page(q, bio, page, len, offset, &same_page);
}
EXPORT_SYMBOL(bio_add_pc_page);
@@ -1370,13 +1366,17 @@ struct bio *bio_map_user_iov(struct request_queue *q,
for (j = 0; j < npages; j++) {
struct page *page = pages[j];
unsigned int n = PAGE_SIZE - offs;
+ bool same_page = false;
if (n > bytes)
n = bytes;
if (!__bio_add_pc_page(q, bio, page, n, offs,
- true))
+ &same_page)) {
+ if (same_page)
+ put_page(page);
break;
+ }
added += n;
bytes -= n;
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: bio_add_pc_page cleanups
2019-08-12 15:39 bio_add_pc_page cleanups Christoph Hellwig
` (2 preceding siblings ...)
2019-08-12 15:39 ` [PATCH 3/3] block: move same page handling from __bio_add_pc_page to the callers Christoph Hellwig
@ 2019-08-22 1:00 ` Christoph Hellwig
2019-08-22 13:15 ` Jens Axboe
4 siblings, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2019-08-22 1:00 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block
On Mon, Aug 12, 2019 at 05:39:55PM +0200, Christoph Hellwig wrote:
> Hi Jens,
>
> this series cleans up the bio_add_pc_page code and reuses more code
> from the regular bio path.
ping?
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: bio_add_pc_page cleanups
2019-08-12 15:39 bio_add_pc_page cleanups Christoph Hellwig
` (3 preceding siblings ...)
2019-08-22 1:00 ` bio_add_pc_page cleanups Christoph Hellwig
@ 2019-08-22 13:15 ` Jens Axboe
4 siblings, 0 replies; 7+ messages in thread
From: Jens Axboe @ 2019-08-22 13:15 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: linux-block
On 8/12/19 9:39 AM, Christoph Hellwig wrote:
> Hi Jens,
>
> this series cleans up the bio_add_pc_page code and reuses more code
> from the regular bio path.
LGTM, applied for 5.4, thanks.
--
Jens Axboe
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 3/3] block: move same page handling from __bio_add_pc_page to the callers
2019-07-03 13:00 Christoph Hellwig
@ 2019-07-03 13:00 ` Christoph Hellwig
0 siblings, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2019-07-03 13:00 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block
Hiding page refcount manipulation inside a low-level bio helper is
somewhat awkward. Instead return the same page information to the
callers, where it fits in much better.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/bio.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 1db626f99bcb..631b590a479f 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -668,7 +668,7 @@ static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,
* @page: page to add
* @len: vec entry length
* @offset: vec entry offset
- * @put_same_page: put the page if it is same with last added page
+ * @same_page: return if the merge happen inside the same page
*
* Attempt to add a page to the bio_vec maplist. This can fail for a
* number of reasons, such as the bio being full or target block device
@@ -679,10 +679,9 @@ static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,
*/
static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset,
- bool put_same_page)
+ bool *same_page)
{
struct bio_vec *bvec;
- bool same_page = false;
/*
* cloned bio must not modify vec list
@@ -694,12 +693,8 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
return 0;
if (bio->bi_vcnt > 0) {
- if (bio_try_merge_pc_page(q, bio, page, len, offset,
- &same_page)) {
- if (put_same_page && same_page)
- put_page(page);
+ if (bio_try_merge_pc_page(q, bio, page, len, offset, same_page))
return len;
- }
/*
* If the queue doesn't support SG gaps and adding this segment
@@ -728,7 +723,8 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
int bio_add_pc_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset)
{
- return __bio_add_pc_page(q, bio, page, len, offset, false);
+ bool same_page = false;
+ return __bio_add_pc_page(q, bio, page, len, offset, &same_page);
}
EXPORT_SYMBOL(bio_add_pc_page);
@@ -1369,13 +1365,17 @@ struct bio *bio_map_user_iov(struct request_queue *q,
for (j = 0; j < npages; j++) {
struct page *page = pages[j];
unsigned int n = PAGE_SIZE - offs;
+ bool same_page = false;
if (n > bytes)
n = bytes;
if (!__bio_add_pc_page(q, bio, page, n, offs,
- true))
+ &same_page)) {
+ if (same_page)
+ put_page(page);
break;
+ }
added += n;
bytes -= n;
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread