Introduce 'enum bvec_merge_flags' and pass it to __bio_try_merge_page,
we have to deal with several cases related with page reference when
merging same page to bio(bvec), such as:
1) only merge to same page without putting reference of the same page,
such as iomap & xfs
2) merge to same page and putting reference of the same page, such as
__bio_iov_iter_get_pages()
Cc: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Cc: linux-xfs@xxxxxxxxxxxxxxx
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/bio.c | 20 ++++++++++++--------
fs/iomap.c | 3 ++-
fs/xfs/xfs_aops.c | 3 ++-
include/linux/bio.h | 14 +++++++++++++-
4 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 683cbb40f051..39e3b931dc3b 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -636,7 +636,7 @@ EXPORT_SYMBOL(bio_clone_fast);
static inline bool page_is_mergeable(const struct bio_vec *bv,
struct page *page, unsigned int len, unsigned int off,
- bool same_page)
+ enum bvec_merge_flags flags)
{
phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) +
bv->bv_offset + bv->bv_len - 1;
@@ -648,13 +648,14 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
return false;
if ((vec_end_addr & PAGE_MASK) != page_addr) {
- if (same_page)
+ if (flags & BVEC_MERGE_TO_SAME_PAGE)
return false;
if (pfn_to_page(PFN_DOWN(vec_end_addr)) + 1 != page)
return false;
}
- WARN_ON_ONCE(same_page && (len + off) > PAGE_SIZE);
+ WARN_ON_ONCE((flags & BVEC_MERGE_TO_SAME_PAGE) &&
+ (len + off) > PAGE_SIZE);
return true;
}
@@ -729,8 +730,9 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
if (bvec_gap_to_prev(q, bvec, offset))
return 0;
- if (page_is_mergeable(bvec, page, len, offset, false) &&
- can_add_page_to_seg(q, bvec, page, len, offset)) {
+ if (page_is_mergeable(bvec, page, len, offset,
+ BVEC_MERGE_DEFAULT) && can_add_page_to_seg(q, bvec,
+ page, len, offset)) {
bvec->bv_len += len;
goto done;
}
@@ -779,7 +781,8 @@ EXPORT_SYMBOL(bio_add_pc_page);
* Return %true on success or %false on failure.
*/
bool __bio_try_merge_page(struct bio *bio, struct page *page,
- unsigned int len, unsigned int off, bool same_page)
+ unsigned int len, unsigned int off,
+ enum bvec_merge_flags flags)
{
if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
return false;
@@ -787,7 +790,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page,
if (bio->bi_vcnt > 0) {
struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
- if (page_is_mergeable(bv, page, len, off, same_page)) {
+ if (page_is_mergeable(bv, page, len, off, flags)) {
bv->bv_len += len;
bio->bi_iter.bi_size += len;
return true;
@@ -837,7 +840,8 @@ EXPORT_SYMBOL_GPL(__bio_add_page);
int bio_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int offset)
{
- if (!__bio_try_merge_page(bio, page, len, offset, false)) {
+ if (!__bio_try_merge_page(bio, page, len, offset,
+ BVEC_MERGE_DEFAULT)) {
if (bio_full(bio))
return 0;
__bio_add_page(bio, page, len, offset);
diff --git a/fs/iomap.c b/fs/iomap.c
index 23ef63fd1669..e04652bbf92a 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -316,7 +316,8 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
*/
sector = iomap_sector(iomap, pos);
if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
- if (__bio_try_merge_page(ctx->bio, page, plen, poff, true))
+ if (__bio_try_merge_page(ctx->bio, page, plen, poff,
+ BVEC_MERGE_TO_SAME_PAGE))
goto done;
is_contig = true;
}
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index a6f0f4761a37..7e7385bc3b9e 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -774,7 +774,8 @@ xfs_add_to_ioend(
wpc->imap.br_state, offset, bdev, sector);
}
- if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) {
+ if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff,
+ BVEC_MERGE_TO_SAME_PAGE)) {
if (iop)
atomic_inc(&iop->write_count);
if (bio_full(wpc->ioend->io_bio))
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 0f23b5682640..ee18895431ba 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -419,11 +419,23 @@ extern void bio_uninit(struct bio *);
extern void bio_reset(struct bio *);
void bio_chain(struct bio *, struct bio *);
+enum bvec_merge_flags {
+ BVEC_MERGE_DEFAULT,
+
+ /*
+ * only merge if new page is same with bio's last page, this
+ * is exactly the behaviour before introducing multi-page
+ * bvec
+ */
+ BVEC_MERGE_TO_SAME_PAGE = BIT(0),
+};
+
extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
unsigned int, unsigned int);
bool __bio_try_merge_page(struct bio *bio, struct page *page,
- unsigned int len, unsigned int off, bool same_page);
+ unsigned int len, unsigned int off,
+ enum bvec_merge_flags flags);
void __bio_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int off);
int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
--
2.20.1
