[PATCH v2] block: Add bio_max_segs

From: Matthew Wilcox (Oracle)
Date: Thu Jan 28 2021 - 23:41:08 EST

It's often inconvenient to use BIO_MAX_PAGES due to min() requiring the
sign to be the same. Introduce bio_max_segs() and change BIO_MAX_PAGES to
be unsigned to make it easier for the users.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
v2:
- Rename from bio_limit() to bio_max_segs()
- Rebase on next-20210128
- Use DIV_ROUND_UP in dm-log-writes.c
- Use DIV_ROUND_UP in iomap/buffered-io.c

block/blk-map.c | 4 +---
drivers/block/xen-blkback/blkback.c | 4 +---
drivers/md/dm-io.c | 4 ++--
drivers/md/dm-log-writes.c | 10 +++++-----
drivers/nvme/target/io-cmd-bdev.c | 8 ++++----
drivers/nvme/target/passthru.c | 4 ++--
drivers/target/target_core_iblock.c | 9 +++------
drivers/target/target_core_pscsi.c | 2 +-
fs/block_dev.c | 10 +++++-----
fs/direct-io.c | 2 +-
fs/erofs/data.c | 4 +---
fs/ext4/readpage.c | 3 +--
fs/f2fs/data.c | 3 +--
fs/f2fs/node.c | 2 +-
fs/iomap/buffered-io.c | 4 ++--
fs/mpage.c | 4 +---
fs/nfs/blocklayout/blocklayout.c | 6 +++---
fs/xfs/xfs_bio_io.c | 2 +-
fs/xfs/xfs_buf.c | 4 ++--
include/linux/bio.h | 7 ++++++-
20 files changed, 44 insertions(+), 52 deletions(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index 21630dccac62..369e204d14d0 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -150,9 +150,7 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
bmd->is_our_pages = !map_data;
bmd->is_null_mapped = (map_data && map_data->null_mapped);

- nr_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE);
- if (nr_pages > BIO_MAX_PAGES)
- nr_pages = BIO_MAX_PAGES;
+ nr_pages = bio_max_segs(DIV_ROUND_UP(offset + len, PAGE_SIZE));

ret = -ENOMEM;
bio = bio_kmalloc(gfp_mask, nr_pages);
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 9ebf53903d7b..2d5ebf2c321b 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -1322,9 +1322,7 @@ static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
pages[i]->page,
seg[i].nsec << 9,
seg[i].offset) == 0)) {
-
- int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES);
- bio = bio_alloc(GFP_KERNEL, nr_iovecs);
+ bio = bio_alloc(GFP_KERNEL, bio_max_segs(nseg - i));
if (unlikely(bio == NULL))
goto fail_put_bio;

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 4312007d2d34..2d3cda0acacb 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -341,8 +341,8 @@ static void do_region(int op, int op_flags, unsigned region,
num_bvecs = 1;
break;
default:
- num_bvecs = min_t(int, BIO_MAX_PAGES,
- dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
+ num_bvecs = bio_max_segs(dm_sector_div_up(remaining,
+ (PAGE_SIZE >> SECTOR_SHIFT)));
}

bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, &io->client->bios);
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index e3d35c6c9f71..57882654ffee 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -264,15 +264,14 @@ static int write_inline_data(struct log_writes_c *lc, void *entry,
size_t entrylen, void *data, size_t datalen,
sector_t sector)
{
- int num_pages, bio_pages, pg_datalen, pg_sectorlen, i;
+ int bio_pages, pg_datalen, pg_sectorlen, i;
struct page *page;
struct bio *bio;
size_t ret;
void *ptr;

while (datalen) {
- num_pages = ALIGN(datalen, PAGE_SIZE) >> PAGE_SHIFT;
- bio_pages = min(num_pages, BIO_MAX_PAGES);
+ bio_pages = bio_max_segs(DIV_ROUND_UP(datalen, PAGE_SIZE));

atomic_inc(&lc->io_blocks);

@@ -364,7 +363,7 @@ static int log_one_block(struct log_writes_c *lc,
goto out;

atomic_inc(&lc->io_blocks);
- bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt, BIO_MAX_PAGES));
+ bio = bio_alloc(GFP_KERNEL, bio_max_segs(block->vec_cnt));
if (!bio) {
DMERR("Couldn't alloc log bio");
goto error;
@@ -386,7 +385,8 @@ static int log_one_block(struct log_writes_c *lc,
if (ret != block->vecs[i].bv_len) {
atomic_inc(&lc->io_blocks);
submit_bio(bio);
- bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt - i, BIO_MAX_PAGES));
+ bio = bio_alloc(GFP_KERNEL,
+ bio_max_segs(block->vec_cnt - i));
if (!bio) {
DMERR("Couldn't alloc log bio");
goto error;
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index bf6e0ac9ad28..86703a0bdc2a 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -185,7 +185,7 @@ static int nvmet_bdev_alloc_bip(struct nvmet_req *req, struct bio *bio,
}

bip = bio_integrity_alloc(bio, GFP_NOIO,
- min_t(unsigned int, req->metadata_sg_cnt, BIO_MAX_PAGES));
+ bio_max_segs(req->metadata_sg_cnt));
if (IS_ERR(bip)) {
pr_err("Unable to allocate bio_integrity_payload\n");
return PTR_ERR(bip);
@@ -225,7 +225,7 @@ static int nvmet_bdev_alloc_bip(struct nvmet_req *req, struct bio *bio,

static void nvmet_bdev_execute_rw(struct nvmet_req *req)
{
- int sg_cnt = req->sg_cnt;
+ unsigned int sg_cnt = req->sg_cnt;
struct bio *bio;
struct scatterlist *sg;
struct blk_plug plug;
@@ -263,7 +263,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
bio = &req->b.inline_bio;
bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
} else {
- bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
+ bio = bio_alloc(GFP_KERNEL, bio_max_segs(sg_cnt));
}
bio_set_dev(bio, req->ns->bdev);
bio->bi_iter.bi_sector = sector;
@@ -290,7 +290,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
}
}

- bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
+ bio = bio_alloc(GFP_KERNEL, bio_max_segs(sg_cnt));
bio_set_dev(bio, req->ns->bdev);
bio->bi_iter.bi_sector = sector;
bio->bi_opf = op;
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index cbc88acdd233..dc902555a35c 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -26,7 +26,7 @@ static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
struct nvme_ctrl *pctrl = ctrl->subsys->passthru_ctrl;
u16 status = NVME_SC_SUCCESS;
struct nvme_id_ctrl *id;
- int max_hw_sectors;
+ unsigned int max_hw_sectors;
int page_shift;

id = kzalloc(sizeof(*id), GFP_KERNEL);
@@ -198,7 +198,7 @@ static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
bio = &req->p.inline_bio;
bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
} else {
- bio = bio_alloc(GFP_KERNEL, min(req->sg_cnt, BIO_MAX_PAGES));
+ bio = bio_alloc(GFP_KERNEL, bio_max_segs(req->sg_cnt));
bio->bi_end_io = bio_put;
}
bio->bi_opf = req_op(rq);
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 8ed93fd205c7..ee3d52061281 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -315,10 +315,8 @@ iblock_get_bio(struct se_cmd *cmd, sector_t lba, u32 sg_num, int op,
* Only allocate as many vector entries as the bio code allows us to,
* we'll loop later on until we have handled the whole request.
*/
- if (sg_num > BIO_MAX_PAGES)
- sg_num = BIO_MAX_PAGES;
-
- bio = bio_alloc_bioset(GFP_NOIO, sg_num, &ib_dev->ibd_bio_set);
+ bio = bio_alloc_bioset(GFP_NOIO, bio_max_segs(sg_num),
+ &ib_dev->ibd_bio_set);
if (!bio) {
pr_err("Unable to allocate memory for bio\n");
return NULL;
@@ -638,8 +636,7 @@ iblock_alloc_bip(struct se_cmd *cmd, struct bio *bio,
return -ENODEV;
}

- bip = bio_integrity_alloc(bio, GFP_NOIO,
- min_t(unsigned int, cmd->t_prot_nents, BIO_MAX_PAGES));
+ bip = bio_integrity_alloc(bio, GFP_NOIO, bio_max_segs(cmd->t_prot_nents));
if (IS_ERR(bip)) {
pr_err("Unable to allocate bio_integrity_payload\n");
return PTR_ERR(bip);
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 33770e5808ce..3cbc074992bc 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -881,7 +881,7 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,

if (!bio) {
new_bio:
- nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
+ nr_vecs = bio_max_segs(nr_pages);
nr_pages -= nr_vecs;
/*
* Calls bio_kmalloc() and sets bio->bi_end_io()
diff --git a/fs/block_dev.c b/fs/block_dev.c
index cf933048f139..9be7ad01110b 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -213,7 +213,7 @@ static void blkdev_bio_end_io_simple(struct bio *bio)

static ssize_t
__blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
- int nr_pages)
+ unsigned int nr_pages)
{
struct file *file = iocb->ki_filp;
struct block_device *bdev = I_BDEV(bdev_file_inode(file));
@@ -347,8 +347,8 @@ static void blkdev_bio_end_io(struct bio *bio)
}
}

-static ssize_t
-__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
+static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
+ unsigned int nr_pages)
{
struct file *file = iocb->ki_filp;
struct inode *inode = bdev_file_inode(file);
@@ -478,7 +478,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
static ssize_t
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
- int nr_pages;
+ unsigned int nr_pages;

if (!iov_iter_count(iter))
return 0;
@@ -487,7 +487,7 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)
return __blkdev_direct_IO_simple(iocb, iter, nr_pages);

- return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES));
+ return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
}

static __init int blkdev_init(void)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 0957e1bb8eb2..b61491bf3166 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -695,7 +695,7 @@ static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
if (ret)
goto out;
sector = start_sector << (sdio->blkbits - 9);
- nr_pages = min(sdio->pages_in_io, BIO_MAX_PAGES);
+ nr_pages = bio_max_segs(sdio->pages_in_io);
BUG_ON(nr_pages <= 0);
dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
sdio->boundary = 0;
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index ea4f693bee22..f88851c5c250 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -215,10 +215,8 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio,
/* max # of continuous pages */
if (nblocks > DIV_ROUND_UP(map.m_plen, PAGE_SIZE))
nblocks = DIV_ROUND_UP(map.m_plen, PAGE_SIZE);
- if (nblocks > BIO_MAX_PAGES)
- nblocks = BIO_MAX_PAGES;

- bio = bio_alloc(GFP_NOIO, nblocks);
+ bio = bio_alloc(GFP_NOIO, bio_max_segs(nblocks));

bio->bi_end_io = erofs_readendio;
bio_set_dev(bio, sb->s_bdev);
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index f014c5e473a9..3db923403505 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -371,8 +371,7 @@ int ext4_mpage_readpages(struct inode *inode,
* bio_alloc will _always_ be able to allocate a bio if
* __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
*/
- bio = bio_alloc(GFP_KERNEL,
- min_t(int, nr_pages, BIO_MAX_PAGES));
+ bio = bio_alloc(GFP_KERNEL, bio_max_segs(nr_pages));
fscrypt_set_bio_crypt_ctx(bio, inode, next_block,
GFP_KERNEL);
ext4_set_bio_post_read_ctx(bio, inode, page->index);
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 862df2477a5d..79008dcf7125 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -969,8 +969,7 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
unsigned int post_read_steps = 0;

bio = bio_alloc_bioset(for_write ? GFP_NOIO : GFP_KERNEL,
- min_t(int, nr_pages, BIO_MAX_PAGES),
- &f2fs_bioset);
+ bio_max_segs(nr_pages), &f2fs_bioset);
if (!bio)
return ERR_PTR(-ENOMEM);

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index a8a0fb890e8d..4b0e2e3c2c88 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -2747,7 +2747,7 @@ int f2fs_restore_node_summary(struct f2fs_sb_info *sbi,
sum_entry = &sum->entries[0];

for (i = 0; i < last_offset; i += nrpages, addr += nrpages) {
- nrpages = min(last_offset - i, BIO_MAX_PAGES);
+ nrpages = bio_max_segs(last_offset - i);

/* readahead node pages */
f2fs_ra_meta_pages(sbi, addr, nrpages, META_POR, true);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 16a1e82e3aeb..0d9d1a6a947e 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -278,14 +278,14 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
if (!is_contig || bio_full(ctx->bio, plen)) {
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
gfp_t orig_gfp = gfp;
- int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);

if (ctx->bio)
submit_bio(ctx->bio);

if (ctx->rac) /* same as readahead_gfp_mask */
gfp |= __GFP_NORETRY | __GFP_NOWARN;
- ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
+ ctx->bio = bio_alloc(gfp, bio_max_segs(nr_vecs));
/*
* If the bio_alloc fails, try it again for a single page to
* avoid having to deal with partial page reads. This emulates
diff --git a/fs/mpage.c b/fs/mpage.c
index 830e6cc2a9e7..961234d68779 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -304,9 +304,7 @@ static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
goto out;
}
args->bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
- min_t(int, args->nr_pages,
- BIO_MAX_PAGES),
- gfp);
+ bio_max_segs(args->nr_pages), gfp);
if (args->bio == NULL)
goto confused;
}
diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 1a96ce28efb0..fe860c538747 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -115,13 +115,13 @@ bl_submit_bio(struct bio *bio)
return NULL;
}

-static struct bio *
-bl_alloc_init_bio(int npg, struct block_device *bdev, sector_t disk_sector,
+static struct bio *bl_alloc_init_bio(unsigned int npg,
+ struct block_device *bdev, sector_t disk_sector,
bio_end_io_t end_io, struct parallel_io *par)
{
struct bio *bio;

- npg = min(npg, BIO_MAX_PAGES);
+ npg = bio_max_segs(npg);
bio = bio_alloc(GFP_NOIO, npg);
if (bio) {
bio->bi_iter.bi_sector = disk_sector;
diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c
index e2148f2d5d6b..17f36db2f792 100644
--- a/fs/xfs/xfs_bio_io.c
+++ b/fs/xfs/xfs_bio_io.c
@@ -6,7 +6,7 @@

static inline unsigned int bio_max_vecs(unsigned int count)
{
- return min_t(unsigned, howmany(count, PAGE_SIZE), BIO_MAX_PAGES);
+ return bio_max_segs(howmany(count, PAGE_SIZE));
}

int
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index f6e5235df7c9..37a1d12762d8 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1480,7 +1480,7 @@ xfs_buf_ioapply_map(
int op)
{
int page_index;
- int total_nr_pages = bp->b_page_count;
+ unsigned int total_nr_pages = bp->b_page_count;
int nr_pages;
struct bio *bio;
sector_t sector = bp->b_maps[map].bm_bn;
@@ -1505,7 +1505,7 @@ xfs_buf_ioapply_map(

next_chunk:
atomic_inc(&bp->b_io_remaining);
- nr_pages = min(total_nr_pages, BIO_MAX_PAGES);
+ nr_pages = bio_max_segs(total_nr_pages);

bio = bio_alloc(GFP_NOIO, nr_pages);
bio_set_dev(bio, bp->b_target->bt_bdev);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index c74857cf1252..354747bbb939 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -20,7 +20,12 @@
#define BIO_BUG_ON
#endif

-#define BIO_MAX_PAGES 256
+#define BIO_MAX_PAGES 256U
+
+static inline unsigned int bio_max_segs(unsigned int nr_segs)
+{
+ return min(nr_segs, BIO_MAX_PAGES);
+}

#define bio_prio(bio) (bio)->bi_ioprio
#define bio_set_prio(bio, prio) ((bio)->bi_ioprio = prio)
--
2.29.2