[PATCH v5 00/20] bio: check return values of bio_add_page

[PATCH v5 00/20] bio: check return values of bio_add_page

[Johannes Thumshirn]

We have two functions for adding a page to a bio, __bio_add_page() which is
used to add a single page to a freshly created bio and bio_add_page() which is
used to add a page to an existing bio.

While __bio_add_page() is expected to succeed, bio_add_page() can fail.

This series converts the callers of bio_add_page() which can easily use
__bio_add_page() to using it and checks the return of bio_add_page() for
callers that don't work on a freshly created bio.

Lastly it marks bio_add_page() as __must_check so we don't have to go again
and audit all callers.

Changes to v4:
- Rebased onto latest Linus' master
- Dropped already merged patches
- Added Sergey's Reviewed-by

Changes to v3:
- Added __bio_add_folio and use it in iomap (Willy)
- Mark bio_add_folio must check (Willy)
- s/GFS/GFS2/ (Andreas)

Changes to v2:
- Removed 'wont fail' comments pointed out by Song

Changes to v1:
- Removed pointless comment pointed out by Willy
- Changed commit messages pointed out by Damien
- Colledted Damien's Reviews and Acks


Johannes Thumshirn (20):
  swap: use __bio_add_page to add page to bio
  drbd: use __bio_add_page to add page to bio
  dm: dm-zoned: use __bio_add_page for adding single metadata page
  fs: buffer: use __bio_add_page to add single page to bio
  md: use __bio_add_page to add single page
  md: raid5-log: use __bio_add_page to add single page
  md: raid5: use __bio_add_page to add single page to new bio
  jfs: logmgr: use __bio_add_page to add single page to bio
  gfs2: use __bio_add_page for adding single page to bio
  zonefs: use __bio_add_page for adding single page to bio
  zram: use __bio_add_page for adding single page to bio
  floppy: use __bio_add_page for adding single page to bio
  md: check for failure when adding pages in alloc_behind_master_bio
  md: raid1: use __bio_add_page for adding single page to bio
  md: raid1: check if adding pages to resync bio fails
  dm-crypt: check if adding pages to clone bio fails
  block: mark bio_add_page as __must_check
  block: add __bio_add_folio
  fs: iomap: use __bio_add_folio where possible
  block: mark bio_add_folio as __must_check

 block/bio.c                      |  8 ++++++++
 drivers/block/drbd/drbd_bitmap.c |  4 +---
 drivers/block/floppy.c           |  2 +-
 drivers/block/zram/zram_drv.c    |  2 +-
 drivers/md/dm-crypt.c            |  9 ++++++++-
 drivers/md/dm-zoned-metadata.c   |  6 +++---
 drivers/md/md.c                  |  4 ++--
 drivers/md/raid1-10.c            | 11 ++++++-----
 drivers/md/raid1.c               |  7 +++++--
 drivers/md/raid10.c              | 20 ++++++++++----------
 drivers/md/raid5-cache.c         |  2 +-
 drivers/md/raid5-ppl.c           |  4 ++--
 fs/buffer.c                      |  2 +-
 fs/gfs2/ops_fstype.c             |  2 +-
 fs/iomap/buffered-io.c           |  6 +++---
 fs/jfs/jfs_logmgr.c              |  4 ++--
 fs/zonefs/super.c                |  2 +-
 include/linux/bio.h              |  5 +++--
 mm/page_io.c                     |  8 ++++----
 19 files changed, 63 insertions(+), 45 deletions(-)


base-commit: 865fdb08197e657c59e74a35fa32362b12397f58
-- 
2.40.0

[PATCH v5 01/20] swap: use __bio_add_page to add page to bio

[Johannes Thumshirn]

The swap code only adds a single page to a newly created bio. So use
__bio_add_page() to add the page which is guaranteed to succeed in this
case.

This brings us closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 mm/page_io.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index 87b682d18850..684cd3c7b59b 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -338,7 +338,7 @@ static void swap_writepage_bdev_sync(struct page *page,
 	bio_init(&bio, sis->bdev, &bv, 1,
 		 REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc));
 	bio.bi_iter.bi_sector = swap_page_sector(page);
-	bio_add_page(&bio, page, thp_size(page), 0);
+	__bio_add_page(&bio, page, thp_size(page), 0);
 
 	bio_associate_blkg_from_page(&bio, page);
 	count_swpout_vm_event(page);
@@ -360,7 +360,7 @@ static void swap_writepage_bdev_async(struct page *page,
 			GFP_NOIO);
 	bio->bi_iter.bi_sector = swap_page_sector(page);
 	bio->bi_end_io = end_swap_bio_write;
-	bio_add_page(bio, page, thp_size(page), 0);
+	__bio_add_page(bio, page, thp_size(page), 0);
 
 	bio_associate_blkg_from_page(bio, page);
 	count_swpout_vm_event(page);
@@ -468,7 +468,7 @@ static void swap_readpage_bdev_sync(struct page *page,
 
 	bio_init(&bio, sis->bdev, &bv, 1, REQ_OP_READ);
 	bio.bi_iter.bi_sector = swap_page_sector(page);
-	bio_add_page(&bio, page, thp_size(page), 0);
+	__bio_add_page(&bio, page, thp_size(page), 0);
 	/*
 	 * Keep this task valid during swap readpage because the oom killer may
 	 * attempt to access it in the page fault retry time check.
@@ -488,7 +488,7 @@ static void swap_readpage_bdev_async(struct page *page,
 	bio = bio_alloc(sis->bdev, 1, REQ_OP_READ, GFP_KERNEL);
 	bio->bi_iter.bi_sector = swap_page_sector(page);
 	bio->bi_end_io = end_swap_bio_read;
-	bio_add_page(bio, page, thp_size(page), 0);
+	__bio_add_page(bio, page, thp_size(page), 0);
 	count_vm_event(PSWPIN);
 	submit_bio(bio);
 }
-- 
2.40.0

[PATCH v5 02/20] drbd: use __bio_add_page to add page to bio

[Johannes Thumshirn]

The drbd code only adds a single page to a newly created bio. So use
__bio_add_page() to add the page which is guaranteed to succeed in this
case.

This brings us closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/block/drbd/drbd_bitmap.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index 6ac8c54b44c7..85ca000a0564 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -1043,9 +1043,7 @@ static void bm_page_io_async(struct drbd_bm_aio_ctx *ctx, int page_nr) __must_ho
 	bio = bio_alloc_bioset(device->ldev->md_bdev, 1, op, GFP_NOIO,
 			&drbd_md_io_bio_set);
 	bio->bi_iter.bi_sector = on_disk_sector;
-	/* bio_add_page of a single page to an empty bio will always succeed,
-	 * according to api.  Do we want to assert that? */
-	bio_add_page(bio, page, len, 0);
+	__bio_add_page(bio, page, len, 0);
 	bio->bi_private = ctx;
 	bio->bi_end_io = drbd_bm_endio;
 
-- 
2.40.0

[PATCH v5 03/20] dm: dm-zoned: use __bio_add_page for adding single metadata page

[Johannes Thumshirn]

dm-zoned uses bio_add_page() for adding a single page to a freshly created
metadata bio.

Use __bio_add_page() instead as adding a single page to a new bio is
always guaranteed to succeed.

This brings us a step closer to marking bio_add_page() __must_check

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/md/dm-zoned-metadata.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c
index 8f0896a6990b..9d3cca8e3dc9 100644
--- a/drivers/md/dm-zoned-metadata.c
+++ b/drivers/md/dm-zoned-metadata.c
@@ -577,7 +577,7 @@ static struct dmz_mblock *dmz_get_mblock_slow(struct dmz_metadata *zmd,
 	bio->bi_iter.bi_sector = dmz_blk2sect(block);
 	bio->bi_private = mblk;
 	bio->bi_end_io = dmz_mblock_bio_end_io;
-	bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
+	__bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
 	submit_bio(bio);
 
 	return mblk;
@@ -728,7 +728,7 @@ static int dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk,
 	bio->bi_iter.bi_sector = dmz_blk2sect(block);
 	bio->bi_private = mblk;
 	bio->bi_end_io = dmz_mblock_bio_end_io;
-	bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
+	__bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
 	submit_bio(bio);
 
 	return 0;
@@ -752,7 +752,7 @@ static int dmz_rdwr_block(struct dmz_dev *dev, enum req_op op,
 	bio = bio_alloc(dev->bdev, 1, op | REQ_SYNC | REQ_META | REQ_PRIO,
 			GFP_NOIO);
 	bio->bi_iter.bi_sector = dmz_blk2sect(block);
-	bio_add_page(bio, page, DMZ_BLOCK_SIZE, 0);
+	__bio_add_page(bio, page, DMZ_BLOCK_SIZE, 0);
 	ret = submit_bio_wait(bio);
 	bio_put(bio);
 
-- 
2.40.0

[PATCH v5 04/20] fs: buffer: use __bio_add_page to add single page to bio

[Johannes Thumshirn]

The buffer_head submission code uses bio_add_page() to add a page to a
newly created bio. bio_add_page() can fail, but the return value is never
checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index a7fc561758b1..5abc26d8399d 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2760,7 +2760,7 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
 
 	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 
-	bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
+	__bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
 	BUG_ON(bio->bi_iter.bi_size != bh->b_size);
 
 	bio->bi_end_io = end_bio_bh_io_sync;
-- 
2.40.0

Re:[PATCH v5 04/20] fs: buffer: use __bio_add_page to add single page to bio

[gouhao]

Re:[PATCH v5 04/20] fs: buffer: use __bio_add_page to add single page to bio

[gouhao]

> 
> The buffer_head submission code uses bio_add_page() to add a page to a
> newly created bio. bio_add_page() can fail, but the return value is never
> checked.
> 
> Use __bio_add_page() as adding a single page to a newly created bio is
> guaranteed to succeed.
> 
> This brings us a step closer to marking bio_add_page() as __must_check.
> 
> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  fs/buffer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index a7fc561758b1..5abc26d8399d 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -2760,7 +2760,7 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
>  
>  	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
>  
> -	bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
> +	__bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
>  	BUG_ON(bio->bi_iter.bi_size != bh->b_size);
Can `BUG_ON` be deleted now ?
>  
>  	bio->bi_end_io = end_bio_bh_io_sync;
> -- 
> 2.40.0
--
thanks,
Gou Hao

[PATCH v5 05/20] md: use __bio_add_page to add single page

[Johannes Thumshirn]

The md-raid superblock writing code uses bio_add_page() to add a page to a
newly created bio. bio_add_page() can fail, but the return value is never
checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Signed-of_-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Song Liu <song@kernel.org>
---
 drivers/md/md.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8e344b4b3444..6a559a7e89c0 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -938,7 +938,7 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 	atomic_inc(&rdev->nr_pending);
 
 	bio->bi_iter.bi_sector = sector;
-	bio_add_page(bio, page, size, 0);
+	__bio_add_page(bio, page, size, 0);
 	bio->bi_private = rdev;
 	bio->bi_end_io = super_written;
 
@@ -979,7 +979,7 @@ int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 		bio.bi_iter.bi_sector = sector + rdev->new_data_offset;
 	else
 		bio.bi_iter.bi_sector = sector + rdev->data_offset;
-	bio_add_page(&bio, page, size, 0);
+	__bio_add_page(&bio, page, size, 0);
 
 	submit_bio_wait(&bio);
 
-- 
2.40.0

[PATCH v5 06/20] md: raid5-log: use __bio_add_page to add single page

[Johannes Thumshirn]

The raid5 log metadata submission code uses bio_add_page() to add a page
to a newly created bio. bio_add_page() can fail, but the return value is
never checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/md/raid5-cache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 46182b955aef..852b265c5db4 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -792,7 +792,7 @@ static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
 	io->current_bio = r5l_bio_alloc(log);
 	io->current_bio->bi_end_io = r5l_log_endio;
 	io->current_bio->bi_private = io;
-	bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
+	__bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
 
 	r5_reserve_log_entry(log, io);
 
-- 
2.40.0

[PATCH v5 07/20] md: raid5: use __bio_add_page to add single page to new bio

[Johannes Thumshirn]

The raid5-ppl submission code uses bio_add_page() to add a page to a
newly created bio. bio_add_page() can fail, but the return value is never
checked. For adding consecutive pages, the return is actually checked and
a new bio is allocated if adding the page fails.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/md/raid5-ppl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index e495939bb3e0..eaea57aee602 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -465,7 +465,7 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
 
 	bio->bi_end_io = ppl_log_endio;
 	bio->bi_iter.bi_sector = log->next_io_sector;
-	bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
+	__bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
 
 	pr_debug("%s: log->current_io_sector: %llu\n", __func__,
 	    (unsigned long long)log->next_io_sector);
@@ -496,7 +496,7 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
 					       prev->bi_opf, GFP_NOIO,
 					       &ppl_conf->bs);
 			bio->bi_iter.bi_sector = bio_end_sector(prev);
-			bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
+			__bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
 
 			bio_chain(bio, prev);
 			ppl_submit_iounit_bio(io, prev);
-- 
2.40.0

[PATCH v5 08/20] jfs: logmgr: use __bio_add_page to add single page to bio

[Johannes Thumshirn]

The JFS IO code uses bio_add_page() to add a page to a newly created bio.
bio_add_page() can fail, but the return value is never checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/jfs/jfs_logmgr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index 695415cbfe98..15c645827dec 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -1974,7 +1974,7 @@ static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp)
 
 	bio = bio_alloc(log->bdev, 1, REQ_OP_READ, GFP_NOFS);
 	bio->bi_iter.bi_sector = bp->l_blkno << (log->l2bsize - 9);
-	bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
+	__bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
 	BUG_ON(bio->bi_iter.bi_size != LOGPSIZE);
 
 	bio->bi_end_io = lbmIODone;
@@ -2115,7 +2115,7 @@ static void lbmStartIO(struct lbuf * bp)
 
 	bio = bio_alloc(log->bdev, 1, REQ_OP_WRITE | REQ_SYNC, GFP_NOFS);
 	bio->bi_iter.bi_sector = bp->l_blkno << (log->l2bsize - 9);
-	bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
+	__bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
 	BUG_ON(bio->bi_iter.bi_size != LOGPSIZE);
 
 	bio->bi_end_io = lbmIODone;
-- 
2.40.0

[PATCH v5 09/20] gfs2: use __bio_add_page for adding single page to bio

[Johannes Thumshirn]

The GFS2 superblock reading code uses bio_add_page() to add a page to a
newly created bio. bio_add_page() can fail, but the return value is never
checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/gfs2/ops_fstype.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 9af9ddb61ca0..cd962985b058 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -254,7 +254,7 @@ static int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector, int silent)
 
 	bio = bio_alloc(sb->s_bdev, 1, REQ_OP_READ | REQ_META, GFP_NOFS);
 	bio->bi_iter.bi_sector = sector * (sb->s_blocksize >> 9);
-	bio_add_page(bio, page, PAGE_SIZE, 0);
+	__bio_add_page(bio, page, PAGE_SIZE, 0);
 
 	bio->bi_end_io = end_bio_io_page;
 	bio->bi_private = page;
-- 
2.40.0

Re: [PATCH v5 09/20] gfs2: use __bio_add_page for adding single page to bio

[Bob Peterson]

On 5/2/23 6:19 AM, Johannes Thumshirn wrote:
> The GFS2 superblock reading code uses bio_add_page() to add a page to a
> newly created bio. bio_add_page() can fail, but the return value is never
> checked.
> 
> Use __bio_add_page() as adding a single page to a newly created bio is
> guaranteed to succeed.
> 
> This brings us a step closer to marking bio_add_page() as __must_check.
> 
> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>   fs/gfs2/ops_fstype.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
> index 9af9ddb61ca0..cd962985b058 100644
> --- a/fs/gfs2/ops_fstype.c
> +++ b/fs/gfs2/ops_fstype.c
> @@ -254,7 +254,7 @@ static int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector, int silent)
>   
>   	bio = bio_alloc(sb->s_bdev, 1, REQ_OP_READ | REQ_META, GFP_NOFS);
>   	bio->bi_iter.bi_sector = sector * (sb->s_blocksize >> 9);
> -	bio_add_page(bio, page, PAGE_SIZE, 0);
> +	__bio_add_page(bio, page, PAGE_SIZE, 0);
>   
>   	bio->bi_end_io = end_bio_io_page;
>   	bio->bi_private = page;
Hi Johannes,

So...I see 6 different calls to bio_add_page() in gfs2.
Why change this particular bio_add_page() to __bio_add_page() and not 
the other five?

Regards,

Bob Peterson

Re: [PATCH v5 09/20] gfs2: use __bio_add_page for adding single page to bio

[Johannes Thumshirn]

On 02.05.23 13:51, Bob Peterson wrote:
> On 5/2/23 6:19 AM, Johannes Thumshirn wrote:
>> The GFS2 superblock reading code uses bio_add_page() to add a page to a
>> newly created bio. bio_add_page() can fail, but the return value is never
>> checked.
>>
>> Use __bio_add_page() as adding a single page to a newly created bio is
>> guaranteed to succeed.
>>
>> This brings us a step closer to marking bio_add_page() as __must_check.
>>
>> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
>> Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
>> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
>> ---
>>   fs/gfs2/ops_fstype.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
>> index 9af9ddb61ca0..cd962985b058 100644
>> --- a/fs/gfs2/ops_fstype.c
>> +++ b/fs/gfs2/ops_fstype.c
>> @@ -254,7 +254,7 @@ static int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector, int silent)
>>   
>>   	bio = bio_alloc(sb->s_bdev, 1, REQ_OP_READ | REQ_META, GFP_NOFS);
>>   	bio->bi_iter.bi_sector = sector * (sb->s_blocksize >> 9);
>> -	bio_add_page(bio, page, PAGE_SIZE, 0);
>> +	__bio_add_page(bio, page, PAGE_SIZE, 0);
>>   
>>   	bio->bi_end_io = end_bio_io_page;
>>   	bio->bi_private = page;
> Hi Johannes,
> 
> So...I see 6 different calls to bio_add_page() in gfs2.
> Why change this particular bio_add_page() to __bio_add_page() and not 
> the other five?
> 

Hi Bob,

Because all the others check the return value of bio_add_page(), only the
one converted doesn't. But it also doesn't need to as we're using 
__bio_add_page() on a newly created bio.

[PATCH v5 10/20] zonefs: use __bio_add_page for adding single page to bio

[Johannes Thumshirn]

The zonefs superblock reading code uses bio_add_page() to add a page to a
newly created bio. bio_add_page() can fail, but the return value is
never checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/zonefs/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index 23b8b299c64e..9350221abfc5 100644
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -1128,7 +1128,7 @@ static int zonefs_read_super(struct super_block *sb)
 
 	bio_init(&bio, sb->s_bdev, &bio_vec, 1, REQ_OP_READ);
 	bio.bi_iter.bi_sector = 0;
-	bio_add_page(&bio, page, PAGE_SIZE, 0);
+	__bio_add_page(&bio, page, PAGE_SIZE, 0);
 
 	ret = submit_bio_wait(&bio);
 	if (ret)
-- 
2.40.0

[PATCH v5 11/20] zram: use __bio_add_page for adding single page to bio

[Johannes Thumshirn]

The zram writeback code uses bio_add_page() to add a page to a newly
created bio. bio_add_page() can fail, but the return value is never
checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/block/zram/zram_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index a84c4268257a..4b9ca6d41b92 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -700,7 +700,7 @@ static ssize_t writeback_store(struct device *dev,
 		bio_init(&bio, zram->bdev, &bio_vec, 1,
 			 REQ_OP_WRITE | REQ_SYNC);
 		bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9);
-		bio_add_page(&bio, page, PAGE_SIZE, 0);
+		__bio_add_page(&bio, page, PAGE_SIZE, 0);
 
 		/*
 		 * XXX: A single page IO would be inefficient for write
-- 
2.40.0

[PATCH v5 12/20] floppy: use __bio_add_page for adding single page to bio

[Johannes Thumshirn]

The floppy code uses bio_add_page() to add a page to a newly created bio.
bio_add_page() can fail, but the return value is never checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/block/floppy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index cec2c20f5e59..28ec6b442e9c 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4147,7 +4147,7 @@ static int __floppy_read_block_0(struct block_device *bdev, int drive)
 	cbdata.drive = drive;
 
 	bio_init(&bio, bdev, &bio_vec, 1, REQ_OP_READ);
-	bio_add_page(&bio, page, block_size(bdev), 0);
+	__bio_add_page(&bio, page, block_size(bdev), 0);
 
 	bio.bi_iter.bi_sector = 0;
 	bio.bi_flags |= (1 << BIO_QUIET);
-- 
2.40.0

[PATCH v5 13/20] md: check for failure when adding pages in alloc_behind_master_bio

[Johannes Thumshirn]

alloc_behind_master_bio() can possibly add multiple pages to a bio, but it
is not checking for the return value of bio_add_page() if adding really
succeeded.

Check if the page adding succeeded and if not bail out.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/md/raid1.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 68a9e2d9985b..8283ef177f6c 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1147,7 +1147,10 @@ static void alloc_behind_master_bio(struct r1bio *r1_bio,
 		if (unlikely(!page))
 			goto free_pages;
 
-		bio_add_page(behind_bio, page, len, 0);
+		if (!bio_add_page(behind_bio, page, len, 0)) {
+			free_page(page);
+			goto free_pages;
+		}
 
 		size -= len;
 		i++;
-- 
2.40.0

[PATCH v5 14/20] md: raid1: use __bio_add_page for adding single page to bio

[Johannes Thumshirn]

The sync request code uses bio_add_page() to add a page to a newly created bio.
bio_add_page() can fail, but the return value is never checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/md/raid1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 8283ef177f6c..ff89839455ec 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2917,7 +2917,7 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
 				 * won't fail because the vec table is big
 				 * enough to hold all these pages
 				 */
-				bio_add_page(bio, page, len, 0);
+				__bio_add_page(bio, page, len, 0);
 			}
 		}
 		nr_sectors += len>>9;
-- 
2.40.0

[PATCH v5 15/20] md: raid1: check if adding pages to resync bio fails

[Johannes Thumshirn]

Check if adding pages to resync bio fails and if bail out.

As the comment above suggests this cannot happen, WARN if it actually
happens.

This way we can mark bio_add_pages as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/md/raid1-10.c | 11 ++++++-----
 drivers/md/raid10.c   | 20 ++++++++++----------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/md/raid1-10.c b/drivers/md/raid1-10.c
index e61f6cad4e08..cd349e69ed77 100644
--- a/drivers/md/raid1-10.c
+++ b/drivers/md/raid1-10.c
@@ -101,11 +101,12 @@ static void md_bio_reset_resync_pages(struct bio *bio, struct resync_pages *rp,
 		struct page *page = resync_fetch_page(rp, idx);
 		int len = min_t(int, size, PAGE_SIZE);
 
-		/*
-		 * won't fail because the vec table is big
-		 * enough to hold all these pages
-		 */
-		bio_add_page(bio, page, len, 0);
+		if (WARN_ON(!bio_add_page(bio, page, len, 0))) {
+			bio->bi_status = BLK_STS_RESOURCE;
+			bio_endio(bio);
+			return;
+		}
+
 		size -= len;
 	} while (idx++ < RESYNC_PAGES && size > 0);
 }
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 4fcfcb350d2b..381c21f7fb06 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3819,11 +3819,11 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 		for (bio= biolist ; bio ; bio=bio->bi_next) {
 			struct resync_pages *rp = get_resync_pages(bio);
 			page = resync_fetch_page(rp, page_idx);
-			/*
-			 * won't fail because the vec table is big enough
-			 * to hold all these pages
-			 */
-			bio_add_page(bio, page, len, 0);
+			if (WARN_ON(!bio_add_page(bio, page, len, 0))) {
+				bio->bi_status = BLK_STS_RESOURCE;
+				bio_endio(bio);
+				goto giveup;
+			}
 		}
 		nr_sectors += len>>9;
 		sector_nr += len>>9;
@@ -4997,11 +4997,11 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
 		if (len > PAGE_SIZE)
 			len = PAGE_SIZE;
 		for (bio = blist; bio ; bio = bio->bi_next) {
-			/*
-			 * won't fail because the vec table is big enough
-			 * to hold all these pages
-			 */
-			bio_add_page(bio, page, len, 0);
+			if (WARN_ON(!bio_add_page(bio, page, len, 0))) {
+				bio->bi_status = BLK_STS_RESOURCE;
+				bio_endio(bio);
+				return sectors_done;
+			}
 		}
 		sector_nr += len >> 9;
 		nr_sectors += len >> 9;
-- 
2.40.0

[PATCH v5 16/20] dm-crypt: check if adding pages to clone bio fails

[Johannes Thumshirn]

Check if adding pages to clone bio fails and if it does retry with
reclaim. This mirrors the behaviour of page allocation in
crypt_alloc_buffer().

This way we can mark bio_add_pages as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/md/dm-crypt.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 8b47b913ee83..b234dc089cee 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1693,7 +1693,14 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size)
 
 		len = (remaining_size > PAGE_SIZE) ? PAGE_SIZE : remaining_size;
 
-		bio_add_page(clone, page, len, 0);
+		if (!bio_add_page(clone, page, len, 0)) {
+			mempool_free(page, &cc->page_pool);
+			crypt_free_buffer_pages(cc, clone);
+			bio_put(clone);
+			gfp_mask |= __GFP_DIRECT_RECLAIM;
+			goto retry;
+
+		}
 
 		remaining_size -= len;
 	}
-- 
2.40.0

Re: [dm-devel] [PATCH v5 16/20] dm-crypt: check if adding pages to clone bio fails

[Mikulas Patocka]

On Tue, 2 May 2023, Johannes Thumshirn wrote:

> Check if adding pages to clone bio fails and if it does retry with
> reclaim. This mirrors the behaviour of page allocation in
> crypt_alloc_buffer().
> 
> This way we can mark bio_add_pages as __must_check.
> 
> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  drivers/md/dm-crypt.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> index 8b47b913ee83..b234dc089cee 100644
> --- a/drivers/md/dm-crypt.c
> +++ b/drivers/md/dm-crypt.c
> @@ -1693,7 +1693,14 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size)
>  
>  		len = (remaining_size > PAGE_SIZE) ? PAGE_SIZE : remaining_size;
>  
> -		bio_add_page(clone, page, len, 0);
> +		if (!bio_add_page(clone, page, len, 0)) {
> +			mempool_free(page, &cc->page_pool);
> +			crypt_free_buffer_pages(cc, clone);
> +			bio_put(clone);
> +			gfp_mask |= __GFP_DIRECT_RECLAIM;
> +			goto retry;
> +
> +		}
>  
>  		remaining_size -= len;
>  	}

Hi

I nack this. This just adds code that can't ever be executed.

dm-crypt already allocates enough entries in the vector (see "unsigned int 
nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;"), so bio_add_page can't 
fail.

If you want to add __must_check to bio_add_page, you should change the 
dm-crypt code to:
if (!bio_add_page(clone, page, len, 0)) {
	WARN(1, "this can't happen");
	return NULL;
}
and not write recovery code for a can't-happen case.

Mikulas

Re: [PATCH v5 16/20] dm-crypt: check if adding pages to clone bio fails

[Mike Snitzer]

On Tue, May 30 2023 at 11:13P -0400,
Mikulas Patocka <mpatocka@redhat.com> wrote:

> 
> 
> On Tue, 2 May 2023, Johannes Thumshirn wrote:
> 
> > Check if adding pages to clone bio fails and if it does retry with
> > reclaim. This mirrors the behaviour of page allocation in
> > crypt_alloc_buffer().
> > 
> > This way we can mark bio_add_pages as __must_check.
> > 
> > Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> > ---
> >  drivers/md/dm-crypt.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> > index 8b47b913ee83..b234dc089cee 100644
> > --- a/drivers/md/dm-crypt.c
> > +++ b/drivers/md/dm-crypt.c
> > @@ -1693,7 +1693,14 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size)
> >  
> >  		len = (remaining_size > PAGE_SIZE) ? PAGE_SIZE : remaining_size;
> >  
> > -		bio_add_page(clone, page, len, 0);
> > +		if (!bio_add_page(clone, page, len, 0)) {
> > +			mempool_free(page, &cc->page_pool);
> > +			crypt_free_buffer_pages(cc, clone);
> > +			bio_put(clone);
> > +			gfp_mask |= __GFP_DIRECT_RECLAIM;
> > +			goto retry;
> > +
> > +		}
> >  
> >  		remaining_size -= len;
> >  	}
> 
> Hi
> 
> I nack this. This just adds code that can't ever be executed.
> 
> dm-crypt already allocates enough entries in the vector (see "unsigned int 
> nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;"), so bio_add_page can't 
> fail.
> 
> If you want to add __must_check to bio_add_page, you should change the 
> dm-crypt code to:
> if (!bio_add_page(clone, page, len, 0)) {
> 	WARN(1, "this can't happen");
> 	return NULL;
> }
> and not write recovery code for a can't-happen case.

Thanks for the review Mikulas. But the proper way forward, in the
context of this patchset, is to simply change bio_add_page() to
__bio_add_page()

Subject becomes: "dm crypt: use __bio_add_page to add single page to clone bio"

And header can explain that "crypt_alloc_buffer() already allocates
enough entries in the clone bio's vector, so bio_add_page can't fail".

Mike

Re: [PATCH v5 16/20] dm-crypt: check if adding pages to clone bio fails

[Mikulas Patocka]

On Tue, 30 May 2023, Mike Snitzer wrote:

> On Tue, May 30 2023 at 11:13P -0400,
> Mikulas Patocka <mpatocka@redhat.com> wrote:
> 
> > Hi
> > 
> > I nack this. This just adds code that can't ever be executed.
> > 
> > dm-crypt already allocates enough entries in the vector (see "unsigned int 
> > nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;"), so bio_add_page can't 
> > fail.
> > 
> > If you want to add __must_check to bio_add_page, you should change the 
> > dm-crypt code to:
> > if (!bio_add_page(clone, page, len, 0)) {
> > 	WARN(1, "this can't happen");
> > 	return NULL;
> > }
> > and not write recovery code for a can't-happen case.
> 
> Thanks for the review Mikulas. But the proper way forward, in the
> context of this patchset, is to simply change bio_add_page() to
> __bio_add_page()
> 
> Subject becomes: "dm crypt: use __bio_add_page to add single page to clone bio"
> 
> And header can explain that "crypt_alloc_buffer() already allocates
> enough entries in the clone bio's vector, so bio_add_page can't fail".
> 
> Mike

Yes, __bio_add_page would look nicer. But bio_add_page can merge adjacent 
pages into a single bvec entry and __bio_add_page can't (I don't know how 
often the merging happens or what is the performance implication of 
non-merging).

I think that for the next merge window, we can apply this patch: 
https://listman.redhat.com/archives/dm-devel/2023-May/054046.html
which makes this discussion irrelevant. (you can change bio_add_page to 
__bio_add_page in it)

Mikukas

Re: [PATCH v5 16/20] dm-crypt: check if adding pages to clone bio fails

[Mike Snitzer]

On Tue, May 30 2023 at  3:43P -0400,
Mikulas Patocka <mpatocka@redhat.com> wrote:

> 
> 
> On Tue, 30 May 2023, Mike Snitzer wrote:
> 
> > On Tue, May 30 2023 at 11:13P -0400,
> > Mikulas Patocka <mpatocka@redhat.com> wrote:
> > 
> > > Hi
> > > 
> > > I nack this. This just adds code that can't ever be executed.
> > > 
> > > dm-crypt already allocates enough entries in the vector (see "unsigned int 
> > > nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;"), so bio_add_page can't 
> > > fail.
> > > 
> > > If you want to add __must_check to bio_add_page, you should change the 
> > > dm-crypt code to:
> > > if (!bio_add_page(clone, page, len, 0)) {
> > > 	WARN(1, "this can't happen");
> > > 	return NULL;
> > > }
> > > and not write recovery code for a can't-happen case.
> > 
> > Thanks for the review Mikulas. But the proper way forward, in the
> > context of this patchset, is to simply change bio_add_page() to
> > __bio_add_page()
> > 
> > Subject becomes: "dm crypt: use __bio_add_page to add single page to clone bio"
> > 
> > And header can explain that "crypt_alloc_buffer() already allocates
> > enough entries in the clone bio's vector, so bio_add_page can't fail".
> > 
> > Mike
> 
> Yes, __bio_add_page would look nicer. But bio_add_page can merge adjacent 
> pages into a single bvec entry and __bio_add_page can't (I don't know how 
> often the merging happens or what is the performance implication of 
> non-merging).
> 
> I think that for the next merge window, we can apply this patch: 
> https://listman.redhat.com/archives/dm-devel/2023-May/054046.html
> which makes this discussion irrelevant. (you can change bio_add_page to 
> __bio_add_page in it)

Yes, your patch is on my TODO list.  I've rebased my dm-6.5 branch on
the latest block 6.5 branch.  I'll be reviewing/rebasing/applying your
patch soon.

Mike

[PATCH v5 17/20] block: mark bio_add_page as __must_check

[Johannes Thumshirn]

Now that all users of bio_add_page check for the return value, mark
bio_add_page as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 include/linux/bio.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index b3e7529ff55e..5d5b081ee062 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -465,7 +465,7 @@ extern void bio_uninit(struct bio *);
 void bio_reset(struct bio *bio, struct block_device *bdev, blk_opf_t opf);
 void bio_chain(struct bio *, struct bio *);
 
-int bio_add_page(struct bio *, struct page *, unsigned len, unsigned off);
+int __must_check bio_add_page(struct bio *, struct page *, unsigned len, unsigned off);
 bool bio_add_folio(struct bio *, struct folio *, size_t len, size_t off);
 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 			   unsigned int, unsigned int);
-- 
2.40.0

[PATCH v5 18/20] block: add __bio_add_folio

[Johannes Thumshirn]

Just like for bio_add_pages() add a no-fail variant for bio_add_folio().

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 block/bio.c         | 8 ++++++++
 include/linux/bio.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index 043944fd46eb..350c653d4a57 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1138,6 +1138,14 @@ int bio_add_page(struct bio *bio, struct page *page,
 }
 EXPORT_SYMBOL(bio_add_page);
 
+void __bio_add_folio(struct bio *bio, struct folio *folio, size_t len,
+		     size_t off)
+{
+	WARN_ON_ONCE(len > UINT_MAX);
+	WARN_ON_ONCE(off > UINT_MAX);
+	__bio_add_page(bio, &folio->page, len, off);
+}
+
 /**
  * bio_add_folio - Attempt to add part of a folio to a bio.
  * @bio: BIO to add to.
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 5d5b081ee062..4232a17e6b10 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -473,6 +473,7 @@ int bio_add_zone_append_page(struct bio *bio, struct page *page,
 			     unsigned int len, unsigned int offset);
 void __bio_add_page(struct bio *bio, struct page *page,
 		unsigned int len, unsigned int off);
+void __bio_add_folio(struct bio *, struct folio *, size_t len, size_t off);
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
 void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter);
 void __bio_release_pages(struct bio *bio, bool mark_dirty);
-- 
2.40.0

[PATCH v5 19/20] fs: iomap: use __bio_add_folio where possible

[Johannes Thumshirn]

When the iomap buffered-io code can't add a folio to a bio, it allocates a
new bio and adds the folio to that one. This is done using bio_add_folio(),
but doesn't check for errors.

As adding a folio to a newly created bio can't fail, use the newly
introduced __bio_add_folio() function.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/iomap/buffered-io.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 063133ec77f4..42c5fc0ad329 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -312,7 +312,7 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
 			ctx->bio->bi_opf |= REQ_RAHEAD;
 		ctx->bio->bi_iter.bi_sector = sector;
 		ctx->bio->bi_end_io = iomap_read_end_io;
-		bio_add_folio(ctx->bio, folio, plen, poff);
+		__bio_add_folio(ctx->bio, folio, plen, poff);
 	}
 
 done:
@@ -539,7 +539,7 @@ static int iomap_read_folio_sync(loff_t block_start, struct folio *folio,
 
 	bio_init(&bio, iomap->bdev, &bvec, 1, REQ_OP_READ);
 	bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
-	bio_add_folio(&bio, folio, plen, poff);
+	__bio_add_folio(&bio, folio, plen, poff);
 	return submit_bio_wait(&bio);
 }
 
@@ -1582,7 +1582,7 @@ iomap_add_to_ioend(struct inode *inode, loff_t pos, struct folio *folio,
 
 	if (!bio_add_folio(wpc->ioend->io_bio, folio, len, poff)) {
 		wpc->ioend->io_bio = iomap_chain_bio(wpc->ioend->io_bio);
-		bio_add_folio(wpc->ioend->io_bio, folio, len, poff);
+		__bio_add_folio(wpc->ioend->io_bio, folio, len, poff);
 	}
 
 	if (iop)
-- 
2.40.0

[PATCH v5 20/20] block: mark bio_add_folio as __must_check

[Johannes Thumshirn]

Now that all callers of bio_add_folio() check the return value, mark it as
__must_check.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 include/linux/bio.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 4232a17e6b10..fef9f3085a02 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -466,7 +466,7 @@ void bio_reset(struct bio *bio, struct block_device *bdev, blk_opf_t opf);
 void bio_chain(struct bio *, struct bio *);
 
 int __must_check bio_add_page(struct bio *, struct page *, unsigned len, unsigned off);
-bool bio_add_folio(struct bio *, struct folio *, size_t len, size_t off);
+bool __must_check bio_add_folio(struct bio *, struct folio *, size_t len, size_t off);
 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 			   unsigned int, unsigned int);
 int bio_add_zone_append_page(struct bio *bio, struct page *page,
-- 
2.40.0

Re: [PATCH v5 00/20] bio: check return values of bio_add_page

[Johannes Thumshirn]

On 02.05.23 12:20, Johannes Thumshirn wrote:
> We have two functions for adding a page to a bio, __bio_add_page() which is
> used to add a single page to a freshly created bio and bio_add_page() which is
> used to add a page to an existing bio.
> 
> While __bio_add_page() is expected to succeed, bio_add_page() can fail.
> 
> This series converts the callers of bio_add_page() which can easily use
> __bio_add_page() to using it and checks the return of bio_add_page() for
> callers that don't work on a freshly created bio.
> 
> Lastly it marks bio_add_page() as __must_check so we don't have to go again
> and audit all callers.
> 
> Changes to v4:
> - Rebased onto latest Linus' master
> - Dropped already merged patches
> - Added Sergey's Reviewed-by
> 
> Changes to v3:
> - Added __bio_add_folio and use it in iomap (Willy)
> - Mark bio_add_folio must check (Willy)
> - s/GFS/GFS2/ (Andreas)
> 
> Changes to v2:
> - Removed 'wont fail' comments pointed out by Song
> 
> Changes to v1:
> - Removed pointless comment pointed out by Willy
> - Changed commit messages pointed out by Damien
> - Colledted Damien's Reviews and Acks

Jens any comments on this?

Re: [PATCH v5 00/20] bio: check return values of bio_add_page

[Jens Axboe]

On 5/5/23 2:09?AM, Johannes Thumshirn wrote:
> On 02.05.23 12:20, Johannes Thumshirn wrote:
>> We have two functions for adding a page to a bio, __bio_add_page() which is
>> used to add a single page to a freshly created bio and bio_add_page() which is
>> used to add a page to an existing bio.
>>
>> While __bio_add_page() is expected to succeed, bio_add_page() can fail.
>>
>> This series converts the callers of bio_add_page() which can easily use
>> __bio_add_page() to using it and checks the return of bio_add_page() for
>> callers that don't work on a freshly created bio.
>>
>> Lastly it marks bio_add_page() as __must_check so we don't have to go again
>> and audit all callers.
>>
>> Changes to v4:
>> - Rebased onto latest Linus' master
>> - Dropped already merged patches
>> - Added Sergey's Reviewed-by
>>
>> Changes to v3:
>> - Added __bio_add_folio and use it in iomap (Willy)
>> - Mark bio_add_folio must check (Willy)
>> - s/GFS/GFS2/ (Andreas)
>>
>> Changes to v2:
>> - Removed 'wont fail' comments pointed out by Song
>>
>> Changes to v1:
>> - Removed pointless comment pointed out by Willy
>> - Changed commit messages pointed out by Damien
>> - Colledted Damien's Reviews and Acks
> 
> Jens any comments on this?

I'll take a look post -rc1.

-- 
Jens Axboe

Re: [PATCH v5 00/20] bio: check return values of bio_add_page

[Johannes Thumshirn]

On 05.05.23 16:12, Jens Axboe wrote:
> On 5/5/23 2:09?AM, Johannes Thumshirn wrote:
>> On 02.05.23 12:20, Johannes Thumshirn wrote:
>>> We have two functions for adding a page to a bio, __bio_add_page() which is
>>> used to add a single page to a freshly created bio and bio_add_page() which is
>>> used to add a page to an existing bio.
>>>
>>> While __bio_add_page() is expected to succeed, bio_add_page() can fail.
>>>
>>> This series converts the callers of bio_add_page() which can easily use
>>> __bio_add_page() to using it and checks the return of bio_add_page() for
>>> callers that don't work on a freshly created bio.
>>>
>>> Lastly it marks bio_add_page() as __must_check so we don't have to go again
>>> and audit all callers.
>>>
>>> Changes to v4:
>>> - Rebased onto latest Linus' master
>>> - Dropped already merged patches
>>> - Added Sergey's Reviewed-by
>>>
>>> Changes to v3:
>>> - Added __bio_add_folio and use it in iomap (Willy)
>>> - Mark bio_add_folio must check (Willy)
>>> - s/GFS/GFS2/ (Andreas)
>>>
>>> Changes to v2:
>>> - Removed 'wont fail' comments pointed out by Song
>>>
>>> Changes to v1:
>>> - Removed pointless comment pointed out by Willy
>>> - Changed commit messages pointed out by Damien
>>> - Colledted Damien's Reviews and Acks
>>
>> Jens any comments on this?
> 
> I'll take a look post -rc1.
> 

Ping again?

Re: [PATCH v5 00/20] bio: check return values of bio_add_page

[Jens Axboe]

On 5/2/23 4:19?AM, Johannes Thumshirn wrote:
> We have two functions for adding a page to a bio, __bio_add_page() which is
> used to add a single page to a freshly created bio and bio_add_page() which is
> used to add a page to an existing bio.
> 
> While __bio_add_page() is expected to succeed, bio_add_page() can fail.
> 
> This series converts the callers of bio_add_page() which can easily use
> __bio_add_page() to using it and checks the return of bio_add_page() for
> callers that don't work on a freshly created bio.
> 
> Lastly it marks bio_add_page() as __must_check so we don't have to go again
> and audit all callers.

Looks fine to me, though it would be nice if the fs and dm people could
give this a quick look. Should not take long, any empty bio addition
should, by definition, be able to use a non-checked page addition for
the first page.

-- 
Jens Axboe

Re: [PATCH v5 00/20] bio: check return values of bio_add_page

[Johannes Thumshirn]

On 24.05.23 17:02, Jens Axboe wrote:
> On 5/2/23 4:19?AM, Johannes Thumshirn wrote:
>> We have two functions for adding a page to a bio, __bio_add_page() which is
>> used to add a single page to a freshly created bio and bio_add_page() which is
>> used to add a page to an existing bio.
>>
>> While __bio_add_page() is expected to succeed, bio_add_page() can fail.
>>
>> This series converts the callers of bio_add_page() which can easily use
>> __bio_add_page() to using it and checks the return of bio_add_page() for
>> callers that don't work on a freshly created bio.
>>
>> Lastly it marks bio_add_page() as __must_check so we don't have to go again
>> and audit all callers.
> 
> Looks fine to me, though it would be nice if the fs and dm people could
> give this a quick look. Should not take long, any empty bio addition
> should, by definition, be able to use a non-checked page addition for
> the first page.
> 

I think the FS side is all covered. @Mike could you have a look at the dm
patches?

Re: [PATCH v5 00/20] bio: check return values of bio_add_page

[Jens Axboe]

On 5/26/23 12:37 AM, Johannes Thumshirn wrote:
> On 24.05.23 17:02, Jens Axboe wrote:
>> On 5/2/23 4:19?AM, Johannes Thumshirn wrote:
>>> We have two functions for adding a page to a bio, __bio_add_page() which is
>>> used to add a single page to a freshly created bio and bio_add_page() which is
>>> used to add a page to an existing bio.
>>>
>>> While __bio_add_page() is expected to succeed, bio_add_page() can fail.
>>>
>>> This series converts the callers of bio_add_page() which can easily use
>>> __bio_add_page() to using it and checks the return of bio_add_page() for
>>> callers that don't work on a freshly created bio.
>>>
>>> Lastly it marks bio_add_page() as __must_check so we don't have to go again
>>> and audit all callers.
>>
>> Looks fine to me, though it would be nice if the fs and dm people could
>> give this a quick look. Should not take long, any empty bio addition
>> should, by definition, be able to use a non-checked page addition for
>> the first page.
>>
> 
> I think the FS side is all covered. @Mike could you have a look at the dm
> patches?

Not the iomap one, that was my main concern. Not that this is tricky stuff,
but still...

-- 
Jens Axboe