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From:   Christoph Hellwig <hch@lst.de>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Pavel Begunkov <asml.silence@gmail.com>,
        Mike Snitzer <snitzer@redhat.com>,
        Ryusuke Konishi <konishi.ryusuke@gmail.com>,
        Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Md . Haris Iqbal " <haris.iqbal@ionos.com>,
        Jack Wang <jinpu.wang@ionos.com>,
        =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.co>,
        Philipp Reisner <philipp.reisner@linbit.com>,
        Lars Ellenberg <lars.ellenberg@linbit.com>,
        linux-block@vger.kernel.org, dm-devel@redhat.com,
        linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
        linux-nilfs@vger.kernel.org, ntfs3@lists.linux.dev,
        xen-devel@lists.xenproject.org, drbd-dev@lists.linbit.com
Subject: [PATCH 05/19] dm: bio_alloc can't fail if it is allowed to sleep
Date:   Tue, 18 Jan 2022 08:19:38 +0100
Message-Id: <20220118071952.1243143-6-hch@lst.de>
In-Reply-To: <20220118071952.1243143-1-hch@lst.de>
References: <20220118071952.1243143-1-hch@lst.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Remove handling of NULL returns from sleeping bio_alloc calls given that
those can't fail.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/dm-crypt.c          |  5 +----
 drivers/md/dm-log-writes.c     | 18 ------------------
 drivers/md/dm-thin.c           | 25 +++++++++----------------
 drivers/md/dm-zoned-metadata.c | 11 -----------
 drivers/md/dm.c                |  2 --
 5 files changed, 10 insertions(+), 51 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index d4ae31558826a..20abe3486aba1 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1673,9 +1673,6 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 		mutex_lock(&cc->bio_alloc_lock);
 
 	clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, &cc->bs);
-	if (!clone)
-		goto out;
-
 	clone_init(io, clone);
 
 	remaining_size = size;
@@ -1702,7 +1699,7 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 		bio_put(clone);
 		clone = NULL;
 	}
-out:
+
 	if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM))
 		mutex_unlock(&cc->bio_alloc_lock);
 
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 139b09b06eda9..25f5e8d2d417b 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -218,10 +218,6 @@ static int write_metadata(struct log_writes_c *lc, void *entry,
 	size_t ret;
 
 	bio = bio_alloc(GFP_KERNEL, 1);
-	if (!bio) {
-		DMERR("Couldn't alloc log bio");
-		goto error;
-	}
 	bio->bi_iter.bi_size = 0;
 	bio->bi_iter.bi_sector = sector;
 	bio_set_dev(bio, lc->logdev->bdev);
@@ -276,11 +272,6 @@ static int write_inline_data(struct log_writes_c *lc, void *entry,
 		atomic_inc(&lc->io_blocks);
 
 		bio = bio_alloc(GFP_KERNEL, bio_pages);
-		if (!bio) {
-			DMERR("Couldn't alloc inline data bio");
-			goto error;
-		}
-
 		bio->bi_iter.bi_size = 0;
 		bio->bi_iter.bi_sector = sector;
 		bio_set_dev(bio, lc->logdev->bdev);
@@ -322,7 +313,6 @@ static int write_inline_data(struct log_writes_c *lc, void *entry,
 error_bio:
 	bio_free_pages(bio);
 	bio_put(bio);
-error:
 	put_io_block(lc);
 	return -1;
 }
@@ -364,10 +354,6 @@ static int log_one_block(struct log_writes_c *lc,
 
 	atomic_inc(&lc->io_blocks);
 	bio = bio_alloc(GFP_KERNEL, bio_max_segs(block->vec_cnt));
-	if (!bio) {
-		DMERR("Couldn't alloc log bio");
-		goto error;
-	}
 	bio->bi_iter.bi_size = 0;
 	bio->bi_iter.bi_sector = sector;
 	bio_set_dev(bio, lc->logdev->bdev);
@@ -387,10 +373,6 @@ static int log_one_block(struct log_writes_c *lc,
 			submit_bio(bio);
 			bio = bio_alloc(GFP_KERNEL,
 					bio_max_segs(block->vec_cnt - i));
-			if (!bio) {
-				DMERR("Couldn't alloc log bio");
-				goto error;
-			}
 			bio->bi_iter.bi_size = 0;
 			bio->bi_iter.bi_sector = sector;
 			bio_set_dev(bio, lc->logdev->bdev);
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index ec119d2422d5d..76a9c2e9aeeea 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1180,24 +1180,17 @@ static void process_prepared_discard_passdown_pt1(struct dm_thin_new_mapping *m)
 	}
 
 	discard_parent = bio_alloc(GFP_NOIO, 1);
-	if (!discard_parent) {
-		DMWARN("%s: unable to allocate top level discard bio for passdown. Skipping passdown.",
-		       dm_device_name(tc->pool->pool_md));
-		queue_passdown_pt2(m);
+	discard_parent->bi_end_io = passdown_endio;
+	discard_parent->bi_private = m;
 
-	} else {
-		discard_parent->bi_end_io = passdown_endio;
-		discard_parent->bi_private = m;
-
-		if (m->maybe_shared)
-			passdown_double_checking_shared_status(m, discard_parent);
-		else {
-			struct discard_op op;
+	if (m->maybe_shared)
+		passdown_double_checking_shared_status(m, discard_parent);
+	else {
+		struct discard_op op;
 
-			begin_discard(&op, tc, discard_parent);
-			r = issue_discard(&op, m->data_block, data_end);
-			end_discard(&op, r);
-		}
+		begin_discard(&op, tc, discard_parent);
+		r = issue_discard(&op, m->data_block, data_end);
+		end_discard(&op, r);
 	}
 }
 
diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c
index ee4626d085574..5718b83cc7182 100644
--- a/drivers/md/dm-zoned-metadata.c
+++ b/drivers/md/dm-zoned-metadata.c
@@ -551,10 +551,6 @@ static struct dmz_mblock *dmz_get_mblock_slow(struct dmz_metadata *zmd,
 		return ERR_PTR(-ENOMEM);
 
 	bio = bio_alloc(GFP_NOIO, 1);
-	if (!bio) {
-		dmz_free_mblock(zmd, mblk);
-		return ERR_PTR(-ENOMEM);
-	}
 
 	spin_lock(&zmd->mblk_lock);
 
@@ -726,10 +722,6 @@ static int dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk,
 		return -EIO;
 
 	bio = bio_alloc(GFP_NOIO, 1);
-	if (!bio) {
-		set_bit(DMZ_META_ERROR, &mblk->state);
-		return -ENOMEM;
-	}
 
 	set_bit(DMZ_META_WRITING, &mblk->state);
 
@@ -760,9 +752,6 @@ static int dmz_rdwr_block(struct dmz_dev *dev, int op,
 		return -EIO;
 
 	bio = bio_alloc(GFP_NOIO, 1);
-	if (!bio)
-		return -ENOMEM;
-
 	bio->bi_iter.bi_sector = dmz_blk2sect(block);
 	bio_set_dev(bio, dev->bdev);
 	bio_set_op_attrs(bio, op, REQ_SYNC | REQ_META | REQ_PRIO);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c0ae8087c6027..81449cbdafa81 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -520,8 +520,6 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
 	struct bio *clone;
 
 	clone = bio_alloc_bioset(GFP_NOIO, 0, &md->io_bs);
-	if (!clone)
-		return NULL;
 
 	tio = container_of(clone, struct dm_target_io, clone);
 	tio->inside_dm_io = true;
-- 
2.30.2