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From: Christoph Hellwig <hch@lst.de>
To: colyli@suse.de
Cc: kent.overstreet@gmail.com, liangchen.linux@gmail.com,
	linux-bcache@vger.kernel.org, linux-block@vger.kernel.org
Subject: [PATCH 4/7] bcache: transfer the sb_page reference to register_{bdev,cache}
Date: Thu, 12 Dec 2019 16:36:01 +0100	[thread overview]
Message-ID: <20191212153604.19540-5-hch@lst.de> (raw)
In-Reply-To: <20191212153604.19540-1-hch@lst.de>

Avoid an extra reference count roundtrip by transferring the sb_page
ownership to the lower level register helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/bcache/super.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index e8013e1b0a14..c11bc0135ae6 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1368,8 +1368,6 @@ static int register_bdev(struct cache_sb *sb, struct page *sb_page,
 
 	bio_init(&dc->sb_bio, dc->sb_bio.bi_inline_vecs, 1);
 	bio_first_bvec_all(&dc->sb_bio)->bv_page = sb_page;
-	get_page(sb_page);
-
 
 	if (cached_dev_init(dc, sb->block_size << 9))
 		goto err;
@@ -2275,7 +2273,6 @@ static int register_cache(struct cache_sb *sb, struct page *sb_page,
 
 	bio_init(&ca->sb_bio, ca->sb_bio.bi_inline_vecs, 1);
 	bio_first_bvec_all(&ca->sb_bio)->bv_page = sb_page;
-	get_page(sb_page);
 
 	if (blk_queue_discard(bdev_get_queue(bdev)))
 		ca->discard = CACHE_DISCARD(&ca->sb);
@@ -2378,7 +2375,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	const char *err;
 	char *path;
 	struct cache_sb *sb;
-	struct block_device *bdev = NULL;
+	struct block_device *bdev;
 	struct page *sb_page;
 	ssize_t ret;
 
@@ -2442,10 +2439,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 		ret = register_bdev(sb, sb_page, bdev, dc);
 		mutex_unlock(&bch_register_lock);
 		/* blkdev_put() will be called in cached_dev_free() */
-		if (ret < 0) {
-			bdev = NULL;
-			goto out_put_sb_page;
-		}
+		if (ret < 0)
+			goto out_free_sb;
 	} else {
 		struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
 
@@ -2453,13 +2448,10 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 			goto out_put_sb_page;
 
 		/* blkdev_put() will be called in bch_cache_release() */
-		if (register_cache(sb, sb_page, bdev, ca) != 0) {
-			bdev = NULL;
-			goto out_put_sb_page;
-		}
+		if (register_cache(sb, sb_page, bdev, ca) != 0)
+			goto out_free_sb;
 	}
 
-	put_page(sb_page);
 done:
 	kfree(sb);
 	kfree(path);
@@ -2469,8 +2461,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 out_put_sb_page:
 	put_page(sb_page);
 out_blkdev_put:
-	if (bdev)
-		blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+	blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
 out_free_sb:
 	kfree(sb);
 out_free_path:
-- 
2.20.1


  parent reply	other threads:[~2019-12-12 15:36 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-12 15:35 bcache superblock reading / writing v2 Christoph Hellwig
2019-12-12 15:35 ` [PATCH 1/7] bcache: cached_dev_free needs to put the sb page Christoph Hellwig
2019-12-12 15:35 ` [PATCH 2/7] bcache: use a separate data structure for the on-disk super block Christoph Hellwig
2019-12-12 15:36 ` [PATCH 3/7] bcache: rework error unwinding in register_bcache Christoph Hellwig
2019-12-12 15:36 ` Christoph Hellwig [this message]
2019-12-12 15:36 ` [PATCH 5/7] bcache: return a pointer to the on-disk sb from read_super Christoph Hellwig
2019-12-12 15:36 ` [PATCH 6/7] bcache: store a pointer to the on-disk sb in the cache and cached_dev structures Christoph Hellwig
2019-12-12 15:36 ` [PATCH 7/7] bcache: use read_cache_page_gfp to read the superblock Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2019-12-09  9:38 bcache kbuild cleanups Christoph Hellwig
2019-12-09  9:38 ` [PATCH 4/7] bcache: transfer the sb_page reference to register_{bdev,cache} Christoph Hellwig

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