[PATCH 06/17] bcache: transfer the sb_page reference to register_{bdev,cache}

colyli
2020-01-23T17:02:43Z

From: Christoph Hellwig <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>
Signed-off-by: Coly Li <colyli@suse.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 fad9c6cbee5e..cf2cafef381f 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 = NULL;
struct cache_sb *sb;
- struct block_device *bdev = NULL;
+ struct block_device *bdev;
struct page *sb_page;
ssize_t ret;

@@ -2444,10 +2441,8 @@ 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);

@@ -2455,13 +2450,10 @@ 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);
@@ -2471,8 +2463,7 @@ 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:
--
2.16.4