From: Christoph Hellwig hch@lst.de
mainline inclusion from mainline-5.6-rc1 commit 6321bef028de43724c47cfa7f9dee69ecb783796 category: feature bugzilla: 43003 CVE: NA ---------------------------
Avoid a pointless dependency on buffer heads in bcache by simply open coding reading a single page. Also add a SB_OFFSET define for the byte offset of the superblock instead of using magic numbers.
Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Coly Li colyli@suse.de Signed-off-by: Jens Axboe axboe@kernel.dk Acked-by: Hanjun Guo guohanjun@huawei.com Reviewed-by: Yufen Yu yuyufen@huawei.com Signed-off-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/md/bcache/super.c | 16 +++++++--------- include/uapi/linux/bcache.h | 1 + 2 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index ae857154cf6e..94045d72952c 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -15,7 +15,6 @@ #include "writeback.h"
#include <linux/blkdev.h> -#include <linux/buffer_head.h> #include <linux/debugfs.h> #include <linux/genhd.h> #include <linux/idr.h> @@ -64,13 +63,14 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev, { const char *err; struct cache_sb_disk *s; - struct buffer_head *bh = __bread(bdev, 1, SB_SIZE); + struct page *page; unsigned int i;
- if (!bh) + page = read_cache_page_gfp(bdev->bd_inode->i_mapping, + SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL); + if (IS_ERR(page)) return "IO error"; - - s = (struct cache_sb_disk *)bh->b_data; + s = page_address(page) + offset_in_page(SB_OFFSET);
sb->offset = le64_to_cpu(s->offset); sb->version = le64_to_cpu(s->version); @@ -188,12 +188,10 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev, }
sb->last_mount = (u32)ktime_get_real_seconds(); - err = NULL; - - get_page(bh->b_page); *res = s; + return NULL; err: - put_bh(bh); + put_page(page); return err; }
diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h index 1d8b3a9fc080..9a1965c6c3d0 100644 --- a/include/uapi/linux/bcache.h +++ b/include/uapi/linux/bcache.h @@ -148,6 +148,7 @@ static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys) #define BCACHE_SB_MAX_VERSION 4
#define SB_SECTOR 8 +#define SB_OFFSET (SB_SECTOR << SECTOR_SHIFT) #define SB_SIZE 4096 #define SB_LABEL_SIZE 32 #define SB_JOURNAL_BUCKETS 256U