In read_super(), after read super block by __bread(), a page is used to
cache the data. But it will cause superblock corrupted when PAGE_SIZE is
8KB or larger, because bh->b_data doesn't always point to the beginning
of the page. So use a bio_vec struct to point the superblock cached.
Signed-off-by: Guoju Fang <fanggu...@gmail.com>
---
drivers/md/bcache/super.c | 33 ++++++++++++++++++---------------
1 file changed, 18 insertions(+), 15 deletions(-)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 30ba9ae..64715a8 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -58,7 +58,7 @@
/* Superblock */
static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
- struct page **res)
+ struct bio_vec *bv)
{
const char *err;
struct cache_sb *s;
@@ -188,7 +188,9 @@ static const char *read_super(struct cache_sb *sb, struct
block_device *bdev,
err = NULL;
get_page(bh->b_page);
- *res = bh->b_page;
+ bv->bv_page = bh->b_page;
+ bv->bv_len = SB_SIZE;
+ bv->bv_offset = (unsigned long)bh->b_data & ~PAGE_MASK;
err:
put_bh(bh);
return err;
@@ -204,7 +206,8 @@ static void write_bdev_super_endio(struct bio *bio)
static void __write_super(struct cache_sb *sb, struct bio *bio)
{
- struct cache_sb *out = page_address(bio_first_page_all(bio));
+ struct cache_sb *out = page_address(bio_first_bvec_all(bio)->bv_page) +
+ bio_first_bvec_all(bio)->bv_offset;
unsigned int i;
bio->bi_iter.bi_sector = SB_SECTOR;
@@ -1277,7 +1280,7 @@ static int cached_dev_init(struct cached_dev *dc,
unsigned int block_size)
/* Cached device - bcache superblock */
-static void register_bdev(struct cache_sb *sb, struct page *sb_page,
+static void register_bdev(struct cache_sb *sb, struct bio_vec *bv,
struct block_device *bdev,
struct cached_dev *dc)
{
@@ -1290,8 +1293,8 @@ static void register_bdev(struct cache_sb *sb, struct
page *sb_page,
dc->bdev->bd_holder = dc;
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);
+ memcpy(bio_first_bvec_all(&dc->sb_bio), bv, sizeof(*bv));
+ get_page(bv->bv_page);
if (cached_dev_init(dc, sb->block_size << 9))
@@ -2089,7 +2092,7 @@ static int cache_alloc(struct cache *ca)
return 0;
}
-static int register_cache(struct cache_sb *sb, struct page *sb_page,
+static int register_cache(struct cache_sb *sb, struct bio_vec *bv,
struct block_device *bdev, struct cache *ca)
{
const char *err = NULL; /* must be set for any error case */
@@ -2101,8 +2104,8 @@ static int register_cache(struct cache_sb *sb, struct
page *sb_page,
ca->bdev->bd_holder = ca;
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);
+ memcpy(bio_first_bvec_all(&ca->sb_bio), bv, sizeof(*bv));
+ get_page(bv->bv_page);
if (blk_queue_discard(bdev_get_queue(bdev)))
ca->discard = CACHE_DISCARD(&ca->sb);
@@ -2195,7 +2198,7 @@ static ssize_t register_bcache(struct kobject *k, struct
kobj_attribute *attr,
char *path = NULL;
struct cache_sb *sb = NULL;
struct block_device *bdev = NULL;
- struct page *sb_page = NULL;
+ struct bio_vec bv = { NULL };
if (!try_module_get(THIS_MODULE))
return -EBUSY;
@@ -2233,7 +2236,7 @@ static ssize_t register_bcache(struct kobject *k, struct
kobj_attribute *attr,
if (set_blocksize(bdev, 4096))
goto err_close;
- err = read_super(sb, bdev, &sb_page);
+ err = read_super(sb, bdev, &bv);
if (err)
goto err_close;
@@ -2245,7 +2248,7 @@ static ssize_t register_bcache(struct kobject *k, struct
kobj_attribute *attr,
goto err_close;
mutex_lock(&bch_register_lock);
- register_bdev(sb, sb_page, bdev, dc);
+ register_bdev(sb, &bv, bdev, dc);
mutex_unlock(&bch_register_lock);
} else {
struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
@@ -2253,12 +2256,12 @@ static ssize_t register_bcache(struct kobject *k,
struct kobj_attribute *attr,
if (!ca)
goto err_close;
- if (register_cache(sb, sb_page, bdev, ca) != 0)
+ if (register_cache(sb, &bv, bdev, ca) != 0)
goto err;
}
out:
- if (sb_page)
- put_page(sb_page);
+ if (bv.bv_page)
+ put_page(bv.bv_page);
kfree(sb);
kfree(path);
module_put(THIS_MODULE);
--
1.8.3.1
