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md/md-bitmap: fix wrong bitmap_limit for clustermd when write sb

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In clustermd, separate write-intent-bitmaps are used for each cluster
node:

0                    4k                     8k                    12k
-------------------------------------------------------------------
| idle                | md super            | bm super [0] + bits |
| bm bits[0, contd]   | bm super[1] + bits  | bm bits[1, contd]   |
| bm super[2] + bits  | bm bits [2, contd]  | bm super[3] + bits  |
| bm bits [3, contd]  |                     |                     |

So in node 1, pg_index in __write_sb_page() could equal to
bitmap->storage.file_pages. Then bitmap_limit will be calculated to
0. md_super_write() will be called with 0 size.
That means the first 4k sb area of node 1 will never be updated
through filemap_write_page().
This bug causes hang of mdadm/clustermd_tests/01r1_Grow_resize.

Here use (pg_index % bitmap->storage.file_pages) to make calculation
of bitmap_limit correct.

Fixes: ab99a87542 ("md/md-bitmap: fix writing non bitmap pages")
Signed-off-by: Su Yue <glass.su@suse.com>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Link: https://lore.kernel.org/linux-raid/20250303033918.32136-1-glass.su@suse.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
This commit is contained in:
Su Yue 2025-03-03 11:39:18 +08:00 • committed by Yu Kuai
parent e879a0d9cb
commit 6130825f34
1 changed files with 3 additions and 3 deletions
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6
drivers/md/md-bitmap.c
View file

@ -428,8 +428,8 @@ static int __write_sb_page(struct md_rdev *rdev, struct bitmap *bitmap,
struct block_device *bdev;
struct mddev *mddev = bitmap->mddev;
struct bitmap_storage *store = &bitmap->storage;
unsigned int bitmap_limit = (bitmap->storage.file_pages - pg_index) <<
PAGE_SHIFT;
unsigned long num_pages = bitmap->storage.file_pages;
unsigned int bitmap_limit = (num_pages - pg_index % num_pages) << PAGE_SHIFT;
loff_t sboff, offset = mddev->bitmap_info.offset;
sector_t ps = pg_index * PAGE_SIZE / SECTOR_SIZE;
unsigned int size = PAGE_SIZE;
@ -438,7 +438,7 @@ static int __write_sb_page(struct md_rdev *rdev, struct bitmap *bitmap,
bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
/* we compare length (page numbers), not page offset. */
if ((pg_index - store->sb_index) == store->file_pages - 1) {
if ((pg_index - store->sb_index) == num_pages - 1) {
unsigned int last_page_size = store->bytes & (PAGE_SIZE - 1);
if (last_page_size == 0)