On 2025-11-05 17:13, Jan Kara wrote:

On Sat 25-10-25 11:22:08, libaokun@huaweicloud.com wrote:

quoted

From: Baokun Li <redacted>

Currently, ext4_mb_get_buddy_page_lock() uses blocks_per_page to calculate
folio index and offset. However, when blocksize is larger than PAGE_SIZE,
blocks_per_page becomes zero, leading to a potential division-by-zero bug.

To support BS > PS, use bytes to compute folio index and offset within
folio to get rid of blocks_per_page.

Also, since ext4_mb_get_buddy_page_lock() already fully supports folio,
rename it to ext4_mb_get_buddy_folio_lock().

Signed-off-by: Baokun Li <redacted>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>

Looks good, just two typo fixes below. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

quoted

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 3494c6fe5bfb..d42d768a705a 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c

@@ -1510,50 +1510,52 @@ static int ext4_mb_init_cache(struct folio *folio, char *incore, gfp_t gfp)
 }
 

Let's fix some typos when updating the comment:

I’ll fix these typos in the next update.

Thank you for your review!


Regards,
Baokun

quoted

 /*
- * Lock the buddy and bitmap pages. This make sure other parallel init_group
- * on the same buddy page doesn't happen whild holding the buddy page lock.
- * Return locked buddy and bitmap pages on e4b struct. If buddy and bitmap
- * are on the same page e4b->bd_buddy_folio is NULL and return value is 0.
+ * Lock the buddy and bitmap folios. This make sure other parallel init_group

					     ^^^ makes

quoted

+ * on the same buddy folio doesn't happen whild holding the buddy folio lock.

					     ^^ while

quoted

+ * Return locked buddy and bitmap folios on e4b struct. If buddy and bitmap
+ * are on the same folio e4b->bd_buddy_folio is NULL and return value is 0.
  */

								Honza