From nobody Tue Dec 2 02:05:54 2025 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 78FAD824A3; Fri, 21 Nov 2025 09:16:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763716618; cv=none; b=nTKGZN2mzBk5WwlzqtEWbsU5t/mxT/Q702JPNwyDXq6vUHxqKGCLYltBpIN0v1DKHMUaau4U49loBvgkv0rRINkjBHJKBqCfGxCK1bCxzAzGWwU3Jpk3heQjCHiQ/kMWWzBEruReLgH3soCyugQS4or+ohtdryT1iHroROYeJbU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763716618; c=relaxed/simple; bh=Zhn/IogLIgUaBuPIWYgGdBw1sRiR+JtODhQ7+icZ7/M=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=ki6ixOSimF9fFYMTaWiAvxnDF4LDmHzotZbHcBO7wmh56z9PpKoJJBShXYANmdL8vlxgA+oBIKLBdVXsBR/2Zq+6v7wXpIp4cb0w73lBIzML0pIWVHoqVOc0JlKkoidWZAUvux7qaOkmjgBfP5q+5rlsjzfK50dqcqyFc0fXXm8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=none smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4dCV2N3NYjzKHMvf; Fri, 21 Nov 2025 17:16:12 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.75]) by mail.maildlp.com (Postfix) with ESMTP id 6F32B1A19B8; Fri, 21 Nov 2025 17:16:43 +0800 (CST) Received: from huaweicloud.com (unknown [10.50.87.129]) by APP2 (Coremail) with SMTP id Syh0CgBHpXv4LSBpaLMDBg--.2072S15; Fri, 21 Nov 2025 17:16:43 +0800 (CST) From: libaokun@huaweicloud.com To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, linux-kernel@vger.kernel.org, kernel@pankajraghav.com, mcgrof@kernel.org, ebiggers@kernel.org, willy@infradead.org, yi.zhang@huawei.com, yangerkun@huawei.com, chengzhihao1@huawei.com, libaokun1@huawei.com, libaokun@huaweicloud.com Subject: [PATCH v4 11/24] ext4: support large block size in ext4_mb_load_buddy_gfp() Date: Fri, 21 Nov 2025 17:06:41 +0800 Message-Id: <20251121090654.631996-12-libaokun@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20251121090654.631996-1-libaokun@huaweicloud.com> References: <20251121090654.631996-1-libaokun@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: Syh0CgBHpXv4LSBpaLMDBg--.2072S15 X-Coremail-Antispam: 1UD129KBjvJXoWxArykWFyUGry7JrW7Jr18Krg_yoWrJF48pF srGrn8Gr48WFnxWwsrZa4Sqr1Fgas3uFWUGFWfWF1fZFy3t3WfKFnrK3WUJF1jqa9rJ3Wk XFW5ZryfuF17W3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQa14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAFwI0_Gr1j6F4UJwAm72CE4IkC6x0Yz7v_Jr0_ Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8c xan2IY04v7M4kE6xkIj40Ew7xC0wCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxG rwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4 vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IY x2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw2 0EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x02 67AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUdsqAUUUUU= X-CM-SenderInfo: 5olet0hnxqqx5xdzvxpfor3voofrz/1tbiAQATBWkf35kfFQAAst From: Baokun Li Currently, ext4_mb_load_buddy_gfp() uses blocks_per_page to calculate the 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, if buddy and bitmap land in the same folio, we get that folio=E2=80= =99s ref instead of looking it up again before updating the buddy. Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara --- fs/ext4/mballoc.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 9087183602e4..143d6ff1fdef 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1642,17 +1642,15 @@ int ext4_mb_init_group(struct super_block *sb, ext4= _group_t group, gfp_t gfp) =20 /* * Locking note: This routine calls ext4_mb_init_cache(), which takes the - * block group lock of all groups for this page; do not hold the BG lock w= hen + * block group lock of all groups for this folio; do not hold the BG lock = when * calling this routine! */ static noinline_for_stack int ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_group_t group, struct ext4_buddy *e4b, gfp_t gfp) { - int blocks_per_page; int block; int pnum; - int poff; struct folio *folio; int ret; struct ext4_group_info *grp; @@ -1662,7 +1660,6 @@ ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_g= roup_t group, might_sleep(); mb_debug(sb, "load group %u\n", group); =20 - blocks_per_page =3D PAGE_SIZE / sb->s_blocksize; grp =3D ext4_get_group_info(sb, group); if (!grp) return -EFSCORRUPTED; @@ -1690,8 +1687,7 @@ ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_g= roup_t group, * So for each group we need two blocks. */ block =3D group * 2; - pnum =3D block / blocks_per_page; - poff =3D block % blocks_per_page; + pnum =3D EXT4_LBLK_TO_PG(inode, block); =20 /* Avoid locking the folio in the fast path ... */ folio =3D __filemap_get_folio(inode->i_mapping, pnum, FGP_ACCESSED, 0); @@ -1723,7 +1719,8 @@ ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_g= roup_t group, goto err; } mb_cmp_bitmaps(e4b, folio_address(folio) + - (poff * sb->s_blocksize)); + offset_in_folio(folio, + EXT4_LBLK_TO_B(inode, block))); } folio_unlock(folio); } @@ -1739,12 +1736,18 @@ ext4_mb_load_buddy_gfp(struct super_block *sb, ext4= _group_t group, =20 /* Folios marked accessed already */ e4b->bd_bitmap_folio =3D folio; - e4b->bd_bitmap =3D folio_address(folio) + (poff * sb->s_blocksize); + e4b->bd_bitmap =3D folio_address(folio) + + offset_in_folio(folio, EXT4_LBLK_TO_B(inode, block)); =20 block++; - pnum =3D block / blocks_per_page; - poff =3D block % blocks_per_page; + pnum =3D EXT4_LBLK_TO_PG(inode, block); + /* buddy and bitmap are on the same folio? */ + if (folio_contains(folio, pnum)) { + folio_get(folio); + goto update_buddy; + } =20 + /* we need another folio for the buddy */ folio =3D __filemap_get_folio(inode->i_mapping, pnum, FGP_ACCESSED, 0); if (IS_ERR(folio) || !folio_test_uptodate(folio)) { if (!IS_ERR(folio)) @@ -1779,9 +1782,11 @@ ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_= group_t group, goto err; } =20 +update_buddy: /* Folios marked accessed already */ e4b->bd_buddy_folio =3D folio; - e4b->bd_buddy =3D folio_address(folio) + (poff * sb->s_blocksize); + e4b->bd_buddy =3D folio_address(folio) + + offset_in_folio(folio, EXT4_LBLK_TO_B(inode, block)); =20 return 0; =20 --=20 2.46.1