From nobody Tue Oct 7 21:01:00 2025 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 1794F2D8DBA; Mon, 7 Jul 2025 14:22:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751898182; cv=none; b=lZHELgtqNqZQdezA4riIK3RdANwbFCpekJfcZcbt1m9bkduPMb8BXj3Scn+XhSCqyVBpus/DZJXDhFYcGhKbrr889dNjpxvZ8kc9XX3Ch8dklMUYDG5EYuwAtGJYNsIJjf2ARxICpXtfvuQpXOzahvHTvkAM5yPKVk6+Fe7d8PQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751898182; c=relaxed/simple; bh=mSpaELxxjIRKdvL366xC/wHU3Z4XsTkmkVgQr6zu/pc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VJhBeET/6U6UD67h8QMz4RvnwVV1DCWgr8eZU/KW5lC9b40HJsLgtRjp7sTjrX+bRq86nrYpleMPPiMMrIU2jsfoCsr9yXhGqFTjCHN7JJrmiTpHvqLCfhEJtWDhx3NQySS/4TkfGuR+EbCaLs3tu/TUIMTOfWkknFIGDUbxhuw= 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=45.249.212.51 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 [172.19.163.235]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4bbRKb3yGhzYQv6V; Mon, 7 Jul 2025 22:22:59 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 5D1C71A0AF1; Mon, 7 Jul 2025 22:22:58 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.112.188]) by APP3 (Coremail) with SMTP id _Ch0CgBnxyQ22GtoNazLAw--.46745S9; Mon, 07 Jul 2025 22:22:58 +0800 (CST) From: Zhang Yi To: linux-ext4@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, ojaswin@linux.ibm.com, sashal@kernel.org, naresh.kamboju@linaro.org, jiangqi903@gmail.com, yi.zhang@huawei.com, yi.zhang@huaweicloud.com, libaokun1@huawei.com, yukuai3@huawei.com, yangerkun@huawei.com Subject: [PATCH v4 05/11] ext4: restart handle if credits are insufficient during allocating blocks Date: Mon, 7 Jul 2025 22:08:08 +0800 Message-ID: <20250707140814.542883-6-yi.zhang@huaweicloud.com> X-Mailer: git-send-email 2.46.1 In-Reply-To: <20250707140814.542883-1-yi.zhang@huaweicloud.com> References: <20250707140814.542883-1-yi.zhang@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _Ch0CgBnxyQ22GtoNazLAw--.46745S9 X-Coremail-Antispam: 1UD129KBjvJXoWxCF17Zw4kWw1rCw45tF1fWFg_yoWrZF45pr W3CFy5Gr17Wry3Wa1Sqw4DXF13W3W0yrWUJF93W3s0va48Gr9xKFs8tF1YyFWvkrWkWa13 XF4jkryUWayjyrJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUma14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkE bVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67 AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUCVW8JwCI 42IY6xIIjxv20xvEc7CjxVAFwI0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCw CI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4UJVWxJrUvcSsG vfC2KfnxnUUI43ZEXa7VU1zpBDUUUUU== X-CM-SenderInfo: d1lo6xhdqjqx5xdzvxpfor3voofrz/ Content-Type: text/plain; charset="utf-8" From: Zhang Yi After large folios are supported on ext4, writing back a sufficiently large and discontinuous folio may consume a significant number of journal credits, placing considerable strain on the journal. For example, in a 20GB filesystem with 1K block size and 1MB journal size, writing back a 2MB folio could require thousands of credits in the worst-case scenario (when each block is discontinuous and distributed across different block groups), potentially exceeding the journal size. This issue can also occur in ext4_write_begin() and ext4_page_mkwrite() when delalloc is not enabled. Fix this by ensuring that there are sufficient journal credits before allocating an extent in mpage_map_one_extent() and ext4_block_write_begin(). If there are not enough credits, return -EAGAIN, exit the current mapping loop, restart a new handle and a new transaction, and allocating blocks on this folio again in the next iteration. Suggested-by: Jan Kara Signed-off-by: Zhang Yi Reviewed-by: Jan Kara --- fs/ext4/inode.c | 41 ++++++++++++++++++++++++++++++++++++----- 1 file changed, 36 insertions(+), 5 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index e73d5379b8f0..10d4f86a5c15 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -877,6 +877,26 @@ static void ext4_update_bh_state(struct buffer_head *b= h, unsigned long flags) } while (unlikely(!try_cmpxchg(&bh->b_state, &old_state, new_state))); } =20 +/* + * Make sure that the current journal transaction has enough credits to map + * one extent. Return -EAGAIN if it cannot extend the current running + * transaction. + */ +static inline int ext4_journal_ensure_extent_credits(handle_t *handle, + struct inode *inode) +{ + int credits; + int ret; + + /* Called from ext4_da_write_begin() which has no handle started? */ + if (!handle) + return 0; + + credits =3D ext4_chunk_trans_blocks(inode, 1); + ret =3D __ext4_journal_ensure_credits(handle, credits, credits, 0); + return ret <=3D 0 ? ret : -EAGAIN; +} + static int _ext4_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh, int flags) { @@ -1175,7 +1195,9 @@ int ext4_block_write_begin(handle_t *handle, struct f= olio *folio, clear_buffer_new(bh); if (!buffer_mapped(bh)) { WARN_ON(bh->b_size !=3D blocksize); - err =3D get_block(inode, block, bh, 1); + err =3D ext4_journal_ensure_extent_credits(handle, inode); + if (!err) + err =3D get_block(inode, block, bh, 1); if (err) break; if (buffer_new(bh)) { @@ -1374,8 +1396,9 @@ static int ext4_write_begin(struct file *file, struct= address_space *mapping, ext4_orphan_del(NULL, inode); } =20 - if (ret =3D=3D -ENOSPC && - ext4_should_retry_alloc(inode->i_sb, &retries)) + if (ret =3D=3D -EAGAIN || + (ret =3D=3D -ENOSPC && + ext4_should_retry_alloc(inode->i_sb, &retries))) goto retry_journal; folio_put(folio); return ret; @@ -2323,6 +2346,11 @@ static int mpage_map_one_extent(handle_t *handle, st= ruct mpage_da_data *mpd) int get_blocks_flags; int err, dioread_nolock; =20 + /* Make sure transaction has enough credits for this extent */ + err =3D ext4_journal_ensure_extent_credits(handle, inode); + if (err < 0) + return err; + trace_ext4_da_write_pages_extent(inode, map); /* * Call ext4_map_blocks() to allocate any delayed allocation blocks, or @@ -2450,7 +2478,7 @@ static int mpage_map_and_submit_extent(handle_t *hand= le, * In the case of ENOSPC, if ext4_count_free_blocks() * is non-zero, a commit should free up blocks. */ - if ((err =3D=3D -ENOMEM) || + if ((err =3D=3D -ENOMEM) || (err =3D=3D -EAGAIN) || (err =3D=3D -ENOSPC && ext4_count_free_clusters(sb))) { /* * We may have already allocated extents for @@ -2956,6 +2984,8 @@ static int ext4_do_writepages(struct mpage_da_data *m= pd) ret =3D 0; continue; } + if (ret =3D=3D -EAGAIN) + ret =3D 0; /* Fatal error - ENOMEM, EIO... */ if (ret) break; @@ -6734,7 +6764,8 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) retry_alloc: /* Start journal and allocate blocks */ err =3D ext4_block_page_mkwrite(inode, folio, get_block); - if (err =3D=3D -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) + if (err =3D=3D -EAGAIN || + (err =3D=3D -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)= )) goto retry_alloc; out_ret: ret =3D vmf_fs_error(err); --=20 2.46.1