From nobody Sat Oct 11 08:29:22 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 EF9212609C7; Wed, 11 Jun 2025 11:29:41 +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=1749641385; cv=none; b=IRm6Wde78xYIItcBqJ0GobOv+u8PkQXVp+FiRz7fAydVE0I/4ubrPw+Uwffm4U2nyNAhagxhkvKN7rq18XyOyMil/RYBERBrrSKg2Iw68TVkFtPPbf3NL01/inDOm92i7PQf55c1RkDj5gLArwu+kAq4eoa35+vzXlFedgKkXrs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749641385; c=relaxed/simple; bh=rzOMd1WZj1UyrCqbzZ7rp3KTElt1HVNQRYgATXSj3u0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LNnUU1++vmlfpIdqwwra5LiRtR4Dc2gVDSQspWMWmAiVXTmytDoK3CfK7wPTq+i/1q/Y7QFAI3dhhUlnq0j0qQyj6Lo1J2XVXSQOVtYGR9CUXRYzfF0+RTMrmATaZ3Nft8yZDyUMSevGz9719f/6vOjIa/3xaZyvQnTVXDDFYxI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass 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=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4bHNjd182rzYQvvR; Wed, 11 Jun 2025 19:29:41 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 288EE1A123A; Wed, 11 Jun 2025 19:29:40 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.112.188]) by APP3 (Coremail) with SMTP id _Ch0CgAXacOXaElofvDPOw--.32023S7; Wed, 11 Jun 2025 19:29:39 +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, yi.zhang@huawei.com, yi.zhang@huaweicloud.com, libaokun1@huawei.com, yukuai3@huawei.com, yangerkun@huawei.com Subject: [PATCH v2 3/6] ext4: restart handle if credits are insufficient during allocating blocks Date: Wed, 11 Jun 2025 19:16:22 +0800 Message-ID: <20250611111625.1668035-4-yi.zhang@huaweicloud.com> X-Mailer: git-send-email 2.46.1 In-Reply-To: <20250611111625.1668035-1-yi.zhang@huaweicloud.com> References: <20250611111625.1668035-1-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: _Ch0CgAXacOXaElofvDPOw--.32023S7 X-Coremail-Antispam: 1UD129KBjvJXoWxCF17Zw4kWw1rCF4DGr4rXwb_yoWruryxpr W3CFy5Gr1jgryfWF4Sqw4DXF1a93W8trWUJF9xW3sYvayDJry3KF4rtFyYya9YkrW8W3W3 ZF4jkryjga1jyrJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUm014x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JrWl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUXVWUAwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWU JVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67 kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY 6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0x vEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVj vjDU0xZFpf9x0JULBMNUUUUU= 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_get_block(). 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 --- fs/ext4/inode.c | 45 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d0db6e3bf158..b51de58518b2 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -877,20 +877,44 @@ static void ext4_update_bh_state(struct buffer_head *= bh, 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 needed_credits; + int ret; + + needed_credits =3D ext4_chunk_trans_blocks(inode, 1); + ret =3D __ext4_journal_ensure_credits(handle, needed_credits, + needed_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) { struct ext4_map_blocks map; + handle_t *handle =3D ext4_journal_current_handle(); int ret =3D 0; =20 if (ext4_has_inline_data(inode)) return -ERANGE; =20 + /* Make sure transaction has enough credits for this extent */ + if (flags & EXT4_GET_BLOCKS_CREATE) { + ret =3D ext4_journal_ensure_extent_credits(handle, inode); + if (ret) + return ret; + } + map.m_lblk =3D iblock; map.m_len =3D bh->b_size >> inode->i_blkbits; =20 - ret =3D ext4_map_blocks(ext4_journal_current_handle(), inode, &map, - flags); + ret =3D ext4_map_blocks(handle, inode, &map, flags); if (ret > 0) { map_bh(bh, inode->i_sb, map.m_pblk); ext4_update_bh_state(bh, map.m_flags); @@ -1374,8 +1398,9 @@ 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; @@ -2324,6 +2349,11 @@ 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 @@ -2446,7 +2476,7 @@ 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 @@ -2953,6 +2983,8 @@ 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; @@ -6722,7 +6754,8 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) } } ext4_journal_stop(handle); - 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