From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8C034421F0F for ; Mon, 20 Jul 2026 13:04:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784552650; cv=none; b=hijwJxwKV3kqPuYU9IpqzCrvEA/SuaCO4KgsflVA+LFx4peqHD+sYlRvhux2gUp6jPg2iFlYhK1DQenixc4WkWmwWoy+9hSvaM80ONAlHyZsbHn4fh5jGz0tTo/ZbYW/oKsvCoRrgpRS4BesT8uu8ujUX4z2e2MixgcTr5AYM/k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784552650; c=relaxed/simple; bh=kbhpVqgA8XQwpv7tAEIMUYsgNHycQRFPbw4n+N+jIQU=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=cin7dch9GoE4es5EyMagCa6g9qWnG5G82zsD67Ce+YAO2AGMwP7DkkEhRbHBjqUwJa5g44deDzDqI/fsifvMF5GksX55iEmqI9YZIe28j0JJiPYn7q0hyO/ViTAXQnBHO/9j3CHrN6V3T9tf3XuCYj6w3U3cYwoE9nhDUdObRbU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=icIhPe5A; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="icIhPe5A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EA8E1F00A3A; Mon, 20 Jul 2026 13:04:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784552649; bh=2FGP1CyS6K5QeqDqPa6rLugNiCYh3YA4zj3d7jzrFL8=; h=Date:Cc:Subject:To:References:From:In-Reply-To; b=icIhPe5AkPuWx3bt5GITDWkcNCA7LoD0Bq4YlXBUT9CfLIf3T3Raqi+VP9W66hXRA UaBPc0HxsGVemYmkCJJEltqNVRRil6SeYqurZ1FLq1ZtzaHnZ0DRqtClPdMEmTAYf4 KzYMDzj4rfADkCz0r5R+gii+MVxpfLLeFX7haEK9dgk1cL3ecaovZPFszj6l9JE8c2 b2115tew9jW3P8OdNgNE31IIGI0MwAKr6+pWDu3EuOq6pDdnAZxrmSZILIO8+UHb2C J8C+gOi8uA67IorzzyZ3tpYmlu/KTuMTPw73loJxIZul3Y1PNSnf3nhZDpV/bLOBfS /Q6FGxiK2hYow== Message-ID: <9aa5a524-de44-4d07-b6df-70776dd7b0e5@kernel.org> Date: Mon, 20 Jul 2026 21:04:06 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, stable@kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to zero post-EOF data when extending file size To: Jaegeuk Kim References: <20260706072606.3709384-1-chao@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/16/26 02:05, Jaegeuk Kim wrote: > This causes sysmtem hang during xfstests. Fixed a potential deadlock issue during checkpoint in v2, though I can not reproduce it. Thanks, > > On 07/06, Chao Yu via Linux-f2fs-devel wrote: >> generic/794 4s ... - output mismatch (see /share/git/fstests/results//generic/794.out.bad) >> --- tests/generic/794.out 2026-06-12 08:46:32.766426241 +0800 >> +++ /share/git/fstests/results//generic/794.out.bad 2026-07-05 18:32:55.000000000 +0800 >> @@ -1,4 +1,16 @@ >> QA output created by 794 >> append_write >> +FAIL: non-zero data in gap [4080,4096) after shutdown+remount >> +000000 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >ZZZZZZZZZZZZZZZZ< >> +* >> +001000 >> truncate_up >> ... >> (Run 'diff -u /share/git/fstests/tests/generic/794.out /share/git/fstests/results//generic/794.out.bad' to see the entire diff) >> Ran: generic/794 >> Failures: generic/794 >> Failed 1 of 1 tests >> >> Steps of generic/794: >> 1. write 4096 bytes to file w/ 0x5a >> 2. use fiemap to get PBA of first block in file >> 3. truncate file to 4080 >> 4. umount; write 4096 bytes to file w/ 0x5a directly via PBA; mount >> 5. extend filesize via >> a) append 4096 from offset 4096, or >> b) truncate 8192, or >> c) fallocate 4096 from offset 4096 >> 6. verify the gap is zeroed in memory [4080,4096) >> 7. sync range 4096 from offset 4096; shutdown -f (flush meta before shutdown) >> 8. umount; mount; verify [4080,4096) is zeroed or not. >> >> When extending file size (e.g. via truncate, fallocate, or write) across an >> unaligned EOF boundary, we need to ensure that post-EOF data in the partial >> page is zeroed out in pagecache and marked dirty, meanwhile, tagging the inode >> with FI_ZERO_POST_EOF, so that following checkpoint() and fsync() can persist >> the page contain zeroed data before committing inode w/ updated i_size. >> >> This help to prevent stale disk data beyond the previous EOF from being exposed >> after remounting or crash recovery. >> >> Since f2fs is a LFS filesystem, we only support direct write via PBA in pinfile, >> and pinfile has section-aligned filesize, so in Android, there should no problem, >> but for other usage in different environment, let's fix this w/ fsync_mode=strict >> mount option. >> >> Cc: stable@kernel.org >> Signed-off-by: Chao Yu >> --- >> fs/f2fs/checkpoint.c | 4 ++++ >> fs/f2fs/f2fs.h | 1 + >> fs/f2fs/file.c | 35 ++++++++++++++++++++++++++++++++--- >> 3 files changed, 37 insertions(+), 3 deletions(-) >> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c >> index 064f5b537423..6f486d3a94c7 100644 >> --- a/fs/f2fs/checkpoint.c >> +++ b/fs/f2fs/checkpoint.c >> @@ -1359,6 +1359,10 @@ static int f2fs_sync_inode_meta(struct f2fs_sb_info *sbi) >> inode = igrab(&fi->vfs_inode); >> spin_unlock(&sbi->inode_lock[DIRTY_META]); >> if (inode) { >> + if (is_inode_flag_set(inode, FI_ZERO_POST_EOF)) { >> + filemap_write_and_wait(inode->i_mapping); >> + clear_inode_flag(inode, FI_ZERO_POST_EOF); >> + } >> sync_inode_metadata(inode, 0); >> >> /* it's on eviction */ >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >> index 8e2fb0bda467..41be09dad43c 100644 >> --- a/fs/f2fs/f2fs.h >> +++ b/fs/f2fs/f2fs.h >> @@ -939,6 +939,7 @@ enum { >> FI_ATOMIC_REPLACE, /* indicate atomic replace */ >> FI_OPENED_FILE, /* indicate file has been opened */ >> FI_DONATE_FINISHED, /* indicate page donation of file has been finished */ >> + FI_ZERO_POST_EOF, /* indicate unaligned EOF gap was zeroed in pagecache */ >> FI_MAX, /* max flag, never be used */ >> }; >> >> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >> index 11cc8d79c235..2e9d585073ec 100644 >> --- a/fs/f2fs/file.c >> +++ b/fs/f2fs/file.c >> @@ -36,21 +36,43 @@ >> #include >> #include >> >> +static int fill_zero(struct inode *inode, pgoff_t index, >> + loff_t start, loff_t len); >> + >> static void f2fs_zero_post_eof_page(struct inode *inode, >> loff_t new_size, bool lock) >> { >> loff_t old_size = i_size_read(inode); >> + unsigned int offset; >> >> if (old_size >= new_size) >> return; >> >> - if (mapping_empty(inode->i_mapping)) >> - return; >> - >> if (lock) >> filemap_invalidate_lock(inode->i_mapping); >> + >> /* zero or drop pages only in range of [old_size, new_size] */ >> truncate_inode_pages_range(inode->i_mapping, old_size, new_size); >> + >> + /* >> + * When expanding an unaligned EOF size, zero post-EOF data in >> + * pagecache and set FI_ZERO_POST_EOF, so following checkpointing >> + * or fsync can persist correct data to disk before committing >> + * inode w/ updated i_size. >> + */ >> + if (F2FS_OPTION(F2FS_I_SB(inode)).fsync_mode != FSYNC_MODE_STRICT) >> + goto out_unlock; >> + >> + offset = old_size & (PAGE_SIZE - 1); >> + if (offset) { >> + unsigned int len = min_t(loff_t, PAGE_SIZE - offset, >> + new_size - old_size); >> + pgoff_t index = old_size >> PAGE_SHIFT; >> + >> + fill_zero(inode, index, offset, len); >> + set_inode_flag(inode, FI_ZERO_POST_EOF); >> + } >> +out_unlock: >> if (lock) >> filemap_invalidate_unlock(inode->i_mapping); >> } >> @@ -304,6 +326,13 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end, >> if (S_ISDIR(inode->i_mode)) >> goto go_write; >> >> + if (is_inode_flag_set(inode, FI_ZERO_POST_EOF)) { >> + ret = filemap_write_and_wait(inode->i_mapping); >> + if (ret) >> + return ret; >> + clear_inode_flag(inode, FI_ZERO_POST_EOF); >> + } >> + >> /* if fdatasync is triggered, let's do in-place-update */ >> if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks) >> set_inode_flag(inode, FI_NEED_IPU); >> -- >> 2.49.0 >> >> >> >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel