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 3CC2D3502A6 for ; Wed, 29 Jul 2026 03:41:54 +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=1785296516; cv=none; b=WcL9XFFEZhDxf/R0AuUNvyAFbdQSqSsJqMxnOcNL0+/vqgtlI0Q7MaCkVvNLv+Yr/yV05pDBECpmEg2MohGdRi/0658+IIaepZYWb4x/qHYkeYAlHWHxHnxvPGEcqrbd9UMSSbhpxRKWhrbnOr3YzXxFbuDuEoLnHIUS0TYv+d4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785296516; c=relaxed/simple; bh=IpBLdpdBKyC37J8GeFrOTm6XVMOEYPYmKY8wcOkrdNI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ihE3y8T+RN/JB5+WAO436b0Ck9EFE4n3SNlLJk5Sj6/KqtCW2nECZYv1Rv3jMTU7RTj1SU+t8l9tVJptF7Rq/MuRySl4PpHjm6lgVI1rs1QKsF8dxUZ5kARg/zteVnqTL9aX/knCo+zab3osAL+ai8m1cDEAiczJqpZaQtolXUM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SFVR1AG4; 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="SFVR1AG4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A4141F00A3D; Wed, 29 Jul 2026 03:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785296514; bh=eHgFkfWejT9do5fnb5Hr+6Q3B6RHUXfwb+ipYzt9I0g=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=SFVR1AG4945SdDvP837m6LiiONVurVoyEN0hS6y0bBO78tR/gOvj7ZxMQZOj7Wpb5 2+idyjd1VN6YKfNZST/gvPmiQcvXT1dTO4oJAcQ4Oduocvl0BrRNQdj1xqbYJkJiaI G7oQuQ2zA7k/IxUoaCQFqQ5xUvt/tG4t7ehUaf+oTfCb8+ue56BRHAmDtV0mWK4+gF p/yBtF1n6Wc0Yz2/S+xen7KjzTOd5zNrxY18uqesND1X1IoS1lxHAZUfEDoDYF6qmU ruGq71PhRXA9ZtBCK0uINP7bn4Q9UkSTvXCt4aTBTEyBIi1bO7J9LTQR5uAgjSgIkW rRE9ozuPR0gGw== Date: Wed, 29 Jul 2026 03:41:53 +0000 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, stable@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to zero post-EOF data when extending file size Message-ID: References: <20260706072606.3709384-1-chao@kernel.org> <9aa5a524-de44-4d07-b6df-70776dd7b0e5@kernel.org> 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=us-ascii Content-Disposition: inline In-Reply-To: <9aa5a524-de44-4d07-b6df-70776dd7b0e5@kernel.org> On 07/20, Chao Yu via Linux-f2fs-devel wrote: > 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. I got this on generic/269 with v2. I'll dequeue the patch first. [ 90.879237] ------------[ cut here ]------------ [ 90.881987] kernel BUG at segment.c:2902! [ 90.884058] Oops: invalid opcode: 0000 [#1] SMP NOPTI [ 90.886628] CPU: 7 UID: 0 PID: 2566 Comm: f2fs_ckpt-252:3 Tainted: G OE 7.2.0-rc5-custom #1 PREEMPT(full) [ 90.891533] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE [ 90.894647] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 [ 90.900014] RIP: 0010:new_curseg+0xa17/0xa60 [f2fs] [ 90.902240] Code: 8b 71 48 e9 16 f8 ff ff 4c 8b 69 08 41 8b 84 24 4c 06 00 00 31 d2 41 8b 8c 24 48 06 00 00 f7 f1 89 45 a4 89 f0 e9 e9 fe ff ff <0f> 0b 49 8b 3c 24 68 40 0c 00 00 45 31 c0 31 c9 41 b9 8b ff ff ff [ 90.910818] RSP: 0018:ffffd4acc4167670 EFLAGS: 00010293 [ 90.913153] RAX: 00000000000000f8 RBX: 0000000000000000 RCX: 0000000000000000 [ 90.916400] RDX: ffffffffffffffff RSI: 00000000000000f8 RDI: 00000000000000f8 [ 90.919494] RBP: ffffd4acc41676d0 R08: ffff8d640bdab2a0 R09: ffffffffc10673eb [ 90.923182] R10: 00000000000000f8 R11: 0000000000000014 R12: ffff8d64892c6000 [ 90.926315] R13: ffff8d648c236b80 R14: 00000000000000f8 R15: 0000000000000000 [ 90.929430] FS: 0000000000000000(0000) GS:ffff8d6504b73000(0000) knlGS:0000000000000000 [ 90.933668] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 90.937206] CR2: 00005577fade9868 CR3: 0000000092d82002 CR4: 0000000000372ef0 [ 90.940305] Call Trace: [ 90.941486] [ 90.942464] f2fs_allocate_data_block+0x69b/0xb10 [f2fs] [ 90.944862] do_write_page+0x72/0x360 [f2fs] [ 90.946798] ? __folio_start_writeback+0x90/0x1d0 [ 90.949485] f2fs_do_write_node_page+0x35/0x70 [f2fs] [ 90.952813] __write_node_folio+0x33c/0x640 [f2fs] [ 90.955104] ? debug_smp_processor_id+0x17/0x20 [ 90.957550] f2fs_sync_node_pages+0x3d8/0x530 [f2fs] [ 90.960954] block_operations+0x41d/0x590 [f2fs] [ 90.963415] ? __pfx_issue_checkpoint_thread+0x10/0x10 [f2fs] [ 90.966293] f2fs_write_checkpoint+0x15a/0x13c0 [f2fs] [ 90.969193] ? update_load_avg+0x79/0x2e0 [ 90.971712] ? kvm_clock_get_cycles+0x18/0x40 [ 90.974030] ? module_sect_read+0x81/0xc0 [ 90.976675] ? __pfx_issue_checkpoint_thread+0x10/0x10 [f2fs] [ 90.980146] __write_checkpoint_sync+0x75/0xb0 [f2fs] [ 90.983100] __checkpoint_and_complete_reqs+0x3b/0x110 [f2fs] [ 90.986332] ? __pfx_issue_checkpoint_thread+0x10/0x10 [f2fs] [ 90.989853] issue_checkpoint_thread+0x4b/0x100 [f2fs] [ 90.992622] ? __pfx_autoremove_wake_function+0x10/0x10 [ 90.995875] kthread+0x10a/0x140 [ 90.998141] ? __pfx_kthread+0x10/0x10 [ 91.000585] ret_from_fork+0x1ef/0x2b0 [ 91.002565] ? __pfx_kthread+0x10/0x10 [ 91.004510] ret_from_fork_asm+0x1a/0x30 > > 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 > > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel