From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 893C423ABA8; Tue, 15 Jul 2025 14:19:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752589194; cv=none; b=MlXMr3mG0jLFbiA8ITKnr7GI0pcZM5v6Vh/KPgQv9Th/gGqIVmW0Q/8MyZTWNQKHzO6rHd5h9A4mBpov337upnUjoeMo2VUwYaX81PiGnkyV00XDjlm8535BWrnGb4OucZykM1BbQ3SFhat3Evj2xl341Syi5uNCVI4/LOULFDg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752589194; c=relaxed/simple; bh=qZ+LC3FTqFJ27mtCLEBJ1uKtZR3TIsj7xDBbTuuliR0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=j+pOqwYotsWHYcHa/04+azBCCN4wLAXRf8SKchZd7b32nwUHRAEN5GYZIX6syB/Ba9C/kW3wFJxYqHkbf9TIauMiZG8ptW42TmzK/M49V8y9A/zcGeRAXpXQmabrsNX0jGkhjr20uGycTG49rDvcm+82mn5FOdiX2dXYGkk1P5c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tkXbgtRc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tkXbgtRc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F651C4CEE3; Tue, 15 Jul 2025 14:19:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752589194; bh=qZ+LC3FTqFJ27mtCLEBJ1uKtZR3TIsj7xDBbTuuliR0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tkXbgtRclBrdKKwGxvl2fyRNA7ZDXaoB+JpC8gJMJZ0co1wjgMD3t/uVkWC0Z1Lwg m+ituiGN8QClgVE6taDhix9JV2m8tLPwxtfhu0DC0tKszE3FMBnAeaHlAW/09f5f1P XFkBEcXhrDjsZJp1yzuZMmJOUynwZwxNXZ6fQFfzn5178LruEEQ5CKonDtpweRdVYy 4Ruu/VLP37alTWyoVwm5XdzPeTa0s1Zh6JNfeM3JX2/lUhXZifcvKlGdDdS6le+kGY +H/L3kvidQDgy+eAHZbWehwEP84xsXp4GVZ6PI3QVFgRzLPGi5BSnS0MpCrPKoumJA QDhs46ChF6lyg== Date: Tue, 15 Jul 2025 07:19:53 -0700 From: "Darrick J. Wong" To: Brian Foster Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, hch@infradead.org, willy@infradead.org Subject: Re: [PATCH v3 5/7] xfs: fill dirty folios on zero range of unwritten mappings Message-ID: <20250715141953.GM2672029@frogsfrogsfrogs> References: <20250714204122.349582-1-bfoster@redhat.com> <20250714204122.349582-6-bfoster@redhat.com> <20250715052811.GQ2672049@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-fsdevel@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: On Tue, Jul 15, 2025 at 08:35:51AM -0400, Brian Foster wrote: > On Mon, Jul 14, 2025 at 10:28:11PM -0700, Darrick J. Wong wrote: > > On Mon, Jul 14, 2025 at 04:41:20PM -0400, Brian Foster wrote: > > > Use the iomap folio batch mechanism to select folios to zero on zero > > > range of unwritten mappings. Trim the resulting mapping if the batch > > > is filled (unlikely for current use cases) to distinguish between a > > > range to skip and one that requires another iteration due to a full > > > batch. > > > > > > Signed-off-by: Brian Foster > > > Reviewed-by: Christoph Hellwig > > > --- > > > fs/xfs/xfs_iomap.c | 23 +++++++++++++++++++++++ > > > 1 file changed, 23 insertions(+) > > > > > > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > > > index b5cf5bc6308d..63054f7ead0e 100644 > > > --- a/fs/xfs/xfs_iomap.c > > > +++ b/fs/xfs/xfs_iomap.c > > > @@ -1691,6 +1691,8 @@ xfs_buffered_write_iomap_begin( > > > struct iomap *iomap, > > > struct iomap *srcmap) > > > { > > > + struct iomap_iter *iter = container_of(iomap, struct iomap_iter, > > > + iomap); > > > struct xfs_inode *ip = XFS_I(inode); > > > struct xfs_mount *mp = ip->i_mount; > > > xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset); > > > @@ -1762,6 +1764,7 @@ xfs_buffered_write_iomap_begin( > > > */ > > > if (flags & IOMAP_ZERO) { > > > xfs_fileoff_t eof_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)); > > > + u64 end; > > > > > > if (isnullstartblock(imap.br_startblock) && > > > offset_fsb >= eof_fsb) > > > @@ -1769,6 +1772,26 @@ xfs_buffered_write_iomap_begin( > > > if (offset_fsb < eof_fsb && end_fsb > eof_fsb) > > > end_fsb = eof_fsb; > > > > > > + /* > > > + * Look up dirty folios for unwritten mappings within EOF. > > > + * Providing this bypasses the flush iomap uses to trigger > > > + * extent conversion when unwritten mappings have dirty > > > + * pagecache in need of zeroing. > > > + * > > > + * Trim the mapping to the end pos of the lookup, which in turn > > > + * was trimmed to the end of the batch if it became full before > > > + * the end of the mapping. > > > + */ > > > + if (imap.br_state == XFS_EXT_UNWRITTEN && > > > + offset_fsb < eof_fsb) { > > > + loff_t len = min(count, > > > + XFS_FSB_TO_B(mp, imap.br_blockcount)); > > > + > > > + end = iomap_fill_dirty_folios(iter, offset, len); > > > + end_fsb = min_t(xfs_fileoff_t, end_fsb, > > > + XFS_B_TO_FSB(mp, end)); > > > > Hrmm. XFS_B_TO_FSB and not _FSBT? Can the rounding up behavior result > > in a missed byte range? I think the answer is no because @end should be > > aligned to a folio boundary, and folios can't be smaller than an > > fsblock. > > > > Hmm.. not that I'm aware of..? Please elaborate if there's a case you're > suspicious of because I could have certainly got my wires crossed. I don't have a specific case in mind. I saw the conversion function and thought "well, what IF the return value from iomap_fill_dirty_folios isn't aligned to a fsblock?" and then went around trying to prove that isn't possible. :) > My thinking is that end_fsb reflects the first fsb beyond the target > range. I.e., it's calculated and used as such in xfs_iomap_end_fsb() and > the various xfs_trim_extent() calls throughout the rest of the function. So I think we're fine here. --D > Brian > > > If the answer to the second question is indeed "no" then I think this is > > ok and > > Reviewed-by: "Darrick J. Wong" > > > > --D > > > > > > > + } > > > + > > > xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb); > > > } > > > > > > -- > > > 2.50.0 > > > > > > > > > >