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 CBE03213E71; Tue, 4 Feb 2025 19:30:57 +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=1738697457; cv=none; b=N7UOHGeIj7XDPQ/KwpLeutNnVEI/dOgdqhIi5mokHkNN9Mq+IULA+mAf+6AXr7YOUeutPZP/emWUv+hqyZDB4pi1T1kso+qVghsEMub2LCPJ3jVfeYQNKMED9FXRkY0uq1j6DeuYw+WhEPhw12QT8jB+ZbYVOPaVuGzTw+jrW/U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738697457; c=relaxed/simple; bh=wK/ICJs34ylxLkSuB4ky/HA7vGnRT0untt070y2Lh9Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=idUkAxuak4CB0Pd3Lz08QlzsQKdRuleJm8cmLwnCsbET4evPJNx5MNFl4tXUj9L5iKHF0D//V1GxcGJYO/G9CEHG29kE7DHvJYcFhZevIN8QltI9UGYHtYFbVGmET+uXznGp7G8R31u/ab0DU9E6FtjxDYgKRmT7/GX/ajqDUDY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BKoWgeEP; 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="BKoWgeEP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36325C4CEE3; Tue, 4 Feb 2025 19:30:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738697457; bh=wK/ICJs34ylxLkSuB4ky/HA7vGnRT0untt070y2Lh9Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BKoWgeEPlXw+CYh6iWv0K48F5D25b+mymjMrbmYZLG2Bw1NOQacYznHbdNFb3HdKt /HQ24A3WJUZmDIwdsCUeP/taFmWC97qtqF3qZr8S/kyhM1TmP+1q5yqskAa3MbsUra FqfNwlNsNxtFzMHPTFe+tanItG05kyQGiqX7vyFaS9ErI9WURxlQfY9x8i2fxvBTEY eHeGMN4oocK4XdDTx26+4kVmMW9l5itDeAg2gMDbQyZLSbJR3MdFC6RSdZJjPM23gA Bg2b5tdjOgmtmz+wPdUINijqrGIv2yD+r18z5LA0a/7rMpH1c17DclBnQiCze/oGjX LHVlpEizxYN+w== Date: Tue, 4 Feb 2025 11:30:56 -0800 From: "Darrick J. Wong" To: Brian Foster Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH v4 02/10] iomap: split out iomap check and reset logic from iter advance Message-ID: <20250204193056.GD21808@frogsfrogsfrogs> References: <20250204133044.80551-1-bfoster@redhat.com> <20250204133044.80551-3-bfoster@redhat.com> 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: <20250204133044.80551-3-bfoster@redhat.com> On Tue, Feb 04, 2025 at 08:30:36AM -0500, Brian Foster wrote: > In preparation for more granular iomap_iter advancing, break out > some of the logic associated with higher level iteration from > iomap_advance_iter(). Specifically, factor the iomap reset code into > a separate helper and lift the iomap.length check into the calling > code, similar to how ->iomap_end() calls are handled. > > Signed-off-by: Brian Foster > Reviewed-by: Christoph Hellwig > --- > fs/iomap/iter.c | 49 ++++++++++++++++++++++++++----------------------- > 1 file changed, 26 insertions(+), 23 deletions(-) > > diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c > index 3790918646af..731ea7267f27 100644 > --- a/fs/iomap/iter.c > +++ b/fs/iomap/iter.c > @@ -7,6 +7,13 @@ > #include > #include "trace.h" > > +static inline void iomap_iter_reset_iomap(struct iomap_iter *iter) > +{ > + iter->processed = 0; > + memset(&iter->iomap, 0, sizeof(iter->iomap)); > + memset(&iter->srcmap, 0, sizeof(iter->srcmap)); > +} > + > /* > * Advance to the next range we need to map. > * > @@ -14,32 +21,24 @@ > * processed - it was aborted because the extent the iomap spanned may have been > * changed during the operation. In this case, the iteration behaviour is to > * remap the unprocessed range of the iter, and that means we may need to remap > - * even when we've made no progress (i.e. iter->processed = 0). Hence the > - * "finished iterating" case needs to distinguish between > - * (processed = 0) meaning we are done and (processed = 0 && stale) meaning we > - * need to remap the entire remaining range. > + * even when we've made no progress (i.e. count = 0). Hence the "finished > + * iterating" case needs to distinguish between (count = 0) meaning we are done > + * and (count = 0 && stale) meaning we need to remap the entire remaining range. > */ > -static inline int iomap_iter_advance(struct iomap_iter *iter) > +static inline int iomap_iter_advance(struct iomap_iter *iter, s64 count) > { > bool stale = iter->iomap.flags & IOMAP_F_STALE; > int ret = 1; > > - /* handle the previous iteration (if any) */ > - if (iter->iomap.length) { > - if (iter->processed < 0) > - return iter->processed; > - if (WARN_ON_ONCE(iter->processed > iomap_length(iter))) > - return -EIO; > - iter->pos += iter->processed; > - iter->len -= iter->processed; > - if (!iter->len || (!iter->processed && !stale)) > - ret = 0; > - } > + if (count < 0) > + return count; > + if (WARN_ON_ONCE(count > iomap_length(iter))) > + return -EIO; > + iter->pos += count; > + iter->len -= count; > + if (!iter->len || (!count && !stale)) > + ret = 0; > > - /* clear the per iteration state */ > - iter->processed = 0; > - memset(&iter->iomap, 0, sizeof(iter->iomap)); > - memset(&iter->srcmap, 0, sizeof(iter->srcmap)); Are there any consequences to not resetting the iter if iter->iomap.length is zero? I think the answer is "no" because callers are supposed to initialize the iter with zeroes and filesystems are never supposed to return zero-length iomaps from ->begin_iomap, right? If the answers are "no" and "yes" then Reviewed-by: "Darrick J. Wong" --D > return ret; > } > > @@ -82,10 +81,14 @@ int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops) > return ret; > } > > + /* advance and clear state from the previous iteration */ > trace_iomap_iter(iter, ops, _RET_IP_); > - ret = iomap_iter_advance(iter); > - if (ret <= 0) > - return ret; > + if (iter->iomap.length) { > + ret = iomap_iter_advance(iter, iter->processed); > + iomap_iter_reset_iomap(iter); > + if (ret <= 0) > + return ret; > + } > > ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags, > &iter->iomap, &iter->srcmap); > -- > 2.48.1 > >