From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 533F3215F4A for ; Wed, 17 Sep 2025 13:08:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758114487; cv=none; b=jGLpKB8yTc3VrqIC3hDsZtYs9PnMZIu6PN17pmqnsvBVU0EkMlRVLuLT7/5Ba4f9RQwz2Y2kfe4rfYEgF7slE0lBzNzsPQpqL2vHYC0eqjCvKNAILvoew+GM8oPx8EU4/GOcgwuynEBVxGqBmHSlEWXrZebxhGxkp4nlzITSClQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758114487; c=relaxed/simple; bh=VC8i9EuI8elmGanm5n7un4HuN+k9TiFlpwIHh4VRuMg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=B+TPNCzp8NksS109SjhhsCHAO2Ajj/ZZ8gJr4veuAqgYRKqEWkIWgINl0PfoHPFnuEvZTlU1WglfvlytgNAztmBdiPql/JnG+eI9KUqDwWUt6eVOvu06cxeYKA5VKOjMFbXsmjEh9oxDtqRn6xaPwYGvKsYePIYiZGUhWQ5OvYI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=duQiKlgi; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="duQiKlgi" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758114484; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9C2dGW9H76hURaUowowv+DpUt4X7AUUikHVR9izs+Tw=; b=duQiKlgicM8CbNZTL64aVfpVaYABzfkkaTh/BQiQW5g/HS2TONvS/FT4vFWXFkcyrfQQH3 ERXUHeJVRNiASvRq+ytAxkzOskAtXm4ytqSwlzx/ZSZSy+KHUPsqVg5h5xsJ6BJflo034v Xmth+Cb01Kh5pzWIHDepgqOSAERR8ro= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-467-RuRJd-1MPwad3PJ5fmq2yA-1; Wed, 17 Sep 2025 09:07:58 -0400 X-MC-Unique: RuRJd-1MPwad3PJ5fmq2yA-1 X-Mimecast-MFC-AGG-ID: RuRJd-1MPwad3PJ5fmq2yA_1758114477 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 77C7D180035C; Wed, 17 Sep 2025 13:07:57 +0000 (UTC) Received: from bfoster (unknown [10.22.64.134]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C9FE918003FC; Wed, 17 Sep 2025 13:07:55 +0000 (UTC) Date: Wed, 17 Sep 2025 09:12:00 -0400 From: Brian Foster To: Joanne Koong Cc: brauner@kernel.org, hch@infradead.org, djwong@kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v1] iomap: simplify iomap_iter_advance() Message-ID: References: <20250917004001.2602922-1-joannelkoong@gmail.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: <20250917004001.2602922-1-joannelkoong@gmail.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On Tue, Sep 16, 2025 at 05:40:01PM -0700, Joanne Koong wrote: > Most callers of iomap_iter_advance() do not need the remaining length > returned. Get rid of the extra iomap_length() call that > iomap_iter_advance() does. If the caller wants the remaining length, > they can make the call to iomap_length(). > > Signed-off-by: Joanne Koong > --- Indeed this does clean up some of the calls that create a local var purely to work around the interface. OTOH, the reason I made the advance update the length was so it was clear the remaining length would be used correctly in those looping callers. Otherwise I'm not sure it's clear the bytes/length value needs to be updated and that felt like an easy mistake to make to me. I don't really have a strong preference so I'll defer to whatever the majority opinion is. I wonder though if something else worth considering is to rename the current helper to __iomap_iter_advance() (or whatever) and make your updated variant of iomap_iter_advance() into a wrapper of it. Brian > fs/dax.c | 28 ++++++++++++---------------- > fs/iomap/buffered-io.c | 16 +++++++++------- > fs/iomap/direct-io.c | 6 +++--- > fs/iomap/iter.c | 14 +++++--------- > fs/iomap/seek.c | 8 ++++---- > include/linux/iomap.h | 6 ++---- > 6 files changed, 35 insertions(+), 43 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 20ecf652c129..29e7a150b6f9 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1534,7 +1534,7 @@ static int dax_zero_iter(struct iomap_iter *iter, bool *did_zero) > > /* already zeroed? we're done. */ > if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > > /* > * invalidate the pages whose sharing state is to be changed > @@ -1563,9 +1563,10 @@ static int dax_zero_iter(struct iomap_iter *iter, bool *did_zero) > if (ret < 0) > return ret; > > - ret = iomap_iter_advance(iter, &length); > + ret = iomap_iter_advance(iter, length); > if (ret) > return ret; > + length = iomap_length(iter); > } while (length > 0); > > if (did_zero) > @@ -1624,7 +1625,7 @@ static int dax_iomap_iter(struct iomap_iter *iomi, struct iov_iter *iter) > > if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) { > done = iov_iter_zero(min(length, end - pos), iter); > - return iomap_iter_advance(iomi, &done); > + return iomap_iter_advance(iomi, done); > } > } > > @@ -1709,11 +1710,12 @@ static int dax_iomap_iter(struct iomap_iter *iomi, struct iov_iter *iter) > map_len, iter); > > length = xfer; > - ret = iomap_iter_advance(iomi, &length); > + ret = iomap_iter_advance(iomi, length); > if (!ret && xfer == 0) > ret = -EFAULT; > if (xfer < map_len) > break; > + length = iomap_length(iomi); > } > dax_read_unlock(id); > > @@ -1946,10 +1948,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, unsigned long *pfnp, > ret |= VM_FAULT_MAJOR; > } > > - if (!(ret & VM_FAULT_ERROR)) { > - u64 length = PAGE_SIZE; > - iter.status = iomap_iter_advance(&iter, &length); > - } > + if (!(ret & VM_FAULT_ERROR)) > + iter.status = iomap_iter_advance(&iter, PAGE_SIZE); > } > > if (iomap_errp) > @@ -2061,10 +2061,8 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, unsigned long *pfnp, > continue; /* actually breaks out of the loop */ > > ret = dax_fault_iter(vmf, &iter, pfnp, &xas, &entry, true); > - if (ret != VM_FAULT_FALLBACK) { > - u64 length = PMD_SIZE; > - iter.status = iomap_iter_advance(&iter, &length); > - } > + if (ret != VM_FAULT_FALLBACK) > + iter.status = iomap_iter_advance(&iter, PMD_SIZE); > } > > unlock_entry: > @@ -2190,7 +2188,6 @@ static int dax_range_compare_iter(struct iomap_iter *it_src, > const struct iomap *smap = &it_src->iomap; > const struct iomap *dmap = &it_dest->iomap; > loff_t pos1 = it_src->pos, pos2 = it_dest->pos; > - u64 dest_len; > void *saddr, *daddr; > int id, ret; > > @@ -2223,10 +2220,9 @@ static int dax_range_compare_iter(struct iomap_iter *it_src, > dax_read_unlock(id); > > advance: > - dest_len = len; > - ret = iomap_iter_advance(it_src, &len); > + ret = iomap_iter_advance(it_src, len); > if (!ret) > - ret = iomap_iter_advance(it_dest, &dest_len); > + ret = iomap_iter_advance(it_dest, len); > return ret; > > out_unlock: > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index fd827398afd2..fe6588ab0922 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -373,7 +373,7 @@ static int iomap_readpage_iter(struct iomap_iter *iter, > ret = iomap_read_inline_data(iter, folio); > if (ret) > return ret; > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > } > > /* zero post-eof blocks as the page may be mapped */ > @@ -434,7 +434,7 @@ static int iomap_readpage_iter(struct iomap_iter *iter, > * iteration. > */ > length = pos - iter->pos + plen; > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > } > > static int iomap_read_folio_iter(struct iomap_iter *iter, > @@ -1036,7 +1036,7 @@ static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i, > } > } else { > total_written += written; > - iomap_iter_advance(iter, &written); > + iomap_iter_advance(iter, written); > } > } while (iov_iter_count(i) && iomap_length(iter)); > > @@ -1305,7 +1305,7 @@ static int iomap_unshare_iter(struct iomap_iter *iter, > int status; > > if (!iomap_want_unshare_iter(iter)) > - return iomap_iter_advance(iter, &bytes); > + return iomap_iter_advance(iter, bytes); > > do { > struct folio *folio; > @@ -1329,9 +1329,10 @@ static int iomap_unshare_iter(struct iomap_iter *iter, > > balance_dirty_pages_ratelimited(iter->inode->i_mapping); > > - status = iomap_iter_advance(iter, &bytes); > + status = iomap_iter_advance(iter, bytes); > if (status) > break; > + bytes = iomap_length(iter); > } while (bytes > 0); > > return status; > @@ -1404,9 +1405,10 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero, > if (WARN_ON_ONCE(!ret)) > return -EIO; > > - status = iomap_iter_advance(iter, &bytes); > + status = iomap_iter_advance(iter, bytes); > if (status) > break; > + bytes = iomap_length(iter); > } while (bytes > 0); > > if (did_zero) > @@ -1518,7 +1520,7 @@ static int iomap_folio_mkwrite_iter(struct iomap_iter *iter, > folio_mark_dirty(folio); > } > > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > } > > vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops, > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index b84f6af2eb4c..e3544a6719a7 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -496,7 +496,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) > /* Undo iter limitation to current extent */ > iov_iter_reexpand(dio->submit.iter, orig_count - copied); > if (copied) > - return iomap_iter_advance(iter, &copied); > + return iomap_iter_advance(iter, copied); > return ret; > } > > @@ -507,7 +507,7 @@ static int iomap_dio_hole_iter(struct iomap_iter *iter, struct iomap_dio *dio) > dio->size += length; > if (!length) > return -EFAULT; > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > } > > static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio) > @@ -539,7 +539,7 @@ static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio) > dio->size += copied; > if (!copied) > return -EFAULT; > - return iomap_iter_advance(iomi, &copied); > + return iomap_iter_advance(iomi, copied); > } > > static int iomap_dio_iter(struct iomap_iter *iter, struct iomap_dio *dio) > diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c > index cef77ca0c20b..91d2024e00da 100644 > --- a/fs/iomap/iter.c > +++ b/fs/iomap/iter.c > @@ -13,17 +13,13 @@ static inline void iomap_iter_reset_iomap(struct iomap_iter *iter) > memset(&iter->srcmap, 0, sizeof(iter->srcmap)); > } > > -/* > - * Advance the current iterator position and output the length remaining for the > - * current mapping. > - */ > -int iomap_iter_advance(struct iomap_iter *iter, u64 *count) > +/* Advance the current iterator position and decrement the remaining length */ > +int iomap_iter_advance(struct iomap_iter *iter, u64 count) > { > - if (WARN_ON_ONCE(*count > iomap_length(iter))) > + if (WARN_ON_ONCE(count > iomap_length(iter))) > return -EIO; > - iter->pos += *count; > - iter->len -= *count; > - *count = iomap_length(iter); > + iter->pos += count; > + iter->len -= count; > return 0; > } > > diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c > index 56db2dd4b10d..6cbc587c93da 100644 > --- a/fs/iomap/seek.c > +++ b/fs/iomap/seek.c > @@ -16,13 +16,13 @@ static int iomap_seek_hole_iter(struct iomap_iter *iter, > *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping, > iter->pos, iter->pos + length, SEEK_HOLE); > if (*hole_pos == iter->pos + length) > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > return 0; > case IOMAP_HOLE: > *hole_pos = iter->pos; > return 0; > default: > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > } > } > > @@ -59,12 +59,12 @@ static int iomap_seek_data_iter(struct iomap_iter *iter, > > switch (iter->iomap.type) { > case IOMAP_HOLE: > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > case IOMAP_UNWRITTEN: > *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping, > iter->pos, iter->pos + length, SEEK_DATA); > if (*hole_pos < 0) > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, length); > return 0; > default: > *hole_pos = iter->pos; > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 73dceabc21c8..4469b2318b08 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -245,7 +245,7 @@ struct iomap_iter { > }; > > int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops); > -int iomap_iter_advance(struct iomap_iter *iter, u64 *count); > +int iomap_iter_advance(struct iomap_iter *iter, u64 count); > > /** > * iomap_length_trim - trimmed length of the current iomap iteration > @@ -282,9 +282,7 @@ static inline u64 iomap_length(const struct iomap_iter *iter) > */ > static inline int iomap_iter_advance_full(struct iomap_iter *iter) > { > - u64 length = iomap_length(iter); > - > - return iomap_iter_advance(iter, &length); > + return iomap_iter_advance(iter, iomap_length(iter)); > } > > /** > -- > 2.47.3 >