From: David Howells <dhowells@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>, asmadeus@codewreck.org
Cc: dhowells@redhat.com, mm-commits@vger.kernel.org,
viro@zeniv.linux.org.uk, stable@vger.kernel.org, ryan@lahfa.xyz,
maximilian@mbosch.me, ct@flyingcircus.io, brauner@kernel.org,
arnout@bzzt.net
Subject: Re: + iov_iter-iterate_folioq-fix-handling-of-offset-=-folio-size.patch added to mm-hotfixes-unstable branch
Date: Tue, 12 Aug 2025 10:38:07 +0100 [thread overview]
Message-ID: <650364.1754991487@warthog.procyon.org.uk> (raw)
In-Reply-To: <20250812010237.B52F8C4CEED@smtp.kernel.org>
Thinking about it again, I think this:
> @@ -168,6 +168,8 @@ size_t iterate_folioq(struct iov_iter *i
> break;
>
> fsize = folioq_folio_size(folioq, slot);
> + if (skip >= fsize)
> + goto next;
> base = kmap_local_folio(folio, skip);
> part = umin(len, PAGE_SIZE - skip % PAGE_SIZE);
> remain = step(base, progress, part, priv, priv2);
> @@ -177,6 +179,7 @@ size_t iterate_folioq(struct iov_iter *i
> progress += consumed;
> skip += consumed;
> if (skip >= fsize) {
> +next:
> skip = 0;
> slot++;
> if (slot == folioq_nr_slots(folioq) && folioq->next) {
Would be much better done as:
> @@ -168,6 +168,8 @@ size_t iterate_folioq(struct iov_iter *i
> break;
>
> fsize = folioq_folio_size(folioq, slot);
> + if (skip < fsize) {
> base = kmap_local_folio(folio, skip);
> part = umin(len, PAGE_SIZE - skip % PAGE_SIZE);
> remain = step(base, progress, part, priv, priv2);
> @@ -177,6 +179,7 @@ size_t iterate_folioq(struct iov_iter *i
> progress += consumed;
> skip += consumed;
> + }
> if (skip >= fsize) {
> skip = 0;
> slot++;
> if (slot == folioq_nr_slots(folioq) && folioq->next) {
With the stuff inside the braces suitably indented. The compiler should be
able to optimise away the extra comparison.
David
next prev parent reply other threads:[~2025-08-12 9:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-12 1:02 + iov_iter-iterate_folioq-fix-handling-of-offset-=-folio-size.patch added to mm-hotfixes-unstable branch Andrew Morton
2025-08-12 9:38 ` David Howells [this message]
2025-08-12 21:20 ` Dominique Martinet
2025-08-12 21:38 ` David Howells
2025-08-13 6:00 ` Dominique Martinet
-- strict thread matches above, loose matches on Subject: below --
2025-08-13 23:15 Andrew Morton
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