From: David Howells Date: Thu, 2 Jul 2026 08:23:02 +0000 (+0100) Subject: netfs: Fix barriering when walking subrequest list X-Git-Tag: v7.2-rc2~14^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5c6ce05e406520290c1d89da97fb3cd70c09137d;p=thirdparty%2Fkernel%2Flinux.git netfs: Fix barriering when walking subrequest list Fix the barriering used when walking the subrequest list in retry as there's a possibility of seeing a subreq that's just been added by the application thread. Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Link: https://sashiko.dev/#/patchset/20260608145432.681865-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/138807.1782980582@warthog.procyon.org.uk Reviewed-by: Paulo Alcantara (Red Hat) cc: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c index f59a70f3a086..2b42758e01ec 100644 --- a/fs/netfs/read_retry.c +++ b/fs/netfs/read_retry.c @@ -98,7 +98,12 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq) goto abandon; } - list_for_each_continue(next, &stream->subrequests) { + for (;;) { + /* Read pointer to subreq before reading subreq state. */ + next = smp_load_acquire(&next->next); + if (next == &stream->subrequests) + break; + subreq = list_entry(next, struct netfs_io_subrequest, rreq_link); if (subreq->start + subreq->transferred != start + len || test_bit(NETFS_SREQ_BOUNDARY, &subreq->flags) || diff --git a/fs/netfs/write_retry.c b/fs/netfs/write_retry.c index 32735abfa03f..058bc7a166a5 100644 --- a/fs/netfs/write_retry.c +++ b/fs/netfs/write_retry.c @@ -72,7 +72,12 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq, !test_bit(NETFS_SREQ_NEED_RETRY, &from->flags)) return; - list_for_each_continue(next, &stream->subrequests) { + for (;;) { + /* Read pointer to subreq before reading subreq state. */ + next = smp_load_acquire(&next->next); + if (next == &stream->subrequests) + break; + subreq = list_entry(next, struct netfs_io_subrequest, rreq_link); if (subreq->start + subreq->transferred != start + len || test_bit(NETFS_SREQ_BOUNDARY, &subreq->flags) ||