6.15-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ Upstream commit da8cf4bd458722d090a788c6e581eeb72695c62f ]
When doing a DIO read, if the subrequests we issue fail and cause the request PAUSE flag to be set to put a pause on subrequest generation, we may complete collection of the subrequests (possibly discarding them) prior to the ALL_QUEUED flags being set.
In such a case, netfs_read_collection() doesn't see ALL_QUEUED being set after netfs_collect_read_results() returns and will just return to the app (the collector can be seen unpausing the generator in the trace log).
The subrequest generator can then set ALL_QUEUED and the app thread reaches netfs_wait_for_request(). This causes netfs_collect_in_app() to be called to see if we're done yet, but there's missing case here.
netfs_collect_in_app() will see that a thread is active and set inactive to false, but won't see any subrequests in the read stream, and so won't set need_collect to true. The function will then just return 0, indicating that the caller should just sleep until further activity (which won't be forthcoming) occurs.
Fix this by making netfs_collect_in_app() check to see if an active thread is complete - i.e. that ALL_QUEUED is set and the subrequests list is empty - and to skip the sleep return path. The collector will then be called which will clear the request IN_PROGRESS flag, allowing the app to progress.
Fixes: 2b1424cd131c ("netfs: Fix wait/wake to be consistent about the waitqueue used") Reported-by: Steve French sfrench@samba.org Signed-off-by: David Howells dhowells@redhat.com Link: https://lore.kernel.org/20250701163852.2171681-2-dhowells@redhat.com Tested-by: Steve French sfrench@samba.org Reviewed-by: Paulo Alcantara pc@manguebit.org cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/netfs/misc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c index 43b67a28a8fa0..0a54b12034868 100644 --- a/fs/netfs/misc.c +++ b/fs/netfs/misc.c @@ -381,7 +381,7 @@ void netfs_wait_for_in_progress_stream(struct netfs_io_request *rreq, static int netfs_collect_in_app(struct netfs_io_request *rreq, bool (*collector)(struct netfs_io_request *rreq)) { - bool need_collect = false, inactive = true; + bool need_collect = false, inactive = true, done = true;
for (int i = 0; i < NR_IO_STREAMS; i++) { struct netfs_io_subrequest *subreq; @@ -400,9 +400,11 @@ static int netfs_collect_in_app(struct netfs_io_request *rreq, need_collect = true; break; } + if (subreq || !test_bit(NETFS_RREQ_ALL_QUEUED, &rreq->flags)) + done = false; }
- if (!need_collect && !inactive) + if (!need_collect && !inactive && !done) return 0; /* Sleep */
__set_current_state(TASK_RUNNING);