diff options
| author | David Howells <dhowells@redhat.com> | 2025-03-14 16:41:56 +0000 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-03-19 10:04:22 +0100 |
| commit | f298e37655288272fad3766b82db0c3c03facbf9 (patch) | |
| tree | 35c8e2995882ff8d73d7db224286c5eee668d9cd | |
| parent | d9ecc77193cad25402ff5517fb26fb22b4db0e10 (diff) | |
netfs: Fix collection of results during pause when collection offloaded
A netfs read request can run in one of two modes: for synchronous reads
writes, the app thread does the collection of results and for asynchronous
reads, this is offloaded to a worker thread. This is controlled by the
NETFS_RREQ_OFFLOAD_COLLECTION flag.
Now, if a subrequest incurs an error, the NETFS_RREQ_PAUSE flag is set to
stop the issuing loop temporarily from issuing more subrequests until a
retry is successful or the request is abandoned.
When the issuing loop sees NETFS_RREQ_PAUSE, it jumps to
netfs_wait_for_pause() which will wait for the PAUSE flag to be cleared -
and whilst it is waiting, it will call out to the collector as more results
acrue... But this is the wrong thing to do if OFFLOAD_COLLECTION is set as
we can then end up with both the app thread and the work item collecting
results simultaneously.
This manifests itself occasionally when running the generic/323 xfstest
against multichannel cifs as an oops that's a bit random but frequently
involving io_submit() (the test does lots of simultaneous async DIO reads).
Fix this by only doing the collection in netfs_wait_for_pause() if the
NETFS_RREQ_OFFLOAD_COLLECTION is not set.
Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reported-by: Steve French <stfrench@microsoft.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20250314164201.1993231-2-dhowells@redhat.com
Acked-by: "Paulo Alcantara (Red Hat)" <pc@manguebit.com>
cc: Paulo Alcantara <pc@manguebit.com>
cc: Jeff Layton <jlayton@kernel.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>
| -rw-r--r-- | fs/netfs/read_collect.c | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c index 636cc5a98ef5..23c75755ad4e 100644 --- a/fs/netfs/read_collect.c +++ b/fs/netfs/read_collect.c @@ -682,14 +682,16 @@ void netfs_wait_for_pause(struct netfs_io_request *rreq) trace_netfs_rreq(rreq, netfs_rreq_trace_wait_queue); prepare_to_wait(&rreq->waitq, &myself, TASK_UNINTERRUPTIBLE); - subreq = list_first_entry_or_null(&stream->subrequests, - struct netfs_io_subrequest, rreq_link); - if (subreq && - (!test_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags) || - test_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags))) { - __set_current_state(TASK_RUNNING); - netfs_read_collection(rreq); - continue; + if (!test_bit(NETFS_RREQ_OFFLOAD_COLLECTION, &rreq->flags)) { + subreq = list_first_entry_or_null(&stream->subrequests, + struct netfs_io_subrequest, rreq_link); + if (subreq && + (!test_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags) || + test_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags))) { + __set_current_state(TASK_RUNNING); + netfs_read_collection(rreq); + continue; + } } if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags) || |