6.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: David Howells <dhowells@xxxxxxxxxx>
[ 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@xxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Link: https://lore.kernel.org/20250701163852.2171681-2-dhowells@xxxxxxxxxx
Tested-by: Steve French <sfrench@xxxxxxxxx>
Reviewed-by: Paulo Alcantara <pc@xxxxxxxxxxxxx>
cc: linux-cifs@xxxxxxxxxxxxxxx
cc: netfs@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.39.5
