Unverified Commit 09623e3a authored by David Howells's avatar David Howells Committed by Christian Brauner
Browse files

netfs: Fix looping in wait functions 



netfs_wait_for_request() and netfs_wait_for_pause() can loop forever if
netfs_collect_in_app() returns 2, indicating that it wants to repeat
because the ALL_QUEUED flag isn't yet set and there are no subreqs left
that haven't been collected.

The problem is that, unless collection is offloaded (OFFLOAD_COLLECTION),
we have to return to the application thread to continue and eventually set
ALL_QUEUED after pausing to deal with a retry - but we never get there.

Fix this by inserting checks for the IN_PROGRESS and PAUSE flags as
appropriate before cycling round - and add cond_resched() for good measure.

Fixes: 2b1424cd ("netfs: Fix wait/wake to be consistent about the waitqueue used")
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250701163852.2171681-5-dhowells@redhat.com


Tested-by: default avatarSteve French <sfrench@samba.org>
Reviewed-by: default avatarPaulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 1a6d45fe

fs/netfs/misc.c

+11 −4
Original line number Diff line number Diff line
@@ -430,7 +430,7 @@ static int netfs_collect_in_app(struct netfs_io_request *rreq, 
/*

 * Wait for a request to complete, successfully or otherwise.

 */

static ssize_t netfs_wait_for_request(struct netfs_io_request *rreq,

static ssize_t netfs_wait_for_in_progress(struct netfs_io_request *rreq,

					  bool (*collector)(struct netfs_io_request *rreq))

{

	DEFINE_WAIT(myself);
@@ -447,6 +447,9 @@ static ssize_t netfs_wait_for_request(struct netfs_io_request *rreq, 
			case 1:

				goto all_collected;

			case 2:

				if (!netfs_check_rreq_in_progress(rreq))

					break;

				cond_resched();

				continue;

			}

		}
@@ -485,12 +488,12 @@ static ssize_t netfs_wait_for_request(struct netfs_io_request *rreq, 


ssize_t netfs_wait_for_read(struct netfs_io_request *rreq)

{

	return netfs_wait_for_request(rreq, netfs_read_collection);

	return netfs_wait_for_in_progress(rreq, netfs_read_collection);

}



ssize_t netfs_wait_for_write(struct netfs_io_request *rreq)

{

	return netfs_wait_for_request(rreq, netfs_write_collection);

	return netfs_wait_for_in_progress(rreq, netfs_write_collection);

}



/*
@@ -514,6 +517,10 @@ static void netfs_wait_for_pause(struct netfs_io_request *rreq, 
			case 1:

				goto all_collected;

			case 2:

				if (!netfs_check_rreq_in_progress(rreq) ||

				    !test_bit(NETFS_RREQ_PAUSE, &rreq->flags))

					break;

				cond_resched();

				continue;

			}

		}