Unverified Commit 7e575234 authored by David Howells's avatar David Howells Committed by Christian Brauner
Browse files

netfs: Fix read abandonment during retry 



Under certain circumstances, all the remaining subrequests from a read
request will get abandoned during retry.  The abandonment process expects
the 'subreq' variable to be set to the place to start abandonment from, but
it doesn't always have a useful value (it will be uninitialised on the
first pass through the loop and it may point to a deleted subrequest on
later passes).

Fix the first jump to "abandon:" to set subreq to the start of the first
subrequest expected to need retry (which, in this abandonment case, turned
out unexpectedly to no longer have NEED_RETRY set).

Also clear the subreq pointer after discarding superfluous retryable
subrequests to cause an oops if we do try to access it.

Fixes: ee4cdf7b ("netfs: Speed up buffered reading")
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/3775287.1773848338@warthog.procyon.org.uk


Reviewed-by: default avatarPaulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo 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 8fb6857f

fs/netfs/read_retry.c

+4 −1
Original line number Diff line number Diff line
@@ -93,8 +93,10 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq) 
		       from->start, from->transferred, from->len);



		if (test_bit(NETFS_SREQ_FAILED, &from->flags) ||

		    !test_bit(NETFS_SREQ_NEED_RETRY, &from->flags))

		    !test_bit(NETFS_SREQ_NEED_RETRY, &from->flags)) {

			subreq = from;

			goto abandon;

		}



		list_for_each_continue(next, &stream->subrequests) {

			subreq = list_entry(next, struct netfs_io_subrequest, rreq_link);
@@ -178,6 +180,7 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq) 
				if (subreq == to)

					break;

			}

			subreq = NULL;

			continue;

		}