Commit 345e1ae0 authored Aug 27, 2021 by David Howells

afs: Fix missing put on afs_read objects and missing get on the key therein



The afs_read objects created by afs_req_issue_op() get leaked because
afs_alloc_read() returns a ref and then afs_fetch_data() gets its own ref
which is released when the operation completes, but the initial ref is
never released.

Fix this by discarding the initial ref at the end of afs_req_issue_op().

This leak also covered another bug whereby a ref isn't got on the key
attached to the read record by afs_req_issue_op().  This isn't a problem as
long as the afs_read req never goes away...

Fix this by calling key_get() in afs_req_issue_op().

This was found by the generic/074 test.  It leaks a bunch of kmalloc-192
objects each time it is run, which can be observed by watching
/proc/slabinfo.

Fixes: f7605fa869cf ("afs: Fix leak of afs_read objects")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-tested-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/163010394740.3035676.8516846193899793357.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/163111665914.283156.3038561975681836591.stgit@warthog.procyon.org.uk/

parent b91db6a0

fs/afs/file.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -295,7 +295,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq)
		fsreq->subreq = subreq;
		fsreq->pos = subreq->start + subreq->transferred;
		fsreq->len = subreq->len - subreq->transferred;
		fsreq->key = subreq->rreq->netfs_priv;
		fsreq->key = key_get(subreq->rreq->netfs_priv);
		fsreq->vnode = vnode;
		fsreq->iter = &fsreq->def_iter;

		@@ -304,6 +304,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq)
		fsreq->pos, fsreq->len);

		afs_fetch_data(fsreq->vnode, fsreq);
		afs_put_read(fsreq);
		}

		static int afs_symlink_readpage(struct page *page)