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/

diff --git a/fs/afs/file.c b/fs/afs/file.c
index db035ae2a13451dc97fc10e97a6aeb50088898a4..6688fff14b0be2dafb73ea427a10d68a5f98ffd2 100644 (file)
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -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)