rpc.idmapd runs out of file descriptors

[Sergio Gelato <sergio.gelato@astro.su.se>]

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Observed on Debian 12 (nfs-utils 2.6.2):

May 28 09:40:25 HOSTNAME rpc.idmapd[3602614]: dirscancb: scandir(/run/rpc_pipefs/nfs): Too many open files
[repeated multiple times]

Investigation with lsof on one of the affected systems shows that file desciptors are not being closed:

[...]
rpc.idmap 675 root  126r      DIR               0,40        0      10813 /run/rpc_pipefs/nfs/clnt11e6 (deleted)
rpc.idmap 675 root  127u     FIFO               0,40      0t0      10817 /run/rpc_pipefs/nfs/clnt11e6/idmap (deleted)
rpc.idmap 675 root  128r      DIR               0,40        0      10834 /run/rpc_pipefs/nfs/clnt11ef (deleted)
rpc.idmap 675 root  129u     FIFO               0,40      0t0      10838 /run/rpc_pipefs/nfs/clnt11ef/idmap (deleted)
rpc.idmap 675 root  130r      DIR               0,40        0      10855 /run/rpc_pipefs/nfs/clnt11f8 (deleted)
rpc.idmap 675 root  131u     FIFO               0,40      0t0      10859 /run/rpc_pipefs/nfs/clnt11f8/idmap (deleted)

Raising the verbosity level to 3 results in no "Stale client:" lines.
strace shows no close() calls other than for the /run/rpc_pipefs/nfs directory.

I believe this is because in dirscancb() the loop is exited prematurely
the first time nfsopen() returns -1, preventing later entries in the queue
from being reaped. I've tested the patch below, which seems indeed to cure
the problem. The bug appears to be still unfixed in the current master branch.

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From: Sergio Gelato <Sergio.Gelato@astro.su.se>
Date: Tue, 4 Jun 2024 16:02:59 +0200
Subject: rpc.idmapd: nfsopen() failures should not be fatal

dirscancb() loops over all clnt* subdirectories of /run/rpc_pipefs/nfs/.
Some of these directories contain /idmap files, others don't. nfsopen()
returns -1 for the latter; we then want to skip the directory, not abort
the entire scan.
---
 utils/idmapd/idmapd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/utils/idmapd/idmapd.c b/utils/idmapd/idmapd.c
index e79c124..f3c540d 100644
--- a/utils/idmapd/idmapd.c
+++ b/utils/idmapd/idmapd.c
@@ -556,7 +556,7 @@ dirscancb(int fd, short UNUSED(which), void *data)
 			if (nfsopen(ic) == -1) {
 				close(ic->ic_dirfd);
 				free(ic);
-				goto out;
+				continue;
 			}
 
 			if (verbose > 2)