NFSv4: Allow entries in the idmap cache to expire
If someone changes the uid/gid mapping in userland, then we do eventually
want those changes to be propagated to the kernel. Currently the kernel
assumes that it may cache entries forever.
Add an expiration time + garbage collector for idmap entries.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index ffb8df9..821edd3 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -54,7 +54,11 @@
#define IDMAP_HASH_SZ 128
+/* Default cache timeout is 10 minutes */
+unsigned int nfs_idmap_cache_timeout = 600 * HZ;
+
struct idmap_hashent {
+ unsigned long ih_expires;
__u32 ih_id;
int ih_namelen;
char ih_name[IDMAP_NAMESZ];
@@ -149,6 +153,8 @@
if (he->ih_namelen != len || memcmp(he->ih_name, name, len) != 0)
return NULL;
+ if (time_after(jiffies, he->ih_expires))
+ return NULL;
return he;
}
@@ -164,6 +170,8 @@
struct idmap_hashent *he = idmap_id_hash(h, id);
if (he->ih_id != id || he->ih_namelen == 0)
return NULL;
+ if (time_after(jiffies, he->ih_expires))
+ return NULL;
return he;
}
@@ -192,6 +200,7 @@
memcpy(he->ih_name, name, namelen);
he->ih_name[namelen] = '\0';
he->ih_namelen = namelen;
+ he->ih_expires = jiffies + nfs_idmap_cache_timeout;
}
/*
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 4625479..e7bd0d9 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -2050,6 +2050,20 @@
module_param_call(callback_tcpport, param_set_port, param_get_int,
&nfs_callback_set_tcpport, 0644);
+static int param_set_idmap_timeout(const char *val, struct kernel_param *kp)
+{
+ char *endp;
+ int num = simple_strtol(val, &endp, 0);
+ int jif = num * HZ;
+ if (endp == val || *endp || num < 0 || jif < num)
+ return -EINVAL;
+ *((int *)kp->arg) = jif;
+ return 0;
+}
+
+module_param_call(idmap_cache_timeout, param_set_idmap_timeout, param_get_int,
+ &nfs_idmap_cache_timeout, 0644);
+
#define nfs4_init_once(nfsi) \
do { \
INIT_LIST_HEAD(&(nfsi)->open_states); \
diff --git a/fs/nfs/sysctl.c b/fs/nfs/sysctl.c
index fdc64b5..4c486eb 100644
--- a/fs/nfs/sysctl.c
+++ b/fs/nfs/sysctl.c
@@ -11,6 +11,7 @@
#include <linux/sysctl.h>
#include <linux/module.h>
#include <linux/nfs4.h>
+#include <linux/nfs_idmap.h>
#include "callback.h"
@@ -35,6 +36,15 @@
.extra1 = (int *)&nfs_set_port_min,
.extra2 = (int *)&nfs_set_port_max,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "idmap_cache_timeout",
+ .data = &nfs_idmap_cache_timeout,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_jiffies,
+ .strategy = &sysctl_jiffies,
+ },
#endif
{ .ctl_name = 0 }
};