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1ac09434bb
nfs-utils/nfs-utils-1.2.10-rc1.patch
Steve Dickson 1ac09434bb Updated to latest upstream RC release: nfs-utils-1-2-10-rc1 
Signed-off-by: Steve Dickson <steved@redhat.com>
2013-11-20 16:31:47 -05:00

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diff --git a/support/include/nfslib.h b/support/include/nfslib.h
index f210a06..ce4b14b 100644
--- a/support/include/nfslib.h
+++ b/support/include/nfslib.h
@@ -128,6 +128,10 @@ void fputrmtabent(FILE *fp, struct rmtabent *xep, long *pos);
void fendrmtabent(FILE *fp);
void frewindrmtabent(FILE *fp);
+/* mydaemon */
+void mydaemon(int nochdir, int noclose, int *pipefds);
+void release_parent(int *pipefds);
+
/*
* wildmat borrowed from INN
*/
diff --git a/support/nfs/Makefile.am b/support/nfs/Makefile.am
index 05c2fc4..fb9b8c1 100644
--- a/support/nfs/Makefile.am
+++ b/support/nfs/Makefile.am
@@ -2,7 +2,7 @@
noinst_LIBRARIES = libnfs.a
libnfs_a_SOURCES = exports.c rmtab.c xio.c rpcmisc.c rpcdispatch.c \
- xlog.c xcommon.c wildmat.c nfsclient.c \
+ xlog.c xcommon.c wildmat.c mydaemon.c nfsclient.c \
nfsexport.c getfh.c nfsctl.c rpc_socket.c getport.c \
svc_socket.c cacheio.c closeall.c nfs_mntent.c conffile.c \
svc_create.c atomicio.c strlcpy.c strlcat.c
diff --git a/support/nfs/mydaemon.c b/support/nfs/mydaemon.c
new file mode 100644
index 0000000..e885d60
--- /dev/null
+++ b/support/nfs/mydaemon.c
@@ -0,0 +1,148 @@
+/*
+ mydaemon.c
+
+ Copyright (c) 2000 The Regents of the University of Michigan.
+ All rights reserved.
+
+ Copyright (c) 2000 Dug Song <dugsong@UMICH.EDU>.
+ Copyright (c) 2002 Andy Adamson <andros@UMICH.EDU>.
+ Copyright (c) 2002 Marius Aamodt Eriksen <marius@UMICH.EDU>.
+ Copyright (c) 2002 J. Bruce Fields <bfields@UMICH.EDU>.
+ Copyright (c) 2013 Jeff Layton <jlayton@redhat.com>
+
+ All rights reserved, all wrongs reversed.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+ 3. Neither the name of the University nor the names of its
+ contributors may be used to endorse or promote products derived
+ from this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*/
+
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <xlog.h>
+
+/**
+ * mydaemon - daemonize, but have parent wait to exit
+ * @nochdir: skip chdir()'ing the child to / after forking if true
+ * @noclose: skip closing stdin/stdout/stderr if true
+ * @pipefds: pointer to 2 element array of pipefds
+ *
+ * This function is like daemon(), but with our own special sauce to delay
+ * the exit of the parent until the child is set up properly. A pipe is created
+ * between parent and child. The parent process will wait to exit until the
+ * child dies or writes a '1' on the pipe signaling that it started
+ * successfully.
+ */
+void
+mydaemon(int nochdir, int noclose, int *pipefds)
+{
+ int pid, status, tempfd;
+
+ if (pipe(pipefds) < 0) {
+ xlog_err("mydaemon: pipe() failed: errno %d (%s)\n",
+ errno, strerror(errno));
+ exit(1);
+ }
+ if ((pid = fork ()) < 0) {
+ xlog_err("mydaemon: fork() failed: errno %d (%s)\n",
+ errno, strerror(errno));
+ exit(1);
+ }
+
+ if (pid != 0) {
+ /*
+ * Parent. Wait for status from child.
+ */
+ close(pipefds[1]);
+ if (read(pipefds[0], &status, 1) != 1)
+ exit(1);
+ exit (0);
+ }
+ /* Child. */
+ close(pipefds[0]);
+ setsid ();
+ if (nochdir == 0) {
+ if (chdir ("/") == -1) {
+ xlog_err("mydaemon: chdir() failed: errno %d (%s)\n",
+ errno, strerror(errno));
+ exit(1);
+ }
+ }
+
+ while (pipefds[1] <= 2) {
+ pipefds[1] = dup(pipefds[1]);
+ if (pipefds[1] < 0) {
+ xlog_err("mydaemon: dup() failed: errno %d (%s)\n",
+ errno, strerror(errno));
+ exit(1);
+ }
+ }
+
+ if (noclose == 0) {
+ tempfd = open("/dev/null", O_RDWR);
+ if (tempfd >= 0) {
+ dup2(tempfd, 0);
+ dup2(tempfd, 1);
+ dup2(tempfd, 2);
+ close(tempfd);
+ } else {
+ xlog_err("mydaemon: can't open /dev/null: errno %d "
+ "(%s)\n", errno, strerror(errno));
+ exit(1);
+ }
+ }
+
+ return;
+}
+
+/**
+ * release_parent - tell the parent that it can exit now
+ * @pipefds: pipefd array that was previously passed to mydaemon()
+ *
+ * This function tells the parent process of mydaemon() that it's now clear
+ * to exit(0).
+ */
+void
+release_parent(int *pipefds)
+{
+ int status;
+
+ if (pipefds[1] > 0) {
+ if (write(pipefds[1], &status, 1) != 1) {
+ xlog_err("WARN: writing to parent pipe failed: errno "
+ "%d (%s)\n", errno, strerror(errno));
+ }
+ close(pipefds[1]);
+ pipefds[1] = -1;
+ }
+}
+
diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
index da5fe21..00667e9 100644
--- a/utils/exportfs/exportfs.c
+++ b/utils/exportfs/exportfs.c
@@ -27,6 +27,10 @@
#include <netdb.h>
#include <errno.h>
#include <dirent.h>
+#include <limits.h>
+#include <time.h>
+
+#define INT_TO_LONG_THRESHOLD_SECS (INT_MAX - (60 * 60 * 24))
#include "sockaddr.h"
#include "misc.h"
@@ -406,17 +410,33 @@ unexportfs(char *arg, int verbose)
static int can_test(void)
{
+ char buf[1024];
int fd;
int n;
- char *setup = "nfsd 0.0.0.0 2147483647 -test-client-\n";
+
fd = open("/proc/net/rpc/auth.unix.ip/channel", O_WRONLY);
- if ( fd < 0) return 0;
- n = write(fd, setup, strlen(setup));
+ if (fd < 0)
+ return 0;
+
+ /*
+ * We introduce tolerance of 1 day to ensure that we use a
+ * LONG_MAX for the expiry timestamp before it is actually
+ * needed. To use LONG_MAX, the kernel code must have
+ * commit 2f74f972 (sunrpc: prepare NFS for 2038).
+ */
+ if (time(NULL) > INT_TO_LONG_THRESHOLD_SECS)
+ sprintf(buf, "nfsd 0.0.0.0 %ld -test-client-\n", LONG_MAX);
+ else
+ sprintf(buf, "nfsd 0.0.0.0 %d -test-client-\n", INT_MAX);
+
+ n = write(fd, buf, strlen(buf));
close(fd);
if (n < 0)
return 0;
+
fd = open("/proc/net/rpc/nfsd.export/channel", O_WRONLY);
- if ( fd < 0) return 0;
+ if (fd < 0)
+ return 0;
close(fd);
return 1;
}
diff --git a/utils/gssd/gssd.c b/utils/gssd/gssd.c
index 8ee478b..fdad153 100644
--- a/utils/gssd/gssd.c
+++ b/utils/gssd/gssd.c
@@ -54,6 +54,7 @@
#include "err_util.h"
#include "gss_util.h"
#include "krb5_util.h"
+#include "nfslib.h"
char pipefs_dir[PATH_MAX] = GSSD_PIPEFS_DIR;
char keytabfile[PATH_MAX] = GSSD_DEFAULT_KEYTAB_FILE;
@@ -63,6 +64,7 @@ int use_memcache = 0;
int root_uses_machine_creds = 1;
unsigned int context_timeout = 0;
char *preferred_realm = NULL;
+int pipefds[2] = { -1, -1 };
void
sig_die(int signal)
@@ -187,8 +189,8 @@ main(int argc, char *argv[])
if (gssd_check_mechs() != 0)
errx(1, "Problem with gssapi library");
- if (!fg && daemon(0, 0) < 0)
- errx(1, "fork");
+ if (!fg)
+ mydaemon(0, 0, pipefds);
signal(SIGINT, sig_die);
signal(SIGTERM, sig_die);
diff --git a/utils/gssd/gssd.h b/utils/gssd/gssd.h
index 86472a1..56a18d6 100644
--- a/utils/gssd/gssd.h
+++ b/utils/gssd/gssd.h
@@ -67,12 +67,14 @@ extern int use_memcache;
extern int root_uses_machine_creds;
extern unsigned int context_timeout;
extern char *preferred_realm;
+extern int pipefds[2];
TAILQ_HEAD(clnt_list_head, clnt_info) clnt_list;
struct clnt_info {
TAILQ_ENTRY(clnt_info) list;
char *dirname;
+ char *pdir;
int dir_fd;
char *servicename;
char *servername;
diff --git a/utils/gssd/gssd_main_loop.c b/utils/gssd/gssd_main_loop.c
index ccf7fe5..9970028 100644
--- a/utils/gssd/gssd_main_loop.c
+++ b/utils/gssd/gssd_main_loop.c
@@ -53,6 +53,7 @@
#include "gssd.h"
#include "err_util.h"
+#include "nfslib.h"
extern struct pollfd *pollarray;
extern unsigned long pollsize;
@@ -245,6 +246,9 @@ gssd_run()
/* Error msg is already printed */
exit(1);
}
+
+ /* release the parent after the initial dir scan */
+ release_parent(pipefds);
}
gssd_poll(pollarray, pollsize);
}
diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index b48d163..2a6ea97 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -256,6 +256,7 @@ read_service_info(char *info_file_name, char **servicename, char **servername,
if ((nbytes = read(fd, buf, INFOBUFLEN)) == -1)
goto fail;
close(fd);
+ fd = -1;
buf[nbytes] = '\0';
numfields = sscanf(buf,"RPC server: %127s\n"
@@ -322,6 +323,7 @@ destroy_client(struct clnt_info *clp)
if (clp->krb5_fd != -1) close(clp->krb5_fd);
if (clp->gssd_fd != -1) close(clp->gssd_fd);
free(clp->dirname);
+ free(clp->pdir);
free(clp->servicename);
free(clp->servername);
free(clp->protocol);
@@ -403,11 +405,10 @@ process_clnt_dir_files(struct clnt_info * clp)
return -1;
snprintf(info_file_name, sizeof(info_file_name), "%s/info",
clp->dirname);
- if ((clp->servicename == NULL) &&
- read_service_info(info_file_name, &clp->servicename,
- &clp->servername, &clp->prog, &clp->vers,
- &clp->protocol, (struct sockaddr *) &clp->addr))
- return -1;
+ if (clp->prog == 0)
+ read_service_info(info_file_name, &clp->servicename,
+ &clp->servername, &clp->prog, &clp->vers,
+ &clp->protocol, (struct sockaddr *) &clp->addr);
return 0;
}
@@ -463,6 +464,9 @@ process_clnt_dir(char *dir, char *pdir)
if (!(clp = insert_new_clnt()))
goto fail_destroy_client;
+ if (!(clp->pdir = strdup(pdir)))
+ goto fail_destroy_client;
+
/* An extra for the '/', and an extra for the null */
if (!(clp->dirname = calloc(strlen(dir) + strlen(pdir) + 2, 1))) {
goto fail_destroy_client;
@@ -527,7 +531,7 @@ update_old_clients(struct dirent **namelist, int size, char *pdir)
/* only compare entries in the global list that are from the
* same pipefs parent directory as "pdir"
*/
- if (strcmp(clp->dirname, pdir) != 0) continue;
+ if (strcmp(clp->pdir, pdir) != 0) continue;
stillhere = 0;
for (i=0; i < size; i++) {
@@ -1040,7 +1044,10 @@ process_krb5_upcall(struct clnt_info *clp, uid_t uid, int fd, char *tgtname,
return;
default:
/* Parent: just wait on child to exit and return */
- wait(&err);
+ do {
+ pid = wait(&err);
+ } while(pid == -1 && errno != -ECHILD);
+
if (WIFSIGNALED(err))
printerr(0, "WARNING: forked child was killed with signal %d\n",
WTERMSIG(err));
@@ -1320,11 +1327,14 @@ handle_gssd_upcall(struct clnt_info *clp)
}
}
- if (strcmp(mech, "krb5") == 0)
+ if (strcmp(mech, "krb5") == 0 && clp->servername)
process_krb5_upcall(clp, uid, clp->gssd_fd, target, service);
- else
- printerr(0, "WARNING: handle_gssd_upcall: "
- "received unknown gss mech '%s'\n", mech);
+ else {
+ if (clp->servername)
+ printerr(0, "WARNING: handle_gssd_upcall: "
+ "received unknown gss mech '%s'\n", mech);
+ do_error_downcall(clp->gssd_fd, uid, -EACCES);
+ }
out:
free(lbuf);
diff --git a/utils/gssd/svcgssd.c b/utils/gssd/svcgssd.c
index 8aee3b2..0385725 100644
--- a/utils/gssd/svcgssd.c
+++ b/utils/gssd/svcgssd.c
@@ -62,91 +62,7 @@
#include "gss_util.h"
#include "err_util.h"
-/*
- * mydaemon creates a pipe between the partent and child
- * process. The parent process will wait until the
- * child dies or writes a '1' on the pipe signaling
- * that it started successfully.
- */
-int pipefds[2] = { -1, -1};
-
-static void
-mydaemon(int nochdir, int noclose)
-{
- int pid, status, tempfd;
-
- if (pipe(pipefds) < 0) {
- printerr(1, "mydaemon: pipe() failed: errno %d (%s)\n",
- errno, strerror(errno));
- exit(1);
- }
- if ((pid = fork ()) < 0) {
- printerr(1, "mydaemon: fork() failed: errno %d (%s)\n",
- errno, strerror(errno));
- exit(1);
- }
-
- if (pid != 0) {
- /*
- * Parent. Wait for status from child.
- */
- close(pipefds[1]);
- if (read(pipefds[0], &status, 1) != 1)
- exit(1);
- exit (0);
- }
- /* Child. */
- close(pipefds[0]);
- setsid ();
- if (nochdir == 0) {
- if (chdir ("/") == -1) {
- printerr(1, "mydaemon: chdir() failed: errno %d (%s)\n",
- errno, strerror(errno));
- exit(1);
- }
- }
-
- while (pipefds[1] <= 2) {
- pipefds[1] = dup(pipefds[1]);
- if (pipefds[1] < 0) {
- printerr(1, "mydaemon: dup() failed: errno %d (%s)\n",
- errno, strerror(errno));
- exit(1);
- }
- }
-
- if (noclose == 0) {
- tempfd = open("/dev/null", O_RDWR);
- if (tempfd >= 0) {
- dup2(tempfd, 0);
- dup2(tempfd, 1);
- dup2(tempfd, 2);
- close(tempfd);
- } else {
- printerr(1, "mydaemon: can't open /dev/null: errno %d "
- "(%s)\n", errno, strerror(errno));
- exit(1);
- }
- }
-
- return;
-}
-
-static void
-release_parent(void)
-{
- int status;
-
- if (pipefds[1] > 0) {
- if (write(pipefds[1], &status, 1) != 1) {
- printerr(1,
- "WARN: writing to parent pipe failed: errno %d (%s)\n",
- errno, strerror(errno));
- }
- close(pipefds[1]);
- pipefds[1] = -1;
- }
-}
+static int pipefds[2] = { -1, -1 };
void
sig_die(int signal)
@@ -242,7 +158,7 @@ main(int argc, char *argv[])
}
if (!fg)
- mydaemon(0, 0);
+ mydaemon(0, 0, pipefds);
signal(SIGINT, sig_die);
signal(SIGTERM, sig_die);
@@ -272,7 +188,7 @@ main(int argc, char *argv[])
}
if (!fg)
- release_parent();
+ release_parent(pipefds);
nfs4_init_name_mapping(NULL); /* XXX: should only do this once */
gssd_run();
diff --git a/utils/idmapd/idmapd.c b/utils/idmapd/idmapd.c
index b6c6231..c02849b 100644
--- a/utils/idmapd/idmapd.c
+++ b/utils/idmapd/idmapd.c
@@ -157,9 +157,6 @@ static int nfsdopenone(struct idmap_client *);
static void nfsdreopen_one(struct idmap_client *);
static void nfsdreopen(void);
-void mydaemon(int, int);
-void release_parent(void);
-
static int verbose = 0;
#define DEFAULT_IDMAP_CACHE_EXPIRY 600 /* seconds */
static int cache_entry_expiration = 0;
@@ -167,6 +164,7 @@ static char pipefsdir[PATH_MAX];
static char *nobodyuser, *nobodygroup;
static uid_t nobodyuid;
static gid_t nobodygid;
+static int pipefds[2] = { -1, -1 };
/* Used by conffile.c in libnfs.a */
char *conf_path;
@@ -305,7 +303,7 @@ main(int argc, char **argv)
errx(1, "Unable to create name to user id mappings.");
if (!fg)
- mydaemon(0, 0);
+ mydaemon(0, 0, pipefds);
event_init();
@@ -382,7 +380,7 @@ main(int argc, char **argv)
if (nfsdret != 0 && fd == 0)
xlog_err("main: Neither NFS client nor NFSd found");
- release_parent();
+ release_parent(pipefds);
if (event_dispatch() < 0)
xlog_err("main: event_dispatch returns errno %d (%s)",
@@ -929,77 +927,3 @@ getfield(char **bpp, char *fld, size_t fldsz)
return (0);
}
-/*
- * mydaemon creates a pipe between the partent and child
- * process. The parent process will wait until the
- * child dies or writes a '1' on the pipe signaling
- * that it started successfully.
- */
-int pipefds[2] = { -1, -1};
-
-void
-mydaemon(int nochdir, int noclose)
-{
- int pid, status, tempfd;
-
- if (pipe(pipefds) < 0)
- err(1, "mydaemon: pipe() failed: errno %d", errno);
-
- if ((pid = fork ()) < 0)
- err(1, "mydaemon: fork() failed: errno %d", errno);
-
- if (pid != 0) {
- /*
- * Parent. Wait for status from child.
- */
- close(pipefds[1]);
- if (read(pipefds[0], &status, 1) != 1)
- exit(1);
- exit (0);
- }
- /* Child. */
- close(pipefds[0]);
- setsid ();
- if (nochdir == 0) {
- if (chdir ("/") == -1)
- err(1, "mydaemon: chdir() failed: errno %d", errno);
- }
-
- while (pipefds[1] <= 2) {
- pipefds[1] = dup(pipefds[1]);
- if (pipefds[1] < 0)
- err(1, "mydaemon: dup() failed: errno %d", errno);
- }
-
- if (noclose == 0) {
- tempfd = open("/dev/null", O_RDWR);
- if (tempfd < 0)
- tempfd = open("/", O_RDONLY);
- if (tempfd >= 0) {
- dup2(tempfd, 0);
- dup2(tempfd, 1);
- dup2(tempfd, 2);
- close(tempfd);
- } else {
- err(1, "mydaemon: can't open /dev/null: errno %d",
- errno);
- exit(1);
- }
- }
-
- return;
-}
-void
-release_parent(void)
-{
- int status;
-
- if (pipefds[1] > 0) {
- if (write(pipefds[1], &status, 1) != 1) {
- err(1, "Writing to parent pipe failed: errno %d (%s)\n",
- errno, strerror(errno));
- }
- close(pipefds[1]);
- pipefds[1] = -1;
- }
-}
diff --git a/utils/mount/network.c b/utils/mount/network.c
index e8e55a5..2853d00 100644
--- a/utils/mount/network.c
+++ b/utils/mount/network.c
@@ -92,6 +92,9 @@ static const char *nfs_version_opttbl[] = {
"v4",
"vers",
"nfsvers",
+ "v4.0",
+ "v4.1",
+ "v4.2",
NULL,
};
@@ -1269,6 +1272,11 @@ nfs_nfs_version(struct mount_options *options, unsigned long *version)
progname);
return 0;
}
+ case 5: /* v4.0 */
+ case 6: /* v4.1 */
+ case 7: /* v4.2 */
+ *version = 4;
+ return 1;
}
/*
diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
index 67031b5..ecc5f64 100644
--- a/utils/mount/nfs.man
+++ b/utils/mount/nfs.man
@@ -856,6 +856,26 @@ In the presence of multiple client network interfaces,
special routing policies,
or atypical network topologies,
the exact address to use for callbacks may be nontrivial to determine.
+.TP 1.5i
+.BR migration " / " nomigration
+Selects whether the client uses an identification string that is compatible
+with NFSv4 Transparent State Migration (TSM).
+If the mounted server supports NFSv4 migration with TSM, specify the
+.B migration
+option.
+.IP
+Some server features misbehave in the face of a migration-compatible
+identification string.
+The
+.B nomigration
+option retains the use of a traditional client indentification string
+which is compatible with legacy NFS servers.
+This is also the behavior if neither option is specified.
+A client's open and lock state cannot be migrated transparently
+when it identifies itself via a traditional identification string.
+.IP
+This mount option has no effect with NFSv4 minor versions newer than zero,
+which always use TSM-compatible client identification strings.
.SH nfs4 FILE SYSTEM TYPE
The
.BR nfs4
@@ -1227,6 +1247,65 @@ If absolute cache coherence among clients is required,
applications should use file locking. Alternatively, applications
can also open their files with the O_DIRECT flag
to disable data caching entirely.
+.SS "File timestamp maintainence"
+NFS servers are responsible for managing file and directory timestamps
+.RB ( atime ,
+.BR ctime ", and"
+.BR mtime ).
+When a file is accessed or updated on an NFS server,
+the file's timestamps are updated just like they would be on a filesystem
+local to an application.
+.P
+NFS clients cache file attributes, including timestamps.
+A file's timestamps are updated on NFS clients when its attributes
+are retrieved from the NFS server.
+Thus there may be some delay before timestamp updates
+on an NFS server appear to applications on NFS clients.
+.P
+To comply with the POSIX filesystem standard, the Linux NFS client
+relies on NFS servers to keep a file's
+.B mtime
+and
+.B ctime
+timestamps properly up to date.
+It does this by flushing local data changes to the server
+before reporting
+.B mtime
+to applications via system calls such as
+.BR stat (2).
+.P
+The Linux client handles
+.B atime
+updates more loosely, however.
+NFS clients maintain good performance by caching data,
+but that means that application reads, which normally update
+.BR atime ,
+are not reflected to the server where a file's
+.B atime
+is actually maintained.
+.P
+Because of this caching behavior,
+the Linux NFS client does not support generic atime-related mount options.
+See
+.BR mount (8)
+for details on these options.
+.P
+In particular, the
+.BR atime / noatime ,
+.BR diratime / nodiratime ,
+.BR relatime / norelatime ,
+and
+.BR strictatime / nostrictatime
+mount options have no effect on NFS mounts.
+.P
+.I /proc/mounts
+may report that the
+.B relatime
+mount option is set on NFS mounts, but in fact the
+.B atime
+semantics are always as described here, and are not like
+.B relatime
+semantics.
.SS "Directory entry caching"
The Linux NFS client caches the result of all NFS LOOKUP requests.
If the requested directory entry exists on the server,
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