From 7d1da6b73706ce2cbbfa9eac302d415757167d57 Mon Sep 17 00:00:00 2001

From: Amar Tumballi <amarts@redhat.com>

Date: Mon, 29 May 2017 17:26:35 +0530

Subject: [PATCH 476/486] fuse: implement "-oauto_unmount"

libfuse has an auto_unmount option which,

if enabled, ensures that the file system

is unmounted at FUSE server termination

by running a separate monitor process

that performs the unmount when that

occurs. (This feature would probably

better be called "robust auto-unmount",

as FUSE servers usually do try to unmount

their file systems upon termination,

it's just this mechanism is not crash

resilient.)

This change implements that option and

behavior for glusterfs.

Note that "auto unmount" (robust or not) is

a leaky abstraction, as the kernel cannot

guarantee that at the path where the FUSE

fs is mounted is actually the toplevel mount

at the time of the umount(2) call, for

multiple reasons, among others, see:

  fuse-devel: "fuse: feasible to distinguish between umount and abort?"

  http://fuse.996288.n3.nabble.com/fuse-feasible-to-distinguish-between-umount-and-abort-tt14358.html

  https://github.com/libfuse/libfuse/issues/122

> Change-Id: Ia4432580c9fd2c156d9c73c3a44f4bfd42437599

> Signed-off-by: Csaba Henk <csaba@redhat.com>

> Reviewed-on: https://review.gluster.org/17230

> Tested-by: Amar Tumballi <amarts@redhat.com>

> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

> Smoke: Gluster Build System <jenkins@build.gluster.org>

> Reviewed-by: Amar Tumballi <amarts@redhat.com>

> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>

BUG: 1424680

Change-Id: I4bae611254bad749b02abaf18d0ed6f447aec7b8

Signed-off-by: Amar Tumballi <amarts@redhat.com>

Reviewed-on: https://code.engineering.redhat.com/gerrit/107571

Reviewed-by: Atin Mukherjee <amukherj@redhat.com>

---

 contrib/fuse-include/fuse-mount.h           |  1 +

 contrib/fuse-lib/mount.c                    | 46 +++++++++++++++++++++++++++++

 xlators/mount/fuse/src/fuse-bridge.c        | 34 +++++++++++++++++++--

 xlators/mount/fuse/src/fuse-bridge.h        |  3 ++

 xlators/mount/fuse/utils/mount.glusterfs.in |  2 +-

 5 files changed, 82 insertions(+), 4 deletions(-)

diff --git a/contrib/fuse-include/fuse-mount.h b/contrib/fuse-include/fuse-mount.h

index 9358ac8..f2f08e3 100644

--- a/contrib/fuse-include/fuse-mount.h

+++ b/contrib/fuse-include/fuse-mount.h

@@ -8,6 +8,7 @@

 */

 void gf_fuse_unmount (const char *mountpoint, int fd);

+int gf_fuse_unmount_daemon (const char *mountpoint, int fd);

 int gf_fuse_mount (const char *mountpoint, char *fsname,

                    unsigned long mountflags, char *mnt_param,

                    pid_t *mtab_pid, int status_fd);

diff --git a/contrib/fuse-lib/mount.c b/contrib/fuse-lib/mount.c

index 5e0b4dd..876ac90 100644

--- a/contrib/fuse-lib/mount.c

+++ b/contrib/fuse-lib/mount.c

@@ -75,6 +75,52 @@ gf_fuse_unmount (const char *mountpoint, int fd)

 /* gluster-specific routines */

+/* Unmounting in a daemon that lurks 'till main process exits */

+int

+gf_fuse_unmount_daemon (const char *mountpoint, int fd)

+{

+        int   ret = -1;

+        pid_t pid = -1;

+

+        if (fd == -1)

+                return -1;

+

+        int ump[2] = {0,};

+

+        ret = pipe(ump);

+        if (ret == -1) {

+                close (fd);

+                return -1;

+        }

+

+        pid = fork ();

+        switch (pid) {

+                char c = 0;

+                sigset_t sigset;

+        case 0:

+

+                close_fds_except (ump, 1);

+

+                setsid();

+                chdir("/");

+                sigfillset(&sigset);

+                sigprocmask(SIG_BLOCK, &sigset, NULL);

+

+                read (ump[0], &c, 1);

+

+                gf_fuse_unmount (mountpoint, fd);

+                exit (0);

+        case -1:

+                close (fd);

+                fd = -1;

+                ret = -1;

+                close (ump[1]);

+        }

+        close (ump[0]);

+

+        return ret;

+}

+

 static char *

 escape (char *s)

 {

diff --git a/xlators/mount/fuse/src/fuse-bridge.c b/xlators/mount/fuse/src/fuse-bridge.c

index a0eb146..a8d936d 100644

--- a/xlators/mount/fuse/src/fuse-bridge.c

+++ b/xlators/mount/fuse/src/fuse-bridge.c

@@ -5089,7 +5089,7 @@ fuse_thread_proc (void *data)

                                                      ZR_MOUNTPOINT_OPT));

         if (mount_point) {

                 gf_log (this->name, GF_LOG_INFO,

-                        "unmounting %s", mount_point);

+                        "initating unmount of %s", mount_point);

         }

         /* Kill the whole process, not just this thread. */

@@ -5711,6 +5711,24 @@ init (xlator_t *this_xl)

         if (!mnt_args)

                 goto cleanup_exit;

+        {

+                char *mnt_tok         = NULL;

+                token_iter_t tit      = {0,};

+                gf_boolean_t iter_end = _gf_false;

+

+                for (mnt_tok = token_iter_init (mnt_args, ',', &tit) ;;) {

+                        iter_end = next_token (&mnt_tok, &tit;;

+

+                        if (strcmp (mnt_tok, "auto_unmount") == 0) {

+                                priv->auto_unmount = _gf_true;

+                                drop_token (mnt_tok, &tit;;

+                        }

+

+                        if (iter_end)

+                                break;

+                }

+        }

+

         if (pipe(priv->status_pipe) < 0) {

                 gf_log (this_xl->name, GF_LOG_ERROR,

                         "could not create pipe to separate mount process");

@@ -5722,6 +5740,11 @@ init (xlator_t *this_xl)

                                   priv->status_pipe[1]);

         if (priv->fd == -1)

                 goto cleanup_exit;

+        if (priv->auto_unmount) {

+                ret = gf_fuse_unmount_daemon (priv->mount_point, priv->fd);

+                if (ret == -1)

+                        goto cleanup_exit;

+        }

         event = eh_new (FUSE_EVENT_HISTORY_SIZE, _gf_false, NULL);

         if (!event) {

@@ -5799,10 +5822,15 @@ fini (xlator_t *this_xl)

                 mount_point = data_to_str (dict_get (this_xl->options,

                                                      ZR_MOUNTPOINT_OPT));

         if (mount_point != NULL) {

+                if (!priv->auto_unmount) {

+                        gf_log (this_xl->name, GF_LOG_INFO,

+                                "Unmounting '%s'.", mount_point);

+                        gf_fuse_unmount (mount_point, priv->fd);

+                }

+

                 gf_log (this_xl->name, GF_LOG_INFO,

-                        "Unmounting '%s'.", mount_point);

+                        "Closing fuse connection to '%s'.", mount_point);

-                gf_fuse_unmount (mount_point, priv->fd);

                 sys_close (priv->fuse_dump_fd);

                 dict_del (this_xl->options, ZR_MOUNTPOINT_OPT);

         }

diff --git a/xlators/mount/fuse/src/fuse-bridge.h b/xlators/mount/fuse/src/fuse-bridge.h

index 40bd17b..0c70189 100644

--- a/xlators/mount/fuse/src/fuse-bridge.h

+++ b/xlators/mount/fuse/src/fuse-bridge.h

@@ -134,6 +134,9 @@ struct fuse_private {

         /* Enable or disable capability support */

         gf_boolean_t         capability;

+

+        /* whether to run the unmount daemon */

+        gf_boolean_t auto_unmount;

 };

 typedef struct fuse_private fuse_private_t;

diff --git a/xlators/mount/fuse/utils/mount.glusterfs.in b/xlators/mount/fuse/utils/mount.glusterfs.in

index 6c4cdfe..2c5e466 100755

--- a/xlators/mount/fuse/utils/mount.glusterfs.in

+++ b/xlators/mount/fuse/utils/mount.glusterfs.in

@@ -538,7 +538,7 @@ without_options()

         "atime"|"noatime"|"diratime"|"nodiratime"|\

         "relatime"|"norelatime"|\

         "strictatime"|"nostrictatime"|"lazyatime"|"nolazyatime"|\

-        "dev"|"nodev"|"exec"|"noexec"|"suid"|"nosuid")

+        "dev"|"nodev"|"exec"|"noexec"|"suid"|"nosuid"|"auto_unmount")

             [ -z "$fuse_mountopts" ] || fuse_mountopts="$fuse_mountopts,"

             fuse_mountopts="${fuse_mountopts}${option}"

             ;;

-- 

1.8.3.1