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fuse: implement "-oauto_unmount"

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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

Updates #153

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>
This commit is contained in:
Csaba Henk 2017-05-09 19:26:40 +02:00 committed by Shyamsundar Ranganathan
parent 98db583e9b
commit 461888bb63
5 changed files with 83 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
contrib/fuse-include/fuse-mount.h
View File

@ -8,5 +8,6 @@
*/
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, char *mnt_param,
pid_t *mtab_pid, int status_fd);

46
contrib/fuse-lib/mount.c
View File

@ -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)
{

36
xlators/mount/fuse/src/fuse-bridge.c
View File

@ -5150,7 +5150,7 @@ 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. */
@ -5779,6 +5779,24 @@ 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");
@ -5790,6 +5808,11 @@ 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) {
@ -5867,10 +5890,15 @@ fini (xlator_t *this_xl)
mount_point = data_to_str (dict_get (this_xl->options,
ZR_MOUNTPOINT_OPT));
if (mount_point != NULL) {
gf_log (this_xl->name, GF_LOG_INFO,
"Unmounting '%s'.", mount_point);
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,
"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);
}

3
xlators/mount/fuse/src/fuse-bridge.h
View File

@ -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;

2
xlators/mount/fuse/utils/mount.glusterfs.in
View File

@ -562,7 +562,7 @@ 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}"
;;