Do not hardcode umount(8) path, emulate lazy umount

1) Use a system-dependent macro for umount(8) location instead of
relying on $PATH  to find it, for security and portability sake.

2) Introduce gf_umount_lazy() to replace umount -l (-l for lazy) invocations,
which is only supported on Linux; On Linux behavior in unchanged. On other
systems, we fork an external process (umountd) that will take care of
periodically attempt to unmount, and optionally rmdir.

Backport of Ia91167c0652f8ddab85136324b08f87c5ac1edd51d

BUG: 1138897
Change-Id: I9d82c87e85af0dee79f2de39bc697c486b7103c8
Signed-off-by: Emmanuel Dreyfus <manu@netbsd.org>
Reviewed-on: http://review.gluster.org/8863
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Csaba Henk <csaba@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

3 files changed, 56 insertions, 1 deletions

diff --git a/libglusterfs/src/Makefile.am b/libglusterfs/src/Makefile.am
index 25ee4c27a8b..318058b3195 100644
--- a/libglusterfs/src/Makefile.am
+++ b/libglusterfs/src/Makefile.am
@@ -4,7 +4,8 @@ libglusterfs_la_CFLAGS = -Wall $(GF_CFLAGS) $(GF_DARWIN_LIBGLUSTERFS_CFLAGS) \
 libglusterfs_la_CPPFLAGS = $(GF_CPPFLAGS) -D__USE_FILE_OFFSET64 \
 	-DXLATORDIR=\"$(libdir)/glusterfs/$(PACKAGE_VERSION)/xlator\" \
 	-I$(top_srcdir)/rpc/rpc-lib/src/ -I$(CONTRIBDIR)/rbtree \
-	-I$(CONTRIBDIR)/libexecinfo
+	-I$(CONTRIBDIR)/libexecinfo \
+	-DSBIN_DIR=\"$(sbindir)\" 
 
 libglusterfs_la_LIBADD = @LEXLIB@
 libglusterfs_la_LDFLAGS = -version-info $(LIBGLUSTERFS_LT_VERSION)
diff --git a/libglusterfs/src/compat.c b/libglusterfs/src/compat.c
index eb6d8d4b7f1..93e7b45a69e 100644
--- a/libglusterfs/src/compat.c
+++ b/libglusterfs/src/compat.c
@@ -15,6 +15,7 @@
 
 #include <string.h>
 #include <stdlib.h>
+#include <unistd.h>
 #include <stdarg.h>
 #include <getopt.h>
 #include <sys/types.h>
@@ -28,6 +29,7 @@
 #include "common-utils.h"
 #include "iatt.h"
 #include "inode.h"
+#include "run.h"
 
 #ifdef GF_SOLARIS_HOST_OS
 int
@@ -543,3 +545,40 @@ strnlen(const char *string, size_t maxlen)
         return len;
 }
 #endif /* STRNLEN */
+
+int
+gf_umount_lazy (char *xlname, char *path, int rmdir_flag)
+{
+        int                   ret               = -1;
+        runner_t              runner            = {0,};
+
+        runinit (&runner);
+#ifdef GF_LINUX_HOST_OS
+        runner_add_args (&runner, _PATH_UMOUNT, "-l", path, NULL);
+#else
+        if (rmdir_flag)
+                runner_add_args (&runner, SBIN_DIR "/umountd",
+                                 "-r", path, NULL);
+        else
+                runner_add_args (&runner, SBIN_DIR "/umountd",
+                                 path, NULL);
+#endif
+        ret = runner_run (&runner);
+        if (ret) {
+                gf_log (xlname, GF_LOG_ERROR,
+                        "Lazy unmount of %s failed: %s",
+                        path, strerror (errno));
+        }
+
+#ifdef GF_LINUX_HOST_OS
+        if (!ret && rmdir_flag) {
+                ret = rmdir (path);
+                if (ret)
+                         gf_log (xlname, GF_LOG_WARNING,
+                                 "rmdir %s failed: %s",
+                                 path, strerror (errno));
+        }
+#endif
+
+        return ret;
+}
diff --git a/libglusterfs/src/compat.h b/libglusterfs/src/compat.h
index 5920fce992b..20d15c44e70 100644
--- a/libglusterfs/src/compat.h
+++ b/libglusterfs/src/compat.h
@@ -40,6 +40,10 @@
 #ifdef HAVE_ENDIAN_H
 #include <endian.h>
 #endif
+
+#ifndef _PATH_UMOUNT
+#define _PATH_UMOUNT "/bin/umount"
+#endif
 #endif /* GF_LINUX_HOST_OS */
 
 #ifdef HAVE_XATTR_H
@@ -161,6 +165,9 @@ enum {
 #define FALLOC_FL_KEEP_SIZE     0x01 /* default is extend size */
 #define FALLOC_FL_PUNCH_HOLE    0x02 /* de-allocates range */
 
+#ifndef _PATH_UMOUNT
+  #define _PATH_UMOUNT "/sbin/umount"
+#endif
 #endif /* GF_BSD_HOST_OS */
 
 #ifdef GF_DARWIN_HOST_OS
@@ -239,6 +246,9 @@ int32_t gf_darwin_compat_listxattr (int len, dict_t *dict, int size);
 int32_t gf_darwin_compat_getxattr (const char *key, dict_t *dict);
 int32_t gf_darwin_compat_setxattr (dict_t *dict);
 
+#ifndef _PATH_UMOUNT
+  #define _PATH_UMOUNT "/sbin/umount"
+#endif
 #endif /* GF_DARWIN_HOST_OS */
 
 #ifdef GF_SOLARIS_HOST_OS
@@ -318,6 +328,9 @@ enum {
 #ifndef _PATH_MOUNTED
  #define _PATH_MOUNTED "/etc/mtab"
 #endif
+#ifndef _PATH_UMOUNT
+ #define _PATH_UMOUNT "/sbin/umount"
+#endif
 
 #ifndef O_ASYNC
   #ifdef FASYNC
@@ -464,4 +477,6 @@ int gf_mkostemp (char *tmpl, int suffixlen, int flags);
 #pragma GCC poison system popen
 #endif
 
+int gf_umount_lazy(char *xlname, char *path, int rmdir);
+
 #endif /* __COMPAT_H__ */