gluster/snapshot: Create missing backend snapshot folder

Snapshot volume bricks are mounted under /var/run/gluster/snaps
folder. In the latest machines /var/run is a symbolic link to
/run folder. In such cases if we use /var/run then there would
be mismatch between mtab entry for the mount and the folder
where we actually mount.

Therefore this patch will get the correct folder and also create
it if the folder is missing.

Change-Id: I267aa7f3e171b486c5b3bb2a9f88cbd4be0e47ea
BUG: 1072253
Signed-off-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-on: http://review.gluster.org/7140

3 files changed, 79 insertions, 47 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-snapshot.c b/xlators/mgmt/glusterd/src/glusterd-snapshot.c
index 7bfede011..116dd5153 100644
--- a/xlators/mgmt/glusterd/src/glusterd-snapshot.c
+++ b/xlators/mgmt/glusterd/src/glusterd-snapshot.c
@@ -44,6 +44,8 @@
 #include <mntent.h>
 #endif
 
+char snap_mount_folder[PATH_MAX];
+
 /* This function will restore a snapshot for the entire
  * volume or the entire CG (Consistency Group)
  *
@@ -717,7 +719,7 @@ glusterd_snapshot_create_prevalidate (dict_t *dict, char **op_errstr,
 
                         ret = snprintf (snap_mount, sizeof(snap_mount) - 1,
                                         "%s/%s%s-brick",
-                                        GLUSTERD_DEFAULT_SNAPS_BRICK_DIR,
+                                        snap_mount_folder,
                                         snap_volname, device);
                         snap_mount[ret] = '\0';
 
@@ -2772,7 +2774,7 @@ glusterd_snap_brick_create (char *device, glusterd_volinfo_t *snap_volinfo,
                 snap_brick_dir++;
 
         snprintf (snap_brick_mount_path, sizeof (snap_brick_mount_path),
-                  "%s/%s%s-brick",  GLUSTERD_DEFAULT_SNAPS_BRICK_DIR,
+                  "%s/%s%s-brick",  snap_mount_folder,
                   snap_volinfo->volname, tmp);
 
         snprintf (snap_brick_path, sizeof (snap_brick_path), "%s/%s",
diff --git a/xlators/mgmt/glusterd/src/glusterd.c b/xlators/mgmt/glusterd/src/glusterd.c
index edb36b7d8..4d5e6310f 100644
--- a/xlators/mgmt/glusterd/src/glusterd.c
+++ b/xlators/mgmt/glusterd/src/glusterd.c
@@ -56,6 +56,8 @@ extern struct rpcsvc_program gd_svc_cli_prog_ro;
 extern struct rpc_clnt_program gd_brick_prog;
 extern struct rpcsvc_program glusterd_mgmt_hndsk_prog;
 
+extern char snap_mount_folder[PATH_MAX];
+
 rpcsvc_cbk_program_t glusterd_cbk_prog = {
         .progname  = "Gluster Callback",
         .prognum   = GLUSTER_CBK_PROGRAM,
@@ -1068,6 +1070,70 @@ glusterd_stop_uds_listener (xlator_t *this)
         return;
 }
 
+static int
+glusterd_init_snap_folder (xlator_t *this)
+{
+        int             ret = -1;
+        struct stat     buf = {0,};
+
+        GF_ASSERT (this);
+
+        /* Snapshot volumes are mounted under /var/run/gluster/snaps folder.
+         * But /var/run is normally a symbolic link to /run folder, which
+         * creates problems as the entry point in the mtab for the mount point
+         * and glusterd maintained entry point will be different. Therefore
+         * identify the correct run folder and use it for snap volume mounting.
+         */
+        ret = lstat (GLUSTERD_VAR_RUN_DIR, &buf);
+        if (ret != 0) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "stat fails on %s, exiting. (errno = %d)",
+                        GLUSTERD_VAR_RUN_DIR, errno);
+                goto out;
+        }
+
+        /* If /var/run is symlink then use /run folder */
+        if (S_ISLNK (buf.st_mode)) {
+                strcpy (snap_mount_folder, GLUSTERD_RUN_DIR);
+        } else {
+                strcpy (snap_mount_folder, GLUSTERD_VAR_RUN_DIR);
+        }
+
+        strcat (snap_mount_folder, GLUSTERD_DEFAULT_SNAPS_BRICK_DIR);
+
+        ret = stat (snap_mount_folder, &buf);
+        if ((ret != 0) && (ENOENT != errno)) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "stat fails on %s, exiting. (errno = %d)",
+                        snap_mount_folder, errno);
+                ret = -1;
+                goto out;
+        }
+
+        if ((!ret) && (!S_ISDIR(buf.st_mode))) {
+                gf_log (this->name, GF_LOG_CRITICAL,
+                        "Provided snap path %s is not a directory,"
+                        "exiting", snap_mount_folder);
+                ret = -1;
+                goto out;
+        }
+
+        if ((-1 == ret) && (ENOENT == errno)) {
+                /* Create missing folders */
+                ret = mkdir_p (snap_mount_folder, 0777, _gf_false);
+
+                if (-1 == ret) {
+                        gf_log (this->name, GF_LOG_CRITICAL,
+                                "Unable to create directory %s"
+                                " ,errno = %d", snap_mount_folder, errno);
+                        goto out;
+                }
+        }
+
+out:
+        return ret;
+}
+
 /*
  * init - called during glusterd initialization
  *
@@ -1085,7 +1151,6 @@ init (xlator_t *this)
         struct stat        buf               = {0,};
         char               storedir [PATH_MAX] = {0,};
         char               workdir [PATH_MAX] = {0,};
-        char               snap_brick_dir[PATH_MAX] = {0, };
         char               hooks_dir [PATH_MAX] = {0,};
         char               cmd_log_filename [PATH_MAX] = {0,};
         int                first_time        = 0;
@@ -1135,42 +1200,12 @@ init (xlator_t *this)
         gf_log (this->name, GF_LOG_INFO, "Using %s as working directory",
                 workdir);
 
-        dir_data = dict_get (this->options, "snap-bricks-path");
-        if (!dir_data) {
-                //Use default working dir
-                strncpy (snap_brick_dir, GLUSTERD_DEFAULT_SNAPS_BRICK_DIR, PATH_MAX);
-        } else {
-                strncpy (snap_brick_dir, dir_data->data, PATH_MAX);
-        }
-
-        ret = stat (snap_brick_dir, &buf);
-        if ((ret != 0) && (ENOENT != errno)) {
-                gf_log (this->name, GF_LOG_ERROR,
-                        "stat fails on %s, exiting. (errno = %d)",
-			workdir, errno);
-                exit (1);
-        }
-
-        if ((!ret) && (!S_ISDIR(buf.st_mode))) {
-                gf_log (this->name, GF_LOG_CRITICAL,
-                        "Provided working area %s is not a directory,"
-                        "exiting", workdir);
-                exit (1);
-        }
-
-
-        if ((-1 == ret) && (ENOENT == errno)) {
-                ret = mkdir (snap_brick_dir, 0777);
-
-                if (-1 == ret) {
-                        gf_log (this->name, GF_LOG_CRITICAL,
-                                "Unable to create directory %s"
-                                " ,errno = %d", snap_brick_dir, errno);
-                        exit (1);
-                }
-
-                first_time = 1;
-        }
+        ret = glusterd_init_snap_folder (this);
+        if (ret) {
+                gf_log (this->name, GF_LOG_CRITICAL, "Unable to create "
+                        "snap backend folder");
+                 exit (1);
+         }
 
         snprintf (cmd_log_filename, PATH_MAX,"%s/.cmd_log_history",
                   DEFAULT_LOG_FILE_DIRECTORY);
diff --git a/xlators/mgmt/glusterd/src/glusterd.h b/xlators/mgmt/glusterd/src/glusterd.h
index bd765349a..8ba626183 100644
--- a/xlators/mgmt/glusterd/src/glusterd.h
+++ b/xlators/mgmt/glusterd/src/glusterd.h
@@ -437,14 +437,9 @@ enum glusterd_vol_comp_status_ {
 #define GLUSTERD_VOL_SNAP_DIR_PREFIX "snaps"
 #define GLUSTERD_VOL_SNAP_CG_DIR_PREFIX "cgs"
 
-/* TODO: It was supposed to be /var/run/gluster. But /var/run seems
-   to be a symbolic link to /run/gluster which creates problems
-   as the entry point in the mtab for the mount point and
-   glusterd maintained entry point will be different. Verify
-   properly on which path should be used for creating the
-   brick directories of snap volumes
-*/
-#define GLUSTERD_DEFAULT_SNAPS_BRICK_DIR "/run/gluster/snaps"
+#define GLUSTERD_DEFAULT_SNAPS_BRICK_DIR        "/gluster/snaps"
+#define GLUSTERD_VAR_RUN_DIR                    "/var/run"
+#define GLUSTERD_RUN_DIR                        "/run"
 
 /* definitions related to replace brick */
 #define RB_CLIENT_MOUNTPOINT    "rb_mount"