libmount: use /run/mount/tmptgt rather than /tmp/mount/mount.<pid>

The unshared namespace is per-process, so we can use the same
directory in all mount(8) instances. It's unnecessary to create
and remove process specific directory.

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/context.c b/libmount/src/context.c
index 8d1250f7c9de6af652ac3922aec17dcc1d223b79..942f7b4e22d9a793f8b1c726a5870452a4886fd8 100644 (file)
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -154,7 +154,6 @@ int mnt_reset_context(struct libmnt_context *cxt)
        free(cxt->helper);
        free(cxt->orig_user);
        free(cxt->subdir);
-       free(cxt->tmptgt);
 
        cxt->fs = NULL;
        cxt->mtab = NULL;
@@ -164,7 +163,6 @@ int mnt_reset_context(struct libmnt_context *cxt)
        cxt->mountflags = 0;
        cxt->user_mountflags = 0;
        cxt->mountdata = NULL;
-       cxt->tmptgt = NULL;
        cxt->subdir = NULL;
        cxt->flags = MNT_FL_DEFAULT;
 
@@ -298,8 +296,6 @@ struct libmnt_context *mnt_copy_context(struct libmnt_context *o)
                goto failed;
        if (strdup_between_structs(n, o, subdir))
                goto failed;
-       if (strdup_between_structs(n, o, tmptgt))
-               goto failed;
 
        n->mountflags = o->mountflags;
        n->mountdata = o->mountdata;
@@ -1887,8 +1883,6 @@ static int is_subdir_required(struct libmnt_context *cxt, int *rc)
        cxt->subdir = strndup(dir, sz);
        if (!cxt->subdir)
                *rc = -ENOMEM;
-       else if (asprintf(&cxt->tmptgt, "%s/mount.%d", MNT_TMPDIR, getpid()) < 0)
-               *rc = -ENOMEM;
 
        return *rc == 0;
 }
@@ -2013,8 +2007,7 @@ int mnt_context_prepare_target(struct libmnt_context *cxt)
            && (cxt->user_mountflags & MNT_MS_XFSTABCOMM)
            && is_subdir_required(cxt, &rc)) {
 
-               DBG(CXT, ul_debugobj(cxt, "subdir %s required, temporary target: %s",
-                                       cxt->subdir, cxt->tmptgt));
+               DBG(CXT, ul_debugobj(cxt, "subdir %s required", cxt->subdir));
        }
 
 

diff --git a/libmount/src/context_mount.c b/libmount/src/context_mount.c
index 78e5aa87aad741275e6fc385a1a4cecb1d190fd3..a0f1efa3193a0e590cb6ab4344f38b90a1801645 100644 (file)
--- a/libmount/src/context_mount.c
+++ b/libmount/src/context_mount.c
@@ -855,11 +855,10 @@ static int do_mount(struct libmnt_context *cxt, const char *try_type)
 
                /* create unhared temporary target */
                if (cxt->subdir) {
-                       rc = mnt_unshared_mkdir(cxt->tmptgt,
-                                       S_IRWXU, &old_ns_fd);
+                       rc = mnt_tmptgt_unshare(&old_ns_fd);
                        if (rc)
                                return rc;
-                       target = cxt->tmptgt;
+                       target = MNT_PATH_TMPTGT;
                }
 
                DBG(CXT, ul_debugobj(cxt, "mount(2) "
@@ -894,10 +893,10 @@ static int do_mount(struct libmnt_context *cxt, const char *try_type)
                 */
                if (cxt->subdir) {
                        target = mnt_fs_get_target(cxt->fs);
-                       rc = do_mount_subdir(cxt, cxt->tmptgt, cxt->subdir, target);
+                       rc = do_mount_subdir(cxt, MNT_PATH_TMPTGT, cxt->subdir, target);
                        if (rc)
                                goto done;
-                       mnt_unshared_rmdir(cxt->tmptgt, old_ns_fd);
+                       mnt_tmptgt_cleanup(old_ns_fd);
                        old_ns_fd = -1;
                }
        }
@@ -910,7 +909,7 @@ static int do_mount(struct libmnt_context *cxt, const char *try_type)
 
 done:
        if (old_ns_fd >= 0)
-               mnt_unshared_rmdir(cxt->tmptgt, old_ns_fd);
+               mnt_tmptgt_cleanup(old_ns_fd);
 
        return rc;
 }

diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
index a2b74b372b10dceb000b3a2b105d2c5aea254fea..b47640daac54e9ff1cfd60d913cd27b9623815e0 100644 (file)
--- a/libmount/src/mountP.h
+++ b/libmount/src/mountP.h
@@ -74,10 +74,11 @@ UL_DEBUG_DECLARE_MASK(libmount);
 #define MNT_MNTTABDIR_EXT      ".fstab"
 
 /* library private paths */
-#define MNT_TMPDIR             "/tmp/mount"
 #define MNT_RUNTIME_TOPDIR     "/run"
-
+/* private userspace mount table */
 #define MNT_PATH_UTAB          MNT_RUNTIME_TOPDIR "/mount/utab"
+/* temporary mount target */
+#define MNT_PATH_TMPTGT                MNT_RUNTIME_TOPDIR "/mount/tmptgt"
 
 #define MNT_UTAB_HEADER        "# libmount utab file\n"
 
@@ -122,8 +123,8 @@ extern char *mnt_get_kernel_cmdline_option(const char *name);
 extern int mnt_stat_mountpoint(const char *target, struct stat *st);
 extern int mnt_lstat_mountpoint(const char *target, struct stat *st);
 
-extern int mnt_unshared_mkdir(const char *path, mode_t mode, int *old_ns_fd);
-extern int mnt_unshared_rmdir(const char *path, int old_ns_fd);
+extern int mnt_tmptgt_unshare(int *old_ns_fd);
+extern int mnt_tmptgt_cleanup(int old_ns_fd);
 
 /* tab.c */
 extern int is_mountinfo(struct libmnt_table *tb);
@@ -292,7 +293,6 @@ struct libmnt_context
        char    *optstr_pattern;        /* for mnt_match_options() */
 
        char    *subdir;                /* X-mount.subdir= */
-       char    *tmptgt;                /* (unshared) private mount target */
 
        struct libmnt_fs *fs;           /* filesystem description (type, mountpoint, device, ...) */
        struct libmnt_fs *fs_template;  /* used for @fs on mnt_reset_context() */

diff --git a/libmount/src/utils.c b/libmount/src/utils.c
index 7da7a5093b0dbb17796d73ad853dda21cc444c20..1a8a29463670e4c8f626383d26cdaff79286d1b4 100644 (file)
--- a/libmount/src/utils.c
+++ b/libmount/src/utils.c
@@ -1136,20 +1136,19 @@ done:
 }
 
 /*
- * like ul_mkdir_p(), but create a new namespace and mark (bind mount)
- * the directory as private.
+ * Initialize MNT_PATH_TMPTGT; mkdir, create a new namespace and
+ * mark (bind mount) the directory as private.
  */
-int mnt_unshared_mkdir(const char *path, mode_t mode, int *old_ns_fd)
+int mnt_tmptgt_unshare(int *old_ns_fd)
 {
        int rc = 0, fd = -1, mounted = 0;
 
-       *old_ns_fd = -1;
+       assert(old_ns_fd);
 
-       if (!path || !old_ns_fd)
-               return -EINVAL;
+       *old_ns_fd = -1;
 
        /* create directory */
-       rc = ul_mkdir_p(path, mode);
+       rc = ul_mkdir_p(MNT_PATH_TMPTGT, S_IRWXU);
        if (rc)
                goto fail;
 
@@ -1163,46 +1162,41 @@ int mnt_unshared_mkdir(const char *path, mode_t mode, int *old_ns_fd)
                goto fail;
 
        /* make the directory private */
-       mounted = mount(path, path, "none", MS_BIND, NULL) == 0;
+       mounted = mount(MNT_PATH_TMPTGT, MNT_PATH_TMPTGT, "none", MS_BIND, NULL) == 0;
        if (!mounted)
                goto fail;
-       if (mount("none", path, NULL, MS_PRIVATE, NULL) != 0)
+       if (mount("none", MNT_PATH_TMPTGT, NULL, MS_PRIVATE, NULL) != 0)
                goto fail;
 
-       DBG(UTILS, ul_debug(" %s unshared", path));
+       DBG(UTILS, ul_debug(MNT_PATH_TMPTGT " unshared"));
        *old_ns_fd = fd;
        return 0;
 fail:
        if (rc == 0)
                rc = errno ? -errno : -EINVAL;
        if (mounted)
-               umount(path);
+               umount(MNT_PATH_TMPTGT);
        if (fd >= 0) {
                setns(fd, CLONE_NEWNS);         /* restore original NS */
                close(fd);
        }
-       rmdir(path);
-       DBG(UTILS, ul_debug(" %s unshare failed", path));
+       DBG(UTILS, ul_debug(MNT_PATH_TMPTGT " unshare failed"));
        return rc;
 }
 
 /*
- * umount, rmdir and switch back to old namespace
+ * Clean up MNT_PATH_TMPTGT; umount and switch back to old namespace
  */
-int mnt_unshared_rmdir(const char *path, int old_ns_fd)
+int mnt_tmptgt_cleanup(int old_ns_fd)
 {
-       if (!path)
-               return -EINVAL;
-
-       umount(path);
-       rmdir(path);
+       umount(MNT_PATH_TMPTGT);
 
        if (old_ns_fd >= 0) {
                setns(old_ns_fd, CLONE_NEWNS);
                close(old_ns_fd);
        }
 
-       DBG(UTILS, ul_debug(" %s removed", path));
+       DBG(UTILS, ul_debug(MNT_PATH_TMPTGT " cleanup done"));
        return 0;
 }