libmount: move btrfs subvol code refactoring

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

diff --git a/libmount/src/tab.c b/libmount/src/tab.c
index b2a8d7fd47ead9ca413cd03be2c09f0c21943b51..cb31de927c112067c4f8d142fac60698375cf575 100644 (file)
--- a/libmount/src/tab.c
+++ b/libmount/src/tab.c
@@ -1223,6 +1223,120 @@ static char *remove_mountpoint_from_path(const char *path, const char *mnt)
        return res;
 }
 
+#ifdef HAVE_BTRFS_SUPPORT
+static int get_btrfs_fs_root(struct libmnt_table *tb, struct libmnt_fs *fs, char **root)
+{
+       char *vol = NULL, *p;
+       size_t sz, volsz = 0;
+
+       DBG(BTRFS, ul_debug("lookup for btrfs FS root"));
+       *root = NULL;
+
+       if (mnt_fs_get_option(fs, "subvolid", &vol, &volsz) == 0) {
+               char *target;
+               struct libmnt_fs *f;
+               char subvolidstr[sizeof(stringify_value(UINT64_MAX))];
+
+               DBG(BTRFS, ul_debug(" found subvolid=%s, checking", vol));
+
+               assert (volsz + 1 < sizeof(stringify_value(UINT64_MAX)));
+               memcpy(subvolidstr, vol, volsz);
+               subvolidstr[volsz] = '\0';
+
+               target = mnt_resolve_target(mnt_fs_get_target(fs), tb->cache);
+               if (!target)
+                       goto err;
+
+               DBG(BTRFS, ul_debug(" tring target=%s subvolid=%s", target, subvolidstr));
+               f = mnt_table_find_target_with_option(tb, target,
+                                       "subvolid", subvolidstr,
+                                       MNT_ITER_BACKWARD);
+               if (!tb->cache)
+                       free(target);
+               if (!f)
+                       goto not_found;
+
+               /* Instead of set of BACKREF queries constructing subvol path
+                * corresponding to a particular subvolid, use the one in
+                * mountinfo. Kernel keeps subvol path up to date.
+                */
+               if (mnt_fs_get_option(f, "subvol", &vol, &volsz) != 0)
+                       goto not_found;
+
+       } else if (mnt_fs_get_option(fs, "subvol", &vol, &volsz) != 0) {
+               /* If fstab entry does not contain "subvol", we have to
+                * check, whether btrfs has default subvolume defined.
+                */
+               uint64_t default_id;
+               char *target;
+               struct libmnt_fs *f;
+               char default_id_str[sizeof(stringify_value(UINT64_MAX))];
+
+               DBG(BTRFS, ul_debug(" subvolid/subvol not found, checking default"));
+
+               default_id = btrfs_get_default_subvol_id(mnt_fs_get_target(fs));
+               if (default_id == UINT64_MAX)
+                       goto not_found;
+
+               /* Volume has default subvolume. Check if it matches to
+                * the one in mountinfo.
+                *
+                * Only kernel >= 4.2 reports subvolid. On older
+                * kernels, there is no reasonable way to detect which
+                * subvolume was mounted.
+                */
+               target = mnt_resolve_target(mnt_fs_get_target(fs), tb->cache);
+               if (!target)
+                       goto err;
+
+               snprintf(default_id_str, sizeof(default_id_str), "%llu",
+                               (unsigned long long int) default_id);
+
+               DBG(BTRFS, ul_debug(" tring target=%s default subvolid=%s",
+                                       target, default_id_str));
+
+               f = mnt_table_find_target_with_option(tb, target,
+                                       "subvolid", default_id_str,
+                                       MNT_ITER_BACKWARD);
+               if (!tb->cache)
+                       free(target);
+               if (!f)
+                       goto not_found;
+
+               /* Instead of set of BACKREF queries constructing
+                * subvol path, use the one in mountinfo. Kernel does
+                * the evaluation for us.
+                */
+               DBG(BTRFS, ul_debug("setting FS root: btrfs default subvolid = %s",
+                                       default_id_str));
+
+               if (mnt_fs_get_option(f, "subvol", &vol, &volsz) != 0)
+                       goto not_found;
+       }
+
+       DBG(BTRFS, ul_debug(" using subvol=%s", vol));
+       sz = volsz;
+       if (*vol != '/')
+               sz++;
+       *root = malloc(sz + 1);
+       if (!*root)
+               goto err;
+       p = *root;
+       if (*vol != '/')
+               *p++ = '/';
+       memcpy(p, vol, volsz);
+       *(*root + sz) = '\0';
+       return 0;
+
+not_found:
+       DBG(BTRFS, ul_debug(" not found btrfs volume setting"));
+       return 1;
+err:
+       DBG(BTRFS, ul_debug(" error on btrfs volume setting evaluation"));
+       return errno ? -errno : -1;
+}
+#endif /* HAVE_BTRFS_SUPPORT */
+
 /*
  * tb: /proc/self/mountinfo
  * fs: filesystem
@@ -1319,106 +1433,8 @@ struct libmnt_fs *mnt_table_get_fs_root(struct libmnt_table *tb,
         * btrfs-subvolume mount -- get subvolume name and use it as a root-fs path
         */
        else if (fstype && (!strcmp(fstype, "btrfs") || !strcmp(fstype, "auto"))) {
-               char *vol = NULL, *p;
-               size_t sz, volsz = 0;
-
-               DBG(BTRFS, ul_debug("lookup for btrfs FS root"));
-
-               if (mnt_fs_get_option(fs, "subvolid", &vol, &volsz) != 0) {
-                       if (mnt_fs_get_option(fs, "subvol", &vol, &volsz) != 0) {
-                               /* If fstab entry does not contain "subvol", we
-                                * have to check, whether btrfs has default
-                                * subvolume defined.
-                                */
-                               uint64_t default_id;
-                               char *target;
-                               struct libmnt_fs *f;
-                               char default_id_str[sizeof(stringify_value(UINT64_MAX))];
-
-                               DBG(BTRFS, ul_debug(" subvolid/subvol not set, checking default"));
-
-                               default_id = btrfs_get_default_subvol_id(mnt_fs_get_target(fs));
-                               if (default_id == UINT64_MAX)
-                                       goto dflt;
-
-                               /* Volume has default subvolume. Check if it
-                                * matches to the one in mountinfo.
-                                *
-                                * Only kernel >= 4.2 reports subvolid. On older
-                                * kernels, there is no reasonable way to detect
-                                * which subvolume was mounted.
-                                */
-                               target = mnt_resolve_target(mnt_fs_get_target(fs), tb->cache);
-                               if (!target)
-                                       goto err;
-
-                               snprintf(default_id_str, sizeof(default_id_str), "%llu",
-                                               (unsigned long long int) default_id);
-
-                               DBG(BTRFS, ul_debug(" tring target=%s default subvolid=%s", target, default_id_str));
-                               f = mnt_table_find_target_with_option(tb, target,
-                                                       "subvolid", default_id_str,
-                                                       MNT_ITER_BACKWARD);
-                               if (!tb->cache)
-                                       free(target);
-                               if (!f)
-                                       goto dflt;
-
-                               /* Instead of set of BACKREF queries constructing
-                                * subvol path, use the one in mountinfo. Kernel
-                                * does the evaluation for us. */
-                               DBG(BTRFS, ul_debug("setting FS root: btrfs default subvolid = %s", default_id_str));
-                               if (mnt_fs_get_option(f, "subvol", &vol, &volsz))
-                                       goto dflt;
-                       } else
-                               DBG(BTRFS, ul_debug(" found subvol=%s", vol));
-               } else {
-                       char *target;
-                       struct libmnt_fs *f;
-                       char subvolidstr[sizeof(stringify_value(UINT64_MAX))];
-
-                       DBG(BTRFS, ul_debug(" found subvolid=%s, checking", vol));
-
-                       assert (volsz + 1 < sizeof(stringify_value(UINT64_MAX)));
-                       memcpy(subvolidstr, vol, volsz);
-                       subvolidstr[volsz] = '\0';
-
-                       target = mnt_resolve_target(mnt_fs_get_target(fs), tb->cache);
-                       if (!target)
-                               goto err;
-
-                       DBG(BTRFS, ul_debug(" tring target=%s subvolid=%s", target, subvolidstr));
-                       f = mnt_table_find_target_with_option(tb, target,
-                                               "subvolid", subvolidstr,
-                                               MNT_ITER_BACKWARD);
-                       if (!tb->cache)
-                               free(target);
-
-                       if (!f)
-                               goto dflt;
-
-                       /* Instead of set of BACKREF queries constructing
-                        * subvol path corresponding to a particular subvolid,
-                        * use the one in mountinfo. Kernel keeps subvol path
-                        * up to date.
-                        */
-                       if (mnt_fs_get_option(f, "subvol", &vol, &volsz))
-                               goto dflt;
-
-                       DBG(BTRFS, ul_debug(" found subvol=%s", vol));
-               }
-
-               sz = volsz;
-               if (*vol != '/')
-                       sz++;
-               root = malloc(sz + 1);
-               if (!root)
+               if (get_btrfs_fs_root(tb, fs, &root) < 0)
                        goto err;
-               p = root;
-               if (*vol != '/')
-                       *p++ = '/';
-               memcpy(p, vol, volsz);
-               *(root + sz) = '\0';
        }
 #endif /* HAVE_BTRFS_SUPPORT */