btrfs-progs: apply realpath for btrfs fi show when mount point is given

For now,
	# btrfs fi show /mnt/btrfs
gives info correctly, while
	# btrfs fi show /mnt/btrfs/
gives nothing.

This implies that the @realpath() function should be applied to
unify the behavior.

Made a more clear comment right above the call as well.

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index cd6b3c6..253f105 100644 (file)
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -901,39 +901,45 @@ static int cmd_show(int argc, char **argv)
                if (strlen(search) == 0)
                        usage(cmd_show_usage);
                type = check_arg_type(search);
+
                /*
-                * needs spl handling if input arg is block dev
-                * And if input arg is mount-point just print it
-                * right away
+                * For search is a device:
+                *     realpath do /dev/mapper/XX => /dev/dm-X
+                *     which is required by BTRFS_SCAN_DEV
+                * For search is a mountpoint:
+                *     realpath do  /mnt/btrfs/  => /mnt/btrfs
+                *     which shall be recognized by btrfs_scan_kernel()
                 */
-               if (type == BTRFS_ARG_BLKDEV) {
-                       if (where == BTRFS_SCAN_LBLKID) {
-                               /* we need to do this because
-                                * legacy BTRFS_SCAN_DEV
-                                * provides /dev/dm-x paths
-                                */
-                               if (realpath(search, path))
-                                       search = path;
+               if (!realpath(search, path)) {
+                       fprintf(stderr, "ERROR: Could not show %s: %s\n",
+                                       search, strerror(errno));
+                       return 1;
+               }
+
+               search = path;
+
+               /*
+                * Needs special handling if input arg is block dev And if
+                * input arg is mount-point just print it right away
+                */
+               if (type == BTRFS_ARG_BLKDEV && where != BTRFS_SCAN_LBLKID) {
+                       ret = get_btrfs_mount(search, mp, sizeof(mp));
+                       if (!ret) {
+                               /* given block dev is mounted */
+                               search = mp;
+                               type = BTRFS_ARG_MNTPOINT;
                        } else {
-                               ret = get_btrfs_mount(search,
-                                               mp, sizeof(mp));
-                               if (!ret) {
-                                       /* given block dev is mounted*/
-                                       search = mp;
-                                       type = BTRFS_ARG_MNTPOINT;
-                               } else {
-                                       ret = dev_to_fsid(search, fsid);
-                                       if (ret) {
-                                               fprintf(stderr,
-                                                       "ERROR: No btrfs on %s\n",
-                                                       search);
-                                               return 1;
-                                       }
-                                       uuid_unparse(fsid, uuid_buf);
-                                       search = uuid_buf;
-                                       type = BTRFS_ARG_UUID;
-                                       goto devs_only;
+                               ret = dev_to_fsid(search, fsid);
+                               if (ret) {
+                                       fprintf(stderr,
+                                               "ERROR: No btrfs on %s\n",
+                                               search);
+                                       return 1;
                                }
+                               uuid_unparse(fsid, uuid_buf);
+                               search = uuid_buf;
+                               type = BTRFS_ARG_UUID;
+                               goto devs_only;
                        }
                }
        }