Btrfs-progs: avoid using btrfs internal subvolume path to send

Steps to reproduce:
	# mkfs.btrfs -f /dev/sda
	# mount /dev/sda /mnt
	# btrfs subvolume create /mnt/foo
	# umount /mnt
	# mount -o subvol=foo /dev/sda /mnt
	# btrfs sub snapshot -r /mnt /mnt/snap
	# btrfs send /mnt/snap > /dev/null

We will fail to send '/mnt/snap',this is because btrfs send try to
open '/mnt/snap' by btrfs internal subvolume path 'foo/snap' rather
than relative path based on mounted point, this will return us 'no
such file or directory',this is not right, fix it.

Reported-by: Thomas Scheiblauer <tom@sharkbay.at>
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/cmds-send.c b/cmds-send.c
index 3d21715..302f5a8 100644 (file)
--- a/cmds-send.c
+++ b/cmds-send.c
@@ -282,31 +282,21 @@ out:
        return ERR_PTR(ret);
 }
 
-static int do_send(struct btrfs_send *send, u64 root_id, u64 parent_root_id,
-                  int is_first_subvol, int is_last_subvol)
+static int do_send(struct btrfs_send *send, u64 parent_root_id,
+                  int is_first_subvol, int is_last_subvol, char *subvol)
 {
        int ret;
        pthread_t t_read;
        pthread_attr_t t_attr;
        struct btrfs_ioctl_send_args io_send;
-       struct subvol_info *si;
        void *t_err = NULL;
        int subvol_fd = -1;
        int pipefd[2] = {-1, -1};
 
-       si = subvol_uuid_search(&send->sus, root_id, NULL, 0, NULL,
-                       subvol_search_by_root_id);
-       if (!si) {
-               ret = -ENOENT;
-               fprintf(stderr, "ERROR: could not find subvol info for %llu",
-                               root_id);
-               goto out;
-       }
-
-       subvol_fd = openat(send->mnt_fd, si->path, O_RDONLY | O_NOATIME);
+       subvol_fd = openat(send->mnt_fd, subvol, O_RDONLY | O_NOATIME);
        if (subvol_fd < 0) {
                ret = -errno;
-               fprintf(stderr, "ERROR: open %s failed. %s\n", si->path,
+               fprintf(stderr, "ERROR: open %s failed. %s\n", subvol,
                                strerror(-ret));
                goto out;
        }
@@ -385,10 +375,6 @@ out:
                close(pipefd[0]);
        if (pipefd[1] != -1)
                close(pipefd[1]);
-       if (si) {
-               free(si->path);
-               free(si);
-       }
        return ret;
 }
 
@@ -664,14 +650,6 @@ int cmd_send(int argc, char **argv)
                        goto out;
                }
 
-               ret = get_root_id(&send, get_subvol_name(send.root_path, subvol),
-                               &root_id);
-               if (ret < 0) {
-                       fprintf(stderr, "ERROR: could not resolve root_id "
-                                       "for %s\n", subvol);
-                       goto out;
-               }
-
                if (!full_send && !parent_root_id) {
                        ret = find_good_parent(&send, root_id, &parent_root_id);
                        if (ret < 0) {
@@ -700,8 +678,8 @@ int cmd_send(int argc, char **argv)
                        is_first_subvol = 1;
                        is_last_subvol = 1;
                }
-               ret = do_send(&send, root_id, parent_root_id,
-                             is_first_subvol, is_last_subvol);
+               ret = do_send(&send, parent_root_id, is_first_subvol,
+                             is_last_subvol, subvol);
                if (ret < 0)
                        goto out;