Re: Unexpected "ERROR: clone: did not find source subvol" on btrfs receive

[Alexander Wetzel]

While compiling I also switched to 
https://github.com/kdave/btrfs-progs.git. Same problem.

I then tracked the error down up to btrfs_uuid_tree_lookup_any():
nr_items is zero after the call
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_arg);
(ret is also zero)

So looks like this is a filesystem issue?

I've now "reused" the ret < 0 output in btrfs_uuid_tree_lookup_any() and 
added nt_items to it, too.

Then I get:

# /home/alex/src/b2/btrfs-progs/btrfs  receive -f test2 .
At snapshot 2021-02-20-TEMP
ioctl(BTRFS_IOC_TREE_SEARCH, uuid, key 483c17093f551dd3, UUID_KEY, 
896d0cfd51ec5cb6, nr_items=0) ret=0, error: No such file or directory
ioctl(BTRFS_IOC_TREE_SEARCH, uuid, key 483c17093f551dd3, UUID_KEY, 
896d0cfd51ec5cb6, nr_items=0) ret=0, error: No such file or directory
ERROR: clone: did not find source subvol si=0, 
uuid=d31d553f-0917-3c48-b65c-ec51fd0c6d89

Any ideas what I can check with that information? The key looks 
interesting...

Here my debug patch against current git:

diff --git a/cmds/receive.c b/cmds/receive.c
index 2aaba3ff..29244f88 100644
--- a/cmds/receive.c
+++ b/cmds/receive.c
@@ -726,6 +726,7 @@ static int process_clone(const char *path, u64 
offset, u64 len,
        char full_path[PATH_MAX];
        const char *subvol_path;
        char full_clone_path[PATH_MAX];
+       char uuid_str[BTRFS_UUID_UNPARSED_SIZE];
        int clone_fd = -1;

        ret = path_cat_out(full_path, rctx->full_subvol_path, path);
@@ -750,7 +751,8 @@ static int process_clone(const char *path, u64 
offset, u64 len,
                                ret = -ENOENT;
                        else
                                ret = PTR_ERR(si);
-                       error("clone: did not find source subvol");
+                       uuid_unparse(clone_uuid, uuid_str);
+                       error("clone: did not find source subvol si=%i, 
uuid=%s", si, uuid_str);
                        goto out;
                }
 		/* strip the subvolume that we are receiving to from the start of 
subvol_path */
diff --git a/kernel-shared/uuid-tree.c b/kernel-shared/uuid-tree.c
index 21115a4d..82f6d078 100644
--- a/kernel-shared/uuid-tree.c
+++ b/kernel-shared/uuid-tree.c
@@ -64,16 +64,17 @@ static int btrfs_uuid_tree_lookup_any(int fd, const 
u8 *uuid, u8 type,
        search_arg.key.max_transid = (u64)-1;
        search_arg.key.nr_items = 1;
        ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_arg);
-       if (ret < 0) {
+       if ((ret < 0) || (search_arg.key.nr_items < 1)) {
                fprintf(stderr,
-			"ioctl(BTRFS_IOC_TREE_SEARCH, uuid, key %016llx, UUID_KEY, %016llx) 
ret=%d, error: %m\n",
+			"ioctl(BTRFS_IOC_TREE_SEARCH, uuid, key %016llx, UUID_KEY, %016llx, 
nr_items=%d) ret=%d, error: %m\n",
                        (unsigned long long)key.objectid,
-                       (unsigned long long)key.offset, ret);
+                       (unsigned long long)key.offset, 
search_arg.key.nr_items, ret);
                ret = -ENOENT;
                goto out;
        }

        if (search_arg.key.nr_items < 1) {
+		fprintf(stderr, "DDD2 ret=%i nr_items=%i\n", ret, 
search_arg.key.nr_items);
                ret = -ENOENT;
                goto out;
        }