Btrfs-progs: debug-tree, add option to dump a single tree

Very often while debugging filesystems with many subvolumes and/or
snapshots, specially when they are large, I want to see only the
content of one of the trees. So this change just adds an option
to btrfs-debug-tree to allow to specify the id of the tree we're
interesting in dumping to stdout.

Example:  btrfs-debug-tree -t 257 /dev/sdc

Will only dump the tree of the first snapshot or subvolume that was
created.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/btrfs-debug-tree.c b/btrfs-debug-tree.c
index cb6c106..36e1115 100644 (file)
--- a/btrfs-debug-tree.c
+++ b/btrfs-debug-tree.c
@@ -41,6 +41,8 @@ static int print_usage(void)
        fprintf(stderr, "\t-u : print info of uuid tree only\n");
        fprintf(stderr, "\t-b block_num : print info of the specified block"
                     " only\n");
+       fprintf(stderr,
+               "\t-t tree_id : print only the tree with the given id\n");
        fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
        exit(1);
 }
@@ -136,12 +138,13 @@ int main(int ac, char **av)
        int root_backups = 0;
        u64 block_only = 0;
        struct btrfs_root *tree_root_scan;
+       u64 tree_id = 0;
 
        radix_tree_init();
 
        while(1) {
                int c;
-               c = getopt(ac, av, "deb:rRu");
+               c = getopt(ac, av, "deb:rRut:");
                if (c < 0)
                        break;
                switch(c) {
@@ -164,6 +167,9 @@ int main(int ac, char **av)
                        case 'b':
                                block_only = arg_strtou64(optarg);
                                break;
+                       case 't':
+                               tree_id = arg_strtou64(optarg);
+                               break;
                        default:
                                print_usage();
                }
@@ -208,7 +214,7 @@ int main(int ac, char **av)
                goto close_root;
        }
 
-       if (!(extent_only || uuid_tree_only)) {
+       if (!(extent_only || uuid_tree_only || tree_id)) {
                if (roots_only) {
                        printf("root tree: %llu level %d\n",
                             (unsigned long long)info->tree_root->node->start,
@@ -268,6 +274,8 @@ again:
                                              0);
                        if (!extent_buffer_uptodate(buf))
                                goto next;
+                       if (tree_id && found_key.objectid != tree_id)
+                               goto next;
 
                        switch(found_key.objectid) {
                        case BTRFS_ROOT_TREE_OBJECTID: