[PATCH v2 7/7] btrfs-progs: btrfstune: Allow to enable bg-tree feature offline

Qu Wenruo
2019-10-08T04:49:52Z

Add a new option '-b' for btrfstune, to enable bg-tree feature for a
unmounted fs.

This feature will convert all BLOCK_GROUP_ITEMs in extent tree to bg
tree, by reusing the existing btrfs_convert_to_bg_tree() function.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
Documentation/btrfstune.asciidoc | 6 +++++
btrfstune.c | 44 ++++++++++++++++++++++++++++++--
2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/Documentation/btrfstune.asciidoc b/Documentation/btrfstune.asciidoc
index 1d6bc98deed8..ed54c2e1597f 100644
--- a/Documentation/btrfstune.asciidoc
+++ b/Documentation/btrfstune.asciidoc
@@ -26,6 +26,12 @@ means. Please refer to the 'FILESYSTEM FEATURES' in `btrfs`(5).
OPTIONS
-------

+-b::
+(since kernel: 5.x)
++
+enable bg-tree feature (faster mount time for large fs), enabled by mkfs
+feature 'bg-tree'.
+
-f::
Allow dangerous changes, e.g. clear the seeding flag or change fsid. Make sure
that you are aware of the dangers.
diff --git a/btrfstune.c b/btrfstune.c
index afa3aae35412..aa1ac568aef0 100644
--- a/btrfstune.c
+++ b/btrfstune.c
@@ -476,11 +476,39 @@ static void print_usage(void)
printf("\t-m change fsid in metadata_uuid to a random UUID\n");
printf("\t (incompat change, more lightweight than -u|-U)\n");
printf("\t-M UUID change fsid in metadata_uuid to UUID\n");
+ printf("\t-b enable bg-tree feature (mkfs: bg-tree, for faster mount time)\n");
printf(" general:\n");
printf("\t-f allow dangerous operations, make sure that you are aware of the dangers\n");
printf("\t--help print this help\n");
}

+static int convert_to_bg_tree(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_trans_handle *trans;
+ int ret;
+
+ trans = btrfs_start_transaction(fs_info->tree_root, 1);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ errno = -ret;
+ error("failed to start transaction: %m");
+ return ret;
+ }
+ ret = btrfs_convert_to_bg_tree(trans);
+ if (ret < 0) {
+ errno = -ret;
+ error("failed to convert: %m");
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ ret = btrfs_commit_transaction(trans, fs_info->tree_root);
+ if (ret < 0) {
+ errno = -ret;
+ error("failed to commit transaction: %m");
+ }
+ return ret;
+}
+
int BOX_MAIN(btrfstune)(int argc, char *argv[])
{
struct btrfs_root *root;
@@ -491,6 +519,7 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
u64 seeding_value = 0;
int random_fsid = 0;
int change_metadata_uuid = 0;
+ bool to_bg_tree = false;
char *new_fsid_str = NULL;
int ret;
u64 super_flags = 0;
@@ -501,7 +530,7 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
{ "help", no_argument, NULL, GETOPT_VAL_HELP},
{ NULL, 0, NULL, 0 }
};
- int c = getopt_long(argc, argv, "S:rxfuU:nmM:", long_options, NULL);
+ int c = getopt_long(argc, argv, "S:rxfuU:nmM:b", long_options, NULL);

if (c < 0)
break;
@@ -539,6 +568,9 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
ctree_flags |= OPEN_CTREE_IGNORE_FSID_MISMATCH;
change_metadata_uuid = 1;
break;
+ case 'b':
+ to_bg_tree = true;
+ break;
case GETOPT_VAL_HELP:
default:
print_usage();
@@ -556,7 +588,7 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
return 1;
}
if (!super_flags && !seeding_flag && !(random_fsid || new_fsid_str) &&
- !change_metadata_uuid) {
+ !change_metadata_uuid && !to_bg_tree) {
error("at least one option should be specified");
print_usage();
return 1;
@@ -602,6 +634,14 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
return 1;
}

+ if (to_bg_tree) {
+ ret = convert_to_bg_tree(root->fs_info);
+ if (ret < 0) {
+ errno = -ret;
+ error("failed to convert to bg-tree feature: %m");
+ goto out;
+ }
+ }
if (seeding_flag) {
if (btrfs_fs_incompat(root->fs_info, METADATA_UUID)) {
fprintf(stderr, "SEED flag cannot be changed on a metadata-uuid changed fs\n");
--
2.23.0