On 2019/10/17 下午12:17, Anand Jain wrote: > > Depending on the size of the FS the convert may take longer, further > fatal error (power loss; pid kill) may leave the FS in a state where > the bg items are in both extent-tree and bg-tree.
That's why I'm using one transaction to convert them all.
So if the convert get interrutped, we're still safe.
Thanks,
Qu
>
> The lessons which lead to the implementation of metadata_uuid fsid
> suggests, for conversions its better to use the btrfstune to only
> flag the bg convert requirement and let the kernel handle of migration
> of the bg items from the extent-tree to the bg-tree as and when the
> bg-items are written.
>
> Thanks, Anand
>
>
> On 10/8/19 12:49 PM, Qu Wenruo wrote:
>> 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 <w...@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");
>>
>
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