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From: Anand Jain <anand.jain@oracle.com>
To: Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2 7/7] btrfs-progs: btrfstune: Allow to enable bg-tree feature offline
Date: Thu, 17 Oct 2019 12:17:27 +0800
Message-ID: <92f936ed-74eb-5c6e-2bf7-6226cdef14fd@oracle.com> (raw)
In-Reply-To: <20191008044936.157873-8-wqu@suse.com>


  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.

  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 <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");
> 


  reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-08  4:49 [PATCH v2 0/7] btrfs-progs: Support for BG_TREE feature Qu Wenruo
2019-10-08  4:49 ` [PATCH v2 1/7] btrfs-progs: Refactor excluded extent functions to use fs_info Qu Wenruo
2019-10-08  9:22   ` Johannes Thumshirn
2019-10-17  2:16   ` Anand Jain
2019-10-08  4:49 ` [PATCH v2 2/7] btrfs-progs: Refactor btrfs_read_block_groups() Qu Wenruo
2019-10-17  3:23   ` Anand Jain
2019-10-17  4:33     ` Qu Wenruo
2019-10-17  5:08       ` Anand Jain
2019-10-08  4:49 ` [PATCH v2 3/7] btrfs-progs: Enable read-write ability for 'bg_tree' feature Qu Wenruo
2019-10-17  4:56   ` Anand Jain
2019-10-08  4:49 ` [PATCH v2 4/7] btrfs-progs: mkfs: Introduce -O bg-tree Qu Wenruo
2019-10-08  8:16   ` [PATCH v2.1 " Qu Wenruo
2019-10-08  4:49 ` [PATCH v2 5/7] btrfs-progs: dump-tree/dump-super: Introduce support for bg tree Qu Wenruo
2019-10-08  4:49 ` [PATCH v2 6/7] btrfs-progs: check: Introduce support for bg-tree feature Qu Wenruo
2019-10-08  4:49 ` [PATCH v2 7/7] btrfs-progs: btrfstune: Allow to enable bg-tree feature offline Qu Wenruo
2019-10-17  4:17   ` Anand Jain [this message]
2019-10-17  4:28     ` Qu Wenruo
2019-10-14 15:17 ` [PATCH v2 0/7] btrfs-progs: Support for BG_TREE feature David Sterba
2019-10-15  0:32   ` Qu Wenruo
2019-10-16 11:16     ` David Sterba
2019-10-16 11:19       ` Qu WenRuo
2019-10-18 17:27         ` David Sterba
2019-10-19  0:04           ` Qu Wenruo
2019-10-21 15:44             ` David Sterba
2019-10-22  0:49               ` Qu Wenruo
2019-10-22  6:30                 ` Qu Wenruo
2019-10-22 12:23                   ` David Sterba
2019-10-22 12:27                     ` Qu Wenruo

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