Re: [PATCH v2] btrfs-progs: chunk tree search solution for btrfs249

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2022/8/15 10:43, Flint.Wang wrote:
> Hi Qu,
> 
> Thanks for your comment. I fix the issue you suggest.
> It is much clean now.
> 
> Btrfs249 failed due to btrfs_ioctl_fs_info() return RW devices for fi_args->num_devices.
> This patch search chunk tree to find rw devices.
> 
> v2 change:
> 1. code style fix.
> 2. noseed_dev => rw_devs, noseed_fsid => fsid.
> 3. remove redundant structure devid_uuid.
> 4. reuse the dev_info structure.
> 5. remove redundant uuid argument.
> 
> Signed-off-by: Flint.Wang <hmsjwzb@zoho.com>

Any update on this patch? IIRC btrfs/249 still fails without this patch.

Although Anand Jain has a similar patchset, but his solution requires a 
new kernel sysfs, which can still cause compatibility problems.

Thus your patch is still the better one, but your commit message still 
needs some update.

Thanks,
Qu
> ---
>   cmds/filesystem-usage.c | 83 ++++++++++++++++++++++++++++++++---------
>   1 file changed, 66 insertions(+), 17 deletions(-)
> 
> diff --git a/cmds/filesystem-usage.c b/cmds/filesystem-usage.c
> index 01729e18..71f0e14c 100644
> --- a/cmds/filesystem-usage.c
> +++ b/cmds/filesystem-usage.c
> @@ -25,6 +25,7 @@
>   #include <getopt.h>
>   #include <fcntl.h>
>   #include <linux/limits.h>
> +#include <uuid/uuid.h>
>   
>   #include "common/utils.h"
>   #include "kerncompat.h"
> @@ -689,6 +690,62 @@ out:
>   	return ret;
>   }
>   
> +static int load_devid(int fd, struct device_info *info,
> +			    int ndev, u8 *fsid)
> +{
> +	struct btrfs_ioctl_search_args_v2 *args2;
> +	struct btrfs_ioctl_search_key *sk;
> +	struct btrfs_ioctl_search_header *sh;
> +	struct btrfs_dev_item *dev_item;
> +	int args2_size = 1024;
> +	char args2_buf[args2_size];
> +	int ret = 0;
> +	int i = 0;
> +	int num = 0;
> +	int rw_devs = 0;
> +	int idx = 0;
> +
> +	args2 = (struct btrfs_ioctl_search_args_v2 *) args2_buf;
> +	sk = &(args2->key);
> +
> +	sk->tree_id = BTRFS_CHUNK_TREE_OBJECTID;
> +	sk->min_objectid = BTRFS_DEV_ITEMS_OBJECTID;
> +	sk->max_objectid = BTRFS_DEV_ITEMS_OBJECTID;
> +	sk->min_type = BTRFS_DEV_ITEM_KEY;
> +	sk->max_type = BTRFS_DEV_ITEM_KEY;
> +	sk->min_offset = 0;
> +	sk->max_offset = (u64)-1;
> +	sk->min_transid = 0;
> +	sk->max_transid = (u64)-1;
> +	sk->nr_items = -1;
> +	args2->buf_size = args2_size - sizeof(struct btrfs_ioctl_search_args_v2);
> +	ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH_V2, args2);
> +	if (ret != 0)
> +	       return -1;
> +
> +	sh = (struct btrfs_ioctl_search_header *) args2->buf;
> +	num = sk->nr_items;
> +
> +	dev_item = (struct btrfs_dev_item *) (sh + 1);
> +	for (i = 0; i < num; i++) {
> +		if (!uuid_compare(dev_item->fsid, fsid)) {
> +			rw_devs += 1;
> +			info[idx++].devid = dev_item->devid;
> +		}
> +		if (idx > ndev) {
> +			error("unexpected number of devices: %d >= %d", idx, ndev);
> +			return -1;
> +		}
> +		sh = (struct btrfs_ioctl_search_header *) dev_item + 1;
> +		dev_item = (struct btrfs_dev_item *) sh + 1;
> +	}
> +
> +	if (ndev != rw_devs)
> +		error("unexpected number of devices: %d != %d", ndev, rw_devs);
> +
> +	return 0;
> +}
> +
>   /*
>    *  This function loads the device_info structure and put them in an array
>    */
> @@ -718,19 +775,17 @@ static int load_device_info(int fd, struct device_info **device_info_ptr,
>   		return 1;
>   	}
>   
> -	for (i = 0, ndevs = 0 ; i <= fi_args.max_id ; i++) {
> -		if (ndevs >= fi_args.num_devices) {
> -			error("unexpected number of devices: %d >= %llu", ndevs,
> -				(unsigned long long)fi_args.num_devices);
> -			error(
> -		"if seed device is used, try running this command as root");
> -			goto out;
> -		}
> +	ret = load_devid(fd, info, fi_args.num_devices, fi_args.fsid);
> +	if (ret == -1)
> +		goto out;
> +
> +	for (i = 0, ndevs = 0 ; i < fi_args.num_devices ; i++) {
>   		memset(&dev_info, 0, sizeof(dev_info));
> -		ret = get_device_info(fd, i, &dev_info);
> +		ret = get_device_info(fd, info[i].devid, &dev_info);
>   
> -		if (ret == -ENODEV)
> -			continue;
> +		if (ret == -ENODEV) {
> +			error("device not found\n");
> +		}
>   		if (ret) {
>   			error("cannot get info about device devid=%d", i);
>   			goto out;
> @@ -759,12 +814,6 @@ static int load_device_info(int fd, struct device_info **device_info_ptr,
>   		++ndevs;
>   	}
>   
> -	if (ndevs != fi_args.num_devices) {
> -		error("unexpected number of devices: %d != %llu", ndevs,
> -				(unsigned long long)fi_args.num_devices);
> -		goto out;
> -	}
> -
>   	qsort(info, fi_args.num_devices,
>   		sizeof(struct device_info), cmp_device_info);
>