Re: [PATCH 3/3] btrfs-progs: fix device missing of btrfs fi show with seeding devices

[Anand Jain <Anand.Jain@oracle.com>]

  Hi Gui,

  Thanks for the attempt to fix this. more below..

On 09/18/2014 11:31 AM, Gui Hecheng wrote:
> *Note*: this handles the problem under umounted state,
> 	the problem under mounted state is already fixed by Anand.
>
> Steps to reproduce:
> 	# mkfs.btrfs -f /dev/sda1
> 	# btrfstune -S 1 /dev/sda1
> 	# mount /dev/sda1 /mnt
> 	# btrfs dev add /dev/sda2 /mnt
> 	# umount /mnt			<== (umounted)
> 	# btrfs fi show /dev/sda2
> result:
> 	Label: none  uuid: XXXXXXXXXXXXXXXXXX
> 	Total devices 2 FS bytes used 368.00KiB
> 	devid    2 size 9.31GiB used 1.25GiB path /dev/sda2
> 	*** Some devices missing
> 	Btrfs v3.16-67-g69f54ea-dirty
>
> It is because the @btrfs_scan_lblkid procedure is not capable of detecting
> seeding devices since the seeding devices have different FSIDs from
> derived devices. So when it tries to show all devices under the derived
> fs, only the derived devices are shown.

  Hmm.. thats not true.  btrfs_scan_lblkid() finds all btrfs devices
  including the seed/sprout devices. However btrfs_scan_lblkid won't
  establish mapping between the seed and sprout devices.

> Actually the @open_ctree deal with the seeding devices properly, so
> we can make use of it to find seeding devices.
> We call @open_ctree on every block device with a btrfs on it,
> and all devices under the opening filesystem including the seed devices
> will be ready to be shown.

  looking at the below code, I doubt if this will work with
  nested seed-sprout relations. ? what did I miss ?

  Its better to keep seed sprout mapping part separate from the device
  scan using lblkid.


Thanks, Anand


> Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
> ---
>   cmds-filesystem.c | 104 ++++++++++++++++++++++++++++++++++++------------------
>   1 file changed, 69 insertions(+), 35 deletions(-)
>
> diff --git a/cmds-filesystem.c b/cmds-filesystem.c
> index dc5185e..f978175 100644
> --- a/cmds-filesystem.c
> +++ b/cmds-filesystem.c
> @@ -28,6 +28,7 @@
>   #include <mntent.h>
>   #include <linux/limits.h>
>   #include <getopt.h>
> +#include <blkid/blkid.h>
>
>   #include "kerncompat.h"
>   #include "ctree.h"
> @@ -268,10 +269,26 @@ static int cmp_device_id(void *priv, struct list_head *a,
>   		da->devid > db->devid ? 1 : 0;
>   }
>
> +static void print_devices(struct btrfs_fs_devices *fs_devices, u64 *devs_found)
> +{
> +	struct btrfs_device *device;
> +	struct list_head *cur;
> +
> +	list_sort(NULL, &fs_devices->devices, cmp_device_id);
> +	list_for_each(cur, &fs_devices->devices) {
> +		device = list_entry(cur, struct btrfs_device, dev_list);
> +
> +		printf("\tdevid %4llu size %s used %s path %s\n",
> +			(unsigned long long)device->devid,
> +			pretty_size(device->total_bytes),
> +			pretty_size(device->bytes_used), device->name);
> +			(*devs_found)++;
> +		}
> +}
> +
>   static void print_one_uuid(struct btrfs_fs_devices *fs_devices)
>   {
>   	char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
> -	struct list_head *cur;
>   	struct btrfs_device *device;
>   	u64 devs_found = 0;
>   	u64 total;
> @@ -293,17 +310,10 @@ static void print_one_uuid(struct btrfs_fs_devices *fs_devices)
>   	       (unsigned long long)total,
>   	       pretty_size(device->super_bytes_used));
>
> -	list_sort(NULL, &fs_devices->devices, cmp_device_id);
> -	list_for_each(cur, &fs_devices->devices) {
> -		device = list_entry(cur, struct btrfs_device, dev_list);
> -
> -		printf("\tdevid %4llu size %s used %s path %s\n",
> -		       (unsigned long long)device->devid,
> -		       pretty_size(device->total_bytes),
> -		       pretty_size(device->bytes_used), device->name);
> +	if (fs_devices->seed)
> +		print_devices(fs_devices->seed, &devs_found);
> +	print_devices(fs_devices, &devs_found);
>
> -		devs_found++;
> -	}
>   	if (devs_found < total) {
>   		printf("\t*** Some devices missing\n");
>   	}
> @@ -489,6 +499,53 @@ out:
>   	return ret;
>   }
>
> +static int scan_all_fs_lblkid(char *search_target)
> +{
> +	blkid_dev_iterate iter = NULL;
> +	blkid_dev dev = NULL;
> +	blkid_cache cache = NULL;
> +	char path[PATH_MAX];
> +	struct btrfs_fs_info *fs_info;
> +	int found = 0;
> +
> +	if (blkid_get_cache(&cache, 0) < 0) {
> +		printf("ERROR: lblkid cache get failed\n");
> +		return -1;
> +	}
> +	blkid_probe_all(cache);
> +	iter = blkid_dev_iterate_begin(cache);
> +	blkid_dev_set_search(iter, "TYPE", "btrfs");
> +	while (blkid_dev_next(iter, &dev) == 0) {
> +		dev = blkid_verify(cache, dev);
> +		if (!dev)
> +			continue;
> +		strncpy(path, blkid_dev_devname(dev), PATH_MAX);
> +		fs_info = open_ctree_fs_info(path, 0, 0, OPEN_CTREE_PARTIAL);
> +		if (!fs_info)
> +			continue;
> +
> +		if (search_target
> +			&& !uuid_search(fs_info->fs_devices, search_target)) {
> +			close_ctree(fs_info->fs_root);
> +			continue;
> +		}
> +
> +		if (search_target)
> +			found = 1;
> +		print_one_uuid(fs_info->fs_devices);
> +
> +		close_ctree(fs_info->fs_root);
> +	}
> +	blkid_dev_iterate_end(iter);
> +	blkid_put_cache(cache);
> +
> +	if (search_target && !found)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +
>   static const char * const cmd_show_usage[] = {
>   	"btrfs filesystem show [options] [<path>|<uuid>|<device>|label]",
>   	"Show the structure of a filesystem",
> @@ -500,9 +557,6 @@ static const char * const cmd_show_usage[] = {
>
>   static int cmd_show(int argc, char **argv)
>   {
> -	struct list_head *all_uuids;
> -	struct btrfs_fs_devices *fs_devices;
> -	struct list_head *cur_uuid;
>   	char *search = NULL;
>   	int ret;
>   	int where = -1; // default, search both kernel and udev
> @@ -511,7 +565,6 @@ static int cmd_show(int argc, char **argv)
>   	char path[PATH_MAX];
>   	__u8 fsid[BTRFS_FSID_SIZE];
>   	char uuid_buf[BTRFS_UUID_UNPARSED_SIZE];
> -	int found = 0;
>
>   	while (1) {
>   		int long_index;
> @@ -601,31 +654,12 @@ static int cmd_show(int argc, char **argv)
>   		goto out;
>
>   devs_only:
> -	ret = btrfs_scan_lblkid(!BTRFS_UPDATE_KERNEL);
> -
> +	ret = scan_all_fs_lblkid(search);
>   	if (ret) {
>   		fprintf(stderr, "ERROR: %d while scanning\n", ret);
>   		return 1;
>   	}
>   	
> -	all_uuids = btrfs_scanned_uuids();
> -	list_for_each(cur_uuid, all_uuids) {
> -		fs_devices = list_entry(cur_uuid, struct btrfs_fs_devices,
> -					list);
> -		if (search && uuid_search(fs_devices, search) == 0)
> -			continue;
> -
> -		print_one_uuid(fs_devices);
> -		found = 1;
> -	}
> -	if (search && !found)
> -		ret = 1;
> -
> -	while (!list_empty(all_uuids)) {
> -		fs_devices = list_entry(all_uuids->next,
> -					struct btrfs_fs_devices, list);
> -		btrfs_close_devices(fs_devices);
> -	}
>   out:
>   	printf("%s\n", BTRFS_BUILD_VERSION);
>   	free_seen_fsid();
>