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

[Gui Hecheng <guihc.fnst@cn.fujitsu.com>]

On Thu, 2014-09-18 at 13:59 +0800, Anand Jain wrote:
> 
>   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.

Yes, I think the seed/sprout mapping relation do have to be clarified.

> > 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 ?

Oh, this seems to be my missing point. I will test it in the next
version.

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

That sounds to be a good idea. So I will keep the original
@btrfs_scan_lblkid() and try to build the seed/sprout mapping after it.

Thanks very much for your comments, please allow me to give a "re-shot".

-Gui

> 
> 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();
> >