[PATCH 1/3 v3] btrfs-progs: there is devid 0 when replace is running

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

From: Anand Jain <anand.jain@oracle.com>

as of now, when we replace a disk, it is added to the
dev list with devid 0. And we fail to obtain details
of devid 0 because we don't query devid 0 at all.

reproducer:

 btrfs rep start /dev/sdb /dev/sdf /btrfs
 btrfs fi show
 Label: none  uuid: f8fb9819-16c8-47b7-b62f-0ff90f8c56cd
        Total devices 3 FS bytes used 1.94GiB
        devid    1 size 1.10GiB used 1.10GiB path /dev/sdb
        devid    2 size 1.10GiB used 1.08GiB path /dev/sdc
        devid    0 size 0.00 used 0.00 path

  this patch will make it proper by querying devid 0.

 btrfs repl start /dev/sdb /dev/sdf /btrfs
 btrfs fi show /btrfs
 Label: none  uuid: f8fb9819-16c8-47b7-b62f-0ff90f8c56cd
        Total devices 3 FS bytes used 1.94GiB
        devid    0 size 1.10GiB used 1.10GiB path /dev/sdf
        devid    1 size 1.10GiB used 1.10GiB path /dev/sdb
        devid    2 size 1.10GiB used 1.08GiB path /dev/sdc

 Its fine to query devid 0 when there is no replace
 activity as well, because we just skip the error ENODEV

 btrfs fi show /btrfs
 Label: none  uuid: f8fb9819-16c8-47b7-b62f-0ff90f8c56cd
        Total devices 2 FS bytes used 1.94GiB
        devid    1 size 1.10GiB used 1.10GiB path /dev/sdf
        devid    2 size 1.10GiB used 1.08GiB path /dev/sdc

Signed-off-by: Anand Jain <Anand.Jain@oracle.com>
---
 v3: it needs to handle per devid probe
 v2: commit message fix

 utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/utils.c b/utils.c
index de513b6..e0c750d 100644
--- a/utils.c
+++ b/utils.c
@@ -1637,7 +1637,7 @@ int get_fs_info(char *path, struct btrfs_ioctl_fs_info_args *fi_args,
 	int fd = -1;
 	int ret = 0;
 	int ndevs = 0;
-	int i = 1;
+	int i = 0;
 	struct btrfs_fs_devices *fs_devices_mnt = NULL;
 	struct btrfs_ioctl_dev_info_args *di_args;
 	char mp[BTRFS_PATH_NAME_MAX + 1];
-- 
1.8.4.2