Btrfs: add support for device replace ioctls

This is the commit that allows to start the device replace
procedure.

An ioctl() interface is added that supports starting and
canceling the device replace procedure, and to retrieve
the status and progress.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 62006ba02719..dabca9cc8c2e 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -30,6 +30,8 @@ struct btrfs_ioctl_vol_args {
         char name[BTRFS_PATH_NAME_MAX + 1];
 };
 
+#define BTRFS_DEVICE_PATH_NAME_MAX 1024
+
 #define BTRFS_SUBVOL_CREATE_ASYNC       (1ULL << 0)
 #define BTRFS_SUBVOL_RDONLY             (1ULL << 1)
 #define BTRFS_SUBVOL_QGROUP_INHERIT     (1ULL << 2)
@@ -127,10 +129,10 @@ struct btrfs_ioctl_scrub_args {
 #define BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID     1
 struct btrfs_ioctl_dev_replace_start_params {
         __u64 srcdevid; /* in, if 0, use srcdev_name instead */
-        __u8 srcdev_name[BTRFS_PATH_NAME_MAX + 1];      /* in */
-        __u8 tgtdev_name[BTRFS_PATH_NAME_MAX + 1];      /* in */
         __u64 cont_reading_from_srcdev_mode;    /* in, see #define
                                                  * above */
+        __u8 srcdev_name[BTRFS_DEVICE_PATH_NAME_MAX + 1];       /* in */
+        __u8 tgtdev_name[BTRFS_DEVICE_PATH_NAME_MAX + 1];       /* in */
 };
 
 #define BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED     0
@@ -165,7 +167,6 @@ struct btrfs_ioctl_dev_replace_args {
         __u64 spare[64];
 };
 
-#define BTRFS_DEVICE_PATH_NAME_MAX 1024
 struct btrfs_ioctl_dev_info_args {
         __u64 devid;                            /* in/out */
         __u8 uuid[BTRFS_UUID_SIZE];             /* in/out */