Btrfs: add basic restriper infrastructure

Add basic restriper infrastructure: extended balancing ioctl and all
related ioctl data structures, add data structure for tracking
restriper's state to fs_info, etc.  The semantics of the old balancing
ioctl are fully preserved.

Explicitly disallow any volume operations when balance is in progress.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 252ae9915de8..c8b37d2c0d77 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -109,6 +109,47 @@ struct btrfs_ioctl_fs_info_args {
         __u64 reserved[124];                    /* pad to 1k */
 };
 
+/*
+ * this is packed, because it should be exactly the same as its disk
+ * byte order counterpart (struct btrfs_disk_balance_args)
+ */
+struct btrfs_balance_args {
+        __u64 profiles;
+        __u64 usage;
+        __u64 devid;
+        __u64 pstart;
+        __u64 pend;
+        __u64 vstart;
+        __u64 vend;
+
+        __u64 target;
+
+        __u64 flags;
+
+        __u64 unused[8];
+} __attribute__ ((__packed__));
+
+/* report balance progress to userspace */
+struct btrfs_balance_progress {
+        __u64 expected;         /* estimated # of chunks that will be
+                                 * relocated to fulfill the request */
+        __u64 considered;       /* # of chunks we have considered so far */
+        __u64 completed;        /* # of chunks relocated so far */
+};
+
+struct btrfs_ioctl_balance_args {
+        __u64 flags;                            /* in/out */
+        __u64 state;                            /* out */
+
+        struct btrfs_balance_args data;         /* in/out */
+        struct btrfs_balance_args meta;         /* in/out */
+        struct btrfs_balance_args sys;          /* in/out */
+
+        struct btrfs_balance_progress stat;     /* out */
+
+        __u64 unused[72];                       /* pad to 1k */
+};
+
 #define BTRFS_INO_LOOKUP_PATH_MAX 4080
 struct btrfs_ioctl_ino_lookup_args {
         __u64 treeid;
@@ -272,6 +313,8 @@ struct btrfs_ioctl_logical_ino_args {
                                  struct btrfs_ioctl_dev_info_args)
 #define BTRFS_IOC_FS_INFO _IOR(BTRFS_IOCTL_MAGIC, 31, \
                                struct btrfs_ioctl_fs_info_args)
+#define BTRFS_IOC_BALANCE_V2 _IOWR(BTRFS_IOCTL_MAGIC, 32, \
+                                   struct btrfs_ioctl_balance_args)
 #define BTRFS_IOC_INO_PATHS _IOWR(BTRFS_IOCTL_MAGIC, 35, \
                                         struct btrfs_ioctl_ino_path_args)
 #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \