btrfs: retrieve more info from FS_INFO ioctl

Provide the basic information about filesystem through the ioctl:
* b-tree node size (same as leaf size)
* sector size
* expected alignment of CLONE_RANGE and EXTENT_SAME ioctl arguments

Backward compatibility: if the values are 0, kernel does not provide
this information, the applications should ignore them.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 901a3c563f60..7554fd381a56 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -181,7 +181,11 @@ struct btrfs_ioctl_fs_info_args {
         __u64 max_id;                           /* out */
         __u64 num_devices;                      /* out */
         __u8 fsid[BTRFS_FSID_SIZE];             /* out */
-        __u64 reserved[124];                    /* pad to 1k */
+        __u32 nodesize;                         /* out */
+        __u32 sectorsize;                       /* out */
+        __u32 clone_alignment;                  /* out */
+        __u32 reserved32;
+        __u64 reserved[122];                    /* pad to 1k */
 };
 
 struct btrfs_ioctl_feature_flags {