nilfs2: add comments for ioctls
Add comments for ioctls in fs/nilfs2/ioctl.c file and describe NILFS2
specific ioctls in Documentation/filesystems/nilfs2.txt.
Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Reviewed-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Wenliang Fan <fanwlexca@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/filesystems/nilfs2.txt b/Documentation/filesystems/nilfs2.txt
index 873a2ab..06887d4 100644
--- a/Documentation/filesystems/nilfs2.txt
+++ b/Documentation/filesystems/nilfs2.txt
@@ -81,6 +81,62 @@
block device when blocks are freed. This is useful
for SSD devices and sparse/thinly-provisioned LUNs.
+Ioctls
+======
+
+There is some NILFS2 specific functionality which can be accessed by applications
+through the system call interfaces. The list of all NILFS2 specific ioctls are
+shown in the table below.
+
+Table of NILFS2 specific ioctls
+..............................................................................
+ Ioctl Description
+ NILFS_IOCTL_CHANGE_CPMODE Change mode of given checkpoint between
+ checkpoint and snapshot state. This ioctl is
+ used in chcp and mkcp utilities.
+
+ NILFS_IOCTL_DELETE_CHECKPOINT Remove checkpoint from NILFS2 file system.
+ This ioctl is used in rmcp utility.
+
+ NILFS_IOCTL_GET_CPINFO Return info about requested checkpoints. This
+ ioctl is used in lscp utility and by
+ nilfs_cleanerd daemon.
+
+ NILFS_IOCTL_GET_CPSTAT Return checkpoints statistics. This ioctl is
+ used by lscp, rmcp utilities and by
+ nilfs_cleanerd daemon.
+
+ NILFS_IOCTL_GET_SUINFO Return segment usage info about requested
+ segments. This ioctl is used in lssu,
+ nilfs_resize utilities and by nilfs_cleanerd
+ daemon.
+
+ NILFS_IOCTL_GET_SUSTAT Return segment usage statistics. This ioctl
+ is used in lssu, nilfs_resize utilities and
+ by nilfs_cleanerd daemon.
+
+ NILFS_IOCTL_GET_VINFO Return information on virtual block addresses.
+ This ioctl is used by nilfs_cleanerd daemon.
+
+ NILFS_IOCTL_GET_BDESCS Return information about descriptors of disk
+ block numbers. This ioctl is used by
+ nilfs_cleanerd daemon.
+
+ NILFS_IOCTL_CLEAN_SEGMENTS Do garbage collection operation in the
+ environment of requested parameters from
+ userspace. This ioctl is used by
+ nilfs_cleanerd daemon.
+
+ NILFS_IOCTL_SYNC Make a checkpoint. This ioctl is used in
+ mkcp utility.
+
+ NILFS_IOCTL_RESIZE Resize NILFS2 volume. This ioctl is used
+ by nilfs_resize utility.
+
+ NILFS_IOCTL_SET_ALLOC_RANGE Define lower limit of segments in bytes and
+ upper limit of segments in bytes. This ioctl
+ is used by nilfs_resize utility.
+
NILFS2 usage
============