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Commit d623a942 authored by Vyacheslav Dubeyko's avatar Vyacheslav Dubeyko Committed by Linus Torvalds
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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: default avatarVyacheslav Dubeyko <slava@dubeyko.com>
Reviewed-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Wenliang Fan <fanwlexca@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4b15d617
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Showing with 418 additions and 1 deletion
Documentation/filesystems/nilfs2.txt
View file @ d623a942
......@@ -81,6 +81,62 @@ nodiscard(*) The discard/TRIM commands are sent to the underlying
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
============
......
fs/nilfs2/ioctl.c
View file @ d623a942
......@@ -37,7 +37,26 @@
#include "sufile.h"
#include "dat.h"
/**
* nilfs_ioctl_wrap_copy - wrapping function of get/set metadata info
* @nilfs: nilfs object
* @argv: vector of arguments from userspace
* @dir: set of direction flags
* @dofunc: concrete function of get/set metadata info
*
* Description: nilfs_ioctl_wrap_copy() gets/sets metadata info by means of
* calling dofunc() function on the basis of @argv argument.
*
* Return Value: On success, 0 is returned and requested metadata info
* is copied into userspace. On error, one of the following
* negative error codes is returned.
*
* %-EINVAL - Invalid arguments from userspace.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-EFAULT - Failure during execution of requested operation.
*/
static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
struct nilfs_argv *argv, int dir,
ssize_t (*dofunc)(struct the_nilfs *,
......@@ -107,6 +126,9 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
return ret;
}
/**
* nilfs_ioctl_getflags - ioctl to support lsattr
*/
static int nilfs_ioctl_getflags(struct inode *inode, void __user *argp)
{
unsigned int flags = NILFS_I(inode)->i_flags & FS_FL_USER_VISIBLE;
......@@ -114,6 +136,9 @@ static int nilfs_ioctl_getflags(struct inode *inode, void __user *argp)
return put_user(flags, (int __user *)argp);
}
/**
* nilfs_ioctl_setflags - ioctl to support chattr
*/
static int nilfs_ioctl_setflags(struct inode *inode, struct file *filp,
void __user *argp)
{
......@@ -166,11 +191,33 @@ static int nilfs_ioctl_setflags(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_getversion - get info about a file's version (generation number)
*/
static int nilfs_ioctl_getversion(struct inode *inode, void __user *argp)
{
return put_user(inode->i_generation, (int __user *)argp);
}
/**
* nilfs_ioctl_change_cpmode - change checkpoint mode (checkpoint/snapshot)
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
*
* Description: nilfs_ioctl_change_cpmode() function changes mode of
* given checkpoint between checkpoint and snapshot state. This ioctl
* is used in chcp and mkcp utilities.
*
* Return Value: On success, 0 is returned and mode of a checkpoint is
* changed. On error, one of the following negative error codes
* is returned.
*
* %-EPERM - Operation not permitted.
*
* %-EFAULT - Failure during checkpoint mode changing.
*/
static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
{
......@@ -206,6 +253,25 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_delete_checkpoint - remove checkpoint
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
*
* Description: nilfs_ioctl_delete_checkpoint() function removes
* checkpoint from NILFS2 file system. This ioctl is used in rmcp
* utility.
*
* Return Value: On success, 0 is returned and a checkpoint is
* removed. On error, one of the following negative error codes
* is returned.
*
* %-EPERM - Operation not permitted.
*
* %-EFAULT - Failure during checkpoint removing.
*/
static int
nilfs_ioctl_delete_checkpoint(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
......@@ -237,6 +303,21 @@ nilfs_ioctl_delete_checkpoint(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_do_get_cpinfo - callback method getting info about checkpoints
* @nilfs: nilfs object
* @posp: pointer on array of checkpoint's numbers
* @flags: checkpoint mode (checkpoint or snapshot)
* @buf: buffer for storing checkponts' info
* @size: size in bytes of one checkpoint info item in array
* @nmembs: number of checkpoints in array (numbers and infos)
*
* Description: nilfs_ioctl_do_get_cpinfo() function returns info about
* requested checkpoints. The NILFS_IOCTL_GET_CPINFO ioctl is used in
* lscp utility and by nilfs_cleanerd daemon.
*
* Return value: count of nilfs_cpinfo structures in output buffer.
*/
static ssize_t
nilfs_ioctl_do_get_cpinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
void *buf, size_t size, size_t nmembs)
......@@ -250,6 +331,27 @@ nilfs_ioctl_do_get_cpinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
return ret;
}
/**
* nilfs_ioctl_get_cpstat - get checkpoints statistics
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
*
* Description: nilfs_ioctl_get_cpstat() returns information about checkpoints.
* The NILFS_IOCTL_GET_CPSTAT ioctl is used by lscp, rmcp utilities
* and by nilfs_cleanerd daemon.
*
* Return Value: On success, 0 is returned, and checkpoints information is
* copied into userspace pointer @argp. On error, one of the following
* negative error codes is returned.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-EFAULT - Failure during getting checkpoints statistics.
*/
static int nilfs_ioctl_get_cpstat(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
{
......@@ -268,6 +370,21 @@ static int nilfs_ioctl_get_cpstat(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_do_get_suinfo - callback method getting segment usage info
* @nilfs: nilfs object
* @posp: pointer on array of segment numbers
* @flags: *not used*
* @buf: buffer for storing suinfo array
* @size: size in bytes of one suinfo item in array
* @nmembs: count of segment numbers and suinfos in array
*
* Description: nilfs_ioctl_do_get_suinfo() function returns segment usage
* info about requested segments. The NILFS_IOCTL_GET_SUINFO ioctl is used
* in lssu, nilfs_resize utilities and by nilfs_cleanerd daemon.
*
* Return value: count of nilfs_suinfo structures in output buffer.
*/
static ssize_t
nilfs_ioctl_do_get_suinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
void *buf, size_t size, size_t nmembs)
......@@ -281,6 +398,27 @@ nilfs_ioctl_do_get_suinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
return ret;
}
/**
* nilfs_ioctl_get_sustat - get segment usage statistics
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
*
* Description: nilfs_ioctl_get_sustat() returns segment usage statistics.
* The NILFS_IOCTL_GET_SUSTAT ioctl is used in lssu, nilfs_resize utilities
* and by nilfs_cleanerd daemon.
*
* Return Value: On success, 0 is returned, and segment usage information is
* copied into userspace pointer @argp. On error, one of the following
* negative error codes is returned.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-EFAULT - Failure during getting segment usage statistics.
*/
static int nilfs_ioctl_get_sustat(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
{
......@@ -299,6 +437,21 @@ static int nilfs_ioctl_get_sustat(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_do_get_vinfo - callback method getting virtual blocks info
* @nilfs: nilfs object
* @posp: *not used*
* @flags: *not used*
* @buf: buffer for storing array of nilfs_vinfo structures
* @size: size in bytes of one vinfo item in array
* @nmembs: count of vinfos in array
*
* Description: nilfs_ioctl_do_get_vinfo() function returns information
* on virtual block addresses. The NILFS_IOCTL_GET_VINFO ioctl is used
* by nilfs_cleanerd daemon.
*
* Return value: count of nilfs_vinfo structures in output buffer.
*/
static ssize_t
nilfs_ioctl_do_get_vinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
void *buf, size_t size, size_t nmembs)
......@@ -311,6 +464,21 @@ nilfs_ioctl_do_get_vinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
return ret;
}
/**
* nilfs_ioctl_do_get_bdescs - callback method getting disk block descriptors
* @nilfs: nilfs object
* @posp: *not used*
* @flags: *not used*
* @buf: buffer for storing array of nilfs_bdesc structures
* @size: size in bytes of one bdesc item in array
* @nmembs: count of bdescs in array
*
* Description: nilfs_ioctl_do_get_bdescs() function returns information
* about descriptors of disk block numbers. The NILFS_IOCTL_GET_BDESCS ioctl
* is used by nilfs_cleanerd daemon.
*
* Return value: count of nilfs_bdescs structures in output buffer.
*/
static ssize_t
nilfs_ioctl_do_get_bdescs(struct the_nilfs *nilfs, __u64 *posp, int flags,
void *buf, size_t size, size_t nmembs)
......@@ -337,6 +505,29 @@ nilfs_ioctl_do_get_bdescs(struct the_nilfs *nilfs, __u64 *posp, int flags,
return nmembs;
}
/**
* nilfs_ioctl_get_bdescs - get disk block descriptors
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
*
* Description: nilfs_ioctl_do_get_bdescs() function returns information
* about descriptors of disk block numbers. The NILFS_IOCTL_GET_BDESCS ioctl
* is used by nilfs_cleanerd daemon.
*
* Return Value: On success, 0 is returned, and disk block descriptors are
* copied into userspace pointer @argp. On error, one of the following
* negative error codes is returned.
*
* %-EINVAL - Invalid arguments from userspace.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-EFAULT - Failure during getting disk block descriptors.
*/
static int nilfs_ioctl_get_bdescs(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
{
......@@ -360,6 +551,26 @@ static int nilfs_ioctl_get_bdescs(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_move_inode_block - prepare data/node block for moving by GC
* @inode: inode object
* @vdesc: descriptor of virtual block number
* @buffers: list of moving buffers
*
* Description: nilfs_ioctl_move_inode_block() function registers data/node
* buffer in the GC pagecache and submit read request.
*
* Return Value: On success, 0 is returned. On error, one of the following
* negative error codes is returned.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-ENOENT - Requested block doesn't exist.
*
* %-EEXIST - Blocks conflict is detected.
*/
static int nilfs_ioctl_move_inode_block(struct inode *inode,
struct nilfs_vdesc *vdesc,
struct list_head *buffers)
......@@ -405,6 +616,19 @@ static int nilfs_ioctl_move_inode_block(struct inode *inode,
return 0;
}
/**
* nilfs_ioctl_move_blocks - move valid inode's blocks during garbage collection
* @sb: superblock object
* @argv: vector of arguments from userspace
* @buf: array of nilfs_vdesc structures
*
* Description: nilfs_ioctl_move_blocks() function reads valid data/node
* blocks that garbage collector specified with the array of nilfs_vdesc
* structures and stores them into page caches of GC inodes.
*
* Return Value: Number of processed nilfs_vdesc structures or
* error code, otherwise.
*/
static int nilfs_ioctl_move_blocks(struct super_block *sb,
struct nilfs_argv *argv, void *buf)
{
......@@ -470,6 +694,25 @@ static int nilfs_ioctl_move_blocks(struct super_block *sb,
return ret;
}
/**
* nilfs_ioctl_delete_checkpoints - delete checkpoints
* @nilfs: nilfs object
* @argv: vector of arguments from userspace
* @buf: array of periods of checkpoints numbers
*
* Description: nilfs_ioctl_delete_checkpoints() function deletes checkpoints
* in the period from p_start to p_end, excluding p_end itself. The checkpoints
* which have been already deleted are ignored.
*
* Return Value: Number of processed nilfs_period structures or
* error code, otherwise.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-EINVAL - invalid checkpoints.
*/
static int nilfs_ioctl_delete_checkpoints(struct the_nilfs *nilfs,
struct nilfs_argv *argv, void *buf)
{
......@@ -487,6 +730,24 @@ static int nilfs_ioctl_delete_checkpoints(struct the_nilfs *nilfs,
return nmembs;
}
/**
* nilfs_ioctl_free_vblocknrs - free virtual block numbers
* @nilfs: nilfs object
* @argv: vector of arguments from userspace
* @buf: array of virtual block numbers
*
* Description: nilfs_ioctl_free_vblocknrs() function frees
* the virtual block numbers specified by @buf and @argv->v_nmembs.
*
* Return Value: Number of processed virtual block numbers or
* error code, otherwise.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-ENOENT - The virtual block number have not been allocated.
*/
static int nilfs_ioctl_free_vblocknrs(struct the_nilfs *nilfs,
struct nilfs_argv *argv, void *buf)
{
......@@ -498,6 +759,24 @@ static int nilfs_ioctl_free_vblocknrs(struct the_nilfs *nilfs,
return (ret < 0) ? ret : nmembs;
}
/**
* nilfs_ioctl_mark_blocks_dirty - mark blocks dirty
* @nilfs: nilfs object
* @argv: vector of arguments from userspace
* @buf: array of block descriptors
*
* Description: nilfs_ioctl_mark_blocks_dirty() function marks
* metadata file or data blocks as dirty.
*
* Return Value: Number of processed block descriptors or
* error code, otherwise.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EIO - I/O error
*
* %-ENOENT - the specified block does not exist (hole block)
*/
static int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs,
struct nilfs_argv *argv, void *buf)
{
......@@ -579,6 +858,20 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
return ret;
}
/**
* nilfs_ioctl_clean_segments - clean segments
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
*
* Description: nilfs_ioctl_clean_segments() function makes garbage
* collection operation in the environment of requested parameters
* from userspace. The NILFS_IOCTL_CLEAN_SEGMENTS ioctl is used by
* nilfs_cleanerd daemon.
*
* Return Value: On success, 0 is returned or error code, otherwise.
*/
static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
{
......@@ -690,6 +983,33 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_sync - make a checkpoint
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
*
* Description: nilfs_ioctl_sync() function constructs a logical segment
* for checkpointing. This function guarantees that all modified data
* and metadata are written out to the device when it successfully
* returned.
*
* Return Value: On success, 0 is retured. On errors, one of the following
* negative error code is returned.
*
* %-EROFS - Read only filesystem.
*
* %-EIO - I/O error
*
* %-ENOSPC - No space left on device (only in a panic state).
*
* %-ERESTARTSYS - Interrupted.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EFAULT - Failure during execution of requested operation.
*/
static int nilfs_ioctl_sync(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
{
......@@ -718,6 +1038,14 @@ static int nilfs_ioctl_sync(struct inode *inode, struct file *filp,
return 0;
}
/**
* nilfs_ioctl_resize - resize NILFS2 volume
* @inode: inode object
* @filp: file object
* @argp: pointer on argument from userspace
*
* Return Value: On success, 0 is returned or error code, otherwise.
*/
static int nilfs_ioctl_resize(struct inode *inode, struct file *filp,
void __user *argp)
{
......@@ -743,6 +1071,17 @@ static int nilfs_ioctl_resize(struct inode *inode, struct file *filp,
return ret;
}
/**
* nilfs_ioctl_set_alloc_range - limit range of segments to be allocated
* @inode: inode object
* @argp: pointer on argument from userspace
*
* Decription: nilfs_ioctl_set_alloc_range() function defines lower limit
* of segments in bytes and upper limit of segments in bytes.
* The NILFS_IOCTL_SET_ALLOC_RANGE is used by nilfs_resize utility.
*
* Return Value: On success, 0 is returned or error code, otherwise.
*/
static int nilfs_ioctl_set_alloc_range(struct inode *inode, void __user *argp)
{
struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
......@@ -775,6 +1114,28 @@ static int nilfs_ioctl_set_alloc_range(struct inode *inode, void __user *argp)
return ret;
}
/**
* nilfs_ioctl_get_info - wrapping function of get metadata info
* @inode: inode object
* @filp: file object
* @cmd: ioctl's request code
* @argp: pointer on argument from userspace
* @membsz: size of an item in bytes
* @dofunc: concrete function of getting metadata info
*
* Description: nilfs_ioctl_get_info() gets metadata info by means of
* calling dofunc() function.
*
* Return Value: On success, 0 is returned and requested metadata info
* is copied into userspace. On error, one of the following
* negative error codes is returned.
*
* %-EINVAL - Invalid arguments from userspace.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-EFAULT - Failure during execution of requested operation.
*/
static int nilfs_ioctl_get_info(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp,
size_t membsz,
......
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