// SPDX-License-Identifier: GPL-2.0+
/*
 * ioctl.c - NILFS ioctl operations.
 *
 * Copyright (C) 2007, 2008 Nippon Telegraph and Telephone Corporation.
 *
 * Written by Koji Sato.
 */

#include <linux/fs.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/capability.h>   /* capable() */
#include <linux/uaccess.h>      /* copy_from_user(), copy_to_user() */
#include <linux/vmalloc.h>
#include <linux/compat.h>       /* compat_ptr() */
#include <linux/mount.h>        /* mnt_want_write_file(), mnt_drop_write_file() */
#include <linux/buffer_head.h>
#include <linux/fileattr.h>
#include "nilfs.h"
#include "segment.h"
#include "bmap.h"
#include "cpfile.h"
#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 *,
                                                   __u64 *, int,
                                                   void *, size_t, size_t))
{
        void *buf;
        void __user *base = (void __user *)(unsigned long)argv->v_base;
        size_t maxmembs, total, n;
        ssize_t nr;
        int ret, i;
        __u64 pos, ppos;

        if (argv->v_nmembs == 0)
                return 0;

        if (argv->v_size > PAGE_SIZE)
                return -EINVAL;

        /*
         * Reject pairs of a start item position (argv->v_index) and a
         * total count (argv->v_nmembs) which leads position 'pos' to
         * overflow by the increment at the end of the loop.
         */
        if (argv->v_index > ~(__u64)0 - argv->v_nmembs)
                return -EINVAL;

        buf = (void *)__get_free_pages(GFP_NOFS, 0);
        if (unlikely(!buf))
                return -ENOMEM;
        maxmembs = PAGE_SIZE / argv->v_size;

        ret = 0;
        total = 0;
        pos = argv->v_index;
        for (i = 0; i < argv->v_nmembs; i += n) {
                n = (argv->v_nmembs - i < maxmembs) ?
                        argv->v_nmembs - i : maxmembs;
                if ((dir & _IOC_WRITE) &&
                    copy_from_user(buf, base + argv->v_size * i,
                                   argv->v_size * n)) {
                        ret = -EFAULT;
                        break;
                }
                ppos = pos;
                nr = dofunc(nilfs, &pos, argv->v_flags, buf, argv->v_size,
                               n);
                if (nr < 0) {
                        ret = nr;
                        break;
                }
                if ((dir & _IOC_READ) &&
                    copy_to_user(base + argv->v_size * i, buf,
                                 argv->v_size * nr)) {
                        ret = -EFAULT;
                        break;
                }
                total += nr;
                if ((size_t)nr < n)
                        break;
                if (pos == ppos)
                        pos += n;
        }
        argv->v_nmembs = total;

        free_pages((unsigned long)buf, 0);
        return ret;
}

/**
 * nilfs_fileattr_get - ioctl to support lsattr
 */
int nilfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
        struct inode *inode = d_inode(dentry);

        fileattr_fill_flags(fa, NILFS_I(inode)->i_flags & FS_FL_USER_VISIBLE);

        return 0;
}

/**
 * nilfs_fileattr_set - ioctl to support chattr
 */
int nilfs_fileattr_set(struct user_namespace *mnt_userns,
                       struct dentry *dentry, struct fileattr *fa)
{
        struct inode *inode = d_inode(dentry);
        struct nilfs_transaction_info ti;
        unsigned int flags, oldflags;
        int ret;

        if (fileattr_has_fsx(fa))
                return -EOPNOTSUPP;

        flags = nilfs_mask_flags(inode->i_mode, fa->flags);

        ret = nilfs_transaction_begin(inode->i_sb, &ti, 0);
        if (ret)
                return ret;

        oldflags = NILFS_I(inode)->i_flags & ~FS_FL_USER_MODIFIABLE;
        NILFS_I(inode)->i_flags = oldflags | (flags & FS_FL_USER_MODIFIABLE);

        nilfs_set_inode_flags(inode);
        inode->i_ctime = current_time(inode);
        if (IS_SYNC(inode))
                nilfs_set_transaction_flag(NILFS_TI_SYNC);

        nilfs_mark_inode_dirty(inode);
        return nilfs_transaction_commit(inode->i_sb);
}

/**
 * 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)
{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct nilfs_transaction_info ti;
        struct nilfs_cpmode cpmode;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(filp);
        if (ret)
                return ret;

        ret = -EFAULT;
        if (copy_from_user(&cpmode, argp, sizeof(cpmode)))
                goto out;

        mutex_lock(&nilfs->ns_snapshot_mount_mutex);

        nilfs_transaction_begin(inode->i_sb, &ti, 0);
        ret = nilfs_cpfile_change_cpmode(
                nilfs->ns_cpfile, cpmode.cm_cno, cpmode.cm_mode);
        if (unlikely(ret < 0))
                nilfs_transaction_abort(inode->i_sb);
        else
                nilfs_transaction_commit(inode->i_sb); /* never fails */

        mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
out:
        mnt_drop_write_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)
{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct nilfs_transaction_info ti;
        __u64 cno;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(filp);
        if (ret)
                return ret;

        ret = -EFAULT;
        if (copy_from_user(&cno, argp, sizeof(cno)))
                goto out;

        nilfs_transaction_begin(inode->i_sb, &ti, 0);
        ret = nilfs_cpfile_delete_checkpoint(nilfs->ns_cpfile, cno);
        if (unlikely(ret < 0))
                nilfs_transaction_abort(inode->i_sb);
        else
                nilfs_transaction_commit(inode->i_sb); /* never fails */
out:
        mnt_drop_write_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)
{
        int ret;

        down_read(&nilfs->ns_segctor_sem);
        ret = nilfs_cpfile_get_cpinfo(nilfs->ns_cpfile, posp, flags, buf,
                                      size, nmembs);
        up_read(&nilfs->ns_segctor_sem);
        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)
{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct nilfs_cpstat cpstat;
        int ret;

        down_read(&nilfs->ns_segctor_sem);
        ret = nilfs_cpfile_get_stat(nilfs->ns_cpfile, &cpstat);
        up_read(&nilfs->ns_segctor_sem);
        if (ret < 0)
                return ret;

        if (copy_to_user(argp, &cpstat, sizeof(cpstat)))
                ret = -EFAULT;
        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)
{
        int ret;

        down_read(&nilfs->ns_segctor_sem);
        ret = nilfs_sufile_get_suinfo(nilfs->ns_sufile, *posp, buf, size,
                                      nmembs);
        up_read(&nilfs->ns_segctor_sem);
        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)
{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct nilfs_sustat sustat;
        int ret;

        down_read(&nilfs->ns_segctor_sem);
        ret = nilfs_sufile_get_stat(nilfs->ns_sufile, &sustat);
        up_read(&nilfs->ns_segctor_sem);
        if (ret < 0)
                return ret;

        if (copy_to_user(argp, &sustat, sizeof(sustat)))
                ret = -EFAULT;
        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)
{
        int ret;

        down_read(&nilfs->ns_segctor_sem);
        ret = nilfs_dat_get_vinfo(nilfs->ns_dat, buf, size, nmembs);
        up_read(&nilfs->ns_segctor_sem);
        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)
{
        struct nilfs_bmap *bmap = NILFS_I(nilfs->ns_dat)->i_bmap;
        struct nilfs_bdesc *bdescs = buf;
        int ret, i;

        down_read(&nilfs->ns_segctor_sem);
        for (i = 0; i < nmembs; i++) {
                ret = nilfs_bmap_lookup_at_level(bmap,
                                                 bdescs[i].bd_offset,
                                                 bdescs[i].bd_level + 1,
                                                 &bdescs[i].bd_blocknr);
                if (ret < 0) {
                        if (ret != -ENOENT) {
                                up_read(&nilfs->ns_segctor_sem);
                                return ret;
                        }
                        bdescs[i].bd_blocknr = 0;
                }
        }
        up_read(&nilfs->ns_segctor_sem);
        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)
{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct nilfs_argv argv;
        int ret;

        if (copy_from_user(&argv, argp, sizeof(argv)))
                return -EFAULT;

        if (argv.v_size != sizeof(struct nilfs_bdesc))
                return -EINVAL;

        ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
                                    nilfs_ioctl_do_get_bdescs);
        if (ret < 0)
                return ret;

        if (copy_to_user(argp, &argv, sizeof(argv)))
                ret = -EFAULT;
        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)
{
        struct buffer_head *bh;
        int ret;

        if (vdesc->vd_flags == 0)
                ret = nilfs_gccache_submit_read_data(
                        inode, vdesc->vd_offset, vdesc->vd_blocknr,
                        vdesc->vd_vblocknr, &bh);
        else
                ret = nilfs_gccache_submit_read_node(
                        inode, vdesc->vd_blocknr, vdesc->vd_vblocknr, &bh);

        if (unlikely(ret < 0)) {
                if (ret == -ENOENT)
                        nilfs_crit(inode->i_sb,
                                   "%s: invalid virtual block address (%s): ino=%llu, cno=%llu, offset=%llu, blocknr=%llu, vblocknr=%llu",
                                   __func__, vdesc->vd_flags ? "node" : "data",
                                   (unsigned long long)vdesc->vd_ino,
                                   (unsigned long long)vdesc->vd_cno,
                                   (unsigned long long)vdesc->vd_offset,
                                   (unsigned long long)vdesc->vd_blocknr,
                                   (unsigned long long)vdesc->vd_vblocknr);
                return ret;
        }
        if (unlikely(!list_empty(&bh->b_assoc_buffers))) {
                nilfs_crit(inode->i_sb,
                           "%s: conflicting %s buffer: ino=%llu, cno=%llu, offset=%llu, blocknr=%llu, vblocknr=%llu",
                           __func__, vdesc->vd_flags ? "node" : "data",
                           (unsigned long long)vdesc->vd_ino,
                           (unsigned long long)vdesc->vd_cno,
                           (unsigned long long)vdesc->vd_offset,
                           (unsigned long long)vdesc->vd_blocknr,
                           (unsigned long long)vdesc->vd_vblocknr);
                brelse(bh);
                return -EEXIST;
        }
        list_add_tail(&bh->b_assoc_buffers, buffers);
        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)
{
        size_t nmembs = argv->v_nmembs;
        struct the_nilfs *nilfs = sb->s_fs_info;
        struct inode *inode;
        struct nilfs_vdesc *vdesc;
        struct buffer_head *bh, *n;
        LIST_HEAD(buffers);
        ino_t ino;
        __u64 cno;
        int i, ret;

        for (i = 0, vdesc = buf; i < nmembs; ) {
                ino = vdesc->vd_ino;
                cno = vdesc->vd_cno;
                inode = nilfs_iget_for_gc(sb, ino, cno);
                if (IS_ERR(inode)) {
                        ret = PTR_ERR(inode);
                        goto failed;
                }
                if (list_empty(&NILFS_I(inode)->i_dirty)) {
                        /*
                         * Add the inode to GC inode list. Garbage Collection
                         * is serialized and no two processes manipulate the
                         * list simultaneously.
                         */
                        igrab(inode);
                        list_add(&NILFS_I(inode)->i_dirty,
                                 &nilfs->ns_gc_inodes);
                }

                do {
                        ret = nilfs_ioctl_move_inode_block(inode, vdesc,
                                                           &buffers);
                        if (unlikely(ret < 0)) {
                                iput(inode);
                                goto failed;
                        }
                        vdesc++;
                } while (++i < nmembs &&
                         vdesc->vd_ino == ino && vdesc->vd_cno == cno);

                iput(inode); /* The inode still remains in GC inode list */
        }

        list_for_each_entry_safe(bh, n, &buffers, b_assoc_buffers) {
                ret = nilfs_gccache_wait_and_mark_dirty(bh);
                if (unlikely(ret < 0)) {
                        WARN_ON(ret == -EEXIST);
                        goto failed;
                }
                list_del_init(&bh->b_assoc_buffers);
                brelse(bh);
        }
        return nmembs;

 failed:
        list_for_each_entry_safe(bh, n, &buffers, b_assoc_buffers) {
                list_del_init(&bh->b_assoc_buffers);
                brelse(bh);
        }
        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)
{
        size_t nmembs = argv->v_nmembs;
        struct inode *cpfile = nilfs->ns_cpfile;
        struct nilfs_period *periods = buf;
        int ret, i;

        for (i = 0; i < nmembs; i++) {
                ret = nilfs_cpfile_delete_checkpoints(
                        cpfile, periods[i].p_start, periods[i].p_end);
                if (ret < 0)
                        return ret;
        }
        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)
{
        size_t nmembs = argv->v_nmembs;
        int ret;

        ret = nilfs_dat_freev(nilfs->ns_dat, buf, nmembs);

        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)
{
        size_t nmembs = argv->v_nmembs;
        struct nilfs_bmap *bmap = NILFS_I(nilfs->ns_dat)->i_bmap;
        struct nilfs_bdesc *bdescs = buf;
        struct buffer_head *bh;
        int ret, i;

        for (i = 0; i < nmembs; i++) {
                /* XXX: use macro or inline func to check liveness */
                ret = nilfs_bmap_lookup_at_level(bmap,
                                                 bdescs[i].bd_offset,
                                                 bdescs[i].bd_level + 1,
                                                 &bdescs[i].bd_blocknr);
                if (ret < 0) {
                        if (ret != -ENOENT)
                                return ret;
                        bdescs[i].bd_blocknr = 0;
                }
                if (bdescs[i].bd_blocknr != bdescs[i].bd_oblocknr)
                        /* skip dead block */
                        continue;
                if (bdescs[i].bd_level == 0) {
                        ret = nilfs_mdt_get_block(nilfs->ns_dat,
                                                  bdescs[i].bd_offset,
                                                  false, NULL, &bh);
                        if (unlikely(ret)) {
                                WARN_ON(ret == -ENOENT);
                                return ret;
                        }
                        mark_buffer_dirty(bh);
                        nilfs_mdt_mark_dirty(nilfs->ns_dat);
                        put_bh(bh);
                } else {
                        ret = nilfs_bmap_mark(bmap, bdescs[i].bd_offset,
                                              bdescs[i].bd_level);
                        if (ret < 0) {
                                WARN_ON(ret == -ENOENT);
                                return ret;
                        }
                }
        }
        return nmembs;
}

int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
                                       struct nilfs_argv *argv, void **kbufs)
{
        const char *msg;
        int ret;

        ret = nilfs_ioctl_delete_checkpoints(nilfs, &argv[1], kbufs[1]);
        if (ret < 0) {
                /*
                 * can safely abort because checkpoints can be removed
                 * independently.
                 */
                msg = "cannot delete checkpoints";
                goto failed;
        }
        ret = nilfs_ioctl_free_vblocknrs(nilfs, &argv[2], kbufs[2]);
        if (ret < 0) {
                /*
                 * can safely abort because DAT file is updated atomically
                 * using a copy-on-write technique.
                 */
                msg = "cannot delete virtual blocks from DAT file";
                goto failed;
        }
        ret = nilfs_ioctl_mark_blocks_dirty(nilfs, &argv[3], kbufs[3]);
        if (ret < 0) {
                /*
                 * can safely abort because the operation is nondestructive.
                 */
                msg = "cannot mark copying blocks dirty";
                goto failed;
        }
        return 0;

 failed:
        nilfs_err(nilfs->ns_sb, "error %d preparing GC: %s", ret, msg);
        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)
{
        struct nilfs_argv argv[5];
        static const size_t argsz[5] = {
                sizeof(struct nilfs_vdesc),
                sizeof(struct nilfs_period),
                sizeof(__u64),
                sizeof(struct nilfs_bdesc),
                sizeof(__u64),
        };
        void __user *base;
        void *kbufs[5];
        struct the_nilfs *nilfs;
        size_t len, nsegs;
        int n, ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(filp);
        if (ret)
                return ret;

        ret = -EFAULT;
        if (copy_from_user(argv, argp, sizeof(argv)))
                goto out;

        ret = -EINVAL;
        nsegs = argv[4].v_nmembs;
        if (argv[4].v_size != argsz[4])
                goto out;
        if (nsegs > UINT_MAX / sizeof(__u64))
                goto out;

        /*
         * argv[4] points to segment numbers this ioctl cleans.  We
         * use kmalloc() for its buffer because memory used for the
         * segment numbers is enough small.
         */
        kbufs[4] = memdup_user((void __user *)(unsigned long)argv[4].v_base,
                               nsegs * sizeof(__u64));
        if (IS_ERR(kbufs[4])) {
                ret = PTR_ERR(kbufs[4]);
                goto out;
        }
        nilfs = inode->i_sb->s_fs_info;

        for (n = 0; n < 4; n++) {
                ret = -EINVAL;
                if (argv[n].v_size != argsz[n])
                        goto out_free;

                if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
                        goto out_free;

                if (argv[n].v_nmembs >= UINT_MAX / argv[n].v_size)
                        goto out_free;

                len = argv[n].v_size * argv[n].v_nmembs;
                base = (void __user *)(unsigned long)argv[n].v_base;
                if (len == 0) {
                        kbufs[n] = NULL;
                        continue;
                }

                kbufs[n] = vmalloc(len);
                if (!kbufs[n]) {
                        ret = -ENOMEM;
                        goto out_free;
                }
                if (copy_from_user(kbufs[n], base, len)) {
                        ret = -EFAULT;
                        vfree(kbufs[n]);
                        goto out_free;
                }
        }

        /*
         * nilfs_ioctl_move_blocks() will call nilfs_iget_for_gc(),
         * which will operates an inode list without blocking.
         * To protect the list from concurrent operations,
         * nilfs_ioctl_move_blocks should be atomic operation.
         */
        if (test_and_set_bit(THE_NILFS_GC_RUNNING, &nilfs->ns_flags)) {
                ret = -EBUSY;
                goto out_free;
        }

        ret = nilfs_ioctl_move_blocks(inode->i_sb, &argv[0], kbufs[0]);
        if (ret < 0) {
                nilfs_err(inode->i_sb,
                          "error %d preparing GC: cannot read source blocks",
                          ret);
        } else {
                if (nilfs_sb_need_update(nilfs))
                        set_nilfs_discontinued(nilfs);
                ret = nilfs_clean_segments(inode->i_sb, argv, kbufs);
        }

        nilfs_remove_all_gcinodes(nilfs);
        clear_nilfs_gc_running(nilfs);

out_free:
        while (--n >= 0)
                vfree(kbufs[n]);
        kfree(kbufs[4]);
out:
        mnt_drop_write_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)
{
        __u64 cno;
        int ret;
        struct the_nilfs *nilfs;

        ret = nilfs_construct_segment(inode->i_sb);
        if (ret < 0)
                return ret;

        nilfs = inode->i_sb->s_fs_info;
        ret = nilfs_flush_device(nilfs);
        if (ret < 0)
                return ret;

        if (argp != NULL) {
                down_read(&nilfs->ns_segctor_sem);
                cno = nilfs->ns_cno - 1;

                up_read(&nilfs->ns_segctor_sem);
                if (copy_to_user(argp, &cno, sizeof(cno)))
                        return -EFAULT;
        }
        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)
{
        __u64 newsize;
        int ret = -EPERM;

        if (!capable(CAP_SYS_ADMIN))
                goto out;

        ret = mnt_want_write_file(filp);
        if (ret)
                goto out;

        ret = -EFAULT;
        if (copy_from_user(&newsize, argp, sizeof(newsize)))
                goto out_drop_write;

        ret = nilfs_resize_fs(inode->i_sb, newsize);

out_drop_write:
        mnt_drop_write_file(filp);
out:
        return ret;
}

/**
 * nilfs_ioctl_trim_fs() - trim ioctl handle function
 * @inode: inode object
 * @argp: pointer on argument from userspace
 *
 * Description: nilfs_ioctl_trim_fs is the FITRIM ioctl handle function. It
 * checks the arguments from userspace and calls nilfs_sufile_trim_fs, which
 * performs the actual trim operation.
 *
 * Return Value: On success, 0 is returned or negative error code, otherwise.
 */
static int nilfs_ioctl_trim_fs(struct inode *inode, void __user *argp)
{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct request_queue *q = bdev_get_queue(nilfs->ns_bdev);
        struct fstrim_range range;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (!blk_queue_discard(q))
                return -EOPNOTSUPP;

        if (copy_from_user(&range, argp, sizeof(range)))
                return -EFAULT;

        range.minlen = max_t(u64, range.minlen, q->limits.discard_granularity);

        down_read(&nilfs->ns_segctor_sem);
        ret = nilfs_sufile_trim_fs(nilfs->ns_sufile, &range);
        up_read(&nilfs->ns_segctor_sem);

        if (ret < 0)
                return ret;

        if (copy_to_user(argp, &range, sizeof(range)))
                return -EFAULT;

        return 0;
}

/**
 * nilfs_ioctl_set_alloc_range - limit range of segments to be allocated
 * @inode: inode object
 * @argp: pointer on argument from userspace
 *
 * Description: 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;
        __u64 range[2];
        __u64 minseg, maxseg;
        unsigned long segbytes;
        int ret = -EPERM;

        if (!capable(CAP_SYS_ADMIN))
                goto out;

        ret = -EFAULT;
        if (copy_from_user(range, argp, sizeof(__u64[2])))
                goto out;

        ret = -ERANGE;
        if (range[1] > i_size_read(inode->i_sb->s_bdev->bd_inode))
                goto out;

        segbytes = nilfs->ns_blocks_per_segment * nilfs->ns_blocksize;

        minseg = range[0] + segbytes - 1;
        do_div(minseg, segbytes);
        maxseg = NILFS_SB2_OFFSET_BYTES(range[1]);
        do_div(maxseg, segbytes);
        maxseg--;

        ret = nilfs_sufile_set_alloc_range(nilfs->ns_sufile, minseg, maxseg);
out:
        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,
                                ssize_t (*dofunc)(struct the_nilfs *,
                                                  __u64 *, int,
                                                  void *, size_t, size_t))

{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct nilfs_argv argv;
        int ret;

        if (copy_from_user(&argv, argp, sizeof(argv)))
                return -EFAULT;

        if (argv.v_size < membsz)
                return -EINVAL;

        ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd), dofunc);
        if (ret < 0)
                return ret;

        if (copy_to_user(argp, &argv, sizeof(argv)))
                ret = -EFAULT;
        return ret;
}

/**
 * nilfs_ioctl_set_suinfo - set segment usage info
 * @inode: inode object
 * @filp: file object
 * @cmd: ioctl's request code
 * @argp: pointer on argument from userspace
 *
 * Description: Expects an array of nilfs_suinfo_update structures
 * encapsulated in nilfs_argv and updates the segment usage info
 * according to the flags in nilfs_suinfo_update.
 *
 * Return Value: On success, 0 is returned. On error, one of the
 * following negative error codes is returned.
 *
 * %-EPERM - Not enough permissions
 *
 * %-EFAULT - Error copying input data
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-EINVAL - Invalid values in input (segment number, flags or nblocks)
 */
static int nilfs_ioctl_set_suinfo(struct inode *inode, struct file *filp,
                                unsigned int cmd, void __user *argp)
{
        struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
        struct nilfs_transaction_info ti;
        struct nilfs_argv argv;
        size_t len;
        void __user *base;
        void *kbuf;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(filp);
        if (ret)
                return ret;

        ret = -EFAULT;
        if (copy_from_user(&argv, argp, sizeof(argv)))
                goto out;

        ret = -EINVAL;
        if (argv.v_size < sizeof(struct nilfs_suinfo_update))
                goto out;

        if (argv.v_nmembs > nilfs->ns_nsegments)
                goto out;

        if (argv.v_nmembs >= UINT_MAX / argv.v_size)
                goto out;

        len = argv.v_size * argv.v_nmembs;
        if (!len) {
                ret = 0;
                goto out;
        }

        base = (void __user *)(unsigned long)argv.v_base;
        kbuf = vmalloc(len);
        if (!kbuf) {
                ret = -ENOMEM;
                goto out;
        }

        if (copy_from_user(kbuf, base, len)) {
                ret = -EFAULT;
                goto out_free;
        }

        nilfs_transaction_begin(inode->i_sb, &ti, 0);
        ret = nilfs_sufile_set_suinfo(nilfs->ns_sufile, kbuf, argv.v_size,
                        argv.v_nmembs);
        if (unlikely(ret < 0))
                nilfs_transaction_abort(inode->i_sb);
        else
                nilfs_transaction_commit(inode->i_sb); /* never fails */

out_free:
        vfree(kbuf);
out:
        mnt_drop_write_file(filp);
        return ret;
}

long nilfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct inode *inode = file_inode(filp);
        void __user *argp = (void __user *)arg;

        switch (cmd) {
        case FS_IOC_GETVERSION:
                return nilfs_ioctl_getversion(inode, argp);
        case NILFS_IOCTL_CHANGE_CPMODE:
                return nilfs_ioctl_change_cpmode(inode, filp, cmd, argp);
        case NILFS_IOCTL_DELETE_CHECKPOINT:
                return nilfs_ioctl_delete_checkpoint(inode, filp, cmd, argp);
        case NILFS_IOCTL_GET_CPINFO:
                return nilfs_ioctl_get_info(inode, filp, cmd, argp,
                                            sizeof(struct nilfs_cpinfo),
                                            nilfs_ioctl_do_get_cpinfo);
        case NILFS_IOCTL_GET_CPSTAT:
                return nilfs_ioctl_get_cpstat(inode, filp, cmd, argp);
        case NILFS_IOCTL_GET_SUINFO:
                return nilfs_ioctl_get_info(inode, filp, cmd, argp,
                                            sizeof(struct nilfs_suinfo),
                                            nilfs_ioctl_do_get_suinfo);
        case NILFS_IOCTL_SET_SUINFO:
                return nilfs_ioctl_set_suinfo(inode, filp, cmd, argp);
        case NILFS_IOCTL_GET_SUSTAT:
                return nilfs_ioctl_get_sustat(inode, filp, cmd, argp);
        case NILFS_IOCTL_GET_VINFO:
                return nilfs_ioctl_get_info(inode, filp, cmd, argp,
                                            sizeof(struct nilfs_vinfo),
                                            nilfs_ioctl_do_get_vinfo);
        case NILFS_IOCTL_GET_BDESCS:
                return nilfs_ioctl_get_bdescs(inode, filp, cmd, argp);
        case NILFS_IOCTL_CLEAN_SEGMENTS:
                return nilfs_ioctl_clean_segments(inode, filp, cmd, argp);
        case NILFS_IOCTL_SYNC:
                return nilfs_ioctl_sync(inode, filp, cmd, argp);
        case NILFS_IOCTL_RESIZE:
                return nilfs_ioctl_resize(inode, filp, argp);
        case NILFS_IOCTL_SET_ALLOC_RANGE:
                return nilfs_ioctl_set_alloc_range(inode, argp);
        case FITRIM:
                return nilfs_ioctl_trim_fs(inode, argp);
        default:
                return -ENOTTY;
        }
}

#ifdef CONFIG_COMPAT
long nilfs_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        switch (cmd) {
        case FS_IOC32_GETVERSION:
                cmd = FS_IOC_GETVERSION;
                break;
        case NILFS_IOCTL_CHANGE_CPMODE:
        case NILFS_IOCTL_DELETE_CHECKPOINT:
        case NILFS_IOCTL_GET_CPINFO:
        case NILFS_IOCTL_GET_CPSTAT:
        case NILFS_IOCTL_GET_SUINFO:
        case NILFS_IOCTL_SET_SUINFO:
        case NILFS_IOCTL_GET_SUSTAT:
        case NILFS_IOCTL_GET_VINFO:
        case NILFS_IOCTL_GET_BDESCS:
        case NILFS_IOCTL_CLEAN_SEGMENTS:
        case NILFS_IOCTL_SYNC:
        case NILFS_IOCTL_RESIZE:
        case NILFS_IOCTL_SET_ALLOC_RANGE:
        case FITRIM:
                break;
        default:
                return -ENOIOCTLCMD;
        }
        return nilfs_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
}
#endif