/*
   *  linux/fs/fat/file.c
   *
   *  Written 1992,1993 by Werner Almesberger
   *
   *  regular file handling primitives for fat-based filesystems
   */

  #include <linux/capability.h>

  #include <linux/module.h>

  #include <linux/compat.h>

  #include <linux/mount.h>

  #include <linux/blkdev.h>

  #include <linux/backing-dev.h>

  #include <linux/fsnotify.h>
  #include <linux/security.h>

  #include <linux/falloc.h>

  #include "fat.h"

  static long fat_fallocate(struct file *file, int mode,
  			  loff_t offset, loff_t len);

  static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
  {
  	u32 attr;

  	inode_lock(inode);

  	attr = fat_make_attrs(inode);

  	inode_unlock(inode);

  
  	return put_user(attr, user_attr);
  }
  
  static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)

  {

  	struct inode *inode = file_inode(file);

  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

  	int is_dir = S_ISDIR(inode->i_mode);
  	u32 attr, oldattr;
  	struct iattr ia;
  	int err;

  	err = get_user(attr, user_attr);
  	if (err)
  		goto out;

  	err = mnt_want_write_file(file);

  	if (err)

  		goto out;

  	inode_lock(inode);

  
  	/*
  	 * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
  	 * prevents the user from turning us into a VFAT
  	 * longname entry.  Also, we obviously can't set
  	 * any of the NTFS attributes in the high 24 bits.
  	 */
  	attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
  	/* Merge in ATTR_VOLUME and ATTR_DIR */
  	attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
  		(is_dir ? ATTR_DIR : 0);
  	oldattr = fat_make_attrs(inode);
  
  	/* Equivalent to a chmod() */
  	ia.ia_valid = ATTR_MODE | ATTR_CTIME;

  	ia.ia_ctime = current_time(inode);

  	if (is_dir)
  		ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
  	else {
  		ia.ia_mode = fat_make_mode(sbi, attr,
  			S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
  	}

  	/* The root directory has no attributes */
  	if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
  		err = -EINVAL;

  		goto out_unlock_inode;

  	}

  	if (sbi->options.sys_immutable &&
  	    ((attr | oldattr) & ATTR_SYS) &&
  	    !capable(CAP_LINUX_IMMUTABLE)) {
  		err = -EPERM;

  		goto out_unlock_inode;

  	}

  	/*
  	 * The security check is questionable...  We single
  	 * out the RO attribute for checking by the security
  	 * module, just because it maps to a file mode.
  	 */
  	err = security_inode_setattr(file->f_path.dentry, &ia);
  	if (err)

  		goto out_unlock_inode;

  	/* This MUST be done before doing anything irreversible... */
  	err = fat_setattr(file->f_path.dentry, &ia);
  	if (err)

  		goto out_unlock_inode;

  
  	fsnotify_change(file->f_path.dentry, ia.ia_valid);
  	if (sbi->options.sys_immutable) {
  		if (attr & ATTR_SYS)
  			inode->i_flags |= S_IMMUTABLE;
  		else

  			inode->i_flags &= ~S_IMMUTABLE;

  	}

  	fat_save_attrs(inode, attr);
  	mark_inode_dirty(inode);

  out_unlock_inode:

  	inode_unlock(inode);

  	mnt_drop_write_file(file);

  out:
  	return err;
  }

  static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  	return put_user(sbi->vol_id, user_attr);
  }

  long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)

  {

  	struct inode *inode = file_inode(filp);

  	u32 __user *user_attr = (u32 __user *)arg;

  	switch (cmd) {
  	case FAT_IOCTL_GET_ATTRIBUTES:

  		return fat_ioctl_get_attributes(inode, user_attr);

  	case FAT_IOCTL_SET_ATTRIBUTES:

  		return fat_ioctl_set_attributes(filp, user_attr);

  	case FAT_IOCTL_GET_VOLUME_ID:
  		return fat_ioctl_get_volume_id(inode, user_attr);

  	default:
  		return -ENOTTY;	/* Inappropriate ioctl for device */
  	}
  }

  #ifdef CONFIG_COMPAT
  static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
  				      unsigned long arg)
  
  {
  	return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
  }
  #endif

  static int fat_file_release(struct inode *inode, struct file *filp)
  {
  	if ((filp->f_mode & FMODE_WRITE) &&
  	     MSDOS_SB(inode->i_sb)->options.flush) {
  		fat_flush_inodes(inode->i_sb, inode, NULL);

  		congestion_wait(BLK_RW_ASYNC, HZ/10);

  	}
  	return 0;
  }

  int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)

  {

  	struct inode *inode = filp->f_mapping->host;

  	int res, err;

  	res = generic_file_fsync(filp, start, end, datasync);

  	err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
  
  	return res ? res : err;
  }

  const struct file_operations fat_file_operations = {

  	.llseek		= generic_file_llseek,

  	.read_iter	= generic_file_read_iter,

  	.write_iter	= generic_file_write_iter,

  	.mmap		= generic_file_mmap,

  	.release	= fat_file_release,

  	.unlocked_ioctl	= fat_generic_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= fat_generic_compat_ioctl,
  #endif

  	.fsync		= fat_file_fsync,

  	.splice_read	= generic_file_splice_read,

  	.fallocate	= fat_fallocate,

  };

  static int fat_cont_expand(struct inode *inode, loff_t size)
  {
  	struct address_space *mapping = inode->i_mapping;
  	loff_t start = inode->i_size, count = size - inode->i_size;
  	int err;
  
  	err = generic_cont_expand_simple(inode, size);
  	if (err)
  		goto out;

  	inode->i_ctime = inode->i_mtime = current_time(inode);

  	mark_inode_dirty(inode);

  	if (IS_SYNC(inode)) {
  		int err2;
  
  		/*
  		 * Opencode syncing since we don't have a file open to use
  		 * standard fsync path.
  		 */
  		err = filemap_fdatawrite_range(mapping, start,
  					       start + count - 1);
  		err2 = sync_mapping_buffers(mapping);
  		if (!err)
  			err = err2;
  		err2 = write_inode_now(inode, 1);
  		if (!err)
  			err = err2;
  		if (!err) {
  			err =  filemap_fdatawait_range(mapping, start,
  						       start + count - 1);
  		}
  	}

  out:
  	return err;
  }

  /*
   * Preallocate space for a file. This implements fat's fallocate file
   * operation, which gets called from sys_fallocate system call. User
   * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set
   * we just allocate clusters without zeroing them out. Otherwise we
   * allocate and zero out clusters via an expanding truncate.
   */
  static long fat_fallocate(struct file *file, int mode,
  			  loff_t offset, loff_t len)
  {
  	int nr_cluster; /* Number of clusters to be allocated */
  	loff_t mm_bytes; /* Number of bytes to be allocated for file */
  	loff_t ondisksize; /* block aligned on-disk size in bytes*/
  	struct inode *inode = file->f_mapping->host;
  	struct super_block *sb = inode->i_sb;
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
  	int err = 0;
  
  	/* No support for hole punch or other fallocate flags. */
  	if (mode & ~FALLOC_FL_KEEP_SIZE)
  		return -EOPNOTSUPP;
  
  	/* No support for dir */
  	if (!S_ISREG(inode->i_mode))
  		return -EOPNOTSUPP;

  	inode_lock(inode);

  	if (mode & FALLOC_FL_KEEP_SIZE) {
  		ondisksize = inode->i_blocks << 9;
  		if ((offset + len) <= ondisksize)
  			goto error;
  
  		/* First compute the number of clusters to be allocated */
  		mm_bytes = offset + len - ondisksize;
  		nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >>
  			sbi->cluster_bits;
  
  		/* Start the allocation.We are not zeroing out the clusters */
  		while (nr_cluster-- > 0) {
  			err = fat_add_cluster(inode);
  			if (err)
  				goto error;
  		}
  	} else {
  		if ((offset + len) <= i_size_read(inode))
  			goto error;
  
  		/* This is just an expanding truncate */
  		err = fat_cont_expand(inode, (offset + len));
  	}
  
  error:

  	inode_unlock(inode);

  	return err;
  }

  /* Free all clusters after the skip'th cluster. */
  static int fat_free(struct inode *inode, int skip)
  {
  	struct super_block *sb = inode->i_sb;
  	int err, wait, free_start, i_start, i_logstart;
  
  	if (MSDOS_I(inode)->i_start == 0)
  		return 0;

  	fat_cache_inval_inode(inode);

  	wait = IS_DIRSYNC(inode);

  	i_start = free_start = MSDOS_I(inode)->i_start;
  	i_logstart = MSDOS_I(inode)->i_logstart;
  
  	/* First, we write the new file size. */
  	if (!skip) {
  		MSDOS_I(inode)->i_start = 0;
  		MSDOS_I(inode)->i_logstart = 0;
  	}
  	MSDOS_I(inode)->i_attrs |= ATTR_ARCH;

  	inode->i_ctime = inode->i_mtime = current_time(inode);

  	if (wait) {
  		err = fat_sync_inode(inode);
  		if (err) {
  			MSDOS_I(inode)->i_start = i_start;
  			MSDOS_I(inode)->i_logstart = i_logstart;
  			return err;
  		}
  	} else
  		mark_inode_dirty(inode);
  
  	/* Write a new EOF, and get the remaining cluster chain for freeing. */

  	if (skip) {
  		struct fat_entry fatent;
  		int ret, fclus, dclus;
  
  		ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
  		if (ret < 0)
  			return ret;
  		else if (ret == FAT_ENT_EOF)
  			return 0;
  
  		fatent_init(&fatent);
  		ret = fat_ent_read(inode, &fatent, dclus);
  		if (ret == FAT_ENT_EOF) {
  			fatent_brelse(&fatent);
  			return 0;
  		} else if (ret == FAT_ENT_FREE) {

  			fat_fs_error(sb,

  				     "%s: invalid cluster chain (i_pos %lld)",

  				     __func__, MSDOS_I(inode)->i_pos);

  			ret = -EIO;
  		} else if (ret > 0) {
  			err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
  			if (err)
  				ret = err;
  		}
  		fatent_brelse(&fatent);
  		if (ret < 0)
  			return ret;
  
  		free_start = ret;

  	}

  	inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
  
  	/* Freeing the remained cluster chain */
  	return fat_free_clusters(inode, free_start);

  }

  void fat_truncate_blocks(struct inode *inode, loff_t offset)

  {

  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

  	const unsigned int cluster_size = sbi->cluster_size;
  	int nr_clusters;
  
  	/*
  	 * This protects against truncating a file bigger than it was then
  	 * trying to write into the hole.
  	 */

  	if (MSDOS_I(inode)->mmu_private > offset)
  		MSDOS_I(inode)->mmu_private = offset;

  	nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;

  	fat_free(inode, nr_clusters);

  	fat_flush_inodes(inode->i_sb, inode, NULL);

  }

  int fat_getattr(const struct path *path, struct kstat *stat,
  		u32 request_mask, unsigned int flags)

  {

  	struct inode *inode = d_inode(path->dentry);

  	generic_fillattr(inode, stat);
  	stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;

  
  	if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
  		/* Use i_pos for ino. This is used as fileid of nfs. */
  		stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
  	}

  	return 0;
  }
  EXPORT_SYMBOL_GPL(fat_getattr);

  static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
  			     struct inode *inode, umode_t *mode_ptr)

  {

  	umode_t mask, perm;

  	/*
  	 * Note, the basic check is already done by a caller of

  	 * (attr->ia_mode & ~FAT_VALID_MODE)

  	 */
  
  	if (S_ISREG(inode->i_mode))

  		mask = sbi->options.fs_fmask;
  	else
  		mask = sbi->options.fs_dmask;

  	perm = *mode_ptr & ~(S_IFMT | mask);

  	/*
  	 * Of the r and x bits, all (subject to umask) must be present. Of the
  	 * w bits, either all (subject to umask) or none must be present.

  	 *
  	 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.

  	 */

  	if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))

  		return -EPERM;

  	if (fat_mode_can_hold_ro(inode)) {
  		if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
  			return -EPERM;
  	} else {
  		if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
  			return -EPERM;
  	}

  	*mode_ptr &= S_IFMT | perm;

  	return 0;
  }

  static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
  {

  	umode_t allow_utime = sbi->options.allow_utime;

  	if (!uid_eq(current_fsuid(), inode->i_uid)) {

  		if (in_group_p(inode->i_gid))
  			allow_utime >>= 3;
  		if (allow_utime & MAY_WRITE)
  			return 1;
  	}
  
  	/* use a default check */
  	return 0;
  }

  #define TIMES_SET_FLAGS	(ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)

  /* valid file mode bits */
  #define FAT_VALID_MODE	(S_IFREG | S_IFDIR | S_IRWXUGO)

  int fat_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);

  	struct inode *inode = d_inode(dentry);

  	unsigned int ia_valid;

  	int error;

  	/* Check for setting the inode time. */
  	ia_valid = attr->ia_valid;

  	if (ia_valid & TIMES_SET_FLAGS) {

  		if (fat_allow_set_time(sbi, inode))

  			attr->ia_valid &= ~TIMES_SET_FLAGS;

  	}

  	error = setattr_prepare(dentry, attr);

  	attr->ia_valid = ia_valid;

  	if (error) {
  		if (sbi->options.quiet)
  			error = 0;
  		goto out;
  	}

  	/*
  	 * Expand the file. Since inode_setattr() updates ->i_size
  	 * before calling the ->truncate(), but FAT needs to fill the
  	 * hole before it. XXX: this is no longer true with new truncate
  	 * sequence.
  	 */
  	if (attr->ia_valid & ATTR_SIZE) {

  		inode_dio_wait(inode);

  		if (attr->ia_size > inode->i_size) {
  			error = fat_cont_expand(inode, attr->ia_size);
  			if (error || attr->ia_valid == ATTR_SIZE)
  				goto out;
  			attr->ia_valid &= ~ATTR_SIZE;
  		}
  	}

  	if (((attr->ia_valid & ATTR_UID) &&

  	     (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||

  	    ((attr->ia_valid & ATTR_GID) &&

  	     (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||

  	    ((attr->ia_valid & ATTR_MODE) &&

  	     (attr->ia_mode & ~FAT_VALID_MODE)))

  		error = -EPERM;
  
  	if (error) {
  		if (sbi->options.quiet)
  			error = 0;
  		goto out;
  	}

  	/*
  	 * We don't return -EPERM here. Yes, strange, but this is too
  	 * old behavior.
  	 */
  	if (attr->ia_valid & ATTR_MODE) {
  		if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
  			attr->ia_valid &= ~ATTR_MODE;
  	}

  	if (attr->ia_valid & ATTR_SIZE) {

  		error = fat_block_truncate_page(inode, attr->ia_size);
  		if (error)
  			goto out;

  		down_write(&MSDOS_I(inode)->truncate_lock);

  		truncate_setsize(inode, attr->ia_size);
  		fat_truncate_blocks(inode, attr->ia_size);

  		up_write(&MSDOS_I(inode)->truncate_lock);

  	}

  	setattr_copy(inode, attr);

  	mark_inode_dirty(inode);

  out:

  	return error;
  }
  EXPORT_SYMBOL_GPL(fat_setattr);

  const struct inode_operations fat_file_inode_operations = {

  	.setattr	= fat_setattr,

  	.getattr	= fat_getattr,

  };