// SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   */
  
  #include <linux/slab.h>
  #include <linux/cred.h>
  #include <linux/buffer_head.h>

  #include <linux/blkdev.h>

  
  #include "exfat_raw.h"
  #include "exfat_fs.h"
  
  static int exfat_cont_expand(struct inode *inode, loff_t size)
  {
  	struct address_space *mapping = inode->i_mapping;
  	loff_t start = i_size_read(inode), count = size - i_size_read(inode);
  	int err, err2;
  
  	err = generic_cont_expand_simple(inode, size);
  	if (err)
  		return err;
  
  	inode->i_ctime = inode->i_mtime = current_time(inode);
  	mark_inode_dirty(inode);
  
  	if (!IS_SYNC(inode))
  		return 0;
  
  	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)
  		return err;
  
  	return filemap_fdatawait_range(mapping, start, start + count - 1);
  }
  
  static bool exfat_allow_set_time(struct exfat_sb_info *sbi, struct inode *inode)
  {
  	mode_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 true;
  	}
  
  	/* use a default check */
  	return false;
  }
  
  static int exfat_sanitize_mode(const struct exfat_sb_info *sbi,
  		struct inode *inode, umode_t *mode_ptr)
  {
  	mode_t i_mode, mask, perm;
  
  	i_mode = inode->i_mode;
  
  	mask = (S_ISREG(i_mode) || S_ISLNK(i_mode)) ?
  		sbi->options.fs_fmask : sbi->options.fs_dmask;
  	perm = *mode_ptr & ~(S_IFMT | mask);
  
  	/* Of the r and x bits, all (subject to umask) must be present.*/
  	if ((perm & 0555) != (i_mode & 0555))
  		return -EPERM;
  
  	if (exfat_mode_can_hold_ro(inode)) {
  		/*
  		 * Of the w bits, either all (subject to umask) or none must
  		 * be present.
  		 */
  		if ((perm & 0222) && ((perm & 0222) != (0222 & ~mask)))
  			return -EPERM;
  	} else {
  		/*
  		 * If exfat_mode_can_hold_ro(inode) is false, can't change
  		 * w bits.
  		 */
  		if ((perm & 0222) != (0222 & ~mask))
  			return -EPERM;
  	}
  
  	*mode_ptr &= S_IFMT | perm;
  
  	return 0;
  }
  
  /* resize the file length */
  int __exfat_truncate(struct inode *inode, loff_t new_size)
  {
  	unsigned int num_clusters_new, num_clusters_phys;
  	unsigned int last_clu = EXFAT_FREE_CLUSTER;
  	struct exfat_chain clu;

  	struct super_block *sb = inode->i_sb;
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
  	struct exfat_inode_info *ei = EXFAT_I(inode);

  	int evict = (ei->dir.dir == DIR_DELETED) ? 1 : 0;
  
  	/* check if the given file ID is opened */
  	if (ei->type != TYPE_FILE && ei->type != TYPE_DIR)
  		return -EPERM;

  	exfat_set_volume_dirty(sb);

  
  	num_clusters_new = EXFAT_B_TO_CLU_ROUND_UP(i_size_read(inode), sbi);
  	num_clusters_phys =
  		EXFAT_B_TO_CLU_ROUND_UP(EXFAT_I(inode)->i_size_ondisk, sbi);
  
  	exfat_chain_set(&clu, ei->start_clu, num_clusters_phys, ei->flags);
  
  	if (new_size > 0) {
  		/*
  		 * Truncate FAT chain num_clusters after the first cluster
  		 * num_clusters = min(new, phys);
  		 */
  		unsigned int num_clusters =
  			min(num_clusters_new, num_clusters_phys);
  
  		/*
  		 * Follow FAT chain
  		 * (defensive coding - works fine even with corrupted FAT table
  		 */
  		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
  			clu.dir += num_clusters;
  			clu.size -= num_clusters;
  		} else {
  			while (num_clusters > 0) {
  				last_clu = clu.dir;
  				if (exfat_get_next_cluster(sb, &(clu.dir)))
  					return -EIO;
  
  				num_clusters--;
  				clu.size--;
  			}
  		}
  	} else {
  		ei->flags = ALLOC_NO_FAT_CHAIN;
  		ei->start_clu = EXFAT_EOF_CLUSTER;
  	}
  
  	i_size_write(inode, new_size);
  
  	if (ei->type == TYPE_FILE)
  		ei->attr |= ATTR_ARCHIVE;
  
  	/* update the directory entry */
  	if (!evict) {
  		struct timespec64 ts;

  		struct exfat_dentry *ep, *ep2;
  		struct exfat_entry_set_cache *es;

  		int err;

  
  		es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry,

  				ES_ALL_ENTRIES);

  		if (!es)
  			return -EIO;

  		ep = exfat_get_dentry_cached(es, 0);
  		ep2 = exfat_get_dentry_cached(es, 1);

  
  		ts = current_time(inode);
  		exfat_set_entry_time(sbi, &ts,
  				&ep->dentry.file.modify_tz,
  				&ep->dentry.file.modify_time,
  				&ep->dentry.file.modify_date,

  				&ep->dentry.file.modify_time_cs);

  		ep->dentry.file.attr = cpu_to_le16(ei->attr);
  
  		/* File size should be zero if there is no cluster allocated */
  		if (ei->start_clu == EXFAT_EOF_CLUSTER) {

  			ep2->dentry.stream.valid_size = 0;
  			ep2->dentry.stream.size = 0;

  		} else {

  			ep2->dentry.stream.valid_size = cpu_to_le64(new_size);

  			ep2->dentry.stream.size = ep2->dentry.stream.valid_size;

  		}
  
  		if (new_size == 0) {
  			/* Any directory can not be truncated to zero */
  			WARN_ON(ei->type != TYPE_FILE);
  
  			ep2->dentry.stream.flags = ALLOC_FAT_CHAIN;
  			ep2->dentry.stream.start_clu = EXFAT_FREE_CLUSTER;
  		}

  		exfat_update_dir_chksum_with_entry_set(es);

  		err = exfat_free_dentry_set(es, inode_needs_sync(inode));
  		if (err)
  			return err;

  	}
  
  	/* cut off from the FAT chain */
  	if (ei->flags == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&
  			last_clu != EXFAT_EOF_CLUSTER) {
  		if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))
  			return -EIO;
  	}
  
  	/* invalidate cache and free the clusters */
  	/* clear exfat cache */
  	exfat_cache_inval_inode(inode);
  
  	/* hint information */
  	ei->hint_bmap.off = EXFAT_EOF_CLUSTER;
  	ei->hint_bmap.clu = EXFAT_EOF_CLUSTER;

  
  	/* hint_stat will be used if this is directory. */
  	ei->hint_stat.eidx = 0;
  	ei->hint_stat.clu = ei->start_clu;
  	ei->hint_femp.eidx = EXFAT_HINT_NONE;
  
  	/* free the clusters */
  	if (exfat_free_cluster(inode, &clu))
  		return -EIO;

  	exfat_clear_volume_dirty(sb);

  
  	return 0;
  }
  
  void exfat_truncate(struct inode *inode, loff_t size)
  {
  	struct super_block *sb = inode->i_sb;
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);

  	unsigned int blocksize = i_blocksize(inode);

  	loff_t aligned_size;
  	int err;
  
  	mutex_lock(&sbi->s_lock);
  	if (EXFAT_I(inode)->start_clu == 0) {
  		/*
  		 * Empty start_clu != ~0 (not allocated)
  		 */
  		exfat_fs_error(sb, "tried to truncate zeroed cluster.");
  		goto write_size;
  	}
  
  	err = __exfat_truncate(inode, i_size_read(inode));
  	if (err)
  		goto write_size;
  
  	inode->i_ctime = inode->i_mtime = current_time(inode);
  	if (IS_DIRSYNC(inode))
  		exfat_sync_inode(inode);
  	else
  		mark_inode_dirty(inode);
  
  	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
  			~(sbi->cluster_size - 1)) >> inode->i_blkbits;
  write_size:
  	aligned_size = i_size_read(inode);
  	if (aligned_size & (blocksize - 1)) {
  		aligned_size |= (blocksize - 1);
  		aligned_size++;
  	}
  
  	if (EXFAT_I(inode)->i_size_ondisk > i_size_read(inode))
  		EXFAT_I(inode)->i_size_ondisk = aligned_size;
  
  	if (EXFAT_I(inode)->i_size_aligned > i_size_read(inode))
  		EXFAT_I(inode)->i_size_aligned = aligned_size;
  	mutex_unlock(&sbi->s_lock);
  }
  
  int exfat_getattr(const struct path *path, struct kstat *stat,
  		unsigned int request_mask, unsigned int query_flags)
  {
  	struct inode *inode = d_backing_inode(path->dentry);
  	struct exfat_inode_info *ei = EXFAT_I(inode);
  
  	generic_fillattr(inode, stat);

  	exfat_truncate_atime(&stat->atime);

  	stat->result_mask |= STATX_BTIME;
  	stat->btime.tv_sec = ei->i_crtime.tv_sec;
  	stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
  	stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;
  	return 0;
  }
  
  int exfat_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
  	struct inode *inode = dentry->d_inode;
  	unsigned int ia_valid;
  	int error;
  
  	if ((attr->ia_valid & ATTR_SIZE) &&
  	    attr->ia_size > i_size_read(inode)) {
  		error = exfat_cont_expand(inode, attr->ia_size);
  		if (error || attr->ia_valid == ATTR_SIZE)
  			return error;
  		attr->ia_valid &= ~ATTR_SIZE;
  	}
  
  	/* Check for setting the inode time. */
  	ia_valid = attr->ia_valid;
  	if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&
  	    exfat_allow_set_time(sbi, inode)) {
  		attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |
  				ATTR_TIMES_SET);
  	}
  
  	error = setattr_prepare(dentry, attr);
  	attr->ia_valid = ia_valid;
  	if (error)
  		goto out;
  
  	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 & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777)))) {
  		error = -EPERM;
  		goto out;
  	}
  
  	/*
  	 * We don't return -EPERM here. Yes, strange, but this is too
  	 * old behavior.
  	 */
  	if (attr->ia_valid & ATTR_MODE) {
  		if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
  			attr->ia_valid &= ~ATTR_MODE;
  	}
  
  	if (attr->ia_valid & ATTR_SIZE) {
  		error = exfat_block_truncate_page(inode, attr->ia_size);
  		if (error)
  			goto out;
  
  		down_write(&EXFAT_I(inode)->truncate_lock);
  		truncate_setsize(inode, attr->ia_size);
  		exfat_truncate(inode, attr->ia_size);
  		up_write(&EXFAT_I(inode)->truncate_lock);
  	}
  
  	setattr_copy(inode, attr);

  	exfat_truncate_atime(&inode->i_atime);

  	mark_inode_dirty(inode);
  
  out:
  	return error;
  }

  int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
  {
  	struct inode *inode = filp->f_mapping->host;
  	int err;
  
  	err = __generic_file_fsync(filp, start, end, datasync);
  	if (err)
  		return err;
  
  	err = sync_blockdev(inode->i_sb->s_bdev);
  	if (err)
  		return err;
  
  	return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
  }

  const struct file_operations exfat_file_operations = {

  	.llseek		= generic_file_llseek,
  	.read_iter	= generic_file_read_iter,
  	.write_iter	= generic_file_write_iter,
  	.mmap		= generic_file_mmap,

  	.fsync		= exfat_file_fsync,

  	.splice_read	= generic_file_splice_read,
  	.splice_write	= iter_file_splice_write,

  };
  
  const struct inode_operations exfat_file_inode_operations = {
  	.setattr     = exfat_setattr,
  	.getattr     = exfat_getattr,
  };