exfat: add inode operations

// SPDX-License-Identifier: GPL-2.0-or-later

/*

 * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.

 */

#include <linux/init.h>

#include <linux/buffer_head.h>

#include <linux/mpage.h>

#include <linux/bio.h>

#include <linux/blkdev.h>

#include <linux/time.h>

#include <linux/writeback.h>

#include <linux/uio.h>

#include <linux/random.h>

#include <linux/iversion.h>

#include "exfat_raw.h"

#include "exfat_fs.h"

static int __exfat_write_inode(struct inode *inode, int sync)

{

	int ret = -EIO;

	unsigned long long on_disk_size;

	struct exfat_dentry *ep, *ep2;

	struct exfat_entry_set_cache *es = NULL;

	struct super_block *sb = inode->i_sb;

	struct exfat_sb_info *sbi = EXFAT_SB(sb);

	struct exfat_inode_info *ei = EXFAT_I(inode);

	bool is_dir = (ei->type == TYPE_DIR) ? true : false;

	if (inode->i_ino == EXFAT_ROOT_INO)

		return 0;

	/*

	 * If the indode is already unlinked, there is no need for updating it.

	 */

	if (ei->dir.dir == DIR_DELETED)

		return 0;

	if (is_dir && ei->dir.dir == sbi->root_dir && ei->entry == -1)

		return 0;

	exfat_set_vol_flags(sb, VOL_DIRTY);

	/* get the directory entry of given file or directory */

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

		&ep);

	if (!es)

		return -EIO;

	ep2 = ep + 1;

	ep->dentry.file.attr = cpu_to_le16(exfat_make_attr(inode));

	/* set FILE_INFO structure using the acquired struct exfat_dentry */

	exfat_set_entry_time(sbi, &ei->i_crtime,

			&ep->dentry.file.create_tz,

			&ep->dentry.file.create_time,

			&ep->dentry.file.create_date,

			&ep->dentry.file.create_time_ms);

	exfat_set_entry_time(sbi, &inode->i_mtime,

			&ep->dentry.file.modify_tz,

			&ep->dentry.file.modify_time,

			&ep->dentry.file.modify_date,

			&ep->dentry.file.modify_time_ms);

	exfat_set_entry_time(sbi, &inode->i_atime,

			&ep->dentry.file.access_tz,

			&ep->dentry.file.access_time,

			&ep->dentry.file.access_date,

			NULL);

	/* File size should be zero if there is no cluster allocated */

	on_disk_size = i_size_read(inode);

	if (ei->start_clu == EXFAT_EOF_CLUSTER)

		on_disk_size = 0;

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

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

	ret = exfat_update_dir_chksum_with_entry_set(sb, es, sync);

	kfree(es);

	return ret;

}

int exfat_write_inode(struct inode *inode, struct writeback_control *wbc)

{

	int ret;

	mutex_lock(&EXFAT_SB(inode->i_sb)->s_lock);

	ret = __exfat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);

	mutex_unlock(&EXFAT_SB(inode->i_sb)->s_lock);

	return ret;

}

void exfat_sync_inode(struct inode *inode)

{

	lockdep_assert_held(&EXFAT_SB(inode->i_sb)->s_lock);

	__exfat_write_inode(inode, 1);

}

/*

 * Input: inode, (logical) clu_offset, target allocation area

 * Output: errcode, cluster number

 * *clu = (~0), if it's unable to allocate a new cluster

 */

static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,

		unsigned int *clu, int create)

{

	int ret, modified = false;

	unsigned int last_clu;

	struct exfat_chain new_clu;

	struct exfat_dentry *ep;

	struct exfat_entry_set_cache *es = NULL;

	struct super_block *sb = inode->i_sb;

	struct exfat_sb_info *sbi = EXFAT_SB(sb);

	struct exfat_inode_info *ei = EXFAT_I(inode);

	unsigned int local_clu_offset = clu_offset;

	unsigned int num_to_be_allocated = 0, num_clusters = 0;

	ei->rwoffset = EXFAT_CLU_TO_B(clu_offset, sbi);

	if (EXFAT_I(inode)->i_size_ondisk > 0)

		num_clusters =

			EXFAT_B_TO_CLU_ROUND_UP(EXFAT_I(inode)->i_size_ondisk,

			sbi);

	if (clu_offset >= num_clusters)

		num_to_be_allocated = clu_offset - num_clusters + 1;

	if (!create && (num_to_be_allocated > 0)) {

		*clu = EXFAT_EOF_CLUSTER;

		return 0;

	}

	*clu = last_clu = ei->start_clu;

	if (ei->flags == ALLOC_NO_FAT_CHAIN) {

		if (clu_offset > 0 && *clu != EXFAT_EOF_CLUSTER) {

			last_clu += clu_offset - 1;

			if (clu_offset == num_clusters)

				*clu = EXFAT_EOF_CLUSTER;

			else

				*clu += clu_offset;

		}

	} else if (ei->type == TYPE_FILE) {

		unsigned int fclus = 0;

		int err = exfat_get_cluster(inode, clu_offset,

				&fclus, clu, &last_clu, 1);

		if (err)

			return -EIO;

		clu_offset -= fclus;

	} else {

		/* hint information */

		if (clu_offset > 0 && ei->hint_bmap.off != EXFAT_EOF_CLUSTER &&

		    ei->hint_bmap.off > 0 && clu_offset >= ei->hint_bmap.off) {

			clu_offset -= ei->hint_bmap.off;

			/* hint_bmap.clu should be valid */

			WARN_ON(ei->hint_bmap.clu < 2);

			*clu = ei->hint_bmap.clu;

		}

		while (clu_offset > 0 && *clu != EXFAT_EOF_CLUSTER) {

			last_clu = *clu;

			if (exfat_get_next_cluster(sb, clu))

				return -EIO;

			clu_offset--;

		}

	}

	if (*clu == EXFAT_EOF_CLUSTER) {

		exfat_set_vol_flags(sb, VOL_DIRTY);

		new_clu.dir = (last_clu == EXFAT_EOF_CLUSTER) ?

				EXFAT_EOF_CLUSTER : last_clu + 1;

		new_clu.size = 0;

		new_clu.flags = ei->flags;

		/* allocate a cluster */

		if (num_to_be_allocated < 1) {

			/* Broken FAT (i_sze > allocated FAT) */

			exfat_fs_error(sb, "broken FAT chain.");

			return -EIO;

		}

		ret = exfat_alloc_cluster(inode, num_to_be_allocated, &new_clu);

		if (ret)

			return ret;

		if (new_clu.dir == EXFAT_EOF_CLUSTER ||

		    new_clu.dir == EXFAT_FREE_CLUSTER) {

			exfat_fs_error(sb,

				"bogus cluster new allocated (last_clu : %u, new_clu : %u)",

				last_clu, new_clu.dir);

			return -EIO;

		}

		/* append to the FAT chain */

		if (last_clu == EXFAT_EOF_CLUSTER) {

			if (new_clu.flags == ALLOC_FAT_CHAIN)

				ei->flags = ALLOC_FAT_CHAIN;

			ei->start_clu = new_clu.dir;

			modified = true;

		} else {

			if (new_clu.flags != ei->flags) {

				/* no-fat-chain bit is disabled,

				 * so fat-chain should be synced with

				 * alloc-bitmap

				 */

				exfat_chain_cont_cluster(sb, ei->start_clu,

					num_clusters);

				ei->flags = ALLOC_FAT_CHAIN;

				modified = true;

			}

			if (new_clu.flags == ALLOC_FAT_CHAIN)

				if (exfat_ent_set(sb, last_clu, new_clu.dir))

					return -EIO;

		}

		num_clusters += num_to_be_allocated;

		*clu = new_clu.dir;

		if (ei->dir.dir != DIR_DELETED) {

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

				ES_ALL_ENTRIES, &ep);

			if (!es)

				return -EIO;

			/* get stream entry */

			ep++;

			/* update directory entry */

			if (modified) {

				if (ep->dentry.stream.flags != ei->flags)

					ep->dentry.stream.flags = ei->flags;

				if (le32_to_cpu(ep->dentry.stream.start_clu) !=

						ei->start_clu)

					ep->dentry.stream.start_clu =

						cpu_to_le32(ei->start_clu);

				ep->dentry.stream.valid_size =

					cpu_to_le64(i_size_read(inode));

				ep->dentry.stream.size =

					ep->dentry.stream.valid_size;

			}

			if (exfat_update_dir_chksum_with_entry_set(sb, es,

			    inode_needs_sync(inode)))

				return -EIO;

			kfree(es);

		} /* end of if != DIR_DELETED */

		inode->i_blocks +=

			num_to_be_allocated << sbi->sect_per_clus_bits;

		/*

		 * Move *clu pointer along FAT chains (hole care) because the

		 * caller of this function expect *clu to be the last cluster.

		 * This only works when num_to_be_allocated >= 2,

		 * *clu = (the first cluster of the allocated chain) =>

		 * (the last cluster of ...)

		 */

		if (ei->flags == ALLOC_NO_FAT_CHAIN) {

			*clu += num_to_be_allocated - 1;

		} else {

			while (num_to_be_allocated > 1) {

				if (exfat_get_next_cluster(sb, clu))

					return -EIO;

				num_to_be_allocated--;

			}

		}

	}

	/* hint information */

	ei->hint_bmap.off = local_clu_offset;

	ei->hint_bmap.clu = *clu;

	return 0;

}

static int exfat_map_new_buffer(struct exfat_inode_info *ei,

		struct buffer_head *bh, loff_t pos)

{

	if (buffer_delay(bh) && pos > ei->i_size_aligned)

		return -EIO;

	set_buffer_new(bh);

	/*

	 * Adjust i_size_aligned if i_size_ondisk is bigger than it.

	 */

	if (ei->i_size_ondisk > ei->i_size_aligned)

		ei->i_size_aligned = ei->i_size_ondisk;

	return 0;

}

static int exfat_get_block(struct inode *inode, sector_t iblock,

		struct buffer_head *bh_result, int create)

{

	struct exfat_inode_info *ei = EXFAT_I(inode);

	struct super_block *sb = inode->i_sb;

	struct exfat_sb_info *sbi = EXFAT_SB(sb);

	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;

	int err = 0;

	unsigned long mapped_blocks = 0;

	unsigned int cluster, sec_offset;

	sector_t last_block;

	sector_t phys = 0;

	loff_t pos;

	mutex_lock(&sbi->s_lock);

	last_block = EXFAT_B_TO_BLK_ROUND_UP(i_size_read(inode), sb);

	if (iblock >= last_block && !create)

		goto done;

	/* Is this block already allocated? */

	err = exfat_map_cluster(inode, iblock >> sbi->sect_per_clus_bits,

			&cluster, create);

	if (err) {

		if (err != -ENOSPC)

			exfat_fs_error_ratelimit(sb,

				"failed to bmap (inode : %p iblock : %llu, err : %d)",

				inode, (unsigned long long)iblock, err);

		goto unlock_ret;

	}

	if (cluster == EXFAT_EOF_CLUSTER)

		goto done;

	/* sector offset in cluster */

	sec_offset = iblock & (sbi->sect_per_clus - 1);

	phys = exfat_cluster_to_sector(sbi, cluster) + sec_offset;

	mapped_blocks = sbi->sect_per_clus - sec_offset;

	max_blocks = min(mapped_blocks, max_blocks);

	/* Treat newly added block / cluster */

	if (iblock < last_block)

		create = 0;

	if (create || buffer_delay(bh_result)) {

		pos = EXFAT_BLK_TO_B((iblock + 1), sb);

		if (ei->i_size_ondisk < pos)

			ei->i_size_ondisk = pos;

	}

	if (create) {

		err = exfat_map_new_buffer(ei, bh_result, pos);

		if (err) {

			exfat_fs_error(sb,

					"requested for bmap out of range(pos : (%llu) > i_size_aligned(%llu)\n",

					pos, ei->i_size_aligned);

			goto unlock_ret;

		}

	}

	if (buffer_delay(bh_result))

		clear_buffer_delay(bh_result);

	map_bh(bh_result, sb, phys);

done:

	bh_result->b_size = EXFAT_BLK_TO_B(max_blocks, sb);

unlock_ret:

	mutex_unlock(&sbi->s_lock);

	return err;

}

static int exfat_readpage(struct file *file, struct page *page)

{

	return mpage_readpage(page, exfat_get_block);

}

static int exfat_readpages(struct file *file, struct address_space *mapping,

		struct list_head *pages, unsigned int nr_pages)

{

	return mpage_readpages(mapping, pages, nr_pages, exfat_get_block);

}

static int exfat_writepage(struct page *page, struct writeback_control *wbc)

{

	return block_write_full_page(page, exfat_get_block, wbc);

}

static int exfat_writepages(struct address_space *mapping,

		struct writeback_control *wbc)

{

	return mpage_writepages(mapping, wbc, exfat_get_block);

}

static void exfat_write_failed(struct address_space *mapping, loff_t to)

{

	struct inode *inode = mapping->host;

	if (to > i_size_read(inode)) {

		truncate_pagecache(inode, i_size_read(inode));

		exfat_truncate(inode, EXFAT_I(inode)->i_size_aligned);

	}

}

static int exfat_write_begin(struct file *file, struct address_space *mapping,

		loff_t pos, unsigned int len, unsigned int flags,

		struct page **pagep, void **fsdata)

{

	int ret;

	*pagep = NULL;

	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,

			       exfat_get_block,

			       &EXFAT_I(mapping->host)->i_size_ondisk);

	if (ret < 0)

		exfat_write_failed(mapping, pos+len);

	return ret;

}

static int exfat_write_end(struct file *file, struct address_space *mapping,

		loff_t pos, unsigned int len, unsigned int copied,

		struct page *pagep, void *fsdata)

{

	struct inode *inode = mapping->host;

	struct exfat_inode_info *ei = EXFAT_I(inode);

	int err;

	err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);

	if (EXFAT_I(inode)->i_size_aligned < i_size_read(inode)) {

		exfat_fs_error(inode->i_sb,

			"invalid size(size(%llu) > aligned(%llu)\n",

			i_size_read(inode), EXFAT_I(inode)->i_size_aligned);

		return -EIO;

	}

	if (err < len)

		exfat_write_failed(mapping, pos+len);

	if (!(err < 0) && !(ei->attr & ATTR_ARCHIVE)) {

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

		ei->attr |= ATTR_ARCHIVE;

		mark_inode_dirty(inode);

	}

	return err;

}

static ssize_t exfat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)

{

	struct address_space *mapping = iocb->ki_filp->f_mapping;

	struct inode *inode = mapping->host;

	loff_t size = iocb->ki_pos + iov_iter_count(iter);

	int rw = iov_iter_rw(iter);

	ssize_t ret;

	if (rw == WRITE) {

		/*

		 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),

		 * so we need to update the ->i_size_aligned to block boundary.

		 *

		 * But we must fill the remaining area or hole by nul for

		 * updating ->i_size_aligned

		 *

		 * Return 0, and fallback to normal buffered write.

		 */

		if (EXFAT_I(inode)->i_size_aligned < size)

			return 0;

	}

	/*

	 * Need to use the DIO_LOCKING for avoiding the race

	 * condition of exfat_get_block() and ->truncate().

	 */

	ret = blockdev_direct_IO(iocb, inode, iter, exfat_get_block);

	if (ret < 0 && (rw & WRITE))

		exfat_write_failed(mapping, size);

	return ret;

}

static sector_t exfat_aop_bmap(struct address_space *mapping, sector_t block)

{

	sector_t blocknr;

	/* exfat_get_cluster() assumes the requested blocknr isn't truncated. */

	down_read(&EXFAT_I(mapping->host)->truncate_lock);

	blocknr = generic_block_bmap(mapping, block, exfat_get_block);

	up_read(&EXFAT_I(mapping->host)->truncate_lock);

	return blocknr;

}

/*

 * exfat_block_truncate_page() zeroes out a mapping from file offset `from'

 * up to the end of the block which corresponds to `from'.

 * This is required during truncate to physically zeroout the tail end

 * of that block so it doesn't yield old data if the file is later grown.

 * Also, avoid causing failure from fsx for cases of "data past EOF"

 */

int exfat_block_truncate_page(struct inode *inode, loff_t from)

{

	return block_truncate_page(inode->i_mapping, from, exfat_get_block);

}

static const struct address_space_operations exfat_aops = {

	.readpage	= exfat_readpage,

	.readpages	= exfat_readpages,

	.writepage	= exfat_writepage,

	.writepages	= exfat_writepages,

	.write_begin	= exfat_write_begin,

	.write_end	= exfat_write_end,

	.direct_IO	= exfat_direct_IO,

	.bmap		= exfat_aop_bmap

};

static inline unsigned long exfat_hash(loff_t i_pos)

{

	return hash_32(i_pos, EXFAT_HASH_BITS);

}

void exfat_hash_inode(struct inode *inode, loff_t i_pos)

{

	struct exfat_sb_info *sbi = EXFAT_SB(inode->i_sb);

	struct hlist_head *head = sbi->inode_hashtable + exfat_hash(i_pos);

	spin_lock(&sbi->inode_hash_lock);

	EXFAT_I(inode)->i_pos = i_pos;

	hlist_add_head(&EXFAT_I(inode)->i_hash_fat, head);

	spin_unlock(&sbi->inode_hash_lock);

}

void exfat_unhash_inode(struct inode *inode)

{

	struct exfat_sb_info *sbi = EXFAT_SB(inode->i_sb);

	spin_lock(&sbi->inode_hash_lock);

	hlist_del_init(&EXFAT_I(inode)->i_hash_fat);

	EXFAT_I(inode)->i_pos = 0;

	spin_unlock(&sbi->inode_hash_lock);

}

struct inode *exfat_iget(struct super_block *sb, loff_t i_pos)

{

	struct exfat_sb_info *sbi = EXFAT_SB(sb);

	struct exfat_inode_info *info;

	struct hlist_head *head = sbi->inode_hashtable + exfat_hash(i_pos);

	struct inode *inode = NULL;

	spin_lock(&sbi->inode_hash_lock);

	hlist_for_each_entry(info, head, i_hash_fat) {

		WARN_ON(info->vfs_inode.i_sb != sb);

		if (i_pos != info->i_pos)

			continue;

		inode = igrab(&info->vfs_inode);

		if (inode)

			break;

	}

	spin_unlock(&sbi->inode_hash_lock);

	return inode;

}

/* doesn't deal with root inode */

static int exfat_fill_inode(struct inode *inode, struct exfat_dir_entry *info)

{

	struct exfat_sb_info *sbi = EXFAT_SB(inode->i_sb);

	struct exfat_inode_info *ei = EXFAT_I(inode);

	loff_t size = info->size;

	memcpy(&ei->dir, &info->dir, sizeof(struct exfat_chain));

	ei->entry = info->entry;

	ei->attr = info->attr;

	ei->start_clu = info->start_clu;

	ei->flags = info->flags;

	ei->type = info->type;

	ei->version = 0;

	ei->hint_stat.eidx = 0;

	ei->hint_stat.clu = info->start_clu;

	ei->hint_femp.eidx = EXFAT_HINT_NONE;

	ei->rwoffset = 0;

	ei->hint_bmap.off = EXFAT_EOF_CLUSTER;

	ei->i_pos = 0;

	inode->i_uid = sbi->options.fs_uid;

	inode->i_gid = sbi->options.fs_gid;

	inode_inc_iversion(inode);

	inode->i_generation = prandom_u32();

	if (info->attr & ATTR_SUBDIR) { /* directory */

		inode->i_generation &= ~1;

		inode->i_mode = exfat_make_mode(sbi, info->attr, 0777);

		inode->i_op = &exfat_dir_inode_operations;

		inode->i_fop = &exfat_dir_operations;

		set_nlink(inode, info->num_subdirs);

	} else { /* regular file */

		inode->i_generation |= 1;

		inode->i_mode = exfat_make_mode(sbi, info->attr, 0777);

		inode->i_op = &exfat_file_inode_operations;

		inode->i_fop = &exfat_file_operations;

		inode->i_mapping->a_ops = &exfat_aops;

		inode->i_mapping->nrpages = 0;

	}

	i_size_write(inode, size);

	/* ondisk and aligned size should be aligned with block size */

	if (size & (inode->i_sb->s_blocksize - 1)) {

		size |= (inode->i_sb->s_blocksize - 1);

		size++;

	}

	ei->i_size_aligned = size;

	ei->i_size_ondisk = size;

	exfat_save_attr(inode, info->attr);

	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &

		~(sbi->cluster_size - 1)) >> inode->i_blkbits;

	inode->i_mtime = info->mtime;

	inode->i_ctime = info->mtime;

	ei->i_crtime = info->crtime;

	inode->i_atime = info->atime;

	exfat_cache_init_inode(inode);

	return 0;

}

struct inode *exfat_build_inode(struct super_block *sb,

		struct exfat_dir_entry *info, loff_t i_pos)

{

	struct inode *inode;

	int err;

	inode = exfat_iget(sb, i_pos);

	if (inode)

		goto out;

	inode = new_inode(sb);

	if (!inode) {

		inode = ERR_PTR(-ENOMEM);

		goto out;

	}

	inode->i_ino = iunique(sb, EXFAT_ROOT_INO);

	inode_set_iversion(inode, 1);

	err = exfat_fill_inode(inode, info);

	if (err) {

		iput(inode);

		inode = ERR_PTR(err);

		goto out;

	}

	exfat_hash_inode(inode, i_pos);

	insert_inode_hash(inode);

out:

	return inode;

}

void exfat_evict_inode(struct inode *inode)

{

	truncate_inode_pages(&inode->i_data, 0);

	if (!inode->i_nlink) {