fs/omfs/file.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * OMFS (as used by RIO Karma) file operations.
  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
  */

 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/buffer_head.h>
 #include <linux/mpage.h>
 #include "omfs.h"

 static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
 {
 	return (sbi->s_sys_blocksize - offset -
 		sizeof(struct omfs_extent)) /
 		sizeof(struct omfs_extent_entry) + 1;
 }

 void omfs_make_empty_table(struct buffer_head *bh, int offset)
 {
 	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];

 	oe->e_next = ~cpu_to_be64(0ULL);
 	oe->e_extent_count = cpu_to_be32(1),
 	oe->e_fill = cpu_to_be32(0x22),
 	oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
 	oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
 }

 int omfs_shrink_inode(struct inode *inode)
 {
 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 	struct omfs_extent *oe;
 	struct omfs_extent_entry *entry;
 	struct buffer_head *bh;
 	u64 next, last;
 	u32 extent_count;
 	u32 max_extents;
 	int ret;

 	/* traverse extent table, freeing each entry that is greater
 	 * than inode->i_size;
 	 */
 	next = inode->i_ino;

 	/* only support truncate -> 0 for now */
 	ret = -EIO;
 	if (inode->i_size != 0)
 		goto out;

 	bh = omfs_bread(inode->i_sb, next);
 	if (!bh)
 		goto out;

 	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
 	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);

 	for (;;) {

 		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
 			goto out_brelse;

 		extent_count = be32_to_cpu(oe->e_extent_count);

 		if (extent_count > max_extents)
 			goto out_brelse;

 		last = next;
 		next = be64_to_cpu(oe->e_next);
 		entry = &oe->e_entry;

 		/* ignore last entry as it is the terminator */
 		for (; extent_count > 1; extent_count--) {
 			u64 start, count;
 			start = be64_to_cpu(entry->e_cluster);
 			count = be64_to_cpu(entry->e_blocks);

 			omfs_clear_range(inode->i_sb, start, (int) count);
 			entry++;
 		}
 		omfs_make_empty_table(bh, (char *) oe - bh->b_data);
 		mark_buffer_dirty(bh);
 		brelse(bh);

 		if (last != inode->i_ino)
 			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);

 		if (next == ~0)
 			break;

 		bh = omfs_bread(inode->i_sb, next);
 		if (!bh)
 			goto out;
 		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
 		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
 	}
 	ret = 0;
 out:
 	return ret;
 out_brelse:
 	brelse(bh);
 	return ret;
 }

 static void omfs_truncate(struct inode *inode)
 {
 	omfs_shrink_inode(inode);
 	mark_inode_dirty(inode);
 }

 /*
  * Add new blocks to the current extent, or create new entries/continuations
  * as necessary.
  */
 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
 			u64 *ret_block)
 {
 	struct omfs_extent_entry *terminator;
 	struct omfs_extent_entry *entry = &oe->e_entry;
 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 	u32 extent_count = be32_to_cpu(oe->e_extent_count);
 	u64 new_block = 0;
 	u32 max_count;
 	int new_count;
 	int ret = 0;

 	/* reached the end of the extent table with no blocks mapped.
 	 * there are three possibilities for adding: grow last extent,
 	 * add a new extent to the current extent table, and add a
 	 * continuation inode.  in last two cases need an allocator for
 	 * sbi->s_cluster_size
 	 */

 	/* TODO: handle holes */

 	/* should always have a terminator */
 	if (extent_count < 1)
 		return -EIO;

 	/* trivially grow current extent, if next block is not taken */
 	terminator = entry + extent_count - 1;
 	if (extent_count > 1) {
 		entry = terminator-1;
 		new_block = be64_to_cpu(entry->e_cluster) +
 			be64_to_cpu(entry->e_blocks);

 		if (omfs_allocate_block(inode->i_sb, new_block)) {
 			be64_add_cpu(&entry->e_blocks, 1);
 			terminator->e_blocks = ~(cpu_to_be64(
 				be64_to_cpu(~terminator->e_blocks) + 1));
 			goto out;
 		}
 	}
 	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);

 	/* TODO: add a continuation block here */
 	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
 		return -EIO;

 	/* try to allocate a new cluster */
 	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
 		&new_block, &new_count);
 	if (ret)
 		goto out_fail;

 	/* copy terminator down an entry */
 	entry = terminator;
 	terminator++;
 	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));

 	entry->e_cluster = cpu_to_be64(new_block);
 	entry->e_blocks = cpu_to_be64((u64) new_count);

 	terminator->e_blocks = ~(cpu_to_be64(
 		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));

 	/* write in new entry */
 	be32_add_cpu(&oe->e_extent_count, 1);

 out:
 	*ret_block = new_block;
 out_fail:
 	return ret;
 }

 /*
  * Scans across the directory table for a given file block number.
  * If block not found, return 0.
  */
 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
 			sector_t block, int count, int *left)
 {
 	/* count > 1 because of terminator */
 	sector_t searched = 0;
 	for (; count > 1; count--) {
 		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
 			be64_to_cpu(ent->e_blocks));

 		if (block >= searched  &&
 		    block < searched + numblocks) {
 			/*
 			 * found it at cluster + (block - searched)
 			 * numblocks - (block - searched) is remainder
 			 */
 			*left = numblocks - (block - searched);
 			return clus_to_blk(OMFS_SB(inode->i_sb),
 				be64_to_cpu(ent->e_cluster)) +
 				block - searched;
 		}
 		searched += numblocks;
 		ent++;
 	}
 	return 0;
 }

 static int omfs_get_block(struct inode *inode, sector_t block,
 			  struct buffer_head *bh_result, int create)
 {
 	struct buffer_head *bh;
 	sector_t next, offset;
 	int ret;
 	u64 new_block;
 	u32 max_extents;
 	int extent_count;
 	struct omfs_extent *oe;
 	struct omfs_extent_entry *entry;
 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 	int max_blocks = bh_result->b_size >> inode->i_blkbits;
 	int remain;

 	ret = -EIO;
 	bh = omfs_bread(inode->i_sb, inode->i_ino);
 	if (!bh)
 		goto out;

 	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
 	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
 	next = inode->i_ino;

 	for (;;) {

 		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
 			goto out_brelse;

 		extent_count = be32_to_cpu(oe->e_extent_count);
 		next = be64_to_cpu(oe->e_next);
 		entry = &oe->e_entry;

 		if (extent_count > max_extents)
 			goto out_brelse;

 		offset = find_block(inode, entry, block, extent_count, &remain);
 		if (offset > 0) {
 			ret = 0;
 			map_bh(bh_result, inode->i_sb, offset);
 			if (remain > max_blocks)
 				remain = max_blocks;
 			bh_result->b_size = (remain << inode->i_blkbits);
 			goto out_brelse;
 		}
 		if (next == ~0)
 			break;

 		brelse(bh);
 		bh = omfs_bread(inode->i_sb, next);
 		if (!bh)
 			goto out;
 		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
 		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
 	}
 	if (create) {
 		ret = omfs_grow_extent(inode, oe, &new_block);
 		if (ret == 0) {
 			mark_buffer_dirty(bh);
 			mark_inode_dirty(inode);
 			map_bh(bh_result, inode->i_sb,
 					clus_to_blk(sbi, new_block));
 		}
 	}
 out_brelse:
 	brelse(bh);
 out:
 	return ret;
 }

 static int omfs_readpage(struct file *file, struct page *page)
 {
 	return block_read_full_page(page, omfs_get_block);
 }

 static void omfs_readahead(struct readahead_control *rac)
 {
 	mpage_readahead(rac, omfs_get_block);
 }

 static int omfs_writepage(struct page *page, struct writeback_control *wbc)
 {
 	return block_write_full_page(page, omfs_get_block, wbc);
 }

 static int
 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
 	return mpage_writepages(mapping, wbc, omfs_get_block);
 }

 static void omfs_write_failed(struct address_space *mapping, loff_t to)
 {
 	struct inode *inode = mapping->host;

 	if (to > inode->i_size) {
 		truncate_pagecache(inode, inode->i_size);
 		omfs_truncate(inode);
 	}
 }

 static int omfs_write_begin(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned flags,
 			struct page **pagep, void **fsdata)
 {
 	int ret;

 	ret = block_write_begin(mapping, pos, len, flags, pagep,
 				omfs_get_block);
 	if (unlikely(ret))
 		omfs_write_failed(mapping, pos + len);

 	return ret;
 }

 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
 {
 	return generic_block_bmap(mapping, block, omfs_get_block);
 }

 const struct file_operations omfs_file_operations = {
 	.llseek = generic_file_llseek,
 	.read_iter = generic_file_read_iter,
 	.write_iter = generic_file_write_iter,
 	.mmap = generic_file_mmap,
 	.fsync = generic_file_fsync,
 	.splice_read = generic_file_splice_read,
 };

 static int omfs_setattr(struct user_namespace *mnt_userns,
 			struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error;

 	error = setattr_prepare(&init_user_ns, dentry, attr);
 	if (error)
 		return error;

 	if ((attr->ia_valid & ATTR_SIZE) &&
 	    attr->ia_size != i_size_read(inode)) {
 		error = inode_newsize_ok(inode, attr->ia_size);
 		if (error)
 			return error;
 		truncate_setsize(inode, attr->ia_size);
 		omfs_truncate(inode);
 	}

 	setattr_copy(&init_user_ns, inode, attr);
 	mark_inode_dirty(inode);
 	return 0;
 }

 const struct inode_operations omfs_file_inops = {
 	.setattr = omfs_setattr,
 };

 const struct address_space_operations omfs_aops = {
 	.readpage = omfs_readpage,
 	.readahead = omfs_readahead,
 	.writepage = omfs_writepage,
 	.writepages = omfs_writepages,
 	.write_begin = omfs_write_begin,
 	.write_end = generic_write_end,
 	.bmap = omfs_bmap,
 };
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* OMFS (as used by RIO Karma) file operations.
	* Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
	*/

	#include <linux/module.h>
	#include <linux/fs.h>
	#include <linux/buffer_head.h>
	#include <linux/mpage.h>
	#include "omfs.h"

	static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
	{
	return (sbi->s_sys_blocksize - offset -
	sizeof(struct omfs_extent)) /
	sizeof(struct omfs_extent_entry) + 1;
	}

	void omfs_make_empty_table(struct buffer_head *bh, int offset)
	{
	struct omfs_extent oe = (struct omfs_extent ) &bh->b_data[offset];

	oe->e_next = ~cpu_to_be64(0ULL);
	oe->e_extent_count = cpu_to_be32(1),
	oe->e_fill = cpu_to_be32(0x22),
	oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
	oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
	}

	int omfs_shrink_inode(struct inode *inode)
	{
	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
	struct omfs_extent *oe;
	struct omfs_extent_entry *entry;
	struct buffer_head *bh;
	u64 next, last;
	u32 extent_count;
	u32 max_extents;
	int ret;

	/* traverse extent table, freeing each entry that is greater
	* than inode->i_size;
	*/
	next = inode->i_ino;

	/* only support truncate -> 0 for now */
	ret = -EIO;
	if (inode->i_size != 0)
	goto out;

	bh = omfs_bread(inode->i_sb, next);
	if (!bh)
	goto out;

	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);

	for (;;) {

	if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
	goto out_brelse;

	extent_count = be32_to_cpu(oe->e_extent_count);

	if (extent_count > max_extents)
	goto out_brelse;

	last = next;
	next = be64_to_cpu(oe->e_next);
	entry = &oe->e_entry;

	/* ignore last entry as it is the terminator */
	for (; extent_count > 1; extent_count--) {
	u64 start, count;
	start = be64_to_cpu(entry->e_cluster);
	count = be64_to_cpu(entry->e_blocks);

	omfs_clear_range(inode->i_sb, start, (int) count);
	entry++;
	}
	omfs_make_empty_table(bh, (char *) oe - bh->b_data);
	mark_buffer_dirty(bh);
	brelse(bh);

	if (last != inode->i_ino)
	omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);

	if (next == ~0)
	break;

	bh = omfs_bread(inode->i_sb, next);
	if (!bh)
	goto out;
	oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
	}
	ret = 0;
	out:
	return ret;
	out_brelse:
	brelse(bh);
	return ret;
	}

	static void omfs_truncate(struct inode *inode)
	{
	omfs_shrink_inode(inode);
	mark_inode_dirty(inode);
	}

	/*
	* Add new blocks to the current extent, or create new entries/continuations
	* as necessary.
	*/
	static int omfs_grow_extent(struct inode inode, struct omfs_extent oe,
	u64 *ret_block)
	{
	struct omfs_extent_entry *terminator;
	struct omfs_extent_entry *entry = &oe->e_entry;
	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
	u32 extent_count = be32_to_cpu(oe->e_extent_count);
	u64 new_block = 0;
	u32 max_count;
	int new_count;
	int ret = 0;

	/* reached the end of the extent table with no blocks mapped.
	* there are three possibilities for adding: grow last extent,
	* add a new extent to the current extent table, and add a
	* continuation inode. in last two cases need an allocator for
	* sbi->s_cluster_size
	*/

	/* TODO: handle holes */

	/* should always have a terminator */
	if (extent_count < 1)
	return -EIO;

	/* trivially grow current extent, if next block is not taken */
	terminator = entry + extent_count - 1;
	if (extent_count > 1) {
	entry = terminator-1;
	new_block = be64_to_cpu(entry->e_cluster) +
	be64_to_cpu(entry->e_blocks);

	if (omfs_allocate_block(inode->i_sb, new_block)) {
	be64_add_cpu(&entry->e_blocks, 1);
	terminator->e_blocks = ~(cpu_to_be64(
	be64_to_cpu(~terminator->e_blocks) + 1));
	goto out;
	}
	}
	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);

	/* TODO: add a continuation block here */
	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
	return -EIO;

	/* try to allocate a new cluster */
	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
	&new_block, &new_count);
	if (ret)
	goto out_fail;

	/* copy terminator down an entry */
	entry = terminator;
	terminator++;
	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));

	entry->e_cluster = cpu_to_be64(new_block);
	entry->e_blocks = cpu_to_be64((u64) new_count);

	terminator->e_blocks = ~(cpu_to_be64(
	be64_to_cpu(~terminator->e_blocks) + (u64) new_count));

	/* write in new entry */
	be32_add_cpu(&oe->e_extent_count, 1);

	out:
	*ret_block = new_block;
	out_fail:
	return ret;
	}

	/*
	* Scans across the directory table for a given file block number.
	* If block not found, return 0.
	*/
	static sector_t find_block(struct inode inode, struct omfs_extent_entry ent,
	sector_t block, int count, int *left)
	{
	/* count > 1 because of terminator */
	sector_t searched = 0;
	for (; count > 1; count--) {
	int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
	be64_to_cpu(ent->e_blocks));

	if (block >= searched &&
	block < searched + numblocks) {
	/*
	* found it at cluster + (block - searched)
	* numblocks - (block - searched) is remainder
	*/
	*left = numblocks - (block - searched);
	return clus_to_blk(OMFS_SB(inode->i_sb),
	be64_to_cpu(ent->e_cluster)) +
	block - searched;
	}
	searched += numblocks;
	ent++;
	}
	return 0;
	}

	static int omfs_get_block(struct inode *inode, sector_t block,
	struct buffer_head *bh_result, int create)
	{
	struct buffer_head *bh;
	sector_t next, offset;
	int ret;
	u64 new_block;
	u32 max_extents;
	int extent_count;
	struct omfs_extent *oe;
	struct omfs_extent_entry *entry;
	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
	int max_blocks = bh_result->b_size >> inode->i_blkbits;
	int remain;

	ret = -EIO;
	bh = omfs_bread(inode->i_sb, inode->i_ino);
	if (!bh)
	goto out;

	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
	next = inode->i_ino;

	for (;;) {

	if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
	goto out_brelse;

	extent_count = be32_to_cpu(oe->e_extent_count);
	next = be64_to_cpu(oe->e_next);
	entry = &oe->e_entry;

	if (extent_count > max_extents)
	goto out_brelse;

	offset = find_block(inode, entry, block, extent_count, &remain);
	if (offset > 0) {
	ret = 0;
	map_bh(bh_result, inode->i_sb, offset);
	if (remain > max_blocks)
	remain = max_blocks;
	bh_result->b_size = (remain << inode->i_blkbits);
	goto out_brelse;
	}
	if (next == ~0)
	break;

	brelse(bh);
	bh = omfs_bread(inode->i_sb, next);
	if (!bh)
	goto out;
	oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
	}
	if (create) {
	ret = omfs_grow_extent(inode, oe, &new_block);
	if (ret == 0) {
	mark_buffer_dirty(bh);
	mark_inode_dirty(inode);
	map_bh(bh_result, inode->i_sb,
	clus_to_blk(sbi, new_block));
	}
	}
	out_brelse:
	brelse(bh);
	out:
	return ret;
	}

	static int omfs_readpage(struct file file, struct page page)
	{
	return block_read_full_page(page, omfs_get_block);
	}

	static void omfs_readahead(struct readahead_control *rac)
	{
	mpage_readahead(rac, omfs_get_block);
	}

	static int omfs_writepage(struct page page, struct writeback_control wbc)
	{
	return block_write_full_page(page, omfs_get_block, wbc);
	}

	static int
	omfs_writepages(struct address_space mapping, struct writeback_control wbc)
	{
	return mpage_writepages(mapping, wbc, omfs_get_block);
	}

	static void omfs_write_failed(struct address_space *mapping, loff_t to)
	{
	struct inode *inode = mapping->host;

	if (to > inode->i_size) {
	truncate_pagecache(inode, inode->i_size);
	omfs_truncate(inode);
	}
	}

	static int omfs_write_begin(struct file file, struct address_space mapping,
	loff_t pos, unsigned len, unsigned flags,
	struct page pagep, void fsdata)
	{
	int ret;

	ret = block_write_begin(mapping, pos, len, flags, pagep,
	omfs_get_block);
	if (unlikely(ret))
	omfs_write_failed(mapping, pos + len);

	return ret;
	}

	static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
	{
	return generic_block_bmap(mapping, block, omfs_get_block);
	}

	const struct file_operations omfs_file_operations = {
	.llseek = generic_file_llseek,
	.read_iter = generic_file_read_iter,
	.write_iter = generic_file_write_iter,
	.mmap = generic_file_mmap,
	.fsync = generic_file_fsync,
	.splice_read = generic_file_splice_read,
	};

	static int omfs_setattr(struct user_namespace *mnt_userns,
	struct dentry dentry, struct iattr attr)
	{
	struct inode *inode = d_inode(dentry);
	int error;

	error = setattr_prepare(&init_user_ns, dentry, attr);
	if (error)
	return error;

	if ((attr->ia_valid & ATTR_SIZE) &&
	attr->ia_size != i_size_read(inode)) {
	error = inode_newsize_ok(inode, attr->ia_size);
	if (error)
	return error;
	truncate_setsize(inode, attr->ia_size);
	omfs_truncate(inode);
	}

	setattr_copy(&init_user_ns, inode, attr);
	mark_inode_dirty(inode);
	return 0;
	}

	const struct inode_operations omfs_file_inops = {
	.setattr = omfs_setattr,
	};

	const struct address_space_operations omfs_aops = {
	.readpage = omfs_readpage,
	.readahead = omfs_readahead,
	.writepage = omfs_writepage,
	.writepages = omfs_writepages,
	.write_begin = omfs_write_begin,
	.write_end = generic_write_end,
	.bmap = omfs_bmap,
	};