fs/logfs/dev_mtd.c - kernel/mindspeed - Git at Google

 /*
  * fs/logfs/dev_mtd.c	- Device access methods for MTD
  *
  * As should be obvious for Linux kernel code, license is GPLv2
  *
  * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
  */
 #include "logfs.h"
 #include <linux/completion.h>
 #include <linux/mount.h>
 #include <linux/sched.h>
 #include <linux/slab.h>

 #define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))

 static int mtd_read(struct super_block *sb, loff_t ofs, size_t len, void *buf)
 {
 	struct mtd_info *mtd = logfs_super(sb)->s_mtd;
 	size_t retlen;
 	int ret;

 	ret = mtd->read(mtd, ofs, len, &retlen, buf);
 	BUG_ON(ret == -EINVAL);
 	if (ret)
 		return ret;

 	/* Not sure if we should loop instead. */
 	if (retlen != len)
 		return -EIO;

 	return 0;
 }

 static int mtd_write(struct super_block *sb, loff_t ofs, size_t len, void *buf)
 {
 	struct logfs_super *super = logfs_super(sb);
 	struct mtd_info *mtd = super->s_mtd;
 	size_t retlen;
 	loff_t page_start, page_end;
 	int ret;

 	if (super->s_flags & LOGFS_SB_FLAG_RO)
 		return -EROFS;

 	BUG_ON((ofs >= mtd->size) || (len > mtd->size - ofs));
 	BUG_ON(ofs != (ofs >> super->s_writeshift) << super->s_writeshift);
 	BUG_ON(len > PAGE_CACHE_SIZE);
 	page_start = ofs & PAGE_CACHE_MASK;
 	page_end = PAGE_CACHE_ALIGN(ofs + len) - 1;
 	ret = mtd->write(mtd, ofs, len, &retlen, buf);
 	if (ret || (retlen != len))
 		return -EIO;

 	return 0;
 }

 /*
  * For as long as I can remember (since about 2001) mtd->erase has been an
  * asynchronous interface lacking the first driver to actually use the
  * asynchronous properties.  So just to prevent the first implementor of such
  * a thing from breaking logfs in 2350, we do the usual pointless dance to
  * declare a completion variable and wait for completion before returning
  * from mtd_erase().  What an exercise in futility!
  */
 static void logfs_erase_callback(struct erase_info *ei)
 {
 	complete((struct completion *)ei->priv);
 }

 static int mtd_erase_mapping(struct super_block *sb, loff_t ofs, size_t len)
 {
 	struct logfs_super *super = logfs_super(sb);
 	struct address_space *mapping = super->s_mapping_inode->i_mapping;
 	struct page *page;
 	pgoff_t index = ofs >> PAGE_SHIFT;

 	for (index = ofs >> PAGE_SHIFT; index < (ofs + len) >> PAGE_SHIFT; index++) {
 		page = find_get_page(mapping, index);
 		if (!page)
 			continue;
 		memset(page_address(page), 0xFF, PAGE_SIZE);
 		page_cache_release(page);
 	}
 	return 0;
 }

 static int mtd_erase(struct super_block *sb, loff_t ofs, size_t len,
 		int ensure_write)
 {
 	struct mtd_info *mtd = logfs_super(sb)->s_mtd;
 	struct erase_info ei;
 	DECLARE_COMPLETION_ONSTACK(complete);
 	int ret;

 	BUG_ON(len % mtd->erasesize);
 	if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
 		return -EROFS;

 	memset(&ei, 0, sizeof(ei));
 	ei.mtd = mtd;
 	ei.addr = ofs;
 	ei.len = len;
 	ei.callback = logfs_erase_callback;
 	ei.priv = (long)&complete;
 	ret = mtd->erase(mtd, &ei);
 	if (ret)
 		return -EIO;

 	wait_for_completion(&complete);
 	if (ei.state != MTD_ERASE_DONE)
 		return -EIO;
 	return mtd_erase_mapping(sb, ofs, len);
 }

 static void mtd_sync(struct super_block *sb)
 {
 	struct mtd_info *mtd = logfs_super(sb)->s_mtd;

 	if (mtd->sync)
 		mtd->sync(mtd);
 }

 static int mtd_readpage(void *_sb, struct page *page)
 {
 	struct super_block *sb = _sb;
 	int err;

 	err = mtd_read(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
 			page_address(page));
 	if (err == -EUCLEAN || err == -EBADMSG) {
 		/* -EBADMSG happens regularly on power failures */
 		err = 0;
 		/* FIXME: force GC this segment */
 	}
 	if (err) {
 		ClearPageUptodate(page);
 		SetPageError(page);
 	} else {
 		SetPageUptodate(page);
 		ClearPageError(page);
 	}
 	unlock_page(page);
 	return err;
 }

 static struct page *mtd_find_first_sb(struct super_block *sb, u64 *ofs)
 {
 	struct logfs_super *super = logfs_super(sb);
 	struct address_space *mapping = super->s_mapping_inode->i_mapping;
 	filler_t *filler = mtd_readpage;
 	struct mtd_info *mtd = super->s_mtd;

 	if (!mtd->block_isbad)
 		return NULL;

 	*ofs = 0;
 	while (mtd->block_isbad(mtd, *ofs)) {
 		*ofs += mtd->erasesize;
 		if (*ofs >= mtd->size)
 			return NULL;
 	}
 	BUG_ON(*ofs & ~PAGE_MASK);
 	return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
 }

 static struct page *mtd_find_last_sb(struct super_block *sb, u64 *ofs)
 {
 	struct logfs_super *super = logfs_super(sb);
 	struct address_space *mapping = super->s_mapping_inode->i_mapping;
 	filler_t *filler = mtd_readpage;
 	struct mtd_info *mtd = super->s_mtd;

 	if (!mtd->block_isbad)
 		return NULL;

 	*ofs = mtd->size - mtd->erasesize;
 	while (mtd->block_isbad(mtd, *ofs)) {
 		*ofs -= mtd->erasesize;
 		if (*ofs <= 0)
 			return NULL;
 	}
 	*ofs = *ofs + mtd->erasesize - 0x1000;
 	BUG_ON(*ofs & ~PAGE_MASK);
 	return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
 }

 static int __mtd_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
 		size_t nr_pages)
 {
 	struct logfs_super *super = logfs_super(sb);
 	struct address_space *mapping = super->s_mapping_inode->i_mapping;
 	struct page *page;
 	int i, err;

 	for (i = 0; i < nr_pages; i++) {
 		page = find_lock_page(mapping, index + i);
 		BUG_ON(!page);

 		err = mtd_write(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
 				page_address(page));
 		unlock_page(page);
 		page_cache_release(page);
 		if (err)
 			return err;
 	}
 	return 0;
 }

 static void mtd_writeseg(struct super_block *sb, u64 ofs, size_t len)
 {
 	struct logfs_super *super = logfs_super(sb);
 	int head;

 	if (super->s_flags & LOGFS_SB_FLAG_RO)
 		return;

 	if (len == 0) {
 		/* This can happen when the object fit perfectly into a
 		 * segment, the segment gets written per sync and subsequently
 		 * closed.
 		 */
 		return;
 	}
 	head = ofs & (PAGE_SIZE - 1);
 	if (head) {
 		ofs -= head;
 		len += head;
 	}
 	len = PAGE_ALIGN(len);
 	__mtd_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
 }

 static void mtd_put_device(struct logfs_super *s)
 {
 	put_mtd_device(s->s_mtd);
 }

 static int mtd_can_write_buf(struct super_block *sb, u64 ofs)
 {
 	struct logfs_super *super = logfs_super(sb);
 	void *buf;
 	int err;

 	buf = kmalloc(super->s_writesize, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 	err = mtd_read(sb, ofs, super->s_writesize, buf);
 	if (err)
 		goto out;
 	if (memchr_inv(buf, 0xff, super->s_writesize))
 		err = -EIO;
 	kfree(buf);
 out:
 	return err;
 }

 static const struct logfs_device_ops mtd_devops = {
 	.find_first_sb	= mtd_find_first_sb,
 	.find_last_sb	= mtd_find_last_sb,
 	.readpage	= mtd_readpage,
 	.writeseg	= mtd_writeseg,
 	.erase		= mtd_erase,
 	.can_write_buf	= mtd_can_write_buf,
 	.sync		= mtd_sync,
 	.put_device	= mtd_put_device,
 };

 int logfs_get_sb_mtd(struct logfs_super *s, int mtdnr)
 {
 	struct mtd_info *mtd = get_mtd_device(NULL, mtdnr);
 	if (IS_ERR(mtd))
 		return PTR_ERR(mtd);

 	s->s_bdev = NULL;
 	s->s_mtd = mtd;
 	s->s_devops = &mtd_devops;
 	return 0;
 }
	/*
	* fs/logfs/dev_mtd.c - Device access methods for MTD
	*
	* As should be obvious for Linux kernel code, license is GPLv2
	*
	* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
	*/
	#include "logfs.h"
	#include <linux/completion.h>
	#include <linux/mount.h>
	#include <linux/sched.h>
	#include <linux/slab.h>

	#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))

	static int mtd_read(struct super_block sb, loff_t ofs, size_t len, void buf)
	{
	struct mtd_info *mtd = logfs_super(sb)->s_mtd;
	size_t retlen;
	int ret;

	ret = mtd->read(mtd, ofs, len, &retlen, buf);
	BUG_ON(ret == -EINVAL);
	if (ret)
	return ret;

	/* Not sure if we should loop instead. */
	if (retlen != len)
	return -EIO;

	return 0;
	}

	static int mtd_write(struct super_block sb, loff_t ofs, size_t len, void buf)
	{
	struct logfs_super *super = logfs_super(sb);
	struct mtd_info *mtd = super->s_mtd;
	size_t retlen;
	loff_t page_start, page_end;
	int ret;

	if (super->s_flags & LOGFS_SB_FLAG_RO)
	return -EROFS;

	BUG_ON((ofs >= mtd->size) \|\| (len > mtd->size - ofs));
	BUG_ON(ofs != (ofs >> super->s_writeshift) << super->s_writeshift);
	BUG_ON(len > PAGE_CACHE_SIZE);
	page_start = ofs & PAGE_CACHE_MASK;
	page_end = PAGE_CACHE_ALIGN(ofs + len) - 1;
	ret = mtd->write(mtd, ofs, len, &retlen, buf);
	if (ret \|\| (retlen != len))
	return -EIO;

	return 0;
	}

	/*
	* For as long as I can remember (since about 2001) mtd->erase has been an
	* asynchronous interface lacking the first driver to actually use the
	* asynchronous properties. So just to prevent the first implementor of such
	* a thing from breaking logfs in 2350, we do the usual pointless dance to
	* declare a completion variable and wait for completion before returning
	* from mtd_erase(). What an exercise in futility!
	*/
	static void logfs_erase_callback(struct erase_info *ei)
	{
	complete((struct completion *)ei->priv);
	}

	static int mtd_erase_mapping(struct super_block *sb, loff_t ofs, size_t len)
	{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	struct page *page;
	pgoff_t index = ofs >> PAGE_SHIFT;

	for (index = ofs >> PAGE_SHIFT; index < (ofs + len) >> PAGE_SHIFT; index++) {
	page = find_get_page(mapping, index);
	if (!page)
	continue;
	memset(page_address(page), 0xFF, PAGE_SIZE);
	page_cache_release(page);
	}
	return 0;
	}

	static int mtd_erase(struct super_block *sb, loff_t ofs, size_t len,
	int ensure_write)
	{
	struct mtd_info *mtd = logfs_super(sb)->s_mtd;
	struct erase_info ei;
	DECLARE_COMPLETION_ONSTACK(complete);
	int ret;

	BUG_ON(len % mtd->erasesize);
	if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
	return -EROFS;

	memset(&ei, 0, sizeof(ei));
	ei.mtd = mtd;
	ei.addr = ofs;
	ei.len = len;
	ei.callback = logfs_erase_callback;
	ei.priv = (long)&complete;
	ret = mtd->erase(mtd, &ei);
	if (ret)
	return -EIO;

	wait_for_completion(&complete);
	if (ei.state != MTD_ERASE_DONE)
	return -EIO;
	return mtd_erase_mapping(sb, ofs, len);
	}

	static void mtd_sync(struct super_block *sb)
	{
	struct mtd_info *mtd = logfs_super(sb)->s_mtd;

	if (mtd->sync)
	mtd->sync(mtd);
	}

	static int mtd_readpage(void _sb, struct page page)
	{
	struct super_block *sb = _sb;
	int err;

	err = mtd_read(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
	page_address(page));
	if (err == -EUCLEAN \|\| err == -EBADMSG) {
	/* -EBADMSG happens regularly on power failures */
	err = 0;
	/* FIXME: force GC this segment */
	}
	if (err) {
	ClearPageUptodate(page);
	SetPageError(page);
	} else {
	SetPageUptodate(page);
	ClearPageError(page);
	}
	unlock_page(page);
	return err;
	}

	static struct page mtd_find_first_sb(struct super_block sb, u64 *ofs)
	{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	filler_t *filler = mtd_readpage;
	struct mtd_info *mtd = super->s_mtd;

	if (!mtd->block_isbad)
	return NULL;

	*ofs = 0;
	while (mtd->block_isbad(mtd, *ofs)) {
	*ofs += mtd->erasesize;
	if (*ofs >= mtd->size)
	return NULL;
	}
	BUG_ON(*ofs & ~PAGE_MASK);
	return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
	}

	static struct page mtd_find_last_sb(struct super_block sb, u64 *ofs)
	{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	filler_t *filler = mtd_readpage;
	struct mtd_info *mtd = super->s_mtd;

	if (!mtd->block_isbad)
	return NULL;

	*ofs = mtd->size - mtd->erasesize;
	while (mtd->block_isbad(mtd, *ofs)) {
	*ofs -= mtd->erasesize;
	if (*ofs <= 0)
	return NULL;
	}
	ofs = ofs + mtd->erasesize - 0x1000;
	BUG_ON(*ofs & ~PAGE_MASK);
	return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
	}

	static int __mtd_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
	size_t nr_pages)
	{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	struct page *page;
	int i, err;

	for (i = 0; i < nr_pages; i++) {
	page = find_lock_page(mapping, index + i);
	BUG_ON(!page);

	err = mtd_write(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
	page_address(page));
	unlock_page(page);
	page_cache_release(page);
	if (err)
	return err;
	}
	return 0;
	}

	static void mtd_writeseg(struct super_block *sb, u64 ofs, size_t len)
	{
	struct logfs_super *super = logfs_super(sb);
	int head;

	if (super->s_flags & LOGFS_SB_FLAG_RO)
	return;

	if (len == 0) {
	/* This can happen when the object fit perfectly into a
	* segment, the segment gets written per sync and subsequently
	* closed.
	*/
	return;
	}
	head = ofs & (PAGE_SIZE - 1);
	if (head) {
	ofs -= head;
	len += head;
	}
	len = PAGE_ALIGN(len);
	__mtd_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
	}

	static void mtd_put_device(struct logfs_super *s)
	{
	put_mtd_device(s->s_mtd);
	}

	static int mtd_can_write_buf(struct super_block *sb, u64 ofs)
	{
	struct logfs_super *super = logfs_super(sb);
	void *buf;
	int err;

	buf = kmalloc(super->s_writesize, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;
	err = mtd_read(sb, ofs, super->s_writesize, buf);
	if (err)
	goto out;
	if (memchr_inv(buf, 0xff, super->s_writesize))
	err = -EIO;
	kfree(buf);
	out:
	return err;
	}

	static const struct logfs_device_ops mtd_devops = {
	.find_first_sb = mtd_find_first_sb,
	.find_last_sb = mtd_find_last_sb,
	.readpage = mtd_readpage,
	.writeseg = mtd_writeseg,
	.erase = mtd_erase,
	.can_write_buf = mtd_can_write_buf,
	.sync = mtd_sync,
	.put_device = mtd_put_device,
	};

	int logfs_get_sb_mtd(struct logfs_super *s, int mtdnr)
	{
	struct mtd_info *mtd = get_mtd_device(NULL, mtdnr);
	if (IS_ERR(mtd))
	return PTR_ERR(mtd);

	s->s_bdev = NULL;
	s->s_mtd = mtd;
	s->s_devops = &mtd_devops;
	return 0;
	}