/* * 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 logfs_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 loffs_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 logfs_mtd_erase().  What an exercise in futility! */static void logfs_erase_callback(struct erase_info *ei){	complete((struct completion *)ei->priv);} static int logfs_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 logfs_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 logfs_mtd_erase_mapping(sb, ofs, len);} static void logfs_mtd_sync(struct super_block *sb){	struct mtd_info *mtd = logfs_super(sb)->s_mtd; 	mtd_sync(mtd);} static int logfs_mtd_readpage(void *_sb, struct page *page){	struct super_block *sb = _sb;	int err; 	err = logfs_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 *logfs_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 = logfs_mtd_readpage;	struct mtd_info *mtd = super->s_mtd; 	*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 *logfs_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 = logfs_mtd_readpage;	struct mtd_info *mtd = super->s_mtd; 	*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 __logfs_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 = loffs_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 logfs_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);	__logfs_mtd_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);} static void logfs_mtd_put_device(struct logfs_super *s){	put_mtd_device(s->s_mtd);} static int logfs_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 = logfs_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	= logfs_mtd_find_first_sb,	.find_last_sb	= logfs_mtd_find_last_sb,	.readpage	= logfs_mtd_readpage,	.writeseg	= logfs_mtd_writeseg,	.erase		= logfs_mtd_erase,	.can_write_buf	= logfs_mtd_can_write_buf,	.sync		= logfs_mtd_sync,	.put_device	= logfs_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;}