[deliverable/linux.git] / fs / logfs / dev_mtd.c

/*
 * 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;

	if (mtd->sync)
		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;

	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 *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;

	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 __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;
}
Commit	Line	Data
5db53f3e JE	1	/*
	2	* fs/logfs/dev_mtd.c - Device access methods for MTD
	3	*
	4	* As should be obvious for Linux kernel code, license is GPLv2
	5	*
	6	* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
	7	*/
	8	#include "logfs.h"
	9	#include <linux/completion.h>
	10	#include <linux/mount.h>
	11	#include <linux/sched.h>
6f485b41	12	#include <linux/slab.h>
5db53f3e JE	13
	14	#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
	15
48d36102 AB	16	static int logfs_mtd_read(struct super_block *sb, loff_t ofs, size_t len,
48d36102 AB	17	void *buf)
5db53f3e JE	18	{
	19	struct mtd_info *mtd = logfs_super(sb)->s_mtd;
	20	size_t retlen;
	21	int ret;
	22
329ad399	23	ret = mtd_read(mtd, ofs, len, &retlen, buf);
5db53f3e JE	24	BUG_ON(ret == -EINVAL);
	25	if (ret)
	26	return ret;
	27
	28	/* Not sure if we should loop instead. */
	29	if (retlen != len)
	30	return -EIO;
	31
	32	return 0;
	33	}
	34
48d36102 AB	35	static int loffs_mtd_write(struct super_block *sb, loff_t ofs, size_t len,
48d36102 AB	36	void *buf)
5db53f3e JE	37	{
	38	struct logfs_super *super = logfs_super(sb);
	39	struct mtd_info *mtd = super->s_mtd;
	40	size_t retlen;
	41	loff_t page_start, page_end;
	42	int ret;
	43
	44	if (super->s_flags & LOGFS_SB_FLAG_RO)
	45	return -EROFS;
	46
	47	BUG_ON((ofs >= mtd->size) \|\| (len > mtd->size - ofs));
	48	BUG_ON(ofs != (ofs >> super->s_writeshift) << super->s_writeshift);
	49	BUG_ON(len > PAGE_CACHE_SIZE);
	50	page_start = ofs & PAGE_CACHE_MASK;
	51	page_end = PAGE_CACHE_ALIGN(ofs + len) - 1;
	52	ret = mtd->write(mtd, ofs, len, &retlen, buf);
	53	if (ret \|\| (retlen != len))
	54	return -EIO;
	55
	56	return 0;
	57	}
	58
	59	/*
	60	* For as long as I can remember (since about 2001) mtd->erase has been an
	61	* asynchronous interface lacking the first driver to actually use the
	62	* asynchronous properties. So just to prevent the first implementor of such
	63	* a thing from breaking logfs in 2350, we do the usual pointless dance to
	64	* declare a completion variable and wait for completion before returning
48d36102	65	* from logfs_mtd_erase(). What an exercise in futility!
5db53f3e JE	66	*/
	67	static void logfs_erase_callback(struct erase_info *ei)
	68	{
	69	complete((struct completion *)ei->priv);
	70	}
	71
48d36102 AB	72	static int logfs_mtd_erase_mapping(struct super_block *sb, loff_t ofs,
48d36102 AB	73	size_t len)
5db53f3e JE	74	{
	75	struct logfs_super *super = logfs_super(sb);
	76	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	77	struct page *page;
	78	pgoff_t index = ofs >> PAGE_SHIFT;
	79
	80	for (index = ofs >> PAGE_SHIFT; index < (ofs + len) >> PAGE_SHIFT; index++) {
	81	page = find_get_page(mapping, index);
	82	if (!page)
	83	continue;
	84	memset(page_address(page), 0xFF, PAGE_SIZE);
	85	page_cache_release(page);
	86	}
	87	return 0;
	88	}
	89
48d36102	90	static int logfs_mtd_erase(struct super_block *sb, loff_t ofs, size_t len,
9421502b	91	int ensure_write)
5db53f3e JE	92	{
	93	struct mtd_info *mtd = logfs_super(sb)->s_mtd;
	94	struct erase_info ei;
	95	DECLARE_COMPLETION_ONSTACK(complete);
	96	int ret;
	97
	98	BUG_ON(len % mtd->erasesize);
	99	if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
	100	return -EROFS;
	101
	102	memset(&ei, 0, sizeof(ei));
	103	ei.mtd = mtd;
	104	ei.addr = ofs;
	105	ei.len = len;
	106	ei.callback = logfs_erase_callback;
	107	ei.priv = (long)&complete;
7e1f0dc0	108	ret = mtd_erase(mtd, &ei);
5db53f3e JE	109	if (ret)
	110	return -EIO;
	111
	112	wait_for_completion(&complete);
	113	if (ei.state != MTD_ERASE_DONE)
	114	return -EIO;
48d36102	115	return logfs_mtd_erase_mapping(sb, ofs, len);
5db53f3e JE	116	}
5db53f3e JE	117
48d36102	118	static void logfs_mtd_sync(struct super_block *sb)
5db53f3e JE	119	{
	120	struct mtd_info *mtd = logfs_super(sb)->s_mtd;
	121
	122	if (mtd->sync)
	123	mtd->sync(mtd);
	124	}
	125
48d36102	126	static int logfs_mtd_readpage(void _sb, struct page page)
5db53f3e JE	127	{
	128	struct super_block *sb = _sb;
	129	int err;
	130
48d36102	131	err = logfs_mtd_read(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
5db53f3e	132	page_address(page));
6f485b41 JE	133	if (err == -EUCLEAN \|\| err == -EBADMSG) {
6f485b41 JE	134	/* -EBADMSG happens regularly on power failures */
5db53f3e JE	135	err = 0;
	136	/* FIXME: force GC this segment */
	137	}
	138	if (err) {
	139	ClearPageUptodate(page);
	140	SetPageError(page);
	141	} else {
	142	SetPageUptodate(page);
	143	ClearPageError(page);
	144	}
	145	unlock_page(page);
	146	return err;
	147	}
	148
48d36102	149	static struct page logfs_mtd_find_first_sb(struct super_block sb, u64 *ofs)
5db53f3e JE	150	{
	151	struct logfs_super *super = logfs_super(sb);
	152	struct address_space *mapping = super->s_mapping_inode->i_mapping;
48d36102	153	filler_t *filler = logfs_mtd_readpage;
5db53f3e JE	154	struct mtd_info *mtd = super->s_mtd;
	155
	156	if (!mtd->block_isbad)
	157	return NULL;
	158
	159	*ofs = 0;
	160	while (mtd->block_isbad(mtd, *ofs)) {
	161	*ofs += mtd->erasesize;
	162	if (*ofs >= mtd->size)
	163	return NULL;
	164	}
	165	BUG_ON(*ofs & ~PAGE_MASK);
	166	return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
	167	}
	168
48d36102	169	static struct page logfs_mtd_find_last_sb(struct super_block sb, u64 *ofs)
5db53f3e JE	170	{
	171	struct logfs_super *super = logfs_super(sb);
	172	struct address_space *mapping = super->s_mapping_inode->i_mapping;
48d36102	173	filler_t *filler = logfs_mtd_readpage;
5db53f3e JE	174	struct mtd_info *mtd = super->s_mtd;
	175
	176	if (!mtd->block_isbad)
	177	return NULL;
	178
	179	*ofs = mtd->size - mtd->erasesize;
	180	while (mtd->block_isbad(mtd, *ofs)) {
	181	*ofs -= mtd->erasesize;
	182	if (*ofs <= 0)
	183	return NULL;
	184	}
	185	ofs = ofs + mtd->erasesize - 0x1000;
	186	BUG_ON(*ofs & ~PAGE_MASK);
	187	return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
	188	}
	189
48d36102	190	static int __logfs_mtd_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
5db53f3e JE	191	size_t nr_pages)
	192	{
	193	struct logfs_super *super = logfs_super(sb);
	194	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	195	struct page *page;
	196	int i, err;
	197
	198	for (i = 0; i < nr_pages; i++) {
	199	page = find_lock_page(mapping, index + i);
	200	BUG_ON(!page);
	201
48d36102 AB	202	err = loffs_mtd_write(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
48d36102 AB	203	page_address(page));
5db53f3e JE	204	unlock_page(page);
	205	page_cache_release(page);
	206	if (err)
	207	return err;
	208	}
	209	return 0;
	210	}
	211
48d36102	212	static void logfs_mtd_writeseg(struct super_block *sb, u64 ofs, size_t len)
5db53f3e JE	213	{
	214	struct logfs_super *super = logfs_super(sb);
	215	int head;
	216
	217	if (super->s_flags & LOGFS_SB_FLAG_RO)
	218	return;
	219
	220	if (len == 0) {
	221	/* This can happen when the object fit perfectly into a
	222	* segment, the segment gets written per sync and subsequently
	223	* closed.
	224	*/
	225	return;
	226	}
	227	head = ofs & (PAGE_SIZE - 1);
	228	if (head) {
	229	ofs -= head;
	230	len += head;
	231	}
	232	len = PAGE_ALIGN(len);
48d36102	233	__logfs_mtd_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
5db53f3e JE	234	}
5db53f3e JE	235
48d36102	236	static void logfs_mtd_put_device(struct logfs_super *s)
5db53f3e	237	{
e5a0726a	238	put_mtd_device(s->s_mtd);
5db53f3e JE	239	}
5db53f3e JE	240
48d36102	241	static int logfs_mtd_can_write_buf(struct super_block *sb, u64 ofs)
6f485b41 JE	242	{
	243	struct logfs_super *super = logfs_super(sb);
	244	void *buf;
	245	int err;
	246
	247	buf = kmalloc(super->s_writesize, GFP_KERNEL);
	248	if (!buf)
	249	return -ENOMEM;
48d36102	250	err = logfs_mtd_read(sb, ofs, super->s_writesize, buf);
6f485b41 JE	251	if (err)
	252	goto out;
	253	if (memchr_inv(buf, 0xff, super->s_writesize))
	254	err = -EIO;
	255	kfree(buf);
	256	out:
	257	return err;
	258	}
	259
5db53f3e	260	static const struct logfs_device_ops mtd_devops = {
48d36102 AB	261	.find_first_sb = logfs_mtd_find_first_sb,
	262	.find_last_sb = logfs_mtd_find_last_sb,
	263	.readpage = logfs_mtd_readpage,
	264	.writeseg = logfs_mtd_writeseg,
	265	.erase = logfs_mtd_erase,
	266	.can_write_buf = logfs_mtd_can_write_buf,
	267	.sync = logfs_mtd_sync,
	268	.put_device = logfs_mtd_put_device,
5db53f3e JE	269	};
5db53f3e JE	270
7d945a3a	271	int logfs_get_sb_mtd(struct logfs_super *s, int mtdnr)
5db53f3e	272	{
0d85c799	273	struct mtd_info *mtd = get_mtd_device(NULL, mtdnr);
7d945a3a	274	if (IS_ERR(mtd))
ccf31c10	275	return PTR_ERR(mtd);
0d85c799 AV	276
	277	s->s_bdev = NULL;
	278	s->s_mtd = mtd;
	279	s->s_devops = &mtd_devops;
7d945a3a	280	return 0;
5db53f3e	281	}