/*
* 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>
#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 excercise 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)
{
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 = 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 super_block *sb)
{
put_mtd_device(logfs_super(sb)->s_mtd);
}
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,
.sync = mtd_sync,
.put_device = mtd_put_device,
};
int logfs_get_sb_mtd(struct file_system_type *type, int flags,
int mtdnr, struct vfsmount *mnt)
{
struct mtd_info *mtd;
const struct logfs_device_ops *devops = &mtd_devops;
mtd = get_mtd_device(NULL, mtdnr);
return logfs_get_sb_device(type, flags, mtd, NULL, devops, mnt);
}
