linux/fs/logfs/dev_mtd.c
Joern Engel 9421502b4f [LogFS] Fix bdev erases
Erases for block devices were always just emulated by writing 0xff.
Some time back the write was removed and only the page cache was
changed to 0xff.  Superficialy a good idea with two problems:
1. Touching the page cache isn't necessary either.
2. However, writing out 0xff _is_ necessary for the journal.  As the
   journal is scanned linearly, an old non-overwritten commit entry
   can be used on next mount and cause havoc.

This should fix both aspects.
2010-03-04 21:30:58 +01:00

254 lines
6.1 KiB
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>
#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,
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 = 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);
}