9421502b4f
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.
254 lines
6.1 KiB
C
254 lines
6.1 KiB
C
/*
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* fs/logfs/dev_mtd.c - Device access methods for MTD
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*
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* As should be obvious for Linux kernel code, license is GPLv2
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*
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* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
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*/
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#include "logfs.h"
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#include <linux/completion.h>
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#include <linux/mount.h>
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#include <linux/sched.h>
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#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
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static int mtd_read(struct super_block *sb, loff_t ofs, size_t len, void *buf)
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{
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struct mtd_info *mtd = logfs_super(sb)->s_mtd;
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size_t retlen;
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int ret;
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ret = mtd->read(mtd, ofs, len, &retlen, buf);
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BUG_ON(ret == -EINVAL);
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if (ret)
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return ret;
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/* Not sure if we should loop instead. */
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if (retlen != len)
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return -EIO;
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return 0;
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}
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static int mtd_write(struct super_block *sb, loff_t ofs, size_t len, void *buf)
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{
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struct logfs_super *super = logfs_super(sb);
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struct mtd_info *mtd = super->s_mtd;
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size_t retlen;
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loff_t page_start, page_end;
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int ret;
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if (super->s_flags & LOGFS_SB_FLAG_RO)
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return -EROFS;
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BUG_ON((ofs >= mtd->size) || (len > mtd->size - ofs));
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BUG_ON(ofs != (ofs >> super->s_writeshift) << super->s_writeshift);
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BUG_ON(len > PAGE_CACHE_SIZE);
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page_start = ofs & PAGE_CACHE_MASK;
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page_end = PAGE_CACHE_ALIGN(ofs + len) - 1;
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ret = mtd->write(mtd, ofs, len, &retlen, buf);
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if (ret || (retlen != len))
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return -EIO;
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return 0;
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}
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/*
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* For as long as I can remember (since about 2001) mtd->erase has been an
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* asynchronous interface lacking the first driver to actually use the
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* asynchronous properties. So just to prevent the first implementor of such
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* a thing from breaking logfs in 2350, we do the usual pointless dance to
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* declare a completion variable and wait for completion before returning
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* from mtd_erase(). What an excercise in futility!
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*/
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static void logfs_erase_callback(struct erase_info *ei)
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{
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complete((struct completion *)ei->priv);
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}
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static int mtd_erase_mapping(struct super_block *sb, loff_t ofs, size_t len)
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{
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struct logfs_super *super = logfs_super(sb);
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struct address_space *mapping = super->s_mapping_inode->i_mapping;
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struct page *page;
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pgoff_t index = ofs >> PAGE_SHIFT;
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for (index = ofs >> PAGE_SHIFT; index < (ofs + len) >> PAGE_SHIFT; index++) {
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page = find_get_page(mapping, index);
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if (!page)
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continue;
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memset(page_address(page), 0xFF, PAGE_SIZE);
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page_cache_release(page);
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}
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return 0;
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}
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static int mtd_erase(struct super_block *sb, loff_t ofs, size_t len,
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int ensure_write)
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{
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struct mtd_info *mtd = logfs_super(sb)->s_mtd;
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struct erase_info ei;
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DECLARE_COMPLETION_ONSTACK(complete);
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int ret;
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BUG_ON(len % mtd->erasesize);
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if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
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return -EROFS;
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memset(&ei, 0, sizeof(ei));
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ei.mtd = mtd;
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ei.addr = ofs;
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ei.len = len;
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ei.callback = logfs_erase_callback;
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ei.priv = (long)&complete;
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ret = mtd->erase(mtd, &ei);
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if (ret)
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return -EIO;
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wait_for_completion(&complete);
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if (ei.state != MTD_ERASE_DONE)
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return -EIO;
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return mtd_erase_mapping(sb, ofs, len);
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}
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static void mtd_sync(struct super_block *sb)
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{
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struct mtd_info *mtd = logfs_super(sb)->s_mtd;
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if (mtd->sync)
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mtd->sync(mtd);
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}
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static int mtd_readpage(void *_sb, struct page *page)
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{
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struct super_block *sb = _sb;
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int err;
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err = mtd_read(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
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page_address(page));
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if (err == -EUCLEAN) {
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err = 0;
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/* FIXME: force GC this segment */
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}
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if (err) {
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ClearPageUptodate(page);
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SetPageError(page);
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} else {
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SetPageUptodate(page);
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ClearPageError(page);
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}
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unlock_page(page);
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return err;
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}
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static struct page *mtd_find_first_sb(struct super_block *sb, u64 *ofs)
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{
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struct logfs_super *super = logfs_super(sb);
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struct address_space *mapping = super->s_mapping_inode->i_mapping;
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filler_t *filler = mtd_readpage;
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struct mtd_info *mtd = super->s_mtd;
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if (!mtd->block_isbad)
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return NULL;
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*ofs = 0;
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while (mtd->block_isbad(mtd, *ofs)) {
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*ofs += mtd->erasesize;
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if (*ofs >= mtd->size)
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return NULL;
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}
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BUG_ON(*ofs & ~PAGE_MASK);
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return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
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}
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static struct page *mtd_find_last_sb(struct super_block *sb, u64 *ofs)
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{
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struct logfs_super *super = logfs_super(sb);
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struct address_space *mapping = super->s_mapping_inode->i_mapping;
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filler_t *filler = mtd_readpage;
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struct mtd_info *mtd = super->s_mtd;
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if (!mtd->block_isbad)
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return NULL;
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*ofs = mtd->size - mtd->erasesize;
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while (mtd->block_isbad(mtd, *ofs)) {
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*ofs -= mtd->erasesize;
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if (*ofs <= 0)
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return NULL;
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}
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*ofs = *ofs + mtd->erasesize - 0x1000;
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BUG_ON(*ofs & ~PAGE_MASK);
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return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb);
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}
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static int __mtd_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
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size_t nr_pages)
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{
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struct logfs_super *super = logfs_super(sb);
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struct address_space *mapping = super->s_mapping_inode->i_mapping;
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struct page *page;
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int i, err;
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for (i = 0; i < nr_pages; i++) {
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page = find_lock_page(mapping, index + i);
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BUG_ON(!page);
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err = mtd_write(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
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page_address(page));
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unlock_page(page);
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page_cache_release(page);
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if (err)
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return err;
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}
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return 0;
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}
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static void mtd_writeseg(struct super_block *sb, u64 ofs, size_t len)
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{
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struct logfs_super *super = logfs_super(sb);
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int head;
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if (super->s_flags & LOGFS_SB_FLAG_RO)
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return;
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if (len == 0) {
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/* This can happen when the object fit perfectly into a
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* segment, the segment gets written per sync and subsequently
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* closed.
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*/
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return;
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}
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head = ofs & (PAGE_SIZE - 1);
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if (head) {
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ofs -= head;
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len += head;
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}
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len = PAGE_ALIGN(len);
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__mtd_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
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}
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static void mtd_put_device(struct super_block *sb)
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{
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put_mtd_device(logfs_super(sb)->s_mtd);
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}
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static const struct logfs_device_ops mtd_devops = {
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.find_first_sb = mtd_find_first_sb,
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.find_last_sb = mtd_find_last_sb,
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.readpage = mtd_readpage,
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.writeseg = mtd_writeseg,
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.erase = mtd_erase,
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.sync = mtd_sync,
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.put_device = mtd_put_device,
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};
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int logfs_get_sb_mtd(struct file_system_type *type, int flags,
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int mtdnr, struct vfsmount *mnt)
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{
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struct mtd_info *mtd;
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const struct logfs_device_ops *devops = &mtd_devops;
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mtd = get_mtd_device(NULL, mtdnr);
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return logfs_get_sb_device(type, flags, mtd, NULL, devops, mnt);
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}
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