| /* |
| * 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 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 == -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 *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 int 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 = 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 = mtd_find_first_sb, |
| .find_last_sb = mtd_find_last_sb, |
| .readpage = mtd_readpage, |
| .writeseg = mtd_writeseg, |
| .erase = mtd_erase, |
| .can_write_buf = mtd_can_write_buf, |
| .sync = mtd_sync, |
| .put_device = 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; |
| } |