path: root/fs/logfs/segment.c

/*
 * fs/logfs/segment.c	- Handling the Object Store
 *
 * As should be obvious for Linux kernel code, license is GPLv2
 *
 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
 *
 * Object store or ostore makes up the complete device with exception of
 * the superblock and journal areas.  Apart from its own metadata it stores
 * three kinds of objects: inodes, dentries and blocks, both data and indirect.
 */
#include "logfs.h"
#include <linux/slab.h>

static int logfs_mark_segment_bad(struct super_block *sb, u32 segno)
{
	struct logfs_super *super = logfs_super(sb);
	struct btree_head32 *head = &super->s_reserved_segments;
	int err;

	err = btree_insert32(head, segno, (void *)1, GFP_NOFS);
	if (err)
		return err;
	logfs_super(sb)->s_bad_segments++;
	/* FIXME: write to journal */
	return 0;
}

int logfs_erase_segment(struct super_block *sb, u32 segno, int ensure_erase)
{
	struct logfs_super *super = logfs_super(sb);

	super->s_gec++;

	return super->s_devops->erase(sb, (u64)segno << super->s_segshift,
			super->s_segsize, ensure_erase);
}

static s64 logfs_get_free_bytes(struct logfs_area *area, size_t bytes)
{
	s32 ofs;

	logfs_open_area(area, bytes);

	ofs = area->a_used_bytes;
	area->a_used_bytes += bytes;
	BUG_ON(area->a_used_bytes >= logfs_super(area->a_sb)->s_segsize);

	return dev_ofs(area->a_sb, area->a_segno, ofs);
}

static struct page *get_mapping_page(struct super_block *sb, pgoff_t index,
		int use_filler)
{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	filler_t *filler = super->s_devops->readpage;
	struct page *page;

	BUG_ON(mapping_gfp_mask(mapping) & __GFP_FS);
	if (use_filler)
		page = read_cache_page(mapping, index, filler, sb);
	else {
		page = find_or_create_page(mapping, index, GFP_NOFS);
		unlock_page(page);
	}
	return page;
}

int __logfs_buf_write(struct logfs_area *area, u64 ofs, void *buf, size_t len,
		int use_filler)
{
	pgoff_t index = ofs >> PAGE_SHIFT;
	struct page *page;
	long offset = ofs & (PAGE_SIZE-1);
	long copylen;

	/* Only logfs_wbuf_recover may use len==0 */
	BUG_ON(!len && !use_filler);
	do {
		copylen = min((ulong)len, PAGE_SIZE - offset);

		page = get_mapping_page(area->a_sb, index, use_filler);
		if (IS_ERR(page))
			return PTR_ERR(page);
		BUG_ON(!page); /* FIXME: reserve a pool */
		SetPageUptodate(page);
		memcpy(page_address(page) + offset, buf, copylen);
		SetPagePrivate(page);
		page_cache_release(page);

		buf += copylen;
		len -= copylen;
		offset = 0;
		index++;
	} while (len);
	return 0;
}

static void pad_partial_page(struct logfs_area *area)
{
	struct super_block *sb = area->a_sb;
	struct page *page;
	u64 ofs = dev_ofs(sb, area->a_segno, area->a_used_bytes);
	pgoff_t index = ofs >> PAGE_SHIFT;
	long offset = ofs & (PAGE_SIZE-1);
	u32 len = PAGE_SIZE - offset;

	if (len % PAGE_SIZE) {
		page = get_mapping_page(sb, index, 0);
		BUG_ON(!page); /* FIXME: reserve a pool */
		memset(page_address(page) + offset, 0xff, len);
		SetPagePrivate(page);
		page_cache_release(page);
	}
}

static void pad_full_pages(struct logfs_area *area)
{
	struct super_block *sb = area->a_sb;
	struct logfs_super *super = logfs_super(sb);
	u64 ofs = dev_ofs(sb, area->a_segno, area->a_used_bytes);
	u32 len = super->s_segsize - area->a_used_bytes;
	pgoff_t index = PAGE_CACHE_ALIGN(ofs) >> PAGE_CACHE_SHIFT;
	pgoff_t no_indizes = len >> PAGE_CACHE_SHIFT;
	struct page *page;

	while (no_indizes) {
		page = get_mapping_page(sb, index,