nilfs2: persistent object allocator

/*

 * alloc.c - NILFS dat/inode allocator

 *

 * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 *

 * Original code was written by Koji Sato <koji@osrg.net>.

 * Two allocators were unified by Ryusuke Konishi <ryusuke@osrg.net>,

 *                                Amagai Yoshiji <amagai@osrg.net>.

 */

#include <linux/types.h>

#include <linux/buffer_head.h>

#include <linux/fs.h>

#include <linux/bitops.h>

#include "mdt.h"

#include "alloc.h"

static inline unsigned long

nilfs_palloc_groups_per_desc_block(const struct inode *inode)

{

	return (1UL << inode->i_blkbits) /

		sizeof(struct nilfs_palloc_group_desc);

}

static inline unsigned long

nilfs_palloc_groups_count(const struct inode *inode)

{

	return 1UL << (BITS_PER_LONG - (inode->i_blkbits + 3 /* log2(8) */));

}

int nilfs_palloc_init_blockgroup(struct inode *inode, unsigned entry_size)

{

	struct nilfs_mdt_info *mi = NILFS_MDT(inode);

	mi->mi_bgl = kmalloc(sizeof(*mi->mi_bgl), GFP_NOFS);

	if (!mi->mi_bgl)

		return -ENOMEM;

	bgl_lock_init(mi->mi_bgl);

	nilfs_mdt_set_entry_size(inode, entry_size, 0);

	mi->mi_blocks_per_group =

		DIV_ROUND_UP(nilfs_palloc_entries_per_group(inode),

			     mi->mi_entries_per_block) + 1;

		/* Number of blocks in a group including entry blocks and

		   a bitmap block */

	mi->mi_blocks_per_desc_block =

		nilfs_palloc_groups_per_desc_block(inode) *

		mi->mi_blocks_per_group + 1;

		/* Number of blocks per descriptor including the

		   descriptor block */

	return 0;

}

static unsigned long nilfs_palloc_group(const struct inode *inode, __u64 nr,

					unsigned long *offset)

{

	__u64 group = nr;

	*offset = do_div(group, nilfs_palloc_entries_per_group(inode));

	return group;

}

static unsigned long

nilfs_palloc_desc_blkoff(const struct inode *inode, unsigned long group)

{

	unsigned long desc_block =

		group / nilfs_palloc_groups_per_desc_block(inode);

	return desc_block * NILFS_MDT(inode)->mi_blocks_per_desc_block;

}

static unsigned long

nilfs_palloc_bitmap_blkoff(const struct inode *inode, unsigned long group)

{

	unsigned long desc_offset =

		group % nilfs_palloc_groups_per_desc_block(inode);

	return nilfs_palloc_desc_blkoff(inode, group) + 1 +

		desc_offset * NILFS_MDT(inode)->mi_blocks_per_group;

}

static unsigned long

nilfs_palloc_group_desc_nfrees(struct inode *inode, unsigned long group,

			       const struct nilfs_palloc_group_desc *desc)

{

	unsigned long nfree;

	spin_lock(nilfs_mdt_bgl_lock(inode, group));

	nfree = le32_to_cpu(desc->pg_nfrees);

	spin_unlock(nilfs_mdt_bgl_lock(inode, group));

	return nfree;

}

static void

nilfs_palloc_group_desc_add_entries(struct inode *inode,

				    unsigned long group,

				    struct nilfs_palloc_group_desc *desc,

				    u32 n)

{

	spin_lock(nilfs_mdt_bgl_lock(inode, group));

	le32_add_cpu(&desc->pg_nfrees, n);

	spin_unlock(nilfs_mdt_bgl_lock(inode, group));

}

static unsigned long

nilfs_palloc_entry_blkoff(const struct inode *inode, __u64 nr)

{

	unsigned long group, group_offset;

	group = nilfs_palloc_group(inode, nr, &group_offset);

	return nilfs_palloc_bitmap_blkoff(inode, group) + 1 +

		group_offset / NILFS_MDT(inode)->mi_entries_per_block;

}

static void nilfs_palloc_desc_block_init(struct inode *inode,

					 struct buffer_head *bh, void *kaddr)

{

	struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh);

	unsigned long n = nilfs_palloc_groups_per_desc_block(inode);

	__le32 nfrees;

	nfrees = cpu_to_le32(nilfs_palloc_entries_per_group(inode));

	while (n-- > 0) {

		desc->pg_nfrees = nfrees;

		desc++;

	}

}

static int nilfs_palloc_get_desc_block(struct inode *inode,

				       unsigned long group,

				       int create, struct buffer_head **bhp)

{

	return nilfs_mdt_get_block(inode,

				   nilfs_palloc_desc_blkoff(inode, group),

				   create, nilfs_palloc_desc_block_init, bhp);

}

static int nilfs_palloc_get_bitmap_block(struct inode *inode,

					 unsigned long group,

					 int create, struct buffer_head **bhp)

{

	return nilfs_mdt_get_block(inode,

				   nilfs_palloc_bitmap_blkoff(inode, group),

				   create, NULL, bhp);

}

int nilfs_palloc_get_entry_block(struct inode *inode, __u64 nr,

				 int create, struct buffer_head **bhp)

{

	return nilfs_mdt_get_block(inode, nilfs_palloc_entry_blkoff(inode, nr),

				   create, NULL, bhp);

}

static struct nilfs_palloc_group_desc *

nilfs_palloc_block_get_group_desc(const struct inode *inode,

				  unsigned long group,

				  const struct buffer_head *bh, void *kaddr)

{

	return (struct nilfs_palloc_group_desc *)(kaddr + bh_offset(bh)) +

		group % nilfs_palloc_groups_per_desc_block(inode);

}

static unsigned char *

nilfs_palloc_block_get_bitmap(const struct inode *inode,

			      const struct buffer_head *bh, void *kaddr)

{

	return (unsigned char *)(kaddr + bh_offset(bh));

}

void *nilfs_palloc_block_get_entry(const struct inode *inode, __u64 nr,

				   const struct buffer_head *bh, void *kaddr)

{

	unsigned long entry_offset, group_offset;

	nilfs_palloc_group(inode, nr, &group_offset);

	entry_offset = group_offset % NILFS_MDT(inode)->mi_entries_per_block;

	return kaddr + bh_offset(bh) +

		entry_offset * NILFS_MDT(inode)->mi_entry_size;

}

static int nilfs_palloc_find_available_slot(struct inode *inode,

					    unsigned long group,

					    unsigned long target,

					    unsigned char *bitmap,

					    int bsize)  /* size in bits */

{

	int curr, pos, end, i;

	if (target > 0) {

		end = (target + BITS_PER_LONG - 1) & ~(BITS_PER_LONG - 1);

		if (end > bsize)

			end = bsize;

		pos = nilfs_find_next_zero_bit(bitmap, end, target);

		if (pos < end &&

		    !nilfs_set_bit_atomic(

			    nilfs_mdt_bgl_lock(inode, group), pos, bitmap))

			return pos;

	} else

		end = 0;

	for (i = 0, curr = end;

	     i < bsize;

	     i += BITS_PER_LONG, curr += BITS_PER_LONG) {

		/* wrap around */

		if (curr >= bsize)

			curr = 0;

		while (*((unsigned long *)bitmap + curr / BITS_PER_LONG)

		       != ~0UL) {

			end = curr + BITS_PER_LONG;

			if (end > bsize)

				end = bsize;

			pos = nilfs_find_next_zero_bit(bitmap, end, curr);

			if ((pos < end) &&

			    !nilfs_set_bit_atomic(

				    nilfs_mdt_bgl_lock(inode, group), pos,

				    bitmap))

				return pos;

		}

	}

	return -ENOSPC;

}

static unsigned long

nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode,

				       unsigned long curr, unsigned long max)

{

	return min_t(unsigned long,

		     nilfs_palloc_groups_per_desc_block(inode) -

		     curr % nilfs_palloc_groups_per_desc_block(inode),

		     max - curr + 1);

}

int nilfs_palloc_prepare_alloc_entry(struct inode *inode,

				     struct nilfs_palloc_req *req)

{

	struct buffer_head *desc_bh, *bitmap_bh;

	struct nilfs_palloc_group_desc *desc;

	unsigned char *bitmap;

	void *desc_kaddr, *bitmap_kaddr;

	unsigned long group, maxgroup, ngroups;

	unsigned long group_offset, maxgroup_offset;

	unsigned long n, entries_per_group, groups_per_desc_block;

	unsigned long i, j;

	int pos, ret;

	ngroups = nilfs_palloc_groups_count(inode);

	maxgroup = ngroups - 1;

	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);

	entries_per_group = nilfs_palloc_entries_per_group(inode);

	groups_per_desc_block = nilfs_palloc_groups_per_desc_block(inode);

	for (i = 0; i < ngroups; i += n) {

		if (group >= ngroups) {

			/* wrap around */

			group = 0;

			maxgroup = nilfs_palloc_group(inode, req->pr_entry_nr,

						      &maxgroup_offset) - 1;

		}

		ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);

		if (ret < 0)

			return ret;

		desc_kaddr = kmap(desc_bh->b_page);

		desc = nilfs_palloc_block_get_group_desc(

			inode, group, desc_bh, desc_kaddr);

		n = nilfs_palloc_rest_groups_in_desc_block(inode, group,

							   maxgroup);

		for (j = 0; j < n; j++, desc++, group++) {

			if (nilfs_palloc_group_desc_nfrees(inode, group, desc)

			    > 0) {

				ret = nilfs_palloc_get_bitmap_block(

					inode, group, 1, &bitmap_bh);

				if (ret < 0)

					goto out_desc;

				bitmap_kaddr = kmap(bitmap_bh->b_page);

				bitmap = nilfs_palloc_block_get_bitmap(

					inode, bitmap_bh, bitmap_kaddr);

				pos = nilfs_palloc_find_available_slot(

					inode, group, group_offset, bitmap,

					entries_per_group);

				if (pos >= 0) {

					/* found a free entry */

					nilfs_palloc_group_desc_add_entries(

						inode, group, desc, -1);

					req->pr_entry_nr =

						entries_per_group * group + pos;

					kunmap(desc_bh->b_page);

					kunmap(bitmap_bh->b_page);

					req->pr_desc_bh = desc_bh;

					req->pr_bitmap_bh = bitmap_bh;

					return 0;

				}

				kunmap(bitmap_bh->b_page);

				brelse(bitmap_bh);

			}

			group_offset = 0;

		}

		kunmap(desc_bh->b_page);

		brelse(desc_bh);

	}

	/* no entries left */

	return -ENOSPC;

 out_desc:

	kunmap(desc_bh->b_page);

	brelse(desc_bh);

	return ret;

}

void nilfs_palloc_commit_alloc_entry(struct inode *inode,

				     struct nilfs_palloc_req *req)

{

	nilfs_mdt_mark_buffer_dirty(req->pr_bitmap_bh);

	nilfs_mdt_mark_buffer_dirty(req->pr_desc_bh);

	nilfs_mdt_mark_dirty(inode);

	brelse(req->pr_bitmap_bh);

	brelse(req->pr_desc_bh);

}

void nilfs_palloc_commit_free_entry(struct inode *inode,

				    struct nilfs_palloc_req *req)

{

	struct nilfs_palloc_group_desc *desc;

	unsigned long group, group_offset;

	unsigned char *bitmap;

	void *desc_kaddr, *bitmap_kaddr;

	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);

	desc_kaddr = kmap(req->pr_desc_bh->b_page);

	desc = nilfs_palloc_block_get_group_desc(inode, group,

						 req->pr_desc_bh, desc_kaddr);

	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);

	bitmap = nilfs_palloc_block_get_bitmap(inode, req->pr_bitmap_bh,

					       bitmap_kaddr);

	if (!nilfs_clear_bit_atomic(nilfs_mdt_bgl_lock(inode, group),

				    group_offset, bitmap))

		printk(KERN_WARNING "%s: entry number %llu already freed\n",

		       __func__, (unsigned long long)req->pr_entry_nr);

	nilfs_palloc_group_desc_add_entries(inode, group, desc, 1);

	kunmap(req->pr_bitmap_bh->b_page);

	kunmap(req->pr_desc_bh->b_page);

	nilfs_mdt_mark_buffer_dirty(req->pr_desc_bh);

	nilfs_mdt_mark_buffer_dirty(req->pr_bitmap_bh);

	nilfs_mdt_mark_dirty(inode);

	brelse(req->pr_bitmap_bh);

	brelse(req->pr_desc_bh);

}

void nilfs_palloc_abort_alloc_entry(struct inode *inode,

				    struct nilfs_palloc_req *req)

{

	struct nilfs_palloc_group_desc *desc;

	void *desc_kaddr, *bitmap_kaddr;

	unsigned char *bitmap;

	unsigned long group, group_offset;

	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);

	desc_kaddr = kmap(req->pr_desc_bh->b_page);

	desc = nilfs_palloc_block_get_group_desc(inode, group,

						 req->pr_desc_bh, desc_kaddr);

	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);

	bitmap = nilfs_palloc_block_get_bitmap(inode, req->pr_bitmap_bh,

					       bitmap_kaddr);

	if (!nilfs_clear_bit_atomic(nilfs_mdt_bgl_lock(inode, group),

				    group_offset, bitmap))

		printk(KERN_WARNING "%s: entry numer %llu already freed\n",

		       __func__, (unsigned long long)req->pr_entry_nr);

	nilfs_palloc_group_desc_add_entries(inode, group, desc, 1);

	kunmap(req->pr_bitmap_bh->b_page);

	kunmap(req->pr_desc_bh->b_page);

	brelse(req->pr_bitmap_bh);

	brelse(req->pr_desc_bh);

	req->pr_entry_nr = 0;

	req->pr_bitmap_bh = NULL;

	req->pr_desc_bh = NULL;

}

int nilfs_palloc_prepare_free_entry(struct inode *inode,

				    struct nilfs_palloc_req *req)

{

	struct buffer_head *desc_bh, *bitmap_bh;

	unsigned long group, group_offset;

	int ret;

	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);

	ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);

	if (ret < 0)

		return ret;

	ret = nilfs_palloc_get_bitmap_block(inode, group, 1, &bitmap_bh);

	if (ret < 0) {

		brelse(desc_bh);

		return ret;

	}

	req->pr_desc_bh = desc_bh;

	req->pr_bitmap_bh = bitmap_bh;

	return 0;

}

void nilfs_palloc_abort_free_entry(struct inode *inode,

				   struct nilfs_palloc_req *req)

{

	brelse(req->pr_bitmap_bh);

	brelse(req->pr_desc_bh);

	req->pr_entry_nr = 0;

	req->pr_bitmap_bh = NULL;

	req->pr_desc_bh = NULL;

}

static int

nilfs_palloc_group_is_in(struct inode *inode, unsigned long group, __u64 nr)

{

	__u64 first, last;

	first = group * nilfs_palloc_entries_per_group(inode);

	last = first + nilfs_palloc_entries_per_group(inode) - 1;

	return (nr >= first) && (nr <= last);

}

int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)

{

	struct buffer_head *desc_bh, *bitmap_bh;

	struct nilfs_palloc_group_desc *desc;

	unsigned char *bitmap;

	void *desc_kaddr, *bitmap_kaddr;

	unsigned long group, group_offset;

	int i, j, n, ret;

	for (i = 0; i < nitems; i += n) {

		group = nilfs_palloc_group(inode, entry_nrs[i], &group_offset);

		ret = nilfs_palloc_get_desc_block(inode, group, 0, &desc_bh);

		if (ret < 0)

			return ret;

		ret = nilfs_palloc_get_bitmap_block(inode, group, 0,

						    &bitmap_bh);

		if (ret < 0) {

			brelse(desc_bh);

			return ret;

		}

		desc_kaddr = kmap(desc_bh->b_page);

		desc = nilfs_palloc_block_get_group_desc(

			inode, group, desc_bh, desc_kaddr);

		bitmap_kaddr = kmap(bitmap_bh->b_page);

		bitmap = nilfs_palloc_block_get_bitmap(

			inode, bitmap_bh, bitmap_kaddr);

		for (j = i, n = 0;

		     (j < nitems) && nilfs_palloc_group_is_in(inode, group,

							      entry_nrs[j]);

		     j++, n++) {

			nilfs_palloc_group(inode, entry_nrs[j], &group_offset);

			if (!nilfs_clear_bit_atomic(

				    nilfs_mdt_bgl_lock(inode, group),

				    group_offset, bitmap)) {

				printk(KERN_WARNING

				       "%s: entry number %llu already freed\n",

				       __func__,

				       (unsigned long long)entry_nrs[j]);

			}

		}

		nilfs_palloc_group_desc_add_entries(inode, group, desc, n);

		kunmap(bitmap_bh->b_page);

		kunmap(desc_bh->b_page);

		nilfs_mdt_mark_buffer_dirty(desc_bh);

		nilfs_mdt_mark_buffer_dirty(bitmap_bh);

		nilfs_mdt_mark_dirty(inode);

		brelse(bitmap_bh);

		brelse(desc_bh);

	}

	return 0;

}

/*

 * alloc.h - persistent object (dat entry/disk inode) allocator/deallocator

 *

 * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 *

 * Original code was written by Koji Sato <koji@osrg.net>.

 * Two allocators were unified by Ryusuke Konishi <ryusuke@osrg.net>,

 *                                Amagai Yoshiji <amagai@osrg.net>.

 */

#ifndef _NILFS_ALLOC_H

#define _NILFS_ALLOC_H

#include <linux/types.h>

#include <linux/buffer_head.h>

#include <linux/fs.h>

static inline unsigned long

nilfs_palloc_entries_per_group(const struct inode *inode)

{

	return 1UL << (inode->i_blkbits + 3 /* log2(8 = CHAR_BITS) */);

}

int nilfs_palloc_init_blockgroup(struct inode *, unsigned);

int nilfs_palloc_get_entry_block(struct inode *, __u64, int,

				 struct buffer_head **);

void *nilfs_palloc_block_get_entry(const struct inode *, __u64,

				   const struct buffer_head *, void *);

/**

 * nilfs_palloc_req - persistent alloctor request and reply

 * @pr_entry_nr: entry number (vblocknr or inode number)

 * @pr_desc_bh: buffer head of the buffer containing block group descriptors

 * @pr_bitmap_bh: buffer head of the buffer containing a block group bitmap

 * @pr_entry_bh: buffer head of the buffer containing translation entries

 */

struct nilfs_palloc_req {

	__u64 pr_entry_nr;

	struct buffer_head *pr_desc_bh;

	struct buffer_head *pr_bitmap_bh;

	struct buffer_head *pr_entry_bh;

};

int nilfs_palloc_prepare_alloc_entry(struct inode *,

				     struct nilfs_palloc_req *);

void nilfs_palloc_commit_alloc_entry(struct inode *,

				     struct nilfs_palloc_req *);

void nilfs_palloc_abort_alloc_entry(struct inode *, struct nilfs_palloc_req *);

void nilfs_palloc_commit_free_entry(struct inode *, struct nilfs_palloc_req *);

int nilfs_palloc_prepare_free_entry(struct inode *, struct nilfs_palloc_req *);

void nilfs_palloc_abort_free_entry(struct inode *, struct nilfs_palloc_req *);

int nilfs_palloc_freev(struct inode *, __u64 *, size_t);

#define nilfs_set_bit_atomic		ext2_set_bit_atomic

#define nilfs_clear_bit_atomic		ext2_clear_bit_atomic

#define nilfs_find_next_zero_bit	ext2_find_next_zero_bit

#endif	/* _NILFS_ALLOC_H */