/*
   * direct.c - NILFS direct block pointer.
   *
   * 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
   *
   * Written by Koji Sato <koji@osrg.net>.
   */
  
  #include <linux/errno.h>
  #include "nilfs.h"
  #include "page.h"
  #include "direct.h"
  #include "alloc.h"
  #include "dat.h"
  
  static inline __le64 *nilfs_direct_dptrs(const struct nilfs_bmap *direct)
  {
  	return (__le64 *)
  		((struct nilfs_direct_node *)direct->b_u.u_data + 1);
  }
  
  static inline __u64
  nilfs_direct_get_ptr(const struct nilfs_bmap *direct, __u64 key)
  {
  	return le64_to_cpu(*(nilfs_direct_dptrs(direct) + key));
  }
  
  static inline void nilfs_direct_set_ptr(struct nilfs_bmap *direct,
  					__u64 key, __u64 ptr)
  {
  	*(nilfs_direct_dptrs(direct) + key) = cpu_to_le64(ptr);
  }
  
  static int nilfs_direct_lookup(const struct nilfs_bmap *direct,
  			       __u64 key, int level, __u64 *ptrp)
  {
  	__u64 ptr;
  
  	if (key > NILFS_DIRECT_KEY_MAX || level != 1)
  		return -ENOENT;
  	ptr = nilfs_direct_get_ptr(direct, key);
  	if (ptr == NILFS_BMAP_INVALID_PTR)
  		return -ENOENT;
  
  	*ptrp = ptr;
  	return 0;
  }
  
  static int nilfs_direct_lookup_contig(const struct nilfs_bmap *direct,
  				      __u64 key, __u64 *ptrp,
  				      unsigned maxblocks)
  {
  	struct inode *dat = NULL;
  	__u64 ptr, ptr2;
  	sector_t blocknr;
  	int ret, cnt;
  
  	if (key > NILFS_DIRECT_KEY_MAX)
  		return -ENOENT;
  	ptr = nilfs_direct_get_ptr(direct, key);
  	if (ptr == NILFS_BMAP_INVALID_PTR)
  		return -ENOENT;
  
  	if (NILFS_BMAP_USE_VBN(direct)) {
  		dat = nilfs_bmap_get_dat(direct);
  		ret = nilfs_dat_translate(dat, ptr, &blocknr);
  		if (ret < 0)
  			return ret;
  		ptr = blocknr;
  	}
  
  	maxblocks = min_t(unsigned, maxblocks, NILFS_DIRECT_KEY_MAX - key + 1);
  	for (cnt = 1; cnt < maxblocks &&
  		     (ptr2 = nilfs_direct_get_ptr(direct, key + cnt)) !=
  		     NILFS_BMAP_INVALID_PTR;
  	     cnt++) {
  		if (dat) {
  			ret = nilfs_dat_translate(dat, ptr2, &blocknr);
  			if (ret < 0)
  				return ret;
  			ptr2 = blocknr;
  		}
  		if (ptr2 != ptr + cnt)
  			break;
  	}
  	*ptrp = ptr;
  	return cnt;
  }
  
  static __u64
  nilfs_direct_find_target_v(const struct nilfs_bmap *direct, __u64 key)
  {
  	__u64 ptr;
  
  	ptr = nilfs_bmap_find_target_seq(direct, key);
  	if (ptr != NILFS_BMAP_INVALID_PTR)
  		/* sequential access */
  		return ptr;
  	else
  		/* block group */
  		return nilfs_bmap_find_target_in_group(direct);
  }
  
  static int nilfs_direct_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
  {
  	union nilfs_bmap_ptr_req req;
  	struct inode *dat = NULL;
  	struct buffer_head *bh;
  	int ret;
  
  	if (key > NILFS_DIRECT_KEY_MAX)
  		return -ENOENT;
  	if (nilfs_direct_get_ptr(bmap, key) != NILFS_BMAP_INVALID_PTR)
  		return -EEXIST;
  
  	if (NILFS_BMAP_USE_VBN(bmap)) {
  		req.bpr_ptr = nilfs_direct_find_target_v(bmap, key);
  		dat = nilfs_bmap_get_dat(bmap);
  	}
  	ret = nilfs_bmap_prepare_alloc_ptr(bmap, &req, dat);
  	if (!ret) {
  		/* ptr must be a pointer to a buffer head. */
  		bh = (struct buffer_head *)((unsigned long)ptr);
  		set_buffer_nilfs_volatile(bh);
  
  		nilfs_bmap_commit_alloc_ptr(bmap, &req, dat);
  		nilfs_direct_set_ptr(bmap, key, req.bpr_ptr);
  
  		if (!nilfs_bmap_dirty(bmap))
  			nilfs_bmap_set_dirty(bmap);
  
  		if (NILFS_BMAP_USE_VBN(bmap))
  			nilfs_bmap_set_target_v(bmap, key, req.bpr_ptr);
  
  		nilfs_inode_add_blocks(bmap->b_inode, 1);
  	}
  	return ret;
  }
  
  static int nilfs_direct_delete(struct nilfs_bmap *bmap, __u64 key)
  {
  	union nilfs_bmap_ptr_req req;
  	struct inode *dat;
  	int ret;
  
  	if (key > NILFS_DIRECT_KEY_MAX ||
  	    nilfs_direct_get_ptr(bmap, key) == NILFS_BMAP_INVALID_PTR)
  		return -ENOENT;
  
  	dat = NILFS_BMAP_USE_VBN(bmap) ? nilfs_bmap_get_dat(bmap) : NULL;
  	req.bpr_ptr = nilfs_direct_get_ptr(bmap, key);
  
  	ret = nilfs_bmap_prepare_end_ptr(bmap, &req, dat);
  	if (!ret) {
  		nilfs_bmap_commit_end_ptr(bmap, &req, dat);
  		nilfs_direct_set_ptr(bmap, key, NILFS_BMAP_INVALID_PTR);
  		nilfs_inode_sub_blocks(bmap->b_inode, 1);
  	}
  	return ret;
  }
  
  static int nilfs_direct_last_key(const struct nilfs_bmap *direct, __u64 *keyp)
  {
  	__u64 key, lastkey;
  
  	lastkey = NILFS_DIRECT_KEY_MAX + 1;
  	for (key = NILFS_DIRECT_KEY_MIN; key <= NILFS_DIRECT_KEY_MAX; key++)
  		if (nilfs_direct_get_ptr(direct, key) !=
  		    NILFS_BMAP_INVALID_PTR)
  			lastkey = key;
  
  	if (lastkey == NILFS_DIRECT_KEY_MAX + 1)
  		return -ENOENT;
  
  	*keyp = lastkey;
  
  	return 0;
  }
  
  static int nilfs_direct_check_insert(const struct nilfs_bmap *bmap, __u64 key)
  {
  	return key > NILFS_DIRECT_KEY_MAX;
  }
  
  static int nilfs_direct_gather_data(struct nilfs_bmap *direct,
  				    __u64 *keys, __u64 *ptrs, int nitems)
  {
  	__u64 key;
  	__u64 ptr;
  	int n;
  
  	if (nitems > NILFS_DIRECT_NBLOCKS)
  		nitems = NILFS_DIRECT_NBLOCKS;
  	n = 0;
  	for (key = 0; key < nitems; key++) {
  		ptr = nilfs_direct_get_ptr(direct, key);
  		if (ptr != NILFS_BMAP_INVALID_PTR) {
  			keys[n] = key;
  			ptrs[n] = ptr;
  			n++;
  		}
  	}
  	return n;
  }
  
  int nilfs_direct_delete_and_convert(struct nilfs_bmap *bmap,
  				    __u64 key, __u64 *keys, __u64 *ptrs, int n)
  {
  	__le64 *dptrs;
  	int ret, i, j;
  
  	/* no need to allocate any resource for conversion */
  
  	/* delete */
  	ret = bmap->b_ops->bop_delete(bmap, key);
  	if (ret < 0)
  		return ret;
  
  	/* free resources */
  	if (bmap->b_ops->bop_clear != NULL)
  		bmap->b_ops->bop_clear(bmap);
  
  	/* convert */
  	dptrs = nilfs_direct_dptrs(bmap);
  	for (i = 0, j = 0; i < NILFS_DIRECT_NBLOCKS; i++) {
  		if ((j < n) && (i == keys[j])) {
  			dptrs[i] = (i != key) ?
  				cpu_to_le64(ptrs[j]) :
  				NILFS_BMAP_INVALID_PTR;
  			j++;
  		} else
  			dptrs[i] = NILFS_BMAP_INVALID_PTR;
  	}
  
  	nilfs_direct_init(bmap);
  	return 0;
  }
  
  static int nilfs_direct_propagate(struct nilfs_bmap *bmap,
  				  struct buffer_head *bh)
  {
  	struct nilfs_palloc_req oldreq, newreq;
  	struct inode *dat;
  	__u64 key;
  	__u64 ptr;
  	int ret;
  
  	if (!NILFS_BMAP_USE_VBN(bmap))
  		return 0;
  
  	dat = nilfs_bmap_get_dat(bmap);
  	key = nilfs_bmap_data_get_key(bmap, bh);
  	ptr = nilfs_direct_get_ptr(bmap, key);
  	if (!buffer_nilfs_volatile(bh)) {
  		oldreq.pr_entry_nr = ptr;
  		newreq.pr_entry_nr = ptr;
  		ret = nilfs_dat_prepare_update(dat, &oldreq, &newreq);
  		if (ret < 0)
  			return ret;
  		nilfs_dat_commit_update(dat, &oldreq, &newreq,
  					bmap->b_ptr_type == NILFS_BMAP_PTR_VS);
  		set_buffer_nilfs_volatile(bh);
  		nilfs_direct_set_ptr(bmap, key, newreq.pr_entry_nr);
  	} else
  		ret = nilfs_dat_mark_dirty(dat, ptr);
  
  	return ret;
  }
  
  static int nilfs_direct_assign_v(struct nilfs_bmap *direct,
  				 __u64 key, __u64 ptr,
  				 struct buffer_head **bh,
  				 sector_t blocknr,
  				 union nilfs_binfo *binfo)
  {
  	struct inode *dat = nilfs_bmap_get_dat(direct);
  	union nilfs_bmap_ptr_req req;
  	int ret;
  
  	req.bpr_ptr = ptr;
  	ret = nilfs_dat_prepare_start(dat, &req.bpr_req);
  	if (!ret) {
  		nilfs_dat_commit_start(dat, &req.bpr_req, blocknr);
  		binfo->bi_v.bi_vblocknr = cpu_to_le64(ptr);
  		binfo->bi_v.bi_blkoff = cpu_to_le64(key);
  	}
  	return ret;
  }
  
  static int nilfs_direct_assign_p(struct nilfs_bmap *direct,
  				 __u64 key, __u64 ptr,
  				 struct buffer_head **bh,
  				 sector_t blocknr,
  				 union nilfs_binfo *binfo)
  {
  	nilfs_direct_set_ptr(direct, key, blocknr);
  
  	binfo->bi_dat.bi_blkoff = cpu_to_le64(key);
  	binfo->bi_dat.bi_level = 0;
  
  	return 0;
  }
  
  static int nilfs_direct_assign(struct nilfs_bmap *bmap,
  			       struct buffer_head **bh,
  			       sector_t blocknr,
  			       union nilfs_binfo *binfo)
  {
  	__u64 key;
  	__u64 ptr;
  
  	key = nilfs_bmap_data_get_key(bmap, *bh);
  	if (unlikely(key > NILFS_DIRECT_KEY_MAX)) {
  		printk(KERN_CRIT "%s: invalid key: %llu
  ", __func__,
  		       (unsigned long long)key);
  		return -EINVAL;
  	}
  	ptr = nilfs_direct_get_ptr(bmap, key);
  	if (unlikely(ptr == NILFS_BMAP_INVALID_PTR)) {
  		printk(KERN_CRIT "%s: invalid pointer: %llu
  ", __func__,
  		       (unsigned long long)ptr);
  		return -EINVAL;
  	}
  
  	return NILFS_BMAP_USE_VBN(bmap) ?
  		nilfs_direct_assign_v(bmap, key, ptr, bh, blocknr, binfo) :
  		nilfs_direct_assign_p(bmap, key, ptr, bh, blocknr, binfo);
  }
  
  static const struct nilfs_bmap_operations nilfs_direct_ops = {
  	.bop_lookup		=	nilfs_direct_lookup,
  	.bop_lookup_contig	=	nilfs_direct_lookup_contig,
  	.bop_insert		=	nilfs_direct_insert,
  	.bop_delete		=	nilfs_direct_delete,
  	.bop_clear		=	NULL,
  
  	.bop_propagate		=	nilfs_direct_propagate,
  
  	.bop_lookup_dirty_buffers	=	NULL,
  
  	.bop_assign		=	nilfs_direct_assign,
  	.bop_mark		=	NULL,
  
  	.bop_last_key		=	nilfs_direct_last_key,
  	.bop_check_insert	=	nilfs_direct_check_insert,
  	.bop_check_delete	=	NULL,
  	.bop_gather_data	=	nilfs_direct_gather_data,
  };
  
  
  int nilfs_direct_init(struct nilfs_bmap *bmap)
  {
  	bmap->b_ops = &nilfs_direct_ops;
  	return 0;
  }