/*
   * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
   */
  
  /*
   * Written by Alexander Zarochentcev.
   *
   * The kernel part of the (on-line) reiserfs resizer.
   */
  
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/vmalloc.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include "reiserfs.h"
  #include <linux/buffer_head.h>
  
  int reiserfs_resize(struct super_block *s, unsigned long block_count_new)
  {
  	int err = 0;
  	struct reiserfs_super_block *sb;
  	struct reiserfs_bitmap_info *bitmap;
  	struct reiserfs_bitmap_info *info;
  	struct reiserfs_bitmap_info *old_bitmap = SB_AP_BITMAP(s);
  	struct buffer_head *bh;
  	struct reiserfs_transaction_handle th;
  	unsigned int bmap_nr_new, bmap_nr;
  	unsigned int block_r_new, block_r;
  
  	struct reiserfs_list_bitmap *jb;
  	struct reiserfs_list_bitmap jbitmap[JOURNAL_NUM_BITMAPS];
  
  	unsigned long int block_count, free_blocks;
  	int i;
  	int copy_size;
  	int depth;
  
  	sb = SB_DISK_SUPER_BLOCK(s);
  
  	if (SB_BLOCK_COUNT(s) >= block_count_new) {
  		printk("can\'t shrink filesystem on-line
  ");
  		return -EINVAL;
  	}
  
  	/* check the device size */
  	depth = reiserfs_write_unlock_nested(s);
  	bh = sb_bread(s, block_count_new - 1);
  	reiserfs_write_lock_nested(s, depth);
  	if (!bh) {
  		printk("reiserfs_resize: can\'t read last block
  ");
  		return -EINVAL;
  	}
  	bforget(bh);
  
  	/*
  	 * old disk layout detection; those partitions can be mounted, but
  	 * cannot be resized
  	 */
  	if (SB_BUFFER_WITH_SB(s)->b_blocknr * SB_BUFFER_WITH_SB(s)->b_size
  	    != REISERFS_DISK_OFFSET_IN_BYTES) {
  		printk
  		    ("reiserfs_resize: unable to resize a reiserfs without distributed bitmap (fs version < 3.5.12)
  ");
  		return -ENOTSUPP;
  	}
  
  	/* count used bits in last bitmap block */
  	block_r = SB_BLOCK_COUNT(s) -
  			(reiserfs_bmap_count(s) - 1) * s->s_blocksize * 8;
  
  	/* count bitmap blocks in new fs */
  	bmap_nr_new = block_count_new / (s->s_blocksize * 8);
  	block_r_new = block_count_new - bmap_nr_new * s->s_blocksize * 8;
  	if (block_r_new)
  		bmap_nr_new++;
  	else
  		block_r_new = s->s_blocksize * 8;
  
  	/* save old values */
  	block_count = SB_BLOCK_COUNT(s);
  	bmap_nr = reiserfs_bmap_count(s);
  
  	/* resizing of reiserfs bitmaps (journal and real), if needed */
  	if (bmap_nr_new > bmap_nr) {
  		/* reallocate journal bitmaps */
  		if (reiserfs_allocate_list_bitmaps(s, jbitmap, bmap_nr_new) < 0) {
  			printk
  			    ("reiserfs_resize: unable to allocate memory for journal bitmaps
  ");
  			return -ENOMEM;
  		}
  		/*
  		 * the new journal bitmaps are zero filled, now we copy i
  		 * the bitmap node pointers from the old journal bitmap
  		 * structs, and then transfer the new data structures
  		 * into the journal struct.
  		 *
  		 * using the copy_size var below allows this code to work for
  		 * both shrinking and expanding the FS.
  		 */
  		copy_size = bmap_nr_new < bmap_nr ? bmap_nr_new : bmap_nr;
  		copy_size =
  		    copy_size * sizeof(struct reiserfs_list_bitmap_node *);
  		for (i = 0; i < JOURNAL_NUM_BITMAPS; i++) {
  			struct reiserfs_bitmap_node **node_tmp;
  			jb = SB_JOURNAL(s)->j_list_bitmap + i;
  			memcpy(jbitmap[i].bitmaps, jb->bitmaps, copy_size);
  
  			/*
  			 * just in case vfree schedules on us, copy the new
  			 * pointer into the journal struct before freeing the
  			 * old one
  			 */
  			node_tmp = jb->bitmaps;
  			jb->bitmaps = jbitmap[i].bitmaps;
  			vfree(node_tmp);
  		}
  
  		/*
  		 * allocate additional bitmap blocks, reallocate
  		 * array of bitmap block pointers
  		 */
  		bitmap =
  		    vzalloc(sizeof(struct reiserfs_bitmap_info) * bmap_nr_new);
  		if (!bitmap) {
  			/*
  			 * Journal bitmaps are still supersized, but the
  			 * memory isn't leaked, so I guess it's ok
  			 */
  			printk("reiserfs_resize: unable to allocate memory.
  ");
  			return -ENOMEM;
  		}
  		for (i = 0; i < bmap_nr; i++)
  			bitmap[i] = old_bitmap[i];
  
  		/*
  		 * This doesn't go through the journal, but it doesn't have to.
  		 * The changes are still atomic: We're synced up when the
  		 * journal transaction begins, and the new bitmaps don't
  		 * matter if the transaction fails.
  		 */
  		for (i = bmap_nr; i < bmap_nr_new; i++) {
  			int depth;
  			/*
  			 * don't use read_bitmap_block since it will cache
  			 * the uninitialized bitmap
  			 */
  			depth = reiserfs_write_unlock_nested(s);
  			bh = sb_bread(s, i * s->s_blocksize * 8);
  			reiserfs_write_lock_nested(s, depth);
  			if (!bh) {
  				vfree(bitmap);
  				return -EIO;
  			}
  			memset(bh->b_data, 0, sb_blocksize(sb));
  			reiserfs_set_le_bit(0, bh->b_data);
  			reiserfs_cache_bitmap_metadata(s, bh, bitmap + i);
  
  			set_buffer_uptodate(bh);
  			mark_buffer_dirty(bh);
  			depth = reiserfs_write_unlock_nested(s);
  			sync_dirty_buffer(bh);
  			reiserfs_write_lock_nested(s, depth);
  			/* update bitmap_info stuff */
  			bitmap[i].free_count = sb_blocksize(sb) * 8 - 1;
  			brelse(bh);
  		}
  		/* free old bitmap blocks array */
  		SB_AP_BITMAP(s) = bitmap;
  		vfree(old_bitmap);
  	}
  
  	/*
  	 * begin transaction, if there was an error, it's fine. Yes, we have
  	 * incorrect bitmaps now, but none of it is ever going to touch the
  	 * disk anyway.
  	 */
  	err = journal_begin(&th, s, 10);
  	if (err)
  		return err;
  
  	/* Extend old last bitmap block - new blocks have been made available */
  	info = SB_AP_BITMAP(s) + bmap_nr - 1;
  	bh = reiserfs_read_bitmap_block(s, bmap_nr - 1);
  	if (!bh) {
  		int jerr = journal_end(&th);
  		if (jerr)
  			return jerr;
  		return -EIO;
  	}
  
  	reiserfs_prepare_for_journal(s, bh, 1);
  	for (i = block_r; i < s->s_blocksize * 8; i++)
  		reiserfs_clear_le_bit(i, bh->b_data);
  	info->free_count += s->s_blocksize * 8 - block_r;
  
  	journal_mark_dirty(&th, bh);
  	brelse(bh);
  
  	/* Correct new last bitmap block - It may not be full */
  	info = SB_AP_BITMAP(s) + bmap_nr_new - 1;
  	bh = reiserfs_read_bitmap_block(s, bmap_nr_new - 1);
  	if (!bh) {
  		int jerr = journal_end(&th);
  		if (jerr)
  			return jerr;
  		return -EIO;
  	}
  
  	reiserfs_prepare_for_journal(s, bh, 1);
  	for (i = block_r_new; i < s->s_blocksize * 8; i++)
  		reiserfs_set_le_bit(i, bh->b_data);
  	journal_mark_dirty(&th, bh);
  	brelse(bh);
  
  	info->free_count -= s->s_blocksize * 8 - block_r_new;
  	/* update super */
  	reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
  	free_blocks = SB_FREE_BLOCKS(s);
  	PUT_SB_FREE_BLOCKS(s,
  			   free_blocks + (block_count_new - block_count -
  					  (bmap_nr_new - bmap_nr)));
  	PUT_SB_BLOCK_COUNT(s, block_count_new);
  	PUT_SB_BMAP_NR(s, bmap_would_wrap(bmap_nr_new) ? : bmap_nr_new);
  
  	journal_mark_dirty(&th, SB_BUFFER_WITH_SB(s));
  
  	SB_JOURNAL(s)->j_must_wait = 1;
  	return journal_end(&th);
  }