/* 
 * 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 <linux/reiserfs_fs.h>
#include <linux/reiserfs_fs_sb.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;

	sb = SB_DISK_SUPER_BLOCK(s);

	if (SB_BLOCK_COUNT(s) >= block_count_new) {
		printk("can\'t shrink filesystem on-line\n");
		return -EINVAL;
	}

	/* check the device size */
	bh = sb_bread(s, block_count_new - 1);
	if (!bh) {
		printk("reiserfs_resize: can\'t read last block\n");
		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)\n");
		return -ENOTSUPP;
	}

	/* count used bits in last bitmap block */
	block_r = SB_BLOCK_COUNT(s) - (SB_BMAP_NR(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 = SB_BMAP_NR(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\n");
			unlock_super(s);
			return -ENOMEM;
		}
		/* the new journal bitmaps are zero filled, now we copy in 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 =
		    vmalloc(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.\n");
			return -ENOMEM;
		}
		memset(bitmap, 0,
		       sizeof(struct reiserfs_bitmap_info) * SB_BMAP_NR(s));
		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++) {
			/* don't use read_bitmap_block since it will cache
			 * the uninitialized bitmap */
			bh = sb_bread(s, i * s->s_blocksize * 8);
			if (!bh) {
				vfree(bitmap);
				return -EIO;
			}
			memset(bh->b_data, 0, sb_blocksize(sb));
			reiserfs_test_and_set_le_bit(0, bh->b_data);
			reiserfs_cache_bitmap_metadata(s, bh, bitmap + i);

			set_buffer_uptodate(bh);
			mark_buffer_dirty(bh);
			sync_dirty_buffer(bh);
			// update bitmap_info stuff
			bitmap[i].first_zero_hint = 1;
			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, s, 10);
		if (jerr)
			return jerr;
		return -EIO;
	}

	reiserfs_prepare_for_journal(s, bh, 1);
	for (i = block_r; i < s->s_blocksize * 8; i++)
		reiserfs_test_and_clear_le_bit(i, bh->b_data);
	info->free_count += s->s_blocksize * 8 - block_r;
	if (!info->first_zero_hint)
		info->first_zero_hint = block_r;

	journal_mark_dirty(&th, s, 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, s, 10);
		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_test_and_set_le_bit(i, bh->b_data);
	journal_mark_dirty(&th, s, bh);
	brelse(bh);

	info->free_count -= s->s_blocksize * 8 - block_r_new;
	/* Extreme case where last bitmap is the only valid block in itself. */
	if (!info->free_count)
		info->first_zero_hint = 0;
	/* 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_nr_new);
	s->s_dirt = 1;

	journal_mark_dirty(&th, s, SB_BUFFER_WITH_SB(s));

	SB_JOURNAL(s)->j_must_wait = 1;
	return journal_end(&th, s, 10);
}