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/*

 * Copyright 2000-2002 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/vmalloc.h>

#include <linux/locks.h>

#include <linux/string.h>

#include <linux/errno.h>

#include <linux/reiserfs_fs.h>

#include <linux/reiserfs_fs_sb.h>

int reiserfs_resize (struct super_block * s, unsigned long block_count_new)

{

        struct reiserfs_super_block * sb;

        struct reiserfs_bitmap_info *bitmap;

        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) {

                reiserfs_warning(s, "can\'t shrink filesystem on-line\n");

                return -EINVAL;

        }

        /* check the device size */

        bh = sb_bread(s, block_count_new - 1);

        if (!bh) {

                reiserfs_warning(s, "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 ) {

                reiserfs_warning(s, "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) {

                reiserfs_warning(s, "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) {

                reiserfs_warning(s, "reiserfs_resize: unable to allocate memory.\n");

                return -ENOMEM;

            }

            for (i = 0; i < bmap_nr; i++)

                bitmap[i] = SB_AP_BITMAP(s)[i];

            for (i = bmap_nr; i < bmap_nr_new; i++) {

                bitmap[i].bh = sb_getblk(s, i * s->s_blocksize * 8);

                memset(bitmap[i].bh->b_data, 0, sb_blocksize(sb));

                reiserfs_test_and_set_le_bit(0, bitmap[i].bh->b_data);

                mark_buffer_dirty(bitmap[i].bh) ;

                mark_buffer_uptodate(bitmap[i].bh, 1);

                ll_rw_block(WRITE, 1, &bitmap[i].bh);

                wait_on_buffer(bitmap[i].bh);

                bitmap[i].first_zero_hint=1;

                bitmap[i].free_count = s->s_blocksize * 8 - 1;

            }

            /* free old bitmap blocks array */

            vfree(SB_AP_BITMAP(s));

            SB_AP_BITMAP(s) = bitmap;

        }

        /* begin transaction */

        journal_begin(&th, s, 10);

        /* correct last bitmap blocks in old and new disk layout */

        reiserfs_prepare_for_journal(s, SB_AP_BITMAP(s)[bmap_nr - 1].bh, 1);

        for (i = block_r; i < s->s_blocksize * 8; i++)

            reiserfs_test_and_clear_le_bit(i,

                                           SB_AP_BITMAP(s)[bmap_nr - 1].bh->b_data);

        SB_AP_BITMAP(s)[bmap_nr - 1].free_count += s->s_blocksize * 8 - block_r;

        if ( !SB_AP_BITMAP(s)[bmap_nr - 1].first_zero_hint)

            SB_AP_BITMAP(s)[bmap_nr - 1].first_zero_hint = block_r;

        journal_mark_dirty(&th, s, SB_AP_BITMAP(s)[bmap_nr - 1].bh);

        reiserfs_prepare_for_journal(s, SB_AP_BITMAP(s)[bmap_nr_new - 1].bh, 1);

        for (i = block_r_new; i < s->s_blocksize * 8; i++)

            reiserfs_test_and_set_le_bit(i,

                                         SB_AP_BITMAP(s)[bmap_nr_new - 1].bh->b_data);

        journal_mark_dirty(&th, s, SB_AP_BITMAP(s)[bmap_nr_new - 1].bh);

        SB_AP_BITMAP(s)[bmap_nr_new - 1].free_count -= s->s_blocksize * 8 - block_r_new;

        /* Extreme case where last bitmap is the only valid block in itself. */

        if ( !SB_AP_BITMAP(s)[bmap_nr_new - 1].free_count )

            SB_AP_BITMAP(s)[bmap_nr_new - 1].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;

        journal_end(&th, s, 10);

        return 0;

}