resize.c

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/*
 * 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;

    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) -
            (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\n");
            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 =
            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.\n");
            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++) {
            /* 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_set_le_bit(0, bh->b_data);
            reiserfs_cache_bitmap_metadata(s, bh, bitmap + i);

            set_buffer_uptodate(bh);
            mark_buffer_dirty(bh);
            reiserfs_write_unlock(s);
            sync_dirty_buffer(bh);
            reiserfs_write_lock(s);
            // 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, 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_clear_le_bit(i, bh->b_data);
    info->free_count += s->s_blocksize * 8 - 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_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;
    /* 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, s, SB_BUFFER_WITH_SB(s));

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