Function Ext2FreeBlock

Ext4Fsd/ext3/generic.c:1173–1323

}

NTSTATUS
Ext2FreeBlock(
    IN PEXT2_IRP_CONTEXT    IrpContext,
    IN PEXT2_VCB            Vcb,
    IN ULONG                Block,
    IN ULONG                Number
)
{
    struct super_block     *sb = &Vcb->sb;
    PEXT2_GROUP_DESC        gd;
    struct buffer_head     *gb = NULL;
    struct buffer_head      bh;
    ext4_fsblk_t            bitmap_blk;

    RTL_BITMAP      BlockBitmap;
    LARGE_INTEGER   Offset;

    PBCB            BitmapBcb;
    PVOID           BitmapCache;

    ULONG           Group;
    ULONG           Index;
    ULONG           Length;
    ULONG           Count;

    NTSTATUS        Status = STATUS_UNSUCCESSFUL;

    ExAcquireResourceExclusiveLite(&Vcb->MetaBlock, TRUE);

    DEBUG(DL_INF, ("Ext2FreeBlock: Block %xh - %x to be freed.\n",
                   Block, Block + Number));

    Group = (Block - EXT2_FIRST_DATA_BLOCK) / BLOCKS_PER_GROUP;
    Index = (Block - EXT2_FIRST_DATA_BLOCK) % BLOCKS_PER_GROUP;

Again:

    if (gb)
        fini_bh(&gb);

    if ( Block < EXT2_FIRST_DATA_BLOCK ||
         Block >= TOTAL_BLOCKS ||
         Group >= Vcb->sbi.s_groups_count) {

        DbgBreak();
        Status = STATUS_SUCCESS;

    } else  {

        gd = ext4_get_group_desc(sb, Group, &gb);
        if (!gd) {
            DbgBreak();
            Status = STATUS_INSUFFICIENT_RESOURCES;
            goto errorout;
        }
        bitmap_blk = ext4_block_bitmap(sb, gd);

        /* check the block is valid or not */