reblock.c

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#include "reblock.h"
#include <string.h> /* memset */


static size_t reblock_readDirect(struct KBlock *b, block_idx_t idx, void *buf, size_t offset, size_t size)
{
    Reblock *r = REBLOCK_CAST(b);

    offset += idx % (r->native_fd->blk_size / r->fd.blk_size) * r->fd.blk_size;
    idx    =  idx / (r->native_fd->blk_size / r->fd.blk_size);

    return kblock_read(r->native_fd, idx, buf, offset, size);
}


static size_t reblock_writeDirect(struct KBlock *b, block_idx_t idx, const void *buf, size_t offset, size_t size)
{
    Reblock *r = REBLOCK_CAST(b);

    offset += idx % (r->native_fd->blk_size / r->fd.blk_size) * r->fd.blk_size;
    idx    =  idx / (r->native_fd->blk_size / r->fd.blk_size);

    return kblock_write(r->native_fd, idx, buf, offset, size);
}


static int reblock_error(struct KBlock *b)
{
    return kblock_error(REBLOCK_CAST(b)->native_fd);
}

static void reblock_clearerr(struct KBlock *b)
{
    kblock_clearerr(REBLOCK_CAST(b)->native_fd);
}

static int reblock_close(struct KBlock *b)
{
    return kblock_close(REBLOCK_CAST(b)->native_fd);
}


static const KBlockVTable reblock_vt =
{
    .readDirect = reblock_readDirect,
    .writeDirect = reblock_writeDirect,

    .error = reblock_error,
    .clearerr = reblock_clearerr,
    .close = reblock_close,
};


/*
 * Initialize reblock device.
 *
 * \param rbl           kblock reblock device
 * \param native_fd     kblock descriptor of the reblocked device
 * \param new_blk_size  new block size to export
 *
 * \note new block size is required to be a submultiple of the
 *       native device block size.
 */
void reblock_init(Reblock *rbl, KBlock *native_fd, size_t new_blk_size)
{
    ASSERT(new_blk_size);
    ASSERT(new_blk_size < native_fd->blk_size);
    ASSERT(native_fd->blk_size % new_blk_size == 0);
    ASSERT(kblock_buffered(native_fd) || kblock_partialWrite(native_fd));

    memset(rbl, 0, sizeof(Reblock));

    DB(rbl->fd.priv.type = KBT_REBLOCK);

    rbl->fd.blk_size = new_blk_size;
    rbl->fd.blk_cnt = native_fd->blk_cnt * (native_fd->blk_size / new_blk_size);

    rbl->fd.priv.flags |= KB_PARTIAL_WRITE;
    rbl->fd.priv.vt = &reblock_vt;

    rbl->native_fd = native_fd;
}