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/* vi: set sw=4 ts=4: */
/*
* bmap.c --- logical to physical block mapping
*
* Copyright (C) 1997 Theodore Ts'o.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Public
* License.
* %End-Header%
*/
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "ext2_fs.h"
#include "ext2fs.h"
extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
struct ext2_inode *inode,
char *block_buf, int bmap_flags,
blk_t block, blk_t *phys_blk);
#define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
static errcode_t block_ind_bmap(ext2_filsys fs, int flags,
blk_t ind, char *block_buf,
int *blocks_alloc,
blk_t nr, blk_t *ret_blk)
{
errcode_t retval;
blk_t b;
if (!ind) {
if (flags & BMAP_SET)
return EXT2_ET_SET_BMAP_NO_IND;
*ret_blk = 0;
return 0;
}
retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
if (retval)
return retval;
if (flags & BMAP_SET) {
b = *ret_blk;
#if BB_BIG_ENDIAN
if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
(fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
b = ext2fs_swab32(b);
#endif
((blk_t *) block_buf)[nr] = b;
return io_channel_write_blk(fs->io, ind, 1, block_buf);
}
b = ((blk_t *) block_buf)[nr];
#if BB_BIG_ENDIAN
if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
(fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
b = ext2fs_swab32(b);
#endif
if (!b && (flags & BMAP_ALLOC)) {
b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
retval = ext2fs_alloc_block(fs, b,
block_buf + fs->blocksize, &b);
if (retval)
return retval;
#if BB_BIG_ENDIAN
if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
(fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
else
#endif
((blk_t *) block_buf)[nr] = b;
retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
if (retval)
return retval;
(*blocks_alloc)++;
}
*ret_blk = b;
return 0;
}
static errcode_t block_dind_bmap(ext2_filsys fs, int flags,
blk_t dind, char *block_buf,
int *blocks_alloc,
blk_t nr, blk_t *ret_blk)
{
blk_t b;
errcode_t retval;
blk_t addr_per_block;
addr_per_block = (blk_t) fs->blocksize >> 2;
retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf,
blocks_alloc, nr / addr_per_block, &b);
if (retval)
return retval;
retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
nr % addr_per_block, ret_blk);
return retval;
}
static errcode_t block_tind_bmap(ext2_filsys fs, int flags,
blk_t tind, char *block_buf,
int *blocks_alloc,
blk_t nr, blk_t *ret_blk)
{
blk_t b;
errcode_t retval;
blk_t addr_per_block;
addr_per_block = (blk_t) fs->blocksize >> 2;
retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf,
blocks_alloc, nr / addr_per_block, &b);
if (retval)
return retval;
retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
nr % addr_per_block, ret_blk);
return retval;
}
errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
char *block_buf, int bmap_flags, blk_t block,
blk_t *phys_blk)
{
struct ext2_inode inode_buf;
blk_t addr_per_block;
blk_t b;
char *buf = 0;
errcode_t retval = 0;
int blocks_alloc = 0, inode_dirty = 0;
if (!(bmap_flags & BMAP_SET))
*phys_blk = 0;
/* Read inode structure if necessary */
if (!inode) {
retval = ext2fs_read_inode(fs, ino, &inode_buf);
if (retval)
return retval;
inode = &inode_buf;
}
addr_per_block = (blk_t) fs->blocksize >> 2;
if (!block_buf) {
retval = ext2fs_get_mem(fs->blocksize * 2, &buf);
if (retval)
return retval;
block_buf = buf;
}
if (block < EXT2_NDIR_BLOCKS) {
if (bmap_flags & BMAP_SET) {
b = *phys_blk;
#if BB_BIG_ENDIAN
if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
(fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
b = ext2fs_swab32(b);
#endif
inode_bmap(inode, block) = b;
inode_dirty++;
goto done;
}
*phys_blk = inode_bmap(inode, block);
b = block ? inode_bmap(inode, block-1) : 0;
if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
retval = ext2fs_alloc_block(fs, b, block_buf, &b);
if (retval)
goto done;
inode_bmap(inode, block) = b;
blocks_alloc++;
*phys_blk = b;
}
goto done;
}
/* Indirect block */
block -= EXT2_NDIR_BLOCKS;
if (block < addr_per_block) {
b = inode_bmap(inode, EXT2_IND_BLOCK);
if (!b) {
if (!(bmap_flags & BMAP_ALLOC)) {
if (bmap_flags & BMAP_SET)
retval = EXT2_ET_SET_BMAP_NO_IND;
goto done;
}
b = inode_bmap(inode, EXT2_IND_BLOCK-1);
retval = ext2fs_alloc_block(fs, b, block_buf, &b);
if (retval)
goto done;
inode_bmap(inode, EXT2_IND_BLOCK) = b;
blocks_alloc++;
}
retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
&blocks_alloc, block, phys_blk);
goto done;
}
/* Doubly indirect block */
block -= addr_per_block;
if (block < addr_per_block * addr_per_block) {
b = inode_bmap(inode, EXT2_DIND_BLOCK);
if (!b) {
if (!(bmap_flags & BMAP_ALLOC)) {
if (bmap_flags & BMAP_SET)
retval = EXT2_ET_SET_BMAP_NO_IND;
goto done;
}
b = inode_bmap(inode, EXT2_IND_BLOCK);
retval = ext2fs_alloc_block(fs, b, block_buf, &b);
if (retval)
goto done;
inode_bmap(inode, EXT2_DIND_BLOCK) = b;
blocks_alloc++;
}
retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
&blocks_alloc, block, phys_blk);
goto done;
}
/* Triply indirect block */
block -= addr_per_block * addr_per_block;
b = inode_bmap(inode, EXT2_TIND_BLOCK);
if (!b) {
if (!(bmap_flags & BMAP_ALLOC)) {
if (bmap_flags & BMAP_SET)
retval = EXT2_ET_SET_BMAP_NO_IND;
goto done;
}
b = inode_bmap(inode, EXT2_DIND_BLOCK);
retval = ext2fs_alloc_block(fs, b, block_buf, &b);
if (retval)
goto done;
inode_bmap(inode, EXT2_TIND_BLOCK) = b;
blocks_alloc++;
}
retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
&blocks_alloc, block, phys_blk);
done:
ext2fs_free_mem(&buf);
if ((retval == 0) && (blocks_alloc || inode_dirty)) {
inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
retval = ext2fs_write_inode(fs, ino, inode);
}
return retval;
}
|
