lib/ext2fs/bmap.c

/*
 * 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 Library
 * General Public License, version 2.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <errno.h>

#include "ext2_fs.h"
#include "ext2fsP.h"

#if defined(__GNUC__) && !defined(NO_INLINE_FUNCS)
#define _BMAP_INLINE_	__inline__
#else
#define _BMAP_INLINE_
#endif

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 _BMAP_INLINE_ 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;
#ifdef WORDS_BIGENDIAN
		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];

#ifdef WORDS_BIGENDIAN
	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;

#ifdef WORDS_BIGENDIAN
		((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
#else
		((blk_t *) block_buf)[nr] = b;
#endif

		retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
		if (retval)
			return retval;

		(*blocks_alloc)++;
	}

	*ret_blk = b;
	return 0;
}

static _BMAP_INLINE_ 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 = 0;
	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 _BMAP_INLINE_ 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 = 0;
	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;
}

static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino,
			     struct ext2_inode *inode,
			     ext2_extent_handle_t handle,
			     char *block_buf, int bmap_flags, blk64_t block,
			     int *ret_flags, int *blocks_alloc,
			     blk64_t *phys_blk);

static errcode_t implied_cluster_alloc(ext2_filsys fs, ext2_ino_t ino,
				       struct ext2_inode *inode,
				       ext2_extent_handle_t handle,
				       blk64_t lblk, blk64_t *phys_blk)
{
	blk64_t	base_block, pblock = 0;
	int i;

	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
					EXT4_FEATURE_RO_COMPAT_BIGALLOC))
		return 0;

	base_block = lblk & ~EXT2FS_CLUSTER_MASK(fs);
	/*
	 * Except for the logical block (lblk) that was passed in, search all
	 * blocks in this logical cluster for a mapping to a physical cluster.
	 * If any such map exists, calculate the physical block that maps to
	 * the logical block and return that.
	 *
	 * The old code wouldn't even look if (block % cluster_ratio) == 0;
	 * this is incorrect if we're allocating blocks in reverse order.
	 */
	for (i = 0; i < EXT2FS_CLUSTER_RATIO(fs); i++) {
		if (base_block + i == lblk)
			continue;
		extent_bmap(fs, ino, inode, handle, 0, 0,
			    base_block + i, 0, 0, &pblock);
		if (pblock)
			break;
	}
	if (pblock == 0)
		return 0;
	*phys_blk = pblock - i + (lblk - base_block);
	return 0;
}

/* Try to map a logical block to an already-allocated physical cluster. */
errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino,
				   struct ext2_inode *inode, blk64_t lblk,
				   blk64_t *pblk)
{
	ext2_extent_handle_t handle;
	errcode_t retval;

	/* Need bigalloc and extents to be enabled */
	*pblk = 0;
	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
					EXT4_FEATURE_RO_COMPAT_BIGALLOC) ||
	    !(inode->i_flags & EXT4_EXTENTS_FL))
		return 0;

	retval = ext2fs_extent_open2(fs, ino, inode, &handle);
	if (retval)
		goto out;

	retval = implied_cluster_alloc(fs, ino, inode, handle, lblk, pblk);
	if (retval)
		goto out2;

out2:
	ext2fs_extent_free(handle);
out:
	return retval;
}

static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino,
			     struct ext2_inode *inode,
			     ext2_extent_handle_t handle,
			     char *block_buf, int bmap_flags, blk64_t block,
			     int *ret_flags, int *blocks_alloc,
			     blk64_t *phys_blk)
{
	struct ext2fs_extent	extent;
	unsigned int		offset;
	errcode_t		retval = 0;
	blk64_t			blk64 = 0;
	int			alloc = 0;

	if (bmap_flags & BMAP_SET) {
		retval = ext2fs_extent_set_bmap(handle, block,
						*phys_blk, 0);
		return retval;
	}
	retval = ext2fs_extent_goto(handle, block);
	if (retval) {
		/* If the extent is not found, return phys_blk = 0 */
		if (retval == EXT2_ET_EXTENT_NOT_FOUND)
			goto got_block;
		return retval;
	}
	retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
	if (retval)
		return retval;
	offset = block - extent.e_lblk;
	if (block >= extent.e_lblk && (offset <= extent.e_len)) {
		*phys_blk = extent.e_pblk + offset;
		if (ret_flags && extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
			*ret_flags |= BMAP_RET_UNINIT;
	}
got_block:
	if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
		implied_cluster_alloc(fs, ino, inode, handle, block, &blk64);
		if (blk64)
			goto set_extent;
		retval = extent_bmap(fs, ino, inode, handle, block_buf,
				     0, block-1, 0, blocks_alloc, &blk64);
		if (retval)
			blk64 = 0;
		retval = ext2fs_alloc_block2(fs, blk64, block_buf,
					     &blk64);
		if (retval)
			return retval;
		blk64 &= ~EXT2FS_CLUSTER_MASK(fs);
		blk64 += EXT2FS_CLUSTER_MASK(fs) & block;
		alloc++;
	set_extent:
		retval = ext2fs_extent_set_bmap(handle, block,
						blk64, 0);
		if (retval)
			return retval;
		/* Update inode after setting extent */
		retval = ext2fs_read_inode(fs, ino, inode);
		if (retval)
			return retval;
		*blocks_alloc += alloc;
		*phys_blk = blk64;
	}
	return 0;
}

int ext2fs_file_block_offset_too_big(ext2_filsys fs,
				     struct ext2_inode *inode,
				     blk64_t offset)
{
	blk64_t addr_per_block, max_map_block;

	/* Kernel seems to cut us off at 4294967294 blocks */
	if (offset >= (1ULL << 32) - 1)
		return 1;

	if (inode->i_flags & EXT4_EXTENTS_FL)
		return 0;

	addr_per_block = fs->blocksize >> 2;
	max_map_block = addr_per_block;
	max_map_block += addr_per_block * addr_per_block;
	max_map_block += addr_per_block * addr_per_block * addr_per_block;
	max_map_block += 12;

	return offset >= max_map_block;
}

errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
		       char *block_buf, int bmap_flags, blk64_t block,
		       int *ret_flags, blk64_t *phys_blk)
{
	struct ext2_inode inode_buf;
	ext2_extent_handle_t handle = 0;
	blk_t addr_per_block;
	blk_t	b, blk32;
	char	*buf = 0;
	errcode_t	retval = 0;
	int		blocks_alloc = 0, inode_dirty = 0;

	if (!(bmap_flags & BMAP_SET))
		*phys_blk = 0;

	if (ret_flags)
		*ret_flags = 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 (ext2fs_file_block_offset_too_big(fs, inode, block))
		return EXT2_ET_FILE_TOO_BIG;

	if (!block_buf) {
		retval = ext2fs_get_array(2, fs->blocksize, &buf);
		if (retval)
			return retval;
		block_buf = buf;
	}

	if (inode->i_flags & EXT4_EXTENTS_FL) {
		retval = ext2fs_extent_open2(fs, ino, inode, &handle);
		if (retval)
			goto done;
		retval = extent_bmap(fs, ino, inode, handle, block_buf,
				     bmap_flags, block, ret_flags,
				     &blocks_alloc, phys_blk);
		goto done;
	}

	if (block < EXT2_NDIR_BLOCKS) {
		if (bmap_flags & BMAP_SET) {
			b = *phys_blk;
			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;
	blk32 = *phys_blk;
	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, &blk32);
		if (retval == 0)
			*phys_blk = blk32;
		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, &blk32);
		if (retval == 0)
			*phys_blk = blk32;
		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, &blk32);
	if (retval == 0)
		*phys_blk = blk32;
done:
	if (buf)
		ext2fs_free_mem(&buf);
	if (handle)
		ext2fs_extent_free(handle);
	if ((retval == 0) && (blocks_alloc || inode_dirty)) {
		ext2fs_iblk_add_blocks(fs, inode, blocks_alloc);
		retval = ext2fs_write_inode(fs, ino, inode);
	}
	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)
{
	errcode_t ret;
	blk64_t	ret_blk = *phys_blk;

	ret = ext2fs_bmap2(fs, ino, inode, block_buf, bmap_flags, block,
			    0, &ret_blk);
	if (ret)
		return ret;
	if (ret_blk >= ((long long) 1 << 32))
		return EOVERFLOW;
	*phys_blk = ret_blk;
	return 0;
}