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usbloadergx/libcustomext2fs/source/punch.c

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/*
* punch.c --- deallocate blocks allocated to an inode
*
* Copyright (C) 2010 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 "config.h"
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <errno.h>
#include "ext2_fs.h"
#include "ext2fs.h"
#undef PUNCH_DEBUG
/*
* This function returns 1 if the specified block is all zeros
*/
static int check_zero_block(char *buf, int blocksize)
{
char *cp = buf;
int left = blocksize;
while (left > 0) {
if (*cp++)
return 0;
left--;
}
return 1;
}
/*
* This clever recursive function handles i_blocks[] as well as
* indirect, double indirect, and triple indirect blocks. It iterates
* over the entries in the i_blocks array or indirect blocks, and for
* each one, will recursively handle any indirect blocks and then
* frees and deallocates the blocks.
*/
static errcode_t ind_punch(ext2_filsys fs, struct ext2_inode *inode,
char *block_buf, blk_t *p, int level,
blk_t start, blk_t count, int max)
{
errcode_t retval;
blk_t b, offset;
int i, incr;
int freed = 0;
#ifdef PUNCH_DEBUG
printf("Entering ind_punch, level %d, start %u, count %u, "
"max %d\n", level, start, count, max);
#endif
incr = 1 << ((EXT2_BLOCK_SIZE_BITS(fs->super)-2)*level);
for (i=0, offset=0; i < max; i++, p++, offset += incr) {
if (offset > count)
break;
if (*p == 0 || (offset+incr) <= start)
continue;
b = *p;
if (level > 0) {
blk_t start2;
#ifdef PUNCH_DEBUG
printf("Reading indirect block %u\n", b);
#endif
retval = ext2fs_read_ind_block(fs, b, block_buf);
if (retval)
return retval;
start2 = (start > offset) ? start - offset : 0;
retval = ind_punch(fs, inode, block_buf + fs->blocksize,
(blk_t *) block_buf, level - 1,
start2, count - offset,
fs->blocksize >> 2);
if (retval)
return retval;
retval = ext2fs_write_ind_block(fs, b, block_buf);
if (retval)
return retval;
if (!check_zero_block(block_buf, fs->blocksize))
continue;
}
#ifdef PUNCH_DEBUG
printf("Freeing block %u (offset %d)\n", b, offset);
#endif
ext2fs_block_alloc_stats(fs, b, -1);
*p = 0;
freed++;
}
#ifdef PUNCH_DEBUG
printf("Freed %d blocks\n", freed);
#endif
return ext2fs_iblk_sub_blocks(fs, inode, freed);
}
static errcode_t ext2fs_punch_ind(ext2_filsys fs, struct ext2_inode *inode,
char *block_buf, blk_t start, blk_t count)
{
errcode_t retval;
char *buf = 0;
int level;
int num = EXT2_NDIR_BLOCKS;
blk_t *bp = inode->i_block;
blk_t addr_per_block;
blk_t max = EXT2_NDIR_BLOCKS;
if (!block_buf) {
retval = ext2fs_get_array(3, fs->blocksize, &buf);
if (retval)
return retval;
block_buf = buf;
}
addr_per_block = (blk_t) fs->blocksize >> 2;
for (level=0; level < 4; level++, max *= addr_per_block) {
#ifdef PUNCH_DEBUG
printf("Main loop level %d, start %u count %u "
"max %d num %d\n", level, start, count, max, num);
#endif
if (start < max) {
retval = ind_punch(fs, inode, block_buf, bp, level,
start, count, num);
if (retval)
goto errout;
if (count > max)
count -= max - start;
else
break;
start = 0;
} else
start -= max;
bp += num;
if (level == 0) {
num = 1;
max = 1;
}
}
retval = 0;
errout:
if (buf)
ext2fs_free_mem(&buf);
return retval;
}
#ifdef PUNCH_DEBUG
#define dbg_printf(f, a...) printf(f, ## a)
static void dbg_print_extent(char *desc, struct ext2fs_extent *extent)
{
if (desc)
printf("%s: ", desc);
printf("extent: lblk %llu--%llu, len %u, pblk %llu, flags: ",
extent->e_lblk, extent->e_lblk + extent->e_len - 1,
extent->e_len, extent->e_pblk);
if (extent->e_flags & EXT2_EXTENT_FLAGS_LEAF)
fputs("LEAF ", stdout);
if (extent->e_flags & EXT2_EXTENT_FLAGS_UNINIT)
fputs("UNINIT ", stdout);
if (extent->e_flags & EXT2_EXTENT_FLAGS_SECOND_VISIT)
fputs("2ND_VISIT ", stdout);
if (!extent->e_flags)
fputs("(none)", stdout);
fputc('\n', stdout);
}
#else
#define dbg_print_extent(desc, ex) do { } while (0)
#define dbg_printf(f, a...) do { } while (0)
#endif
static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino,
struct ext2_inode *inode,
blk64_t start, blk64_t end)
{
ext2_extent_handle_t handle = 0;
struct ext2fs_extent extent;
errcode_t retval;
blk64_t free_start, next;
__u32 free_count, newlen;
int freed = 0;
retval = ext2fs_extent_open2(fs, ino, inode, &handle);
if (retval)
return retval;
ext2fs_extent_goto(handle, start);
retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
if (retval)
goto errout;
while (1) {
dbg_print_extent("main loop", &extent);
next = extent.e_lblk + extent.e_len;
dbg_printf("start %llu, end %llu, next %llu\n",
(unsigned long long) start,
(unsigned long long) end,
(unsigned long long) next);
if (start <= extent.e_lblk) {
if (end < extent.e_lblk)
goto next_extent;
dbg_printf("Case #%d\n", 1);
/* Start of deleted region before extent;
adjust beginning of extent */
free_start = extent.e_pblk;
if (next > end)
free_count = end - extent.e_lblk + 1;
else
free_count = extent.e_len;
extent.e_len -= free_count;
extent.e_lblk += free_count;
extent.e_pblk += free_count;
} else if (end >= next-1) {
if (start >= next)
break;
/* End of deleted region after extent;
adjust end of extent */
dbg_printf("Case #%d\n", 2);
newlen = start - extent.e_lblk;
free_start = extent.e_pblk + newlen;
free_count = extent.e_len - newlen;
extent.e_len = newlen;
} else {
struct ext2fs_extent newex;
dbg_printf("Case #%d\n", 3);
/* The hard case; we need to split the extent */
newex.e_pblk = extent.e_pblk +
(end + 1 - extent.e_lblk);
newex.e_lblk = end + 1;
newex.e_len = next - end - 1;
newex.e_flags = extent.e_flags;
extent.e_len = start - extent.e_lblk;
free_start = extent.e_pblk + extent.e_len;
free_count = end - start + 1;
dbg_print_extent("inserting", &newex);
retval = ext2fs_extent_insert(handle,
EXT2_EXTENT_INSERT_AFTER, &newex);
if (retval)
goto errout;
/* Now pointing at inserted extent; so go back */
retval = ext2fs_extent_get(handle,
EXT2_EXTENT_PREV_LEAF,
&newex);
if (retval)
goto errout;
}
if (extent.e_len) {
dbg_print_extent("replacing", &extent);
retval = ext2fs_extent_replace(handle, 0, &extent);
} else {
dbg_printf("deleting current extent%s\n", "");
retval = ext2fs_extent_delete(handle, 0);
}
if (retval)
goto errout;
dbg_printf("Free start %llu, free count = %u\n",
free_start, free_count);
while (free_count-- > 0) {
ext2fs_block_alloc_stats(fs, free_start++, -1);
freed++;
}
next_extent:
retval = ext2fs_extent_get(handle, EXT2_EXTENT_NEXT_LEAF,
&extent);
if (retval == EXT2_ET_EXTENT_NO_NEXT)
break;
if (retval)
goto errout;
}
dbg_printf("Freed %d blocks\n", freed);
retval = ext2fs_iblk_sub_blocks(fs, inode, freed);
errout:
ext2fs_extent_free(handle);
return retval;
}
/*
* Deallocate all logical blocks starting at start to end, inclusive.
* If end is ~0, then this is effectively truncate.
*/
extern errcode_t ext2fs_punch(ext2_filsys fs, ext2_ino_t ino,
struct ext2_inode *inode,
char *block_buf, blk64_t start,
blk64_t end)
{
errcode_t retval;
struct ext2_inode inode_buf;
if (start > end)
return EINVAL;
if (start == end)
return 0;
/* Read inode structure if necessary */
if (!inode) {
retval = ext2fs_read_inode(fs, ino, &inode_buf);
if (retval)
return retval;
inode = &inode_buf;
}
if (inode->i_flags & EXT4_EXTENTS_FL)
retval = ext2fs_punch_extent(fs, ino, inode, start, end);
else {
blk_t count;
if (start > ~0U)
return 0;
count = ((end - start) < ~0U) ? (end - start) : ~0U;
retval = ext2fs_punch_ind(fs, inode, block_buf,
(blk_t) start, count);
}
if (retval)
return retval;
return ext2fs_write_inode(fs, ino, inode);
}
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