2010-07-22 17:37:35 +04:00
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/*
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* punch.c --- deallocate blocks allocated to an inode
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*
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* Copyright (C) 2010 Theodore Ts'o.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Library
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* General Public License, version 2.
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* %End-Header%
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*/
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#include <stdio.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <errno.h>
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#include "ext2_fs.h"
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#include "ext2fs.h"
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#undef PUNCH_DEBUG
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/*
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* This function returns 1 if the specified block is all zeros
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*/
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static int check_zero_block(char *buf, int blocksize)
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{
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char *cp = buf;
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int left = blocksize;
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while (left > 0) {
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if (*cp++)
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return 0;
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left--;
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}
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return 1;
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}
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/*
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* This clever recursive function handles i_blocks[] as well as
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* indirect, double indirect, and triple indirect blocks. It iterates
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* over the entries in the i_blocks array or indirect blocks, and for
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* each one, will recursively handle any indirect blocks and then
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* frees and deallocates the blocks.
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*/
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static errcode_t ind_punch(ext2_filsys fs, struct ext2_inode *inode,
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char *block_buf, blk_t *p, int level,
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blk_t start, blk_t count, int max)
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{
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errcode_t retval;
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blk_t b, offset;
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int i, incr;
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int freed = 0;
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#ifdef PUNCH_DEBUG
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printf("Entering ind_punch, level %d, start %u, count %u, "
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"max %d\n", level, start, count, max);
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#endif
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incr = 1 << ((EXT2_BLOCK_SIZE_BITS(fs->super)-2)*level);
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for (i=0, offset=0; i < max; i++, p++, offset += incr) {
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if (offset > count)
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break;
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if (*p == 0 || (offset+incr) <= start)
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continue;
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b = *p;
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if (level > 0) {
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blk_t start2;
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#ifdef PUNCH_DEBUG
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printf("Reading indirect block %u\n", b);
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#endif
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retval = ext2fs_read_ind_block(fs, b, block_buf);
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if (retval)
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return retval;
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start2 = (start > offset) ? start - offset : 0;
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retval = ind_punch(fs, inode, block_buf + fs->blocksize,
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(blk_t *) block_buf, level - 1,
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start2, count - offset,
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fs->blocksize >> 2);
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if (retval)
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return retval;
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retval = ext2fs_write_ind_block(fs, b, block_buf);
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if (retval)
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return retval;
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if (!check_zero_block(block_buf, fs->blocksize))
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continue;
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}
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#ifdef PUNCH_DEBUG
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printf("Freeing block %u (offset %d)\n", b, offset);
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#endif
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ext2fs_block_alloc_stats(fs, b, -1);
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*p = 0;
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freed++;
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}
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#ifdef PUNCH_DEBUG
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printf("Freed %d blocks\n", freed);
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#endif
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return ext2fs_iblk_sub_blocks(fs, inode, freed);
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}
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static errcode_t ext2fs_punch_ind(ext2_filsys fs, struct ext2_inode *inode,
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char *block_buf, blk_t start, blk_t count)
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{
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errcode_t retval;
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char *buf = 0;
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int level;
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int num = EXT2_NDIR_BLOCKS;
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blk_t *bp = inode->i_block;
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blk_t addr_per_block;
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blk_t max = EXT2_NDIR_BLOCKS;
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if (!block_buf) {
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retval = ext2fs_get_array(3, fs->blocksize, &buf);
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if (retval)
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return retval;
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block_buf = buf;
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}
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addr_per_block = (blk_t) fs->blocksize >> 2;
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for (level=0; level < 4; level++, max *= addr_per_block) {
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#ifdef PUNCH_DEBUG
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printf("Main loop level %d, start %u count %u "
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"max %d num %d\n", level, start, count, max, num);
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#endif
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if (start < max) {
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retval = ind_punch(fs, inode, block_buf, bp, level,
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start, count, num);
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if (retval)
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goto errout;
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if (count > max)
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count -= max - start;
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else
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break;
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start = 0;
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} else
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start -= max;
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bp += num;
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if (level == 0) {
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num = 1;
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max = 1;
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}
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}
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retval = 0;
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errout:
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if (buf)
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ext2fs_free_mem(&buf);
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return retval;
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}
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#ifdef PUNCH_DEBUG
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#define dbg_printf(f, a...) printf(f, ## a)
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static void dbg_print_extent(char *desc, struct ext2fs_extent *extent)
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{
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if (desc)
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printf("%s: ", desc);
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printf("extent: lblk %llu--%llu, len %u, pblk %llu, flags: ",
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extent->e_lblk, extent->e_lblk + extent->e_len - 1,
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extent->e_len, extent->e_pblk);
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if (extent->e_flags & EXT2_EXTENT_FLAGS_LEAF)
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fputs("LEAF ", stdout);
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if (extent->e_flags & EXT2_EXTENT_FLAGS_UNINIT)
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fputs("UNINIT ", stdout);
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if (extent->e_flags & EXT2_EXTENT_FLAGS_SECOND_VISIT)
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fputs("2ND_VISIT ", stdout);
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if (!extent->e_flags)
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fputs("(none)", stdout);
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fputc('\n', stdout);
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}
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#else
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#define dbg_print_extent(desc, ex) do { } while (0)
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#define dbg_printf(f, a...) do { } while (0)
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#endif
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static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino,
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struct ext2_inode *inode,
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blk64_t start, blk64_t end)
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{
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ext2_extent_handle_t handle = 0;
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struct ext2fs_extent extent;
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errcode_t retval;
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blk64_t free_start, next;
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__u32 free_count, newlen;
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int freed = 0;
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retval = ext2fs_extent_open2(fs, ino, inode, &handle);
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if (retval)
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return retval;
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ext2fs_extent_goto(handle, start);
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retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
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if (retval)
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goto errout;
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while (1) {
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dbg_print_extent("main loop", &extent);
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next = extent.e_lblk + extent.e_len;
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dbg_printf("start %llu, end %llu, next %llu\n",
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(unsigned long long) start,
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(unsigned long long) end,
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(unsigned long long) next);
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if (start <= extent.e_lblk) {
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if (end < extent.e_lblk)
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goto next_extent;
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2011-07-07 21:50:22 +04:00
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dbg_printf("Case #%d\n", 1);
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2010-07-22 17:37:35 +04:00
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/* Start of deleted region before extent;
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adjust beginning of extent */
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free_start = extent.e_pblk;
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if (next > end)
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free_count = end - extent.e_lblk + 1;
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else
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free_count = extent.e_len;
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extent.e_len -= free_count;
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extent.e_lblk += free_count;
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extent.e_pblk += free_count;
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} else if (end >= next-1) {
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if (start >= next)
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break;
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/* End of deleted region after extent;
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adjust end of extent */
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2011-07-07 21:50:22 +04:00
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dbg_printf("Case #%d\n", 2);
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2010-07-22 17:37:35 +04:00
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newlen = start - extent.e_lblk;
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free_start = extent.e_pblk + newlen;
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free_count = extent.e_len - newlen;
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extent.e_len = newlen;
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} else {
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struct ext2fs_extent newex;
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2011-07-07 21:50:22 +04:00
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dbg_printf("Case #%d\n", 3);
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2010-07-22 17:37:35 +04:00
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/* The hard case; we need to split the extent */
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newex.e_pblk = extent.e_pblk +
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(end + 1 - extent.e_lblk);
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newex.e_lblk = end + 1;
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newex.e_len = next - end - 1;
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newex.e_flags = extent.e_flags;
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extent.e_len = start - extent.e_lblk;
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free_start = extent.e_pblk + extent.e_len;
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free_count = end - start + 1;
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dbg_print_extent("inserting", &newex);
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retval = ext2fs_extent_insert(handle,
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EXT2_EXTENT_INSERT_AFTER, &newex);
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if (retval)
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goto errout;
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/* Now pointing at inserted extent; so go back */
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retval = ext2fs_extent_get(handle,
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EXT2_EXTENT_PREV_LEAF,
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&newex);
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if (retval)
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goto errout;
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}
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if (extent.e_len) {
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dbg_print_extent("replacing", &extent);
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retval = ext2fs_extent_replace(handle, 0, &extent);
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} else {
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2011-07-07 21:50:22 +04:00
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dbg_printf("deleting current extent%s\n", "");
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2010-07-22 17:37:35 +04:00
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retval = ext2fs_extent_delete(handle, 0);
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}
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if (retval)
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goto errout;
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dbg_printf("Free start %llu, free count = %u\n",
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free_start, free_count);
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while (free_count-- > 0) {
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ext2fs_block_alloc_stats(fs, free_start++, -1);
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freed++;
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}
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next_extent:
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retval = ext2fs_extent_get(handle, EXT2_EXTENT_NEXT_LEAF,
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&extent);
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if (retval == EXT2_ET_EXTENT_NO_NEXT)
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break;
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if (retval)
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goto errout;
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}
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dbg_printf("Freed %d blocks\n", freed);
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retval = ext2fs_iblk_sub_blocks(fs, inode, freed);
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errout:
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ext2fs_extent_free(handle);
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return retval;
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}
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/*
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* Deallocate all logical blocks starting at start to end, inclusive.
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* If end is ~0, then this is effectively truncate.
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*/
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extern errcode_t ext2fs_punch(ext2_filsys fs, ext2_ino_t ino,
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struct ext2_inode *inode,
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char *block_buf, blk64_t start,
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blk64_t end)
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{
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errcode_t retval;
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struct ext2_inode inode_buf;
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if (start > end)
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return EINVAL;
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if (start == end)
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return 0;
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/* Read inode structure if necessary */
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if (!inode) {
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retval = ext2fs_read_inode(fs, ino, &inode_buf);
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if (retval)
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return retval;
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inode = &inode_buf;
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}
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if (inode->i_flags & EXT4_EXTENTS_FL)
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retval = ext2fs_punch_extent(fs, ino, inode, start, end);
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else {
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blk_t count;
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if (start > ~0U)
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return 0;
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count = ((end - start) < ~0U) ? (end - start) : ~0U;
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retval = ext2fs_punch_ind(fs, inode, block_buf,
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(blk_t) start, count);
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}
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if (retval)
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return retval;
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return ext2fs_write_inode(fs, ino, inode);
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}
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