510 lines
13 KiB
C
510 lines
13 KiB
C
/*
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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 "config.h"
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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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#include "ext2fsP.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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blk64_t start, blk64_t count, int max)
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{
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errcode_t retval;
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blk_t b;
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int i;
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blk64_t offset, 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 %llu, count %llu, "
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"max %d\n", level, start, count, max);
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#endif
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incr = 1ULL << ((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 >= start + 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 %llu)\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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#define BLK_T_MAX ((blk_t)~0ULL)
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static errcode_t ext2fs_punch_ind(ext2_filsys fs, struct ext2_inode *inode,
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char *block_buf, blk64_t start, blk64_t end)
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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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blk64_t max = EXT2_NDIR_BLOCKS;
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blk_t count;
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/* Check start/end don't overflow the 2^32-1 indirect block limit */
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if (start > BLK_T_MAX)
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return 0;
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if (end >= BLK_T_MAX || end - start + 1 >= BLK_T_MAX)
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count = BLK_T_MAX - start;
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else
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count = end - start + 1;
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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 *= (blk64_t)addr_per_block) {
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#ifdef PUNCH_DEBUG
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printf("Main loop level %d, start %llu count %u "
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"max %llu 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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#undef BLK_T_MAX
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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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/* Free a range of blocks, respecting cluster boundaries */
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static errcode_t punch_extent_blocks(ext2_filsys fs, ext2_ino_t ino,
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struct ext2_inode *inode,
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blk64_t lfree_start, blk64_t free_start,
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__u32 free_count, int *freed)
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{
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blk64_t pblk;
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int freed_now = 0;
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__u32 cluster_freed;
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errcode_t retval = 0;
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/* No bigalloc? Just free each block. */
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if (EXT2FS_CLUSTER_RATIO(fs) == 1) {
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*freed += free_count;
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while (free_count-- > 0)
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ext2fs_block_alloc_stats2(fs, free_start++, -1);
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return retval;
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}
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/*
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* Try to free up to the next cluster boundary. We assume that all
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* blocks in a logical cluster map to blocks from the same physical
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* cluster, and that the offsets within the [pl]clusters match.
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*/
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if (free_start & EXT2FS_CLUSTER_MASK(fs)) {
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retval = ext2fs_map_cluster_block(fs, ino, inode,
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lfree_start, &pblk);
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if (retval)
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goto errout;
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if (!pblk) {
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ext2fs_block_alloc_stats2(fs, free_start, -1);
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freed_now++;
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}
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cluster_freed = EXT2FS_CLUSTER_RATIO(fs) -
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(free_start & EXT2FS_CLUSTER_MASK(fs));
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if (cluster_freed > free_count)
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cluster_freed = free_count;
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free_count -= cluster_freed;
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free_start += cluster_freed;
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lfree_start += cluster_freed;
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}
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/* Free whole clusters from the middle of the range. */
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while (free_count > 0 && free_count >= (unsigned) EXT2FS_CLUSTER_RATIO(fs)) {
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ext2fs_block_alloc_stats2(fs, free_start, -1);
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freed_now++;
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cluster_freed = EXT2FS_CLUSTER_RATIO(fs);
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free_count -= cluster_freed;
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free_start += cluster_freed;
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lfree_start += cluster_freed;
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}
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/* Try to free the last cluster. */
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if (free_count > 0) {
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retval = ext2fs_map_cluster_block(fs, ino, inode,
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lfree_start, &pblk);
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if (retval)
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goto errout;
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if (!pblk) {
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ext2fs_block_alloc_stats2(fs, free_start, -1);
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freed_now++;
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}
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}
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errout:
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*freed += freed_now;
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return retval;
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}
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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, lfree_start;
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__u32 free_count, newlen;
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int freed = 0;
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int op;
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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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/*
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* Find the extent closest to the start of the punch range. We don't
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* check the return value because _goto() sets the current node to the
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* next-lowest extent if 'start' is in a hole, and doesn't set a
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* current node if there was a real error reading the extent tree.
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* In that case, _get() will error out.
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*
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* Note: If _get() returns 'no current node', that simply means that
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* there aren't any blocks mapped past this point in the file, so we're
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* done.
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*/
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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 == EXT2_ET_NO_CURRENT_NODE) {
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retval = 0;
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goto errout;
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} else if (retval)
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goto errout;
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while (1) {
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op = EXT2_EXTENT_NEXT_LEAF;
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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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/*
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* Have we iterated past the end of the punch region?
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* If so, we can stop.
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*/
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if (end < extent.e_lblk)
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break;
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dbg_printf("Case #%d\n", 1);
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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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lfree_start = extent.e_lblk;
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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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/*
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* Is the punch region beyond this extent? This can
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* happen if start is already inside a hole. Try to
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* advance to the next extent if this is the case.
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*/
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if (start >= next)
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goto next_extent;
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/* End of deleted region after extent;
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adjust end of extent */
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dbg_printf("Case #%d\n", 2);
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newlen = start - extent.e_lblk;
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free_start = extent.e_pblk + newlen;
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lfree_start = extent.e_lblk + 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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dbg_printf("Case #%d\n", 3);
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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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lfree_start = extent.e_lblk + 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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retval = ext2fs_extent_fix_parents(handle);
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if (retval)
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goto errout;
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/*
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* Now pointing at inserted extent; so go back.
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*
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* We cannot use EXT2_EXTENT_PREV to go back; note the
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* subtlety in the comment for fix_parents().
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*/
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retval = ext2fs_extent_goto(handle, extent.e_lblk);
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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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if (retval)
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goto errout;
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retval = ext2fs_extent_fix_parents(handle);
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} else {
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struct ext2fs_extent newex;
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blk64_t old_lblk, next_lblk;
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dbg_printf("deleting current extent%s\n", "");
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/*
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* Save the location of the next leaf, then slip
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* back to the current extent.
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*/
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retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT,
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&newex);
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if (retval)
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goto errout;
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old_lblk = newex.e_lblk;
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retval = ext2fs_extent_get(handle,
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EXT2_EXTENT_NEXT_LEAF,
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&newex);
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if (retval == EXT2_ET_EXTENT_NO_NEXT)
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next_lblk = old_lblk;
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else if (retval)
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goto errout;
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else
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next_lblk = newex.e_lblk;
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retval = ext2fs_extent_goto(handle, old_lblk);
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if (retval)
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goto errout;
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/* Now delete the extent. */
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retval = ext2fs_extent_delete(handle, 0);
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if (retval)
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goto errout;
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retval = ext2fs_extent_fix_parents(handle);
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if (retval && retval != EXT2_ET_NO_CURRENT_NODE)
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goto errout;
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retval = 0;
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/*
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* Jump forward to the next extent. If there are
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* errors, the ext2fs_extent_get down below will
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* capture them for us.
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*/
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(void)ext2fs_extent_goto(handle, next_lblk);
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op = EXT2_EXTENT_CURRENT;
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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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retval = punch_extent_blocks(fs, ino, inode, lfree_start,
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free_start, free_count, &freed);
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if (retval)
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goto errout;
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next_extent:
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retval = ext2fs_extent_get(handle, op,
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&extent);
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if (retval == EXT2_ET_EXTENT_NO_NEXT ||
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retval == EXT2_ET_NO_CURRENT_NODE)
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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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static errcode_t ext2fs_punch_inline_data(ext2_filsys fs, ext2_ino_t ino,
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struct ext2_inode *inode,
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blk64_t start,
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blk64_t end EXT2FS_ATTR((unused)))
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{
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errcode_t retval;
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/*
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* In libext2fs ext2fs_punch is based on block unit. So that
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* means that if start > 0 we don't need to do nothing. Due
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* to this we will remove all inline data in ext2fs_punch()
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* now.
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*/
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if (start > 0)
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return 0;
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memset((char *)inode->i_block, 0, EXT4_MIN_INLINE_DATA_SIZE);
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inode->i_size = 0;
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retval = ext2fs_write_inode(fs, ino, inode);
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if (retval)
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return retval;
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return ext2fs_inline_data_ea_remove(fs, ino);
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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 ~0ULL, then this is effectively truncate.
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*/
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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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/* 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_INLINE_DATA_FL)
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return ext2fs_punch_inline_data(fs, ino, inode, start, end);
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else if (inode->i_flags & EXT4_EXTENTS_FL)
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retval = ext2fs_punch_extent(fs, ino, inode, start, end);
|
|
else
|
|
retval = ext2fs_punch_ind(fs, inode, block_buf, start, end);
|
|
if (retval)
|
|
return retval;
|
|
|
|
#ifdef PUNCH_DEBUG
|
|
printf("%u: write inode size now %lu blocks %u\n",
|
|
ino, EXT2_I_SIZE(inode), inode->i_blocks);
|
|
#endif
|
|
return ext2fs_write_inode(fs, ino, inode);
|
|
}
|