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/*-
* Copyright (c) 2008-2012 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
static int __verify_addfrag(WT_SESSION_IMPL *, WT_BLOCK *, off_t, off_t);
static int __verify_checkfrag(WT_SESSION_IMPL *, WT_BLOCK *);
static int __verify_freelist(WT_SESSION_IMPL *, WT_BLOCK *);
/*
* __wt_block_verify_start --
* Start file verification.
*/
int
__wt_block_verify_start(WT_SESSION_IMPL *session, WT_BLOCK *block, int *emptyp)
{
off_t file_size;
file_size = block->fh->file_size;
/*
* We're done if the file has no data pages (this is what happens if
* we verify a file immediately after creation).
*/
if (file_size == WT_BLOCK_DESC_SECTOR) {
*emptyp = 1;
return (0);
}
*emptyp = 0;
/*
* The file size should be a multiple of the allocsize, offset by the
* size of the descriptor sector, the first 512B of the file.
*/
if (file_size > WT_BLOCK_DESC_SECTOR)
file_size -= WT_BLOCK_DESC_SECTOR;
if (file_size % block->allocsize != 0)
WT_RET_MSG(session, WT_ERROR,
"the file size is not a multiple of the allocation size");
/*
* Allocate a bit array, where each bit represents a single allocation
* size piece of the file (this is how we track the parts of the file
* we've verified, and check for multiply referenced or unreferenced
* blocks). Storing this on the heap seems reasonable, verifying a 1TB
* file with an 512B allocation size would require a 256MB bit array:
*
* (((1 * 2^40) / 512) / 8) = 256 * 2^20
*
* To verify larger files than we can handle in this way, we'd have to
* write parts of the bit array into a disk file.
*
* We also have a minimum maximum verifiable file size of 16TB because
* the underlying bit package takes a 32-bit count of bits to allocate:
*
* 2^32 * 512 * 8 = 16 * 2^40
*/
if (file_size / block->allocsize > UINT32_MAX)
WT_RET_MSG(
session, WT_ERROR, "the file is too large to verify");
block->frags = (uint32_t)(file_size / block->allocsize);
WT_RET(__bit_alloc(session, block->frags, &block->fragbits));
/* Verify the free-list. */
WT_RET(__verify_freelist(session, block));
return (0);
}
/*
* __wt_block_verify_end --
* End file verification.
*/
int
__wt_block_verify_end(WT_SESSION_IMPL *session, WT_BLOCK *block)
{
int ret;
/* Verify we read every file block. */
ret = __verify_checkfrag(session, block);
__wt_free(session, block->fragbits);
return (ret);
}
/*
* __wt_block_verify_addr --
* Verify an address.
*/
int
__wt_block_verify_addr(WT_SESSION_IMPL *session,
WT_BLOCK *block, const uint8_t *addr, uint32_t addr_size)
{
off_t offset;
uint32_t size;
WT_UNUSED(addr_size);
/* Crack the cookie. */
WT_RET(__wt_block_buffer_to_addr(block, addr, &offset, &size, NULL));
WT_RET(__verify_addfrag(session, block, offset, (off_t)size));
return (0);
}
/*
* __verify_freelist --
* Add the freelist fragments to the list of verified fragments.
*/
static int
__verify_freelist(WT_SESSION_IMPL *session, WT_BLOCK *block)
{
WT_EXT *ext;
int ret;
ret = 0;
WT_EXT_FOREACH(ext, block->free.off) {
if (ext->off + (off_t)ext->size > block->fh->file_size)
WT_RET_MSG(session, WT_ERROR,
"free-list entry offset %" PRIuMAX "references "
"non-existent file pages",
(uintmax_t)ext->off);
WT_VERBOSE(session, verify,
"free-list range %" PRIdMAX "-%" PRIdMAX,
(intmax_t)ext->off, (intmax_t)(ext->off + ext->size));
WT_TRET(__verify_addfrag(session, block, ext->off, ext->size));
}
return (ret);
}
/* The bit list ignores the first sector: convert to/from an frag/offset. */
#define WT_OFF_TO_FRAG(block, off) \
(((off) - WT_BLOCK_DESC_SECTOR) / (block)->allocsize)
#define WT_FRAG_TO_OFF(block, frag) \
(((off_t)(frag)) * (block)->allocsize + WT_BLOCK_DESC_SECTOR)
/*
* __verify_addfrag --
* Add the fragments to the list, and complain if we've already verified
* this chunk of the file.
*/
static int
__verify_addfrag(
WT_SESSION_IMPL *session, WT_BLOCK *block, off_t offset, off_t size)
{
uint32_t frag, frags, i;
frag = (uint32_t)WT_OFF_TO_FRAG(block, offset);
frags = (uint32_t)(size / block->allocsize);
for (i = 0; i < frags; ++i)
if (__bit_test(block->fragbits, frag + i))
WT_RET_MSG(session, WT_ERROR,
"file fragment at offset %" PRIuMAX
" already verified",
(uintmax_t)offset);
__bit_nset(block->fragbits, frag, frag + (frags - 1));
return (0);
}
/*
* __verify_checkfrag --
* Verify we've checked all the fragments in the file.
*/
static int
__verify_checkfrag(WT_SESSION_IMPL *session, WT_BLOCK *block)
{
uint32_t first, last, frags;
uint8_t *fragbits;
int ret;
fragbits = block->fragbits;
frags = block->frags;
ret = 0;
/*
* Check for file fragments we haven't verified -- every time we find
* a bit that's clear, complain. We re-start the search each time
* after setting the clear bit(s) we found: it's simpler and this isn't
* supposed to happen a lot.
*/
for (;;) {
if (__bit_ffc(fragbits, frags, &first) != 0)
break;
__bit_set(fragbits, first);
for (last = first + 1; last < frags; ++last) {
if (__bit_test(fragbits, last))
break;
__bit_set(fragbits, last);
}
__wt_errx(session,
"file range %" PRIuMAX "-%" PRIuMAX " was never verified",
(uintmax_t)WT_FRAG_TO_OFF(block, first),
(uintmax_t)WT_FRAG_TO_OFF(block, last));
ret = WT_ERROR;
}
return (ret);
}
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