qemu/block/bochs.c
Vladimir Sementsov-Ogievskiy f7ef38dd13 block: use int64_t instead of uint64_t in driver read handlers
We are generally moving to int64_t for both offset and bytes parameters
on all io paths.

Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.

We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).

So, convert driver read handlers parameters which are already 64bit to
signed type.

While being here, convert also flags parameter to be BdrvRequestFlags.

Now let's consider all callers. Simple

  git grep '\->bdrv_\(aio\|co\)_preadv\(_part\)\?'

shows that's there three callers of driver function:

 bdrv_driver_preadv() in block/io.c, passes int64_t, checked by
   bdrv_check_qiov_request() to be non-negative.

 qcow2_load_vmstate() does bdrv_check_qiov_request().

 do_perform_cow_read() has uint64_t argument. And a lot of things in
 qcow2 driver are uint64_t, so converting it is big job. But we must
 not work with requests that don't satisfy bdrv_check_qiov_request(),
 so let's just assert it here.

Still, the functions may be called directly, not only by drv->...
Let's check:

git grep '\.bdrv_\(aio\|co\)_preadv\(_part\)\?\s*=' | \
awk '{print $4}' | sed 's/,//' | sed 's/&//' | sort | uniq | \
while read func; do git grep "$func(" | \
grep -v "$func(BlockDriverState"; done

The only one such caller:

    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, &data, 1);
    ...
    ret = bdrv_replace_test_co_preadv(bs, 0, 1, &qiov, 0);

in tests/unit/test-bdrv-drain.c, and it's OK obviously.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-4-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: fix typos]
Signed-off-by: Eric Blake <eblake@redhat.com>
2021-09-29 13:46:31 -05:00

313 lines
9.3 KiB
C

/*
* Block driver for the various disk image formats used by Bochs
* Currently only for "growing" type in read-only mode
*
* Copyright (c) 2005 Alex Beregszaszi
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "block/block_int.h"
#include "qemu/module.h"
#include "qemu/bswap.h"
#include "qemu/error-report.h"
/**************************************************************/
#define HEADER_MAGIC "Bochs Virtual HD Image"
#define HEADER_VERSION 0x00020000
#define HEADER_V1 0x00010000
#define HEADER_SIZE 512
#define REDOLOG_TYPE "Redolog"
#define GROWING_TYPE "Growing"
// not allocated: 0xffffffff
// always little-endian
struct bochs_header {
char magic[32]; /* "Bochs Virtual HD Image" */
char type[16]; /* "Redolog" */
char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */
uint32_t version;
uint32_t header; /* size of header */
uint32_t catalog; /* num of entries */
uint32_t bitmap; /* bitmap size */
uint32_t extent; /* extent size */
union {
struct {
uint32_t reserved; /* for ??? */
uint64_t disk; /* disk size */
char padding[HEADER_SIZE - 64 - 20 - 12];
} QEMU_PACKED redolog;
struct {
uint64_t disk; /* disk size */
char padding[HEADER_SIZE - 64 - 20 - 8];
} QEMU_PACKED redolog_v1;
char padding[HEADER_SIZE - 64 - 20];
} extra;
} QEMU_PACKED;
typedef struct BDRVBochsState {
CoMutex lock;
uint32_t *catalog_bitmap;
uint32_t catalog_size;
uint32_t data_offset;
uint32_t bitmap_blocks;
uint32_t extent_blocks;
uint32_t extent_size;
} BDRVBochsState;
static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
{
const struct bochs_header *bochs = (const void *)buf;
if (buf_size < HEADER_SIZE)
return 0;
if (!strcmp(bochs->magic, HEADER_MAGIC) &&
!strcmp(bochs->type, REDOLOG_TYPE) &&
!strcmp(bochs->subtype, GROWING_TYPE) &&
((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
(le32_to_cpu(bochs->version) == HEADER_V1)))
return 100;
return 0;
}
static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVBochsState *s = bs->opaque;
uint32_t i;
struct bochs_header bochs;
int ret;
/* No write support yet */
ret = bdrv_apply_auto_read_only(bs, NULL, errp);
if (ret < 0) {
return ret;
}
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
BDRV_CHILD_IMAGE, false, errp);
if (!bs->file) {
return -EINVAL;
}
ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
if (ret < 0) {
return ret;
}
if (strcmp(bochs.magic, HEADER_MAGIC) ||
strcmp(bochs.type, REDOLOG_TYPE) ||
strcmp(bochs.subtype, GROWING_TYPE) ||
((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
(le32_to_cpu(bochs.version) != HEADER_V1))) {
error_setg(errp, "Image not in Bochs format");
return -EINVAL;
}
if (le32_to_cpu(bochs.version) == HEADER_V1) {
bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
} else {
bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
}
/* Limit to 1M entries to avoid unbounded allocation. This is what is
* needed for the largest image that bximage can create (~8 TB). */
s->catalog_size = le32_to_cpu(bochs.catalog);
if (s->catalog_size > 0x100000) {
error_setg(errp, "Catalog size is too large");
return -EFBIG;
}
s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
if (s->catalog_size && s->catalog_bitmap == NULL) {
error_setg(errp, "Could not allocate memory for catalog");
return -ENOMEM;
}
ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
s->catalog_size * 4);
if (ret < 0) {
goto fail;
}
for (i = 0; i < s->catalog_size; i++)
le32_to_cpus(&s->catalog_bitmap[i]);
s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
s->extent_size = le32_to_cpu(bochs.extent);
if (s->extent_size < BDRV_SECTOR_SIZE) {
/* bximage actually never creates extents smaller than 4k */
error_setg(errp, "Extent size must be at least 512");
ret = -EINVAL;
goto fail;
} else if (!is_power_of_2(s->extent_size)) {
error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
s->extent_size);
ret = -EINVAL;
goto fail;
} else if (s->extent_size > 0x800000) {
error_setg(errp, "Extent size %" PRIu32 " is too large",
s->extent_size);
ret = -EINVAL;
goto fail;
}
if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
s->extent_size / BDRV_SECTOR_SIZE))
{
error_setg(errp, "Catalog size is too small for this disk size");
ret = -EINVAL;
goto fail;
}
qemu_co_mutex_init(&s->lock);
return 0;
fail:
g_free(s->catalog_bitmap);
return ret;
}
static void bochs_refresh_limits(BlockDriverState *bs, Error **errp)
{
bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
}
static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
{
BDRVBochsState *s = bs->opaque;
uint64_t offset = sector_num * 512;
uint64_t extent_index, extent_offset, bitmap_offset;
char bitmap_entry;
int ret;
// seek to sector
extent_index = offset / s->extent_size;
extent_offset = (offset % s->extent_size) / 512;
if (s->catalog_bitmap[extent_index] == 0xffffffff) {
return 0; /* not allocated */
}
bitmap_offset = s->data_offset +
(512 * (uint64_t) s->catalog_bitmap[extent_index] *
(s->extent_blocks + s->bitmap_blocks));
/* read in bitmap for current extent */
ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
&bitmap_entry, 1);
if (ret < 0) {
return ret;
}
if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
return 0; /* not allocated */
}
return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
}
static int coroutine_fn
bochs_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, BdrvRequestFlags flags)
{
BDRVBochsState *s = bs->opaque;
uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
int nb_sectors = bytes >> BDRV_SECTOR_BITS;
uint64_t bytes_done = 0;
QEMUIOVector local_qiov;
int ret;
assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
qemu_iovec_init(&local_qiov, qiov->niov);
qemu_co_mutex_lock(&s->lock);
while (nb_sectors > 0) {
int64_t block_offset = seek_to_sector(bs, sector_num);
if (block_offset < 0) {
ret = block_offset;
goto fail;
}
qemu_iovec_reset(&local_qiov);
qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512);
if (block_offset > 0) {
ret = bdrv_co_preadv(bs->file, block_offset, 512,
&local_qiov, 0);
if (ret < 0) {
goto fail;
}
} else {
qemu_iovec_memset(&local_qiov, 0, 0, 512);
}
nb_sectors--;
sector_num++;
bytes_done += 512;
}
ret = 0;
fail:
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&local_qiov);
return ret;
}
static void bochs_close(BlockDriverState *bs)
{
BDRVBochsState *s = bs->opaque;
g_free(s->catalog_bitmap);
}
static BlockDriver bdrv_bochs = {
.format_name = "bochs",
.instance_size = sizeof(BDRVBochsState),
.bdrv_probe = bochs_probe,
.bdrv_open = bochs_open,
.bdrv_child_perm = bdrv_default_perms,
.bdrv_refresh_limits = bochs_refresh_limits,
.bdrv_co_preadv = bochs_co_preadv,
.bdrv_close = bochs_close,
.is_format = true,
};
static void bdrv_bochs_init(void)
{
bdrv_register(&bdrv_bochs);
}
block_init(bdrv_bochs_init);