qemu/hw/block/hd-geometry.c
Kevin Wolf 421919d76b block: Remove blk_pread_unthrottled()
The functionality offered by blk_pread_unthrottled() goes back to commit
498e386c58. Then, we couldn't perform I/O throttling with synchronous
requests because timers wouldn't be executed in polling loops. So the
commit automatically disabled I/O throttling as soon as a synchronous
request was issued.

However, for geometry detection during disk initialisation, we always
used (and still use) synchronous requests even if guest requests use AIO
later. Geometry detection was not wanted to disable I/O throttling, so
bdrv_pread_unthrottled() was introduced which disabled throttling only
temporarily.

All of this isn't necessary any more because we do run timers in polling
loop and even synchronous requests are now using coroutine
infrastructure internally. For this reason, commit 90c78624f already
removed the automatic disabling of I/O throttling.

It's time to get rid of the workaround for the removed code, and its
abuse of blk_root_drained_begin()/end(), as well.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
2019-08-16 10:25:16 +02:00

164 lines
5.7 KiB
C

/*
* Hard disk geometry utilities
*
* Copyright (C) 2012 Red Hat, Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
* This file incorporates work covered by the following copyright and
* permission notice:
*
* Copyright (c) 2003 Fabrice Bellard
*
* 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 "sysemu/block-backend.h"
#include "qapi/qapi-types-block.h"
#include "qemu/bswap.h"
#include "hw/block/block.h"
#include "trace.h"
struct partition {
uint8_t boot_ind; /* 0x80 - active */
uint8_t head; /* starting head */
uint8_t sector; /* starting sector */
uint8_t cyl; /* starting cylinder */
uint8_t sys_ind; /* What partition type */
uint8_t end_head; /* end head */
uint8_t end_sector; /* end sector */
uint8_t end_cyl; /* end cylinder */
uint32_t start_sect; /* starting sector counting from 0 */
uint32_t nr_sects; /* nr of sectors in partition */
} QEMU_PACKED;
/* try to guess the disk logical geometry from the MSDOS partition table.
Return 0 if OK, -1 if could not guess */
static int guess_disk_lchs(BlockBackend *blk,
int *pcylinders, int *pheads, int *psectors)
{
uint8_t buf[BDRV_SECTOR_SIZE];
int i, heads, sectors, cylinders;
struct partition *p;
uint32_t nr_sects;
uint64_t nb_sectors;
blk_get_geometry(blk, &nb_sectors);
if (blk_pread(blk, 0, buf, BDRV_SECTOR_SIZE) < 0) {
return -1;
}
/* test msdos magic */
if (buf[510] != 0x55 || buf[511] != 0xaa) {
return -1;
}
for (i = 0; i < 4; i++) {
p = ((struct partition *)(buf + 0x1be)) + i;
nr_sects = le32_to_cpu(p->nr_sects);
if (nr_sects && p->end_head) {
/* We make the assumption that the partition terminates on
a cylinder boundary */
heads = p->end_head + 1;
sectors = p->end_sector & 63;
if (sectors == 0) {
continue;
}
cylinders = nb_sectors / (heads * sectors);
if (cylinders < 1 || cylinders > 16383) {
continue;
}
*pheads = heads;
*psectors = sectors;
*pcylinders = cylinders;
trace_hd_geometry_lchs_guess(blk, cylinders, heads, sectors);
return 0;
}
}
return -1;
}
static void guess_chs_for_size(BlockBackend *blk,
uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs)
{
uint64_t nb_sectors;
int cylinders;
blk_get_geometry(blk, &nb_sectors);
cylinders = nb_sectors / (16 * 63);
if (cylinders > 16383) {
cylinders = 16383;
} else if (cylinders < 2) {
cylinders = 2;
}
*pcyls = cylinders;
*pheads = 16;
*psecs = 63;
}
void hd_geometry_guess(BlockBackend *blk,
uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs,
int *ptrans)
{
int cylinders, heads, secs, translation;
HDGeometry geo;
/* Try to probe the backing device geometry, otherwise fallback
to the old logic. (as of 12/2014 probing only succeeds on DASDs) */
if (blk_probe_geometry(blk, &geo) == 0) {
*pcyls = geo.cylinders;
*psecs = geo.sectors;
*pheads = geo.heads;
translation = BIOS_ATA_TRANSLATION_NONE;
} else if (guess_disk_lchs(blk, &cylinders, &heads, &secs) < 0) {
/* no LCHS guess: use a standard physical disk geometry */
guess_chs_for_size(blk, pcyls, pheads, psecs);
translation = hd_bios_chs_auto_trans(*pcyls, *pheads, *psecs);
} else if (heads > 16) {
/* LCHS guess with heads > 16 means that a BIOS LBA
translation was active, so a standard physical disk
geometry is OK */
guess_chs_for_size(blk, pcyls, pheads, psecs);
translation = *pcyls * *pheads <= 131072
? BIOS_ATA_TRANSLATION_LARGE
: BIOS_ATA_TRANSLATION_LBA;
} else {
/* LCHS guess with heads <= 16: use as physical geometry */
*pcyls = cylinders;
*pheads = heads;
*psecs = secs;
/* disable any translation to be in sync with
the logical geometry */
translation = BIOS_ATA_TRANSLATION_NONE;
}
if (ptrans) {
*ptrans = translation;
}
trace_hd_geometry_guess(blk, *pcyls, *pheads, *psecs, translation);
}
int hd_bios_chs_auto_trans(uint32_t cyls, uint32_t heads, uint32_t secs)
{
return cyls <= 1024 && heads <= 16 && secs <= 63
? BIOS_ATA_TRANSLATION_NONE
: BIOS_ATA_TRANSLATION_LBA;
}