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lvm2/lib/device/dev-io.c

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/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License v.2.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "lib.h"
#include "lvm-types.h"
#include "device.h"
#include "metadata.h"
#include "lvmcache.h"
#include "memlock.h"
#include "locking.h"
#include <limits.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#ifdef linux
# define u64 uint64_t /* Missing without __KERNEL__ */
# undef WNOHANG /* Avoid redefinition */
# undef WUNTRACED /* Avoid redefinition */
# include <linux/fs.h> /* For block ioctl definitions */
# define BLKSIZE_SHIFT SECTOR_SHIFT
# ifndef BLKGETSIZE64 /* fs.h out-of-date */
# define BLKGETSIZE64 _IOR(0x12, 114, size_t)
# endif /* BLKGETSIZE64 */
#else
# include <sys/disk.h>
# define BLKBSZGET DKIOCGETBLOCKSIZE
# define BLKSSZGET DKIOCGETBLOCKSIZE
# define BLKGETSIZE64 DKIOCGETBLOCKCOUNT
# define BLKFLSBUF DKIOCSYNCHRONIZECACHE
# define BLKSIZE_SHIFT 0
#endif
#ifdef O_DIRECT_SUPPORT
# ifndef O_DIRECT
# error O_DIRECT support configured but O_DIRECT definition not found in headers
# endif
#endif
static LIST_INIT(_open_devices);
/*-----------------------------------------------------------------
* The standard io loop that keeps submitting an io until it's
* all gone.
*---------------------------------------------------------------*/
static int _io(struct device_area *where, void *buffer, int should_write)
{
int fd = dev_fd(where->dev);
ssize_t n = 0;
size_t total = 0;
if (fd < 0) {
log_error("Attempt to read an unopened device (%s).",
dev_name(where->dev));
return 0;
}
/*
* Skip all writes in test mode.
*/
if (should_write && test_mode())
return 1;
if (where->size > SSIZE_MAX) {
log_error("Read size too large: %" PRIu64, where->size);
return 0;
}
if (lseek(fd, (off_t) where->start, SEEK_SET) < 0) {
log_error("%s: lseek %" PRIu64 " failed: %s",
dev_name(where->dev), (uint64_t) where->start,
strerror(errno));
return 0;
}
while (total < (size_t) where->size) {
do
n = should_write ?
write(fd, buffer, (size_t) where->size - total) :
read(fd, buffer, (size_t) where->size - total);
while ((n < 0) && ((errno == EINTR) || (errno == EAGAIN)));
if (n < 0)
log_error("%s: %s failed after %" PRIu64 " of %" PRIu64
" at %" PRIu64 ": %s", dev_name(where->dev),
should_write ? "write" : "read",
(uint64_t) total,
(uint64_t) where->size,
(uint64_t) where->start, strerror(errno));
if (n <= 0)
break;
total += n;
buffer += n;
}
return (total == (size_t) where->size);
}
/*-----------------------------------------------------------------
* LVM2 uses O_DIRECT when performing metadata io, which requires
* block size aligned accesses. If any io is not aligned we have
* to perform the io via a bounce buffer, obviously this is quite
* inefficient.
*---------------------------------------------------------------*/
/*
* Get the sector size from an _open_ device.
*/
static int _get_block_size(struct device *dev, unsigned int *size)
{
const char *name = dev_name(dev);
if ((dev->block_size == -1)) {
if (ioctl(dev_fd(dev), BLKBSZGET, &dev->block_size) < 0) {
log_sys_error("ioctl BLKBSZGET", name);
return 0;
}
log_debug("%s: block size is %u bytes", name, dev->block_size);
}
*size = (unsigned int) dev->block_size;
return 1;
}
/*
* Widens a region to be an aligned region.
*/
static void _widen_region(unsigned int block_size, struct device_area *region,
struct device_area *result)
{
uint64_t mask = block_size - 1, delta;
memcpy(result, region, sizeof(*result));
/* adjust the start */
delta = result->start & mask;
if (delta) {
result->start -= delta;
result->size += delta;
}
/* adjust the end */
delta = (result->start + result->size) & mask;
if (delta)
result->size += block_size - delta;
}
static int _aligned_io(struct device_area *where, void *buffer,
int should_write)
{
void *bounce;
unsigned int block_size = 0;
uintptr_t mask;
struct device_area widened;
if (!(where->dev->flags & DEV_REGULAR) &&
!_get_block_size(where->dev, &block_size)) {
stack;
return 0;
}
if (!block_size)
block_size = getpagesize();
_widen_region(block_size, where, &widened);
/* Do we need to use a bounce buffer? */
mask = block_size - 1;
if (!memcmp(where, &widened, sizeof(widened)) &&
!((uintptr_t) buffer & mask))
return _io(where, buffer, should_write);
/* Allocate a bounce buffer with an extra block */
if (!(bounce = alloca((size_t) widened.size + block_size))) {
log_error("Bounce buffer alloca failed");
return 0;
}
/*
* Realign start of bounce buffer (using the extra sector)
*/
if (((uintptr_t) bounce) & mask)
bounce = (void *) ((((uintptr_t) bounce) + mask) & ~mask);
/* channel the io through the bounce buffer */
if (!_io(&widened, bounce, 0)) {
if (!should_write) {
stack;
return 0;
}
/* FIXME pre-extend the file */
memset(bounce, '\n', widened.size);
}
if (should_write) {
memcpy(bounce + (where->start - widened.start), buffer,
(size_t) where->size);
/* ... then we write */
return _io(&widened, bounce, 1);
}
memcpy(buffer, bounce + (where->start - widened.start),
(size_t) where->size);
return 1;
}
static int _dev_get_size_file(const struct device *dev, uint64_t *size)
{
const char *name = dev_name(dev);
struct stat info;
if (stat(name, &info)) {
log_sys_error("stat", name);
return 0;
}
*size = info.st_size;
*size >>= SECTOR_SHIFT; /* Convert to sectors */
log_very_verbose("%s: size is %" PRIu64 " sectors", name, *size);
return 1;
}
static int _dev_get_size_dev(const struct device *dev, uint64_t *size)
{
int fd;
const char *name = dev_name(dev);
if ((fd = open(name, O_RDONLY)) < 0) {
log_sys_error("open", name);
return 0;
}
if (ioctl(fd, BLKGETSIZE64, size) < 0) {
log_sys_error("ioctl BLKGETSIZE64", name);
if (close(fd))
log_sys_error("close", name);
return 0;
}
*size >>= BLKSIZE_SHIFT; /* Convert to sectors */
if (close(fd))
log_sys_error("close", name);
log_very_verbose("%s: size is %" PRIu64 " sectors", name, *size);
return 1;
}
/*-----------------------------------------------------------------
* Public functions
*---------------------------------------------------------------*/
int dev_get_size(const struct device *dev, uint64_t *size)
{
if ((dev->flags & DEV_REGULAR))
return _dev_get_size_file(dev, size);
else
return _dev_get_size_dev(dev, size);
}
/* FIXME Unused
int dev_get_sectsize(struct device *dev, uint32_t *size)
{
int fd;
int s;
const char *name = dev_name(dev);
if ((fd = open(name, O_RDONLY)) < 0) {
log_sys_error("open", name);
return 0;
}
if (ioctl(fd, BLKSSZGET, &s) < 0) {
log_sys_error("ioctl BLKSSZGET", name);
close(fd);
return 0;
}
close(fd);
*size = (uint32_t) s;
log_very_verbose("%s: sector size is %" PRIu32 " bytes", name, *size);
return 1;
}
*/
void dev_flush(struct device *dev)
{
if (!(dev->flags & DEV_REGULAR) && ioctl(dev->fd, BLKFLSBUF, 0) >= 0)
return;
if (fsync(dev->fd) >= 0)
return;
sync();
}
int dev_open_flags(struct device *dev, int flags, int direct, int quiet)
{
struct stat buf;
const char *name;
int need_excl = 0, need_rw = 0;
if ((flags & O_ACCMODE) == O_RDWR)
need_rw = 1;
if ((flags & O_EXCL))
need_excl = 1;
if (dev->fd >= 0) {
if (((dev->flags & DEV_OPENED_RW) || !need_rw) &&
((dev->flags & DEV_OPENED_EXCL) || !need_excl)) {
dev->open_count++;
return 1;
}
if (dev->open_count && !need_excl) {
/* FIXME Ensure we never get here */
log_debug("WARNING: %s already opened read-only",
dev_name(dev));
dev->open_count++;
}
dev_close_immediate(dev);
}
if (memlock())
log_error("WARNING: dev_open(%s) called while suspended",
dev_name(dev));
if (dev->flags & DEV_REGULAR)
name = dev_name(dev);
else if (!(name = dev_name_confirmed(dev, quiet))) {
stack;
return 0;
}
if (!(dev->flags & DEV_REGULAR) &&
((stat(name, &buf) < 0) || (buf.st_rdev != dev->dev))) {
log_error("%s: stat failed: Has device name changed?", name);
return 0;
}
#ifdef O_DIRECT_SUPPORT
if (direct) {
if (!(dev->flags & DEV_O_DIRECT_TESTED))
dev->flags |= DEV_O_DIRECT;
if ((dev->flags & DEV_O_DIRECT))
flags |= O_DIRECT;
}
#endif
#ifdef O_NOATIME
/* Don't update atime on device inodes */
if (!(dev->flags & DEV_REGULAR))
flags |= O_NOATIME;
#endif
if ((dev->fd = open(name, flags, 0777)) < 0) {
#ifdef O_DIRECT_SUPPORT
if (direct && !(dev->flags & DEV_O_DIRECT_TESTED)) {
flags &= ~O_DIRECT;
if ((dev->fd = open(name, flags, 0777)) >= 0) {
dev->flags &= ~DEV_O_DIRECT;
log_debug("%s: Not using O_DIRECT", name);
goto opened;
}
}
#endif
if (quiet)
log_sys_debug("open", name);
else
log_sys_error("open", name);
return 0;
}
#ifdef O_DIRECT_SUPPORT
opened:
if (direct)
dev->flags |= DEV_O_DIRECT_TESTED;
#endif
dev->open_count++;
dev->flags &= ~DEV_ACCESSED_W;
if (need_rw)
dev->flags |= DEV_OPENED_RW;
else
dev->flags &= ~DEV_OPENED_RW;
if (need_excl)
dev->flags |= DEV_OPENED_EXCL;
else
dev->flags &= ~DEV_OPENED_EXCL;
if (!(dev->flags & DEV_REGULAR) &&
((fstat(dev->fd, &buf) < 0) || (buf.st_rdev != dev->dev))) {
log_error("%s: fstat failed: Has device name changed?", name);
dev_close_immediate(dev);
dev->open_count = 0;
return 0;
}
#ifndef O_DIRECT_SUPPORT
if (!(dev->flags & DEV_REGULAR))
dev_flush(dev);
#endif
if ((flags & O_CREAT) && !(flags & O_TRUNC))
dev->end = lseek(dev->fd, (off_t) 0, SEEK_END);
list_add(&_open_devices, &dev->open_list);
log_debug("Opened %s %s%s%s", dev_name(dev),
dev->flags & DEV_OPENED_RW ? "RW" : "RO",
dev->flags & DEV_OPENED_EXCL ? " O_EXCL" : "",
dev->flags & DEV_O_DIRECT ? " O_DIRECT" : "");
return 1;
}
int dev_open_quiet(struct device *dev)
{
int flags;
flags = vg_write_lock_held() ? O_RDWR : O_RDONLY;
return dev_open_flags(dev, flags, 1, 1);
}
int dev_open(struct device *dev)
{
int flags;
flags = vg_write_lock_held() ? O_RDWR : O_RDONLY;
return dev_open_flags(dev, flags, 1, 0);
}
int dev_test_excl(struct device *dev)
{
int flags;
int r;
flags = vg_write_lock_held() ? O_RDWR : O_RDONLY;
flags |= O_EXCL;
r = dev_open_flags(dev, flags, 1, 1);
if (r)
dev_close_immediate(dev);
return r;
}
static void _close(struct device *dev)
{
if (close(dev->fd))
log_sys_error("close", dev_name(dev));
dev->fd = -1;
dev->block_size = -1;
list_del(&dev->open_list);
log_debug("Closed %s", dev_name(dev));
if (dev->flags & DEV_ALLOCED) {
dm_free((void *) list_item(dev->aliases.n, struct str_list)->
str);
dm_free(dev->aliases.n);
dm_free(dev);
}
}
static int _dev_close(struct device *dev, int immediate)
{
struct lvmcache_info *info;
if (dev->fd < 0) {
log_error("Attempt to close device '%s' "
"which is not open.", dev_name(dev));
return 0;
}
#ifndef O_DIRECT_SUPPORT
if (dev->flags & DEV_ACCESSED_W)
dev_flush(dev);
#endif
if (dev->open_count > 0)
dev->open_count--;
if (immediate && dev->open_count) {
log_debug("%s: Immediate close attempt while still referenced",
dev_name(dev));
dev->open_count = 0;
}
/* Close unless device is known to belong to a locked VG */
if (immediate ||
(dev->open_count < 1 &&
(!(info = info_from_pvid(dev->pvid)) ||
!info->vginfo ||
!vgname_is_locked(info->vginfo->vgname))))
_close(dev);
return 1;
}
int dev_close(struct device *dev)
{
return _dev_close(dev, 0);
}
int dev_close_immediate(struct device *dev)
{
return _dev_close(dev, 1);
}
void dev_close_all(void)
{
struct list *doh, *doht;
struct device *dev;
list_iterate_safe(doh, doht, &_open_devices) {
dev = list_struct_base(doh, struct device, open_list);
if (dev->open_count < 1)
_close(dev);
}
}
int dev_read(struct device *dev, uint64_t offset, size_t len, void *buffer)
{
struct device_area where;
if (!dev->open_count) {
stack;
return 0;
}
where.dev = dev;
where.start = offset;
where.size = len;
return _aligned_io(&where, buffer, 0);
}
/* FIXME If O_DIRECT can't extend file, dev_extend first; dev_truncate after.
* But fails if concurrent processes writing
*/
/* FIXME pre-extend the file */
int dev_append(struct device *dev, size_t len, void *buffer)
{
int r;
if (!dev->open_count) {
stack;
return 0;
}
r = dev_write(dev, dev->end, len, buffer);
dev->end += (uint64_t) len;
#ifndef O_DIRECT_SUPPORT
dev_flush(dev);
#endif
return r;
}
int dev_write(struct device *dev, uint64_t offset, size_t len, void *buffer)
{
struct device_area where;
if (!dev->open_count) {
stack;
return 0;
}
where.dev = dev;
where.start = offset;
where.size = len;
dev->flags |= DEV_ACCESSED_W;
return _aligned_io(&where, buffer, 1);
}
int dev_zero(struct device *dev, uint64_t offset, size_t len)
{
size_t s;
char buffer[4096];
if (!dev_open(dev)) {
stack;
return 0;
}
if ((offset % SECTOR_SIZE) || (len % SECTOR_SIZE))
log_debug("Wiping %s at %" PRIu64 " length %" PRIsize_t,
dev_name(dev), offset, len);
else
log_debug("Wiping %s at sector %" PRIu64 " length %" PRIsize_t
" sectors", dev_name(dev), offset >> SECTOR_SHIFT,
len >> SECTOR_SHIFT);
memset(buffer, 0, sizeof(buffer));
while (1) {
s = len > sizeof(buffer) ? sizeof(buffer) : len;
if (!dev_write(dev, offset, s, buffer))
break;
len -= s;
if (!len)
break;
offset += s;
}
dev->flags |= DEV_ACCESSED_W;
if (!dev_close(dev))
stack;
return (len == 0);
}
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