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lvm2/lib/device/dev-io.c
Peter Rajnoha c8591b2ac7 dev-io: open device read-only to obtain readahead value 
There's no need to have the device open RW while obtaining the readahead value.
The RW open used before caused the CHANGE udev event to be generated if the
WATCH udev rule was set for the underlying device (and that is normally the
case both for non-dm and dm devices by default).

This did not cause any problems before since we were not interested in
*underlying* devices. However, with upcoming changes (autoactivation), we're
watching for events on underlying devices marked as PVs and such a spurious
event could cause the autoactivation code to be triggered. So when trying
to deactivate the volume, we could end up with immediate activation just after
that because of the CHANGE event originated in the WATCH udev rule since the
underlying device was open RW during the deactivation process.

Though maybe a better solution would be to completely filter such spurious
events out of the autoactivation process somehow, it's still useful if there
are as least spurious events generated as possible in the system itself.
2012-06-25 11:55:37 +02:00

786 lines
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/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2012 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 Lesser General Public License v.2.1.
*
* You should have received a copy of the GNU Lesser 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# ifndef BLKGETSIZE64 /* fs.h out-of-date */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 */
# ifndef BLKDISCARD
# define BLKDISCARD _IO(0x12,119)
# endif
#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 DM_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, char *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_once("%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, char *buffer,
int should_write)
{
char *bounce, *bounce_buf;
unsigned int block_size = 0;
uintptr_t mask;
struct device_area widened;
int r = 0;
if (!(where->dev->flags & DEV_REGULAR) &&
!_get_block_size(where->dev, &block_size))
return_0;
if (!block_size)
block_size = lvm_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_buf = bounce = dm_malloc((size_t) widened.size + block_size))) {
log_error("Bounce buffer malloc failed");
return 0;
}
/*
* Realign start of bounce buffer (using the extra sector)
*/
if (((uintptr_t) bounce) & mask)
bounce = (char *) ((((uintptr_t) bounce) + mask) & ~mask);
/* channel the io through the bounce buffer */
if (!_io(&widened, bounce, 0)) {
if (!should_write)
goto_out;
/* 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 */
if (!(r = _io(&widened, bounce, 1)))
stack;
goto out;
}
memcpy(buffer, bounce + (where->start - widened.start),
(size_t) where->size);
r = 1;
out:
dm_free(bounce_buf);
return r;
}
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;
}
static int _dev_read_ahead_dev(struct device *dev, uint32_t *read_ahead)
{
long read_ahead_long;
if (dev->read_ahead != -1) {
*read_ahead = (uint32_t) dev->read_ahead;
return 1;
}
if (!dev_open_readonly(dev))
return_0;
if (ioctl(dev->fd, BLKRAGET, &read_ahead_long) < 0) {
log_sys_error("ioctl BLKRAGET", dev_name(dev));
if (!dev_close(dev))
stack;
return 0;
}
*read_ahead = (uint32_t) read_ahead_long;
dev->read_ahead = read_ahead_long;
log_very_verbose("%s: read_ahead is %u sectors",
dev_name(dev), *read_ahead);
if (!dev_close(dev))
stack;
return 1;
}
static int _dev_discard_blocks(struct device *dev, uint64_t offset_bytes, uint64_t size_bytes)
{
uint64_t discard_range[2];
if (!dev_open(dev))
return_0;
discard_range[0] = offset_bytes;
discard_range[1] = size_bytes;
log_debug("Discarding %" PRIu64 " bytes offset %" PRIu64 " bytes on %s.",
size_bytes, offset_bytes, dev_name(dev));
if (ioctl(dev->fd, BLKDISCARD, &discard_range) < 0) {
log_error("%s: BLKDISCARD ioctl at offset %" PRIu64 " size %" PRIu64 " failed: %s.",
dev_name(dev), offset_bytes, size_bytes, strerror(errno));
if (!dev_close(dev))
stack;
/* It doesn't matter if discard failed, so return success. */
return 1;
}
if (!dev_close(dev))
stack;
return 1;
}
/*-----------------------------------------------------------------
* Public functions
*---------------------------------------------------------------*/
int dev_get_size(const struct device *dev, uint64_t *size)
{
if (!dev)
return 0;
if ((dev->flags & DEV_REGULAR))
return _dev_get_size_file(dev, size);
else
return _dev_get_size_dev(dev, size);
}
int dev_get_read_ahead(struct device *dev, uint32_t *read_ahead)
{
if (!dev)
return 0;
if (dev->flags & DEV_REGULAR) {
*read_ahead = 0;
return 1;
}
return _dev_read_ahead_dev(dev, read_ahead);
}
int dev_discard_blocks(struct device *dev, uint64_t offset_bytes, uint64_t size_bytes)
{
if (!dev)
return 0;
if (dev->flags & DEV_REGULAR)
return 1;
return _dev_discard_blocks(dev, offset_bytes, size_bytes);
}
/* 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);
if (close(fd))
log_sys_error("close", name);
return 0;
}
if (close(fd))
log_sys_error("close", name);
*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) {
log_debug("%s already opened read-only. Upgrading "
"to read-write.", dev_name(dev));
dev->open_count++;
}
dev_close_immediate(dev);
}
if (critical_section())
/* FIXME Make this log_error */
log_verbose("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)))
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);
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);
dm_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)
{
return dev_open_flags(dev, O_RDWR, 1, 1);
}
int dev_open(struct device *dev)
{
return dev_open_flags(dev, O_RDWR, 1, 0);
}
int dev_open_readonly(struct device *dev)
{
return dev_open_flags(dev, O_RDONLY, 1, 0);
}
int dev_open_readonly_buffered(struct device *dev)
{
return dev_open_flags(dev, O_RDONLY, 0, 0);
}
int dev_open_readonly_quiet(struct device *dev)
{
return dev_open_flags(dev, O_RDONLY, 1, 1);
}
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;
dm_list_del(&dev->open_list);
log_debug("Closed %s", dev_name(dev));
if (dev->flags & DEV_ALLOCED) {
dm_free((void *) dm_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)
{
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));
/* Close unless device is known to belong to a locked VG */
if (immediate ||
(dev->open_count < 1 && !lvmcache_pvid_is_locked(dev->pvid)))
_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 dm_list *doh, *doht;
struct device *dev;
dm_list_iterate_safe(doh, doht, &_open_devices) {
dev = dm_list_struct_base(doh, struct device, open_list);
if (dev->open_count < 1)
_close(dev);
}
}
static inline int _dev_is_valid(struct device *dev)
{
return (dev->max_error_count == NO_DEV_ERROR_COUNT_LIMIT ||
dev->error_count < dev->max_error_count);
}
static void _dev_inc_error_count(struct device *dev)
{
if (++dev->error_count == dev->max_error_count)
log_warn("WARNING: Error counts reached a limit of %d. "
"Device %s was disabled",
dev->max_error_count, dev_name(dev));
}
int dev_read(struct device *dev, uint64_t offset, size_t len, void *buffer)
{
struct device_area where;
int ret;
if (!dev->open_count)
return_0;
if (!_dev_is_valid(dev))
return 0;
where.dev = dev;
where.start = offset;
where.size = len;
// fprintf(stderr, "READ: %s, %lld, %d\n", dev_name(dev), offset, len);
ret = _aligned_io(&where, buffer, 0);
if (!ret)
_dev_inc_error_count(dev);
return ret;
}
/*
* Read from 'dev' into 'buf', possibly in 2 distinct regions, denoted
* by (offset,len) and (offset2,len2). Thus, the total size of
* 'buf' should be len+len2.
*/
int dev_read_circular(struct device *dev, uint64_t offset, size_t len,
uint64_t offset2, size_t len2, char *buf)
{
if (!dev_read(dev, offset, len, buf)) {
log_error("Read from %s failed", dev_name(dev));
return 0;
}
/*
* The second region is optional, and allows for
* a circular buffer on the device.
*/
if (!len2)
return 1;
if (!dev_read(dev, offset2, len2, buf + len)) {
log_error("Circular read from %s failed",
dev_name(dev));
return 0;
}
return 1;
}
/* 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, char *buffer)
{
int r;
if (!dev->open_count)
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;
int ret;
if (!dev->open_count)
return_0;
if (!_dev_is_valid(dev))
return 0;
where.dev = dev;
where.start = offset;
where.size = len;
dev->flags |= DEV_ACCESSED_W;
ret = _aligned_io(&where, buffer, 1);
if (!ret)
_dev_inc_error_count(dev);
return ret;
}
int dev_set(struct device *dev, uint64_t offset, size_t len, int value)
{
size_t s;
char buffer[4096] __attribute__((aligned(8)));
if (!dev_open(dev))
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, value, 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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