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Use sysfs to set/get of read-ahead

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If we know major:minor number of device (which is known after resume) we will
try to use  sysfs to set/get read ahead parameters of device.
This avoid potential problem of blocking commands like 'dmsetup info' awaiting
for device being usable for open/close - i.e. overfilled thin pool may block
such command.
This commit is contained in:
Zdenek Kabelac 2012-01-09 12:26:14 +00:00
parent 51c8cf97af
commit 6cf41f5503
4 changed files with 115 additions and 27 deletions
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1
WHATS_NEW_DM
View File

@ -1,5 +1,6 @@
Version 1.02.68 -
==================================
Use sysfs to set/get of read-ahead setting if possible.
Fix lvm2-monitor init script to use normalized output when using vgs.
Add test for max length (DM_MAX_TYPE_NAME) of target type name.
Include a copy of kernel DM documentation in doc/kernel.

10
libdm/ioctl/libdm-iface.c
View File

@ -1,6 +1,6 @@
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2011 Red Hat, Inc. All rights reserved.
* Copyright (C) 2004-2012 Red Hat, Inc. All rights reserved.
*
* This file is part of the device-mapper userspace tools.
*
@ -665,7 +665,8 @@ uint32_t dm_task_get_read_ahead(const struct dm_task *dmt, uint32_t *read_ahead)
return 0;
}
return get_dev_node_read_ahead(dev_name, read_ahead);
return get_dev_node_read_ahead(dev_name, MAJOR(dmt->dmi.v4->dev),
MINOR(dmt->dmi.v4->dev), read_ahead);
}
const char *dm_task_get_name(const struct dm_task *dmt)
@ -1818,8 +1819,9 @@ repeat_ioctl:
MINOR(dmi->dev), dmt->uid, dmt->gid,
dmt->mode, check_udev, rely_on_udev);
/* FIXME Kernel needs to fill in dmi->name */
set_dev_node_read_ahead(dmt->dev_name, dmt->read_ahead,
dmt->read_ahead_flags);
set_dev_node_read_ahead(dmt->dev_name,
MAJOR(dmi->dev), MINOR(dmi->dev),
dmt->read_ahead, dmt->read_ahead_flags);
break;
case DM_DEVICE_MKNODES:

120
libdm/libdm-common.c
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@ -1,6 +1,6 @@
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
* Copyright (C) 2004-2012 Red Hat, Inc. All rights reserved.
*
* This file is part of the device-mapper userspace tools.
*
@ -59,6 +59,7 @@ union semun
static char _dm_dir[PATH_MAX] = DEV_DIR DM_DIR;
static char _sysfs_dir[PATH_MAX] = "/sys/";
static char _path0[PATH_MAX]; /* path buffer, safe 4kB on stack */
static int _verbose = 0;
static int _suspended_dev_counter = 0;
@ -658,12 +659,53 @@ static int _open_dev_node(const char *dev_name)
return fd;
}
int get_dev_node_read_ahead(const char *dev_name, uint32_t *read_ahead)
int get_dev_node_read_ahead(const char *dev_name, uint32_t major, uint32_t minor,
uint32_t *read_ahead)
{
char buf[24];
int len;
int r = 1;
int fd;
long read_ahead_long;
/*
* If we know the device number, use sysfs if we can.
* Otherwise use BLKRAGET ioctl.
*/
if (*_sysfs_dir && major != 0) {
if (dm_snprintf(_path0, sizeof(_path0), "%sdev/block/%" PRIu32
":%" PRIu32 "/bdi/read_ahead_kb", _sysfs_dir,
major, minor) < 0) {
log_error("Failed to build sysfs_path.");
return 0;
}
if ((fd = open(_path0, O_RDONLY, 0)) != -1) {
/* Reading from sysfs, expecting number\n */
if ((len = read(fd, buf, sizeof(buf))) < 1) {
log_sys_error("read", _path0);
r = 0;
} else {
buf[len] = 0; /* kill \n and ensure \0 */
*read_ahead = atoi(buf) * 2;
log_debug("%s (%d:%d): read ahead is %" PRIu32,
dev_name, major, minor, *read_ahead);
}
if (close(fd))
log_sys_debug("close", _path0);
return r;
}
log_sys_debug("open", _path0);
/* Fall back to use dev_name */
}
/*
* Open/close dev_name may block the process
* (i.e. overfilled thin pool volume)
*/
if (!*dev_name) {
log_error("Empty device name passed to BLKRAGET");
return 0;
@ -682,17 +724,58 @@ int get_dev_node_read_ahead(const char *dev_name, uint32_t *read_ahead)
}
if (close(fd))
stack;
log_sys_debug("close", dev_name);
return r;
}
static int _set_read_ahead(const char *dev_name, uint32_t read_ahead)
static int _set_read_ahead(const char *dev_name, uint32_t major, uint32_t minor,
uint32_t read_ahead)
{
char buf[24];
int len;
int r = 1;
int fd;
long read_ahead_long = (long) read_ahead;
log_debug("%s (%d:%d): Setting read ahead to %" PRIu32, dev_name,
major, minor, read_ahead);
/*
* If we know the device number, use sysfs if we can.
* Otherwise use BLKRASET ioctl. RA is set after resume.
*/
if (*_sysfs_dir && major != 0) {
if (dm_snprintf(_path0, sizeof(_path0), "%sdev/block/%" PRIu32
":%" PRIu32 "/bdi/read_ahead_kb",
_sysfs_dir, major, minor) < 0) {
log_error("Failed to build sysfs_path.");
return 0;
}
/* Sysfs is kB based, round up to kB */
if ((len = dm_snprintf(buf, sizeof(buf), "%" PRIu32,
(read_ahead + 1) / 2)) < 0) {
log_error("Failed to build size in kB.");
return 0;
}
if ((fd = open(_path0, O_WRONLY, 0)) != -1) {
if (write(fd, buf, len) < len) {
log_sys_error("write", _path0);
r = 0;
}
if (close(fd))
log_sys_debug("close", _path0);
return r;
}
log_sys_debug("open", _path0);
/* Fall back to use dev_name */
}
if (!*dev_name) {
log_error("Empty device name passed to BLKRAGET");
return 0;
@ -701,21 +784,20 @@ static int _set_read_ahead(const char *dev_name, uint32_t read_ahead)
if ((fd = _open_dev_node(dev_name)) < 0)
return_0;
log_debug("%s: Setting read ahead to %" PRIu32, dev_name, read_ahead);
if (ioctl(fd, BLKRASET, read_ahead_long)) {
log_sys_error("BLKRASET", dev_name);
r = 0;
}
if (close(fd))
stack;
log_sys_debug("close", dev_name);
return r;
}
static int _set_dev_node_read_ahead(const char *dev_name, uint32_t read_ahead,
uint32_t read_ahead_flags)
static int _set_dev_node_read_ahead(const char *dev_name,
uint32_t major, uint32_t minor,
uint32_t read_ahead, uint32_t read_ahead_flags)
{
uint32_t current_read_ahead;
@ -726,7 +808,7 @@ static int _set_dev_node_read_ahead(const char *dev_name, uint32_t read_ahead,
read_ahead = 0;
if (read_ahead_flags & DM_READ_AHEAD_MINIMUM_FLAG) {
if (!get_dev_node_read_ahead(dev_name, &current_read_ahead))
if (!get_dev_node_read_ahead(dev_name, major, minor, &current_read_ahead))
return_0;
if (current_read_ahead > read_ahead) {
@ -737,7 +819,7 @@ static int _set_dev_node_read_ahead(const char *dev_name, uint32_t read_ahead,
}
}
return _set_read_ahead(dev_name, read_ahead);
return _set_read_ahead(dev_name, major, minor, read_ahead);
}
#else
@ -749,8 +831,9 @@ int get_dev_node_read_ahead(const char *dev_name, uint32_t *read_ahead)
return 1;
}
static int _set_dev_node_read_ahead(const char *dev_name, uint32_t read_ahead,
uint32_t read_ahead_flags)
static int _set_dev_node_read_ahead(const char *dev_name,
uint32_t major, uint32_t minor,
uint32_t read_ahead, uint32_t read_ahead_flags)
{
return 1;
}
@ -778,8 +861,8 @@ static int _do_node_op(node_op_t type, const char *dev_name, uint32_t major,
case NODE_RENAME:
return _rename_dev_node(old_name, dev_name, warn_if_udev_failed);
case NODE_READ_AHEAD:
return _set_dev_node_read_ahead(dev_name, read_ahead,
read_ahead_flags);
return _set_dev_node_read_ahead(dev_name, major, minor,
read_ahead, read_ahead_flags);
default:
; /* NOTREACHED */
}
@ -993,13 +1076,14 @@ int rm_dev_node(const char *dev_name, int check_udev, unsigned rely_on_udev)
0, 0, "", 0, 0, check_udev, rely_on_udev);
}
int set_dev_node_read_ahead(const char *dev_name, uint32_t read_ahead,
uint32_t read_ahead_flags)
int set_dev_node_read_ahead(const char *dev_name,
uint32_t major, uint32_t minor,
uint32_t read_ahead, uint32_t read_ahead_flags)
{
if (read_ahead == DM_READ_AHEAD_AUTO)
return 1;
return _stack_node_op(NODE_READ_AHEAD, dev_name, 0, 0, 0, 0,
return _stack_node_op(NODE_READ_AHEAD, dev_name, major, minor, 0, 0,
0, "", read_ahead, read_ahead_flags, 0, 0);
}

9
libdm/libdm-common.h
View File

@ -1,6 +1,6 @@
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
* Copyright (C) 2004-2012 Red Hat, Inc. All rights reserved.
*
* This file is part of the device-mapper userspace tools.
*
@ -27,9 +27,10 @@ int add_dev_node(const char *dev_name, uint32_t minor, uint32_t major,
int rm_dev_node(const char *dev_name, int check_udev, unsigned rely_on_udev);
int rename_dev_node(const char *old_name, const char *new_name,
int check_udev, unsigned rely_on_udev);
int get_dev_node_read_ahead(const char *dev_name, uint32_t *read_ahead);
int set_dev_node_read_ahead(const char *dev_name, uint32_t read_ahead,
uint32_t read_ahead_flags);
int get_dev_node_read_ahead(const char *dev_name, uint32_t major, uint32_t minor,
uint32_t *read_ahead);
int set_dev_node_read_ahead(const char *dev_name, uint32_t major, uint32_t minor,
uint32_t read_ahead, uint32_t read_ahead_flags);
void update_devs(void);
void selinux_release(void);