linux/drivers/md/dm-log-userspace-transfer.c

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/*
* Copyright (C) 2006-2009 Red Hat, Inc.
*
* This file is released under the LGPL.
*/
#include <linux/kernel.h>
#include <linux/module.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 09:04:11 +01:00
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/workqueue.h>
#include <linux/connector.h>
#include <linux/device-mapper.h>
#include <linux/dm-log-userspace.h>
#include "dm-log-userspace-transfer.h"
static uint32_t dm_ulog_seq;
/*
* Netlink/Connector is an unreliable protocol. How long should
* we wait for a response before assuming it was lost and retrying?
* (If we do receive a response after this time, it will be discarded
* and the response to the resent request will be waited for.
*/
#define DM_ULOG_RETRY_TIMEOUT (15 * HZ)
/*
* Pre-allocated space for speed
*/
#define DM_ULOG_PREALLOCED_SIZE 512
static struct cn_msg *prealloced_cn_msg;
static struct dm_ulog_request *prealloced_ulog_tfr;
static struct cb_id ulog_cn_id = {
.idx = CN_IDX_DM,
.val = CN_VAL_DM_USERSPACE_LOG
};
static DEFINE_MUTEX(dm_ulog_lock);
struct receiving_pkg {
struct list_head list;
struct completion complete;
uint32_t seq;
int error;
size_t *data_size;
char *data;
};
static DEFINE_SPINLOCK(receiving_list_lock);
static struct list_head receiving_list;
static int dm_ulog_sendto_server(struct dm_ulog_request *tfr)
{
int r;
struct cn_msg *msg = prealloced_cn_msg;
memset(msg, 0, sizeof(struct cn_msg));
msg->id.idx = ulog_cn_id.idx;
msg->id.val = ulog_cn_id.val;
msg->ack = 0;
msg->seq = tfr->seq;
msg->len = sizeof(struct dm_ulog_request) + tfr->data_size;
r = cn_netlink_send(msg, 0, gfp_any());
return r;
}
/*
* Parameters for this function can be either msg or tfr, but not
* both. This function fills in the reply for a waiting request.
* If just msg is given, then the reply is simply an ACK from userspace
* that the request was received.
*
* Returns: 0 on success, -ENOENT on failure
*/
static int fill_pkg(struct cn_msg *msg, struct dm_ulog_request *tfr)
{
uint32_t rtn_seq = (msg) ? msg->seq : (tfr) ? tfr->seq : 0;
struct receiving_pkg *pkg;
/*
* The 'receiving_pkg' entries in this list are statically
* allocated on the stack in 'dm_consult_userspace'.
* Each process that is waiting for a reply from the user
* space server will have an entry in this list.
*
* We are safe to do it this way because the stack space
* is unique to each process, but still addressable by
* other processes.
*/
list_for_each_entry(pkg, &receiving_list, list) {
if (rtn_seq != pkg->seq)
continue;
if (msg) {
pkg->error = -msg->ack;
/*
* If we are trying again, we will need to know our
* storage capacity. Otherwise, along with the
* error code, we make explicit that we have no data.
*/
if (pkg->error != -EAGAIN)
*(pkg->data_size) = 0;
} else if (tfr->data_size > *(pkg->data_size)) {
DMERR("Insufficient space to receive package [%u] "
"(%u vs %zu)", tfr->request_type,
tfr->data_size, *(pkg->data_size));
*(pkg->data_size) = 0;
pkg->error = -ENOSPC;
} else {
pkg->error = tfr->error;
memcpy(pkg->data, tfr->data, tfr->data_size);
*(pkg->data_size) = tfr->data_size;
}
complete(&pkg->complete);
return 0;
}
return -ENOENT;
}
/*
* This is the connector callback that delivers data
* that was sent from userspace.
*/
static void cn_ulog_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
if (!cap_raised(current_cap(), CAP_SYS_ADMIN))
return;
spin_lock(&receiving_list_lock);
if (msg->len == 0)
fill_pkg(msg, NULL);
else if (msg->len < sizeof(*tfr))
DMERR("Incomplete message received (expected %u, got %u): [%u]",
(unsigned)sizeof(*tfr), msg->len, msg->seq);
else
fill_pkg(NULL, tfr);
spin_unlock(&receiving_list_lock);
}
/**
* dm_consult_userspace
dm log: userspace add luid to distinguish between concurrent log instances Device-mapper userspace logs (like the clustered log) are identified by a universally unique identifier (UUID). This identifier is used to associate requests from the kernel to a specific log in userspace. The UUID must be unique everywhere, since multiple machines may use this identifier when communicating about a particular log, as is the case for cluster logs. Sometimes, device-mapper/LVM may re-use a UUID. This is the case during pvmoves, when moving from one segment of an LV to another, or when resizing a mirror, etc. In these cases, a new log is created with the same UUID and loaded in the "inactive" slot. When a device-mapper "resume" is issued, the "live" table is deactivated and the new "inactive" table becomes "live". (The "inactive" table can also be removed via a device-mapper 'clear' command.) The above two issues were colliding. More than one log was being created with the same UUID, and there was no way to distinguish between them. So, sometimes the wrong log would be swapped out during the exchange. The solution is to create a locally unique identifier, 'luid', to go along with the UUID. This new identifier is used to determine exactly which log is being referenced by the kernel when the log exchange is made. The identifier is not universally safe, but it does not need to be, since create/destroy/suspend/resume operations are bound to a specific machine; and these are the operations that make up the exchange. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2009-09-04 21:40:34 +02:00
* @uuid: log's universal unique identifier (must be DM_UUID_LEN in size)
* @luid: log's local unique identifier
* @request_type: found in include/linux/dm-log-userspace.h
* @data: data to tx to the server
* @data_size: size of data in bytes
* @rdata: place to put return data from server
* @rdata_size: value-result (amount of space given/amount of space used)
*
* rdata_size is undefined on failure.
*
* Memory used to communicate with userspace is zero'ed
* before populating to ensure that no unwanted bits leak
* from kernel space to user-space. All userspace log communications
* between kernel and user space go through this function.
*
* Returns: 0 on success, -EXXX on failure
**/
dm log: userspace add luid to distinguish between concurrent log instances Device-mapper userspace logs (like the clustered log) are identified by a universally unique identifier (UUID). This identifier is used to associate requests from the kernel to a specific log in userspace. The UUID must be unique everywhere, since multiple machines may use this identifier when communicating about a particular log, as is the case for cluster logs. Sometimes, device-mapper/LVM may re-use a UUID. This is the case during pvmoves, when moving from one segment of an LV to another, or when resizing a mirror, etc. In these cases, a new log is created with the same UUID and loaded in the "inactive" slot. When a device-mapper "resume" is issued, the "live" table is deactivated and the new "inactive" table becomes "live". (The "inactive" table can also be removed via a device-mapper 'clear' command.) The above two issues were colliding. More than one log was being created with the same UUID, and there was no way to distinguish between them. So, sometimes the wrong log would be swapped out during the exchange. The solution is to create a locally unique identifier, 'luid', to go along with the UUID. This new identifier is used to determine exactly which log is being referenced by the kernel when the log exchange is made. The identifier is not universally safe, but it does not need to be, since create/destroy/suspend/resume operations are bound to a specific machine; and these are the operations that make up the exchange. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2009-09-04 21:40:34 +02:00
int dm_consult_userspace(const char *uuid, uint64_t luid, int request_type,
char *data, size_t data_size,
char *rdata, size_t *rdata_size)
{
int r = 0;
size_t dummy = 0;
int overhead_size = sizeof(struct dm_ulog_request) + sizeof(struct cn_msg);
struct dm_ulog_request *tfr = prealloced_ulog_tfr;
struct receiving_pkg pkg;
/*
* Given the space needed to hold the 'struct cn_msg' and
* 'struct dm_ulog_request' - do we have enough payload
* space remaining?
*/
if (data_size > (DM_ULOG_PREALLOCED_SIZE - overhead_size)) {
DMINFO("Size of tfr exceeds preallocated size");
return -EINVAL;
}
if (!rdata_size)
rdata_size = &dummy;
resend:
/*
* We serialize the sending of requests so we can
* use the preallocated space.
*/
mutex_lock(&dm_ulog_lock);
memset(tfr, 0, DM_ULOG_PREALLOCED_SIZE - sizeof(struct cn_msg));
memcpy(tfr->uuid, uuid, DM_UUID_LEN);
tfr->version = DM_ULOG_REQUEST_VERSION;
dm log: userspace add luid to distinguish between concurrent log instances Device-mapper userspace logs (like the clustered log) are identified by a universally unique identifier (UUID). This identifier is used to associate requests from the kernel to a specific log in userspace. The UUID must be unique everywhere, since multiple machines may use this identifier when communicating about a particular log, as is the case for cluster logs. Sometimes, device-mapper/LVM may re-use a UUID. This is the case during pvmoves, when moving from one segment of an LV to another, or when resizing a mirror, etc. In these cases, a new log is created with the same UUID and loaded in the "inactive" slot. When a device-mapper "resume" is issued, the "live" table is deactivated and the new "inactive" table becomes "live". (The "inactive" table can also be removed via a device-mapper 'clear' command.) The above two issues were colliding. More than one log was being created with the same UUID, and there was no way to distinguish between them. So, sometimes the wrong log would be swapped out during the exchange. The solution is to create a locally unique identifier, 'luid', to go along with the UUID. This new identifier is used to determine exactly which log is being referenced by the kernel when the log exchange is made. The identifier is not universally safe, but it does not need to be, since create/destroy/suspend/resume operations are bound to a specific machine; and these are the operations that make up the exchange. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2009-09-04 21:40:34 +02:00
tfr->luid = luid;
tfr->seq = dm_ulog_seq++;
/*
* Must be valid request type (all other bits set to
* zero). This reserves other bits for possible future
* use.
*/
tfr->request_type = request_type & DM_ULOG_REQUEST_MASK;
tfr->data_size = data_size;
if (data && data_size)
memcpy(tfr->data, data, data_size);
memset(&pkg, 0, sizeof(pkg));
init_completion(&pkg.complete);
pkg.seq = tfr->seq;
pkg.data_size = rdata_size;
pkg.data = rdata;
spin_lock(&receiving_list_lock);
list_add(&(pkg.list), &receiving_list);
spin_unlock(&receiving_list_lock);
r = dm_ulog_sendto_server(tfr);
mutex_unlock(&dm_ulog_lock);
if (r) {
DMERR("Unable to send log request [%u] to userspace: %d",
request_type, r);
spin_lock(&receiving_list_lock);
list_del_init(&(pkg.list));
spin_unlock(&receiving_list_lock);
goto out;
}
r = wait_for_completion_timeout(&(pkg.complete), DM_ULOG_RETRY_TIMEOUT);
spin_lock(&receiving_list_lock);
list_del_init(&(pkg.list));
spin_unlock(&receiving_list_lock);
if (!r) {
DMWARN("[%s] Request timed out: [%u/%u] - retrying",
(strlen(uuid) > 8) ?
(uuid + (strlen(uuid) - 8)) : (uuid),
request_type, pkg.seq);
goto resend;
}
r = pkg.error;
if (r == -EAGAIN)
goto resend;
out:
return r;
}
int dm_ulog_tfr_init(void)
{
int r;
void *prealloced;
INIT_LIST_HEAD(&receiving_list);
prealloced = kmalloc(DM_ULOG_PREALLOCED_SIZE, GFP_KERNEL);
if (!prealloced)
return -ENOMEM;
prealloced_cn_msg = prealloced;
prealloced_ulog_tfr = prealloced + sizeof(struct cn_msg);
r = cn_add_callback(&ulog_cn_id, "dmlogusr", cn_ulog_callback);
if (r) {
cn_del_callback(&ulog_cn_id);
return r;
}
return 0;
}
void dm_ulog_tfr_exit(void)
{
cn_del_callback(&ulog_cn_id);
kfree(prealloced_cn_msg);
}