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-rw-r--r--drivers/md/Kconfig11
-rw-r--r--drivers/md/Makefile3
-rw-r--r--drivers/md/dm-log-userspace-base.c696
-rw-r--r--drivers/md/dm-log-userspace-transfer.c276
-rw-r--r--drivers/md/dm-log-userspace-transfer.h18
5 files changed, 1004 insertions, 0 deletions
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 09f93fa..020f957 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -231,6 +231,17 @@ config DM_MIRROR
Allow volume managers to mirror logical volumes, also
needed for live data migration tools such as 'pvmove'.
+config DM_LOG_USERSPACE
+ tristate "Mirror userspace logging (EXPERIMENTAL)"
+ depends on DM_MIRROR && EXPERIMENTAL && NET
+ select CONNECTOR
+ ---help---
+ The userspace logging module provides a mechanism for
+ relaying the dm-dirty-log API to userspace. Log designs
+ which are more suited to userspace implementation (e.g.
+ shared storage logs) or experimental logs can be implemented
+ by leveraging this framework.
+
config DM_ZERO
tristate "Zero target"
depends on BLK_DEV_DM
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index dade52f..1dc4185 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -8,6 +8,8 @@ dm-multipath-y += dm-path-selector.o dm-mpath.o
dm-snapshot-y += dm-snap.o dm-exception-store.o dm-snap-transient.o \
dm-snap-persistent.o
dm-mirror-y += dm-raid1.o
+dm-log-userspace-y \
+ += dm-log-userspace-base.o dm-log-userspace-transfer.o
md-mod-y += md.o bitmap.o
raid456-y += raid5.o
raid6_pq-y += raid6algos.o raid6recov.o raid6tables.o \
@@ -40,6 +42,7 @@ obj-$(CONFIG_DM_MULTIPATH_QL) += dm-queue-length.o
obj-$(CONFIG_DM_MULTIPATH_ST) += dm-service-time.o
obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
obj-$(CONFIG_DM_MIRROR) += dm-mirror.o dm-log.o dm-region-hash.o
+obj-$(CONFIG_DM_LOG_USERSPACE) += dm-log-userspace.o
obj-$(CONFIG_DM_ZERO) += dm-zero.o
quiet_cmd_unroll = UNROLL $@
diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c
new file mode 100644
index 0000000..e69b965
--- /dev/null
+++ b/drivers/md/dm-log-userspace-base.c
@@ -0,0 +1,696 @@
+/*
+ * Copyright (C) 2006-2009 Red Hat, Inc.
+ *
+ * This file is released under the LGPL.
+ */
+
+#include <linux/bio.h>
+#include <linux/dm-dirty-log.h>
+#include <linux/device-mapper.h>
+#include <linux/dm-log-userspace.h>
+
+#include "dm-log-userspace-transfer.h"
+
+struct flush_entry {
+ int type;
+ region_t region;
+ struct list_head list;
+};
+
+struct log_c {
+ struct dm_target *ti;
+ uint32_t region_size;
+ region_t region_count;
+ char uuid[DM_UUID_LEN];
+
+ char *usr_argv_str;
+ uint32_t usr_argc;
+
+ /*
+ * in_sync_hint gets set when doing is_remote_recovering. It
+ * represents the first region that needs recovery. IOW, the
+ * first zero bit of sync_bits. This can be useful for to limit
+ * traffic for calls like is_remote_recovering and get_resync_work,
+ * but be take care in its use for anything else.
+ */
+ uint64_t in_sync_hint;
+
+ spinlock_t flush_lock;
+ struct list_head flush_list; /* only for clear and mark requests */
+};
+
+static mempool_t *flush_entry_pool;
+
+static void *flush_entry_alloc(gfp_t gfp_mask, void *pool_data)
+{
+ return kmalloc(sizeof(struct flush_entry), gfp_mask);
+}
+
+static void flush_entry_free(void *element, void *pool_data)
+{
+ kfree(element);
+}
+
+static int userspace_do_request(struct log_c *lc, const char *uuid,
+ int request_type, char *data, size_t data_size,
+ char *rdata, size_t *rdata_size)
+{
+ int r;
+
+ /*
+ * If the server isn't there, -ESRCH is returned,
+ * and we must keep trying until the server is
+ * restored.
+ */
+retry:
+ r = dm_consult_userspace(uuid, request_type, data,
+ data_size, rdata, rdata_size);
+
+ if (r != -ESRCH)
+ return r;
+
+ DMERR(" Userspace log server not found.");
+ while (1) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(2*HZ);
+ DMWARN("Attempting to contact userspace log server...");
+ r = dm_consult_userspace(uuid, DM_ULOG_CTR, lc->usr_argv_str,
+ strlen(lc->usr_argv_str) + 1,
+ NULL, NULL);
+ if (!r)
+ break;
+ }
+ DMINFO("Reconnected to userspace log server... DM_ULOG_CTR complete");
+ r = dm_consult_userspace(uuid, DM_ULOG_RESUME, NULL,
+ 0, NULL, NULL);
+ if (!r)
+ goto retry;
+
+ DMERR("Error trying to resume userspace log: %d", r);
+
+ return -ESRCH;
+}
+
+static int build_constructor_string(struct dm_target *ti,
+ unsigned argc, char **argv,
+ char **ctr_str)
+{
+ int i, str_size;
+ char *str = NULL;
+
+ *ctr_str = NULL;
+
+ for (i = 0, str_size = 0; i < argc; i++)
+ str_size += strlen(argv[i]) + 1; /* +1 for space between args */
+
+ str_size += 20; /* Max number of chars in a printed u64 number */
+
+ str = kzalloc(str_size, GFP_KERNEL);
+ if (!str) {
+ DMWARN("Unable to allocate memory for constructor string");
+ return -ENOMEM;
+ }
+
+ for (i = 0, str_size = 0; i < argc; i++)
+ str_size += sprintf(str + str_size, "%s ", argv[i]);
+ str_size += sprintf(str + str_size, "%llu",
+ (unsigned long long)ti->len);
+
+ *ctr_str = str;
+ return str_size;
+}
+
+/*
+ * userspace_ctr
+ *
+ * argv contains:
+ * <UUID> <other args>
+ * Where 'other args' is the userspace implementation specific log
+ * arguments. An example might be:
+ * <UUID> clustered_disk <arg count> <log dev> <region_size> [[no]sync]
+ *
+ * So, this module will strip off the <UUID> for identification purposes
+ * when communicating with userspace about a log; but will pass on everything
+ * else.
+ */
+static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
+ unsigned argc, char **argv)
+{
+ int r = 0;
+ int str_size;
+ char *ctr_str = NULL;
+ struct log_c *lc = NULL;
+ uint64_t rdata;
+ size_t rdata_size = sizeof(rdata);
+
+ if (argc < 3) {
+ DMWARN("Too few arguments to userspace dirty log");
+ return -EINVAL;
+ }
+
+ lc = kmalloc(sizeof(*lc), GFP_KERNEL);
+ if (!lc) {
+ DMWARN("Unable to allocate userspace log context.");
+ return -ENOMEM;
+ }
+
+ lc->ti = ti;
+
+ if (strlen(argv[0]) > (DM_UUID_LEN - 1)) {
+ DMWARN("UUID argument too long.");
+ kfree(lc);
+ return -EINVAL;
+ }
+
+ strncpy(lc->uuid, argv[0], DM_UUID_LEN);
+ spin_lock_init(&lc->flush_lock);
+ INIT_LIST_HEAD(&lc->flush_list);
+
+ str_size = build_constructor_string(ti, argc - 1, argv + 1, &ctr_str);
+ if (str_size < 0) {
+ kfree(lc);
+ return str_size;
+ }
+
+ /* Send table string */
+ r = dm_consult_userspace(lc->uuid, DM_ULOG_CTR,
+ ctr_str, str_size, NULL, NULL);
+
+ if (r == -ESRCH) {
+ DMERR("Userspace log server not found");
+ goto out;
+ }
+
+ /* Since the region size does not change, get it now */
+ rdata_size = sizeof(rdata);
+ r = dm_consult_userspace(lc->uuid, DM_ULOG_GET_REGION_SIZE,
+ NULL, 0, (char *)&rdata, &rdata_size);
+
+ if (r) {
+ DMERR("Failed to get region size of dirty log");
+ goto out;
+ }
+
+ lc->region_size = (uint32_t)rdata;
+ lc->region_count = dm_sector_div_up(ti->len, lc->region_size);
+
+out:
+ if (r) {
+ kfree(lc);
+ kfree(ctr_str);
+ } else {
+ lc->usr_argv_str = ctr_str;
+ lc->usr_argc = argc;
+ log->context = lc;
+ }
+
+ return r;
+}
+
+static void userspace_dtr(struct dm_dirty_log *log)
+{
+ int r;
+ struct log_c *lc = log->context;
+
+ r = dm_consult_userspace(lc->uuid, DM_ULOG_DTR,
+ NULL, 0,
+ NULL, NULL);
+
+ kfree(lc->usr_argv_str);
+ kfree(lc);
+
+ return;
+}
+
+static int userspace_presuspend(struct dm_dirty_log *log)
+{
+ int r;
+ struct log_c *lc = log->context;
+
+ r = dm_consult_userspace(lc->uuid, DM_ULOG_PRESUSPEND,
+ NULL, 0,
+ NULL, NULL);
+
+ return r;
+}
+
+static int userspace_postsuspend(struct dm_dirty_log *log)
+{
+ int r;
+ struct log_c *lc = log->context;
+
+ r = dm_consult_userspace(lc->uuid, DM_ULOG_POSTSUSPEND,
+ NULL, 0,
+ NULL, NULL);
+
+ return r;
+}
+
+static int userspace_resume(struct dm_dirty_log *log)
+{
+ int r;
+ struct log_c *lc = log->context;
+
+ lc->in_sync_hint = 0;
+ r = dm_consult_userspace(lc->uuid, DM_ULOG_RESUME,
+ NULL, 0,
+ NULL, NULL);
+
+ return r;
+}
+
+static uint32_t userspace_get_region_size(struct dm_dirty_log *log)
+{
+ struct log_c *lc = log->context;
+
+ return lc->region_size;
+}
+
+/*
+ * userspace_is_clean
+ *
+ * Check whether a region is clean. If there is any sort of
+ * failure when consulting the server, we return not clean.
+ *
+ * Returns: 1 if clean, 0 otherwise
+ */
+static int userspace_is_clean(struct dm_dirty_log *log, region_t region)
+{
+ int r;
+ uint64_t region64 = (uint64_t)region;
+ int64_t is_clean;
+ size_t rdata_size;
+ struct log_c *lc = log->context;
+
+ rdata_size = sizeof(is_clean);
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_CLEAN,
+ (char *)&region64, sizeof(region64),
+ (char *)&is_clean, &rdata_size);
+
+ return (r) ? 0 : (int)is_clean;
+}
+
+/*
+ * userspace_in_sync
+ *
+ * Check if the region is in-sync. If there is any sort
+ * of failure when consulting the server, we assume that
+ * the region is not in sync.
+ *
+ * If 'can_block' is set, return immediately
+ *
+ * Returns: 1 if in-sync, 0 if not-in-sync, -EWOULDBLOCK
+ */
+static int userspace_in_sync(struct dm_dirty_log *log, region_t region,
+ int can_block)
+{
+ int r;
+ uint64_t region64 = region;
+ int64_t in_sync;
+ size_t rdata_size;
+ struct log_c *lc = log->context;
+
+ /*
+ * We can never respond directly - even if in_sync_hint is
+ * set. This is because another machine could see a device
+ * failure and mark the region out-of-sync. If we don't go
+ * to userspace to ask, we might think the region is in-sync
+ * and allow a read to pick up data that is stale. (This is
+ * very unlikely if a device actually fails; but it is very
+ * likely if a connection to one device from one machine fails.)
+ *
+ * There still might be a problem if the mirror caches the region
+ * state as in-sync... but then this call would not be made. So,
+ * that is a mirror problem.
+ */
+ if (!can_block)
+ return -EWOULDBLOCK;
+
+ rdata_size = sizeof(in_sync);
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_IN_SYNC,
+ (char *)&region64, sizeof(region64),
+ (char *)&in_sync, &rdata_size);
+ return (r) ? 0 : (int)in_sync;
+}
+
+/*
+ * userspace_flush
+ *
+ * This function is ok to block.
+ * The flush happens in two stages. First, it sends all
+ * clear/mark requests that are on the list. Then it
+ * tells the server to commit them. This gives the
+ * server a chance to optimise the commit, instead of
+ * doing it for every request.
+ *
+ * Additionally, we could implement another thread that
+ * sends the requests up to the server - reducing the
+ * load on flush. Then the flush would have less in
+ * the list and be responsible for the finishing commit.
+ *
+ * Returns: 0 on success, < 0 on failure
+ */
+static int userspace_flush(struct dm_dirty_log *log)
+{
+ int r = 0;
+ unsigned long flags;
+ struct log_c *lc = log->context;
+ LIST_HEAD(flush_list);
+ struct flush_entry *fe, *tmp_fe;
+
+ spin_lock_irqsave(&lc->flush_lock, flags);
+ list_splice_init(&lc->flush_list, &flush_list);
+ spin_unlock_irqrestore(&lc->flush_lock, flags);
+
+ if (list_empty(&flush_list))
+ return 0;
+
+ /*
+ * FIXME: Count up requests, group request types,
+ * allocate memory to stick all requests in and
+ * send to server in one go. Failing the allocation,
+ * do it one by one.
+ */
+
+ list_for_each_entry(fe, &flush_list, list) {
+ r = userspace_do_request(lc, lc->uuid, fe->type,
+ (char *)&fe->region,
+ sizeof(fe->region),
+ NULL, NULL);
+ if (r)
+ goto fail;
+ }
+
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
+ NULL, 0, NULL, NULL);
+
+fail:
+ /*
+ * We can safely remove these entries, even if failure.
+ * Calling code will receive an error and will know that
+ * the log facility has failed.
+ */
+ list_for_each_entry_safe(fe, tmp_fe, &flush_list, list) {
+ list_del(&fe->list);
+ mempool_free(fe, flush_entry_pool);
+ }
+
+ if (r)
+ dm_table_event(lc->ti->table);
+
+ return r;
+}
+
+/*
+ * userspace_mark_region
+ *
+ * This function should avoid blocking unless absolutely required.
+ * (Memory allocation is valid for blocking.)
+ */
+static void userspace_mark_region(struct dm_dirty_log *log, region_t region)
+{
+ unsigned long flags;
+ struct log_c *lc = log->context;
+ struct flush_entry *fe;
+
+ /* Wait for an allocation, but _never_ fail */
+ fe = mempool_alloc(flush_entry_pool, GFP_NOIO);
+ BUG_ON(!fe);
+
+ spin_lock_irqsave(&lc->flush_lock, flags);
+ fe->type = DM_ULOG_MARK_REGION;
+ fe->region = region;
+ list_add(&fe->list, &lc->flush_list);
+ spin_unlock_irqrestore(&lc->flush_lock, flags);
+
+ return;
+}
+
+/*
+ * userspace_clear_region
+ *
+ * This function must not block.
+ * So, the alloc can't block. In the worst case, it is ok to
+ * fail. It would simply mean we can't clear the region.
+ * Does nothing to current sync context, but does mean
+ * the region will be re-sync'ed on a reload of the mirror
+ * even though it is in-sync.
+ */
+static void userspace_clear_region(struct dm_dirty_log *log, region_t region)
+{
+ unsigned long flags;
+ struct log_c *lc = log->context;
+ struct flush_entry *fe;
+
+ /*
+ * If we fail to allocate, we skip the clearing of
+ * the region. This doesn't hurt us in any way, except
+ * to cause the region to be resync'ed when the
+ * device is activated next time.
+ */
+ fe = mempool_alloc(flush_entry_pool, GFP_ATOMIC);
+ if (!fe) {
+ DMERR("Failed to allocate memory to clear region.");
+ return;
+ }
+
+ spin_lock_irqsave(&lc->flush_lock, flags);
+ fe->type = DM_ULOG_CLEAR_REGION;
+ fe->region = region;
+ list_add(&fe->list, &lc->flush_list);
+ spin_unlock_irqrestore(&lc->flush_lock, flags);
+
+ return;
+}
+
+/*
+ * userspace_get_resync_work
+ *
+ * Get a region that needs recovery. It is valid to return
+ * an error for this function.
+ *
+ * Returns: 1 if region filled, 0 if no work, <0 on error
+ */
+static int userspace_get_resync_work(struct dm_dirty_log *log, region_t *region)
+{
+ int r;
+ size_t rdata_size;
+ struct log_c *lc = log->context;
+ struct {
+ int64_t i; /* 64-bit for mix arch compatibility */
+ region_t r;
+ } pkg;
+
+ if (lc->in_sync_hint >= lc->region_count)
+ return 0;
+
+ rdata_size = sizeof(pkg);
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_RESYNC_WORK,
+ NULL, 0,
+ (char *)&pkg, &rdata_size);
+
+ *region = pkg.r;
+ return (r) ? r : (int)pkg.i;
+}
+
+/*
+ * userspace_set_region_sync
+ *
+ * Set the sync status of a given region. This function
+ * must not fail.
+ */
+static void userspace_set_region_sync(struct dm_dirty_log *log,
+ region_t region, int in_sync)
+{
+ int r;
+ struct log_c *lc = log->context;
+ struct {
+ region_t r;
+ int64_t i;
+ } pkg;
+
+ pkg.r = region;
+ pkg.i = (int64_t)in_sync;
+
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_SET_REGION_SYNC,
+ (char *)&pkg, sizeof(pkg),
+ NULL, NULL);
+
+ /*
+ * It would be nice to be able to report failures.
+ * However, it is easy emough to detect and resolve.
+ */
+ return;
+}
+
+/*
+ * userspace_get_sync_count
+ *
+ * If there is any sort of failure when consulting the server,
+ * we assume that the sync count is zero.
+ *
+ * Returns: sync count on success, 0 on failure
+ */
+static region_t userspace_get_sync_count(struct dm_dirty_log *log)
+{
+ int r;
+ size_t rdata_size;
+ uint64_t sync_count;
+ struct log_c *lc = log->context;
+
+ rdata_size = sizeof(sync_count);
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_SYNC_COUNT,
+ NULL, 0,
+ (char *)&sync_count, &rdata_size);
+
+ if (r)
+ return 0;
+
+ if (sync_count >= lc->region_count)
+ lc->in_sync_hint = lc->region_count;
+
+ return (region_t)sync_count;
+}
+
+/*
+ * userspace_status
+ *
+ * Returns: amount of space consumed
+ */
+static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
+ char *result, unsigned maxlen)
+{
+ int r = 0;
+ size_t sz = (size_t)maxlen;
+ struct log_c *lc = log->context;
+
+ switch (status_type) {
+ case STATUSTYPE_INFO:
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_STATUS_INFO,
+ NULL, 0,
+ result, &sz);
+
+ if (r) {
+ sz = 0;
+ DMEMIT("%s 1 COM_FAILURE", log->type->name);
+ }
+ break;
+ case STATUSTYPE_TABLE:
+ sz = 0;
+ DMEMIT("%s %u %s %s", log->type->name, lc->usr_argc + 1,
+ lc->uuid, lc->usr_argv_str);
+ break;
+ }
+ return (r) ? 0 : (int)sz;
+}
+
+/*
+ * userspace_is_remote_recovering
+ *
+ * Returns: 1 if region recovering, 0 otherwise
+ */
+static int userspace_is_remote_recovering(struct dm_dirty_log *log,
+ region_t region)
+{
+ int r;
+ uint64_t region64 = region;
+ struct log_c *lc = log->context;
+ static unsigned long long limit;
+ struct {
+ int64_t is_recovering;
+ uint64_t in_sync_hint;
+ } pkg;
+ size_t rdata_size = sizeof(pkg);
+
+ /*
+ * Once the mirror has been reported to be in-sync,
+ * it will never again ask for recovery work. So,
+ * we can safely say there is not a remote machine
+ * recovering if the device is in-sync. (in_sync_hint
+ * must be reset at resume time.)
+ */
+ if (region < lc->in_sync_hint)
+ return 0;
+ else if (jiffies < limit)
+ return 1;
+
+ limit = jiffies + (HZ / 4);
+ r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_REMOTE_RECOVERING,
+ (char *)&region64, sizeof(region64),
+ (char *)&pkg, &rdata_size);
+ if (r)
+ return 1;
+
+ lc->in_sync_hint = pkg.in_sync_hint;
+
+ return (int)pkg.is_recovering;
+}
+
+static struct dm_dirty_log_type _userspace_type = {
+ .name = "userspace",
+ .module = THIS_MODULE,
+ .ctr = userspace_ctr,
+ .dtr = userspace_dtr,
+ .presuspend = userspace_presuspend,
+ .postsuspend = userspace_postsuspend,
+ .resume = userspace_resume,
+ .get_region_size = userspace_get_region_size,
+ .is_clean = userspace_is_clean,
+ .in_sync = userspace_in_sync,
+ .flush = userspace_flush,
+ .mark_region = userspace_mark_region,
+ .clear_region = userspace_clear_region,
+ .get_resync_work = userspace_get_resync_work,
+ .set_region_sync = userspace_set_region_sync,
+ .get_sync_count = userspace_get_sync_count,
+ .status = userspace_status,
+ .is_remote_recovering = userspace_is_remote_recovering,
+};
+
+static int __init userspace_dirty_log_init(void)
+{
+ int r = 0;
+
+ flush_entry_pool = mempool_create(100, flush_entry_alloc,
+ flush_entry_free, NULL);
+
+ if (!flush_entry_pool) {
+ DMWARN("Unable to create flush_entry_pool: No memory.");
+ return -ENOMEM;
+ }
+
+ r = dm_ulog_tfr_init();
+ if (r) {
+ DMWARN("Unable to initialize userspace log communications");
+ mempool_destroy(flush_entry_pool);
+ return r;
+ }
+
+ r = dm_dirty_log_type_register(&_userspace_type);
+ if (r) {
+ DMWARN("Couldn't register userspace dirty log type");
+ dm_ulog_tfr_exit();
+ mempool_destroy(flush_entry_pool);
+ return r;
+ }
+
+ DMINFO("version 1.0.0 loaded");
+ return 0;
+}
+
+static void __exit userspace_dirty_log_exit(void)
+{
+ dm_dirty_log_type_unregister(&_userspace_type);
+ dm_ulog_tfr_exit();
+ mempool_destroy(flush_entry_pool);
+
+ DMINFO("version 1.0.0 unloaded");
+ return;
+}
+
+module_init(userspace_dirty_log_init);
+module_exit(userspace_dirty_log_exit);
+
+MODULE_DESCRIPTION(DM_NAME " userspace dirty log link");
+MODULE_AUTHOR("Jonathan Brassow <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/md/dm-log-userspace-transfer.c b/drivers/md/dm-log-userspace-transfer.c
new file mode 100644
index 0000000..0ca1ee7
--- /dev/null
+++ b/drivers/md/dm-log-userspace-transfer.c
@@ -0,0 +1,276 @@
+/*
+ * Copyright (C) 2006-2009 Red Hat, Inc.
+ *
+ * This file is released under the LGPL.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.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 %lu)", 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(void *data)
+{
+ struct cn_msg *msg = (struct cn_msg *)data;
+ struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
+
+ 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
+ * @uuid: log's uuid (must be DM_UUID_LEN in size)
+ * @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
+ **/
+int dm_consult_userspace(const char *uuid, 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;
+
+ 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 - overhead_size);
+ memcpy(tfr->uuid, uuid, DM_UUID_LEN);
+ 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);
+}
diff --git a/drivers/md/dm-log-userspace-transfer.h b/drivers/md/dm-log-userspace-transfer.h
new file mode 100644
index 0000000..c26d8e4
--- /dev/null
+++ b/drivers/md/dm-log-userspace-transfer.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2006-2009 Red Hat, Inc.
+ *
+ * This file is released under the LGPL.
+ */
+
+#ifndef __DM_LOG_USERSPACE_TRANSFER_H__
+#define __DM_LOG_USERSPACE_TRANSFER_H__
+
+#define DM_MSG_PREFIX "dm-log-userspace"
+
+int dm_ulog_tfr_init(void);
+void dm_ulog_tfr_exit(void);
+int dm_consult_userspace(const char *uuid, int request_type,
+ char *data, size_t data_size,
+ char *rdata, size_t *rdata_size);
+
+#endif /* __DM_LOG_USERSPACE_TRANSFER_H__ */
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