OSCL-LXR linux-6.0.1/​drivers/​md/​dm-log-userspace-base.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * Copyright (C) 2006-2009 Red Hat, Inc.
  *
  * This file is released under the LGPL.
  */
 
 #include <linux/bio.h>
 #include <linux/slab.h>
 #include <linux/jiffies.h>
 #include <linux/dm-dirty-log.h>
 #include <linux/device-mapper.h>
 #include <linux/dm-log-userspace.h>
 #include <linux/module.h>
 #include <linux/workqueue.h>
 
 #include "dm-log-userspace-transfer.h"
 
 #define DM_LOG_USERSPACE_VSN "1.3.0"
 
 #define FLUSH_ENTRY_POOL_SIZE 16
 
 struct dm_dirty_log_flush_entry {
     int type;
     region_t region;
     struct list_head list;
 };
 
 /*
  * This limit on the number of mark and clear request is, to a degree,
  * arbitrary.  However, there is some basis for the choice in the limits
  * imposed on the size of data payload by dm-log-userspace-transfer.c:
  * dm_consult_userspace().
  */
 #define MAX_FLUSH_GROUP_COUNT 32
 
 struct log_c {
     struct dm_target *ti;
     struct dm_dev *log_dev;
 
     char *usr_argv_str;
     uint32_t usr_argc;
 
     uint32_t region_size;
     region_t region_count;
     uint64_t luid;
     char uuid[DM_UUID_LEN];
 
     /*
      * Mark and clear requests are held until a flush is issued
      * so that we can group, and thereby limit, the amount of
      * network traffic between kernel and userspace.  The 'flush_lock'
      * is used to protect these lists.
      */
     spinlock_t flush_lock;
     struct list_head mark_list;
     struct list_head clear_list;
 
     /*
      * 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;
 
     /*
      * Workqueue for flush of clear region requests.
      */
     struct workqueue_struct *dmlog_wq;
     struct delayed_work flush_log_work;
     atomic_t sched_flush;
 
     /*
      * Combine userspace flush and mark requests for efficiency.
      */
     uint32_t integrated_flush;
 
     mempool_t flush_entry_pool;
 };
 
 static struct kmem_cache *_flush_entry_cache;
 
 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, lc->luid, 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, lc->luid, 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, lc->luid, 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;
 
     /*
      * Determine overall size of the string.
      */
     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;
     }
 
     str_size = sprintf(str, "%llu", (unsigned long long)ti->len);
     for (i = 0; i < argc; i++)
         str_size += sprintf(str + str_size, " %s", argv[i]);
 
     *ctr_str = str;
     return str_size;
 }
 
 static void do_flush(struct work_struct *work)
 {
     int r;
     struct log_c *lc = container_of(work, struct log_c, flush_log_work.work);
 
     atomic_set(&lc->sched_flush, 0);
 
     r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH, NULL, 0, NULL, NULL);
 
     if (r)
         dm_table_event(lc->ti->table);
 }
 
 /*
  * userspace_ctr
  *
  * argv contains:
  *  <UUID> [integrated_flush] <other args>
  * Where 'other args' are the userspace implementation-specific log
  * arguments.
  *
  * Example:
  *  <UUID> [integrated_flush] clustered-disk <arg count> <log dev>
  *  <region_size> [[no]sync]
  *
  * This module strips off the <UUID> and uses it for identification
  * purposes when communicating with userspace about a log.
  *
  * If integrated_flush is defined, the kernel combines flush
  * and mark requests.
  *
  * The rest of the line, beginning with 'clustered-disk', is passed
  * to the userspace ctr function.
  */
 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);
     char *devices_rdata = NULL;
     size_t devices_rdata_size = DM_NAME_LEN;
 
     if (argc < 3) {
         DMWARN("Too few arguments to userspace dirty log");
         return -EINVAL;
     }
 
     lc = kzalloc(sizeof(*lc), GFP_KERNEL);
     if (!lc) {
         DMWARN("Unable to allocate userspace log context.");
         return -ENOMEM;
     }
 
     /* The ptr value is sufficient for local unique id */
     lc->luid = (unsigned long)lc;
 
     lc->ti = ti;
 
     if (strlen(argv[0]) > (DM_UUID_LEN - 1)) {
         DMWARN("UUID argument too long.");
         kfree(lc);
         return -EINVAL;
     }
 
     lc->usr_argc = argc;
 
     strncpy(lc->uuid, argv[0], DM_UUID_LEN);
     argc--;
     argv++;
     spin_lock_init(&lc->flush_lock);
     INIT_LIST_HEAD(&lc->mark_list);
     INIT_LIST_HEAD(&lc->clear_list);
 
     if (!strcasecmp(argv[0], "integrated_flush")) {
         lc->integrated_flush = 1;
         argc--;
         argv++;
     }
 
     str_size = build_constructor_string(ti, argc, argv, &ctr_str);
     if (str_size < 0) {
         kfree(lc);
         return str_size;
     }
 
     devices_rdata = kzalloc(devices_rdata_size, GFP_KERNEL);
     if (!devices_rdata) {
         DMERR("Failed to allocate memory for device information");
         r = -ENOMEM;
         goto out;
     }
 
     r = mempool_init_slab_pool(&lc->flush_entry_pool, FLUSH_ENTRY_POOL_SIZE,
                    _flush_entry_cache);
     if (r) {
         DMERR("Failed to create flush_entry_pool");
         goto out;
     }
 
     /*
      * Send table string and get back any opened device.
      */
     r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_CTR,
                  ctr_str, str_size,
                  devices_rdata, &devices_rdata_size);
 
     if (r < 0) {
         if (r == -ESRCH)
             DMERR("Userspace log server not found");
         else
             DMERR("Userspace log server failed to create log");
         goto out;
     }
 
     /* Since the region size does not change, get it now */
     rdata_size = sizeof(rdata);
     r = dm_consult_userspace(lc->uuid, lc->luid, 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);
 
     if (devices_rdata_size) {
         if (devices_rdata[devices_rdata_size - 1] != '\0') {
             DMERR("DM_ULOG_CTR device return string not properly terminated");
             r = -EINVAL;
             goto out;
         }
         r = dm_get_device(ti, devices_rdata,
                   dm_table_get_mode(ti->table), &lc->log_dev);
         if (r)
             DMERR("Failed to register %s with device-mapper",
                   devices_rdata);
     }
 
     if (lc->integrated_flush) {
         lc->dmlog_wq = alloc_workqueue("dmlogd", WQ_MEM_RECLAIM, 0);
         if (!lc->dmlog_wq) {
             DMERR("couldn't start dmlogd");
             r = -ENOMEM;
             goto out;
         }
 
         INIT_DELAYED_WORK(&lc->flush_log_work, do_flush);
         atomic_set(&lc->sched_flush, 0);
     }
 
 out:
     kfree(devices_rdata);
     if (r) {
         mempool_exit(&lc->flush_entry_pool);
         kfree(lc);
         kfree(ctr_str);
     } else {
         lc->usr_argv_str = ctr_str;
         log->context = lc;
     }
 
     return r;
 }
 
 static void userspace_dtr(struct dm_dirty_log *log)
 {
     struct log_c *lc = log->context;
 
     if (lc->integrated_flush) {
         /* flush workqueue */
         if (atomic_read(&lc->sched_flush))
             flush_delayed_work(&lc->flush_log_work);
 
         destroy_workqueue(lc->dmlog_wq);
     }
 
     (void) dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_DTR,
                     NULL, 0, NULL, NULL);
 
     if (lc->log_dev)
         dm_put_device(lc->ti, lc->log_dev);
 
     mempool_exit(&lc->flush_entry_pool);
 
     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, lc->luid, 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;
 
     /*
      * Run planned flush earlier.
      */
     if (lc->integrated_flush && atomic_read(&lc->sched_flush))
         flush_delayed_work(&lc->flush_log_work);
 
     r = dm_consult_userspace(lc->uuid, lc->luid, 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, lc->luid, 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;
 }
 
 static int flush_one_by_one(struct log_c *lc, struct list_head *flush_list)
 {
     int r = 0;
     struct dm_dirty_log_flush_entry *fe;
 
     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)
             break;
     }
 
     return r;
 }
 
 static int flush_by_group(struct log_c *lc, struct list_head *flush_list,
               int flush_with_payload)
 {
     int r = 0;
     int count;
     uint32_t type = 0;
     struct dm_dirty_log_flush_entry *fe, *tmp_fe;
     LIST_HEAD(tmp_list);
     uint64_t group[MAX_FLUSH_GROUP_COUNT];
 
     /*
      * Group process the requests
      */
     while (!list_empty(flush_list)) {
         count = 0;
 
         list_for_each_entry_safe(fe, tmp_fe, flush_list, list) {
             group[count] = fe->region;
             count++;
 
             list_move(&fe->list, &tmp_list);
 
             type = fe->type;
             if (count >= MAX_FLUSH_GROUP_COUNT)
                 break;
         }
 
         if (flush_with_payload) {
             r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
                          (char *)(group),
                          count * sizeof(uint64_t),
                          NULL, NULL);
             /*
              * Integrated flush failed.
              */
             if (r)
                 break;
         } else {
             r = userspace_do_request(lc, lc->uuid, type,
                          (char *)(group),
                          count * sizeof(uint64_t),
                          NULL, NULL);
             if (r) {
                 /*
                  * Group send failed.  Attempt one-by-one.
                  */
                 list_splice_init(&tmp_list, flush_list);
                 r = flush_one_by_one(lc, flush_list);
                 break;
             }
         }
     }
 
     /*
      * Must collect flush_entrys that were successfully processed
      * as a group so that they will be free'd by the caller.
      */
     list_splice_init(&tmp_list, flush_list);
 
     return r;
 }
 
 /*
  * 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(mark_list);
     LIST_HEAD(clear_list);
     int mark_list_is_empty;
     int clear_list_is_empty;
     struct dm_dirty_log_flush_entry *fe, *tmp_fe;
     mempool_t *flush_entry_pool = &lc->flush_entry_pool;
 
     spin_lock_irqsave(&lc->flush_lock, flags);
     list_splice_init(&lc->mark_list, &mark_list);
     list_splice_init(&lc->clear_list, &clear_list);
     spin_unlock_irqrestore(&lc->flush_lock, flags);
 
     mark_list_is_empty = list_empty(&mark_list);
     clear_list_is_empty = list_empty(&clear_list);
 
     if (mark_list_is_empty && clear_list_is_empty)
         return 0;
 
     r = flush_by_group(lc, &clear_list, 0);
     if (r)
         goto out;
 
     if (!lc->integrated_flush) {
         r = flush_by_group(lc, &mark_list, 0);
         if (r)
             goto out;
         r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
                      NULL, 0, NULL, NULL);
         goto out;
     }
 
     /*
      * Send integrated flush request with mark_list as payload.
      */
     r = flush_by_group(lc, &mark_list, 1);
     if (r)
         goto out;
 
     if (mark_list_is_empty && !atomic_read(&lc->sched_flush)) {
         /*
          * When there are only clear region requests,
          * we schedule a flush in the future.
          */
         queue_delayed_work(lc->dmlog_wq, &lc->flush_log_work, 3 * HZ);
         atomic_set(&lc->sched_flush, 1);
     } else {
         /*
          * Cancel pending flush because we
          * have already flushed in mark_region.
          */
         cancel_delayed_work(&lc->flush_log_work);
         atomic_set(&lc->sched_flush, 0);
     }
 
 out:
     /*
      * We can safely remove these entries, even after failure.
      * Calling code will receive an error and will know that
      * the log facility has failed.
      */
     list_for_each_entry_safe(fe, tmp_fe, &mark_list, list) {
         list_del(&fe->list);
         mempool_free(fe, flush_entry_pool);
     }
     list_for_each_entry_safe(fe, tmp_fe, &clear_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 dm_dirty_log_flush_entry *fe;
 
     /* Wait for an allocation, but _never_ fail */
     fe = mempool_alloc(&lc->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->mark_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 dm_dirty_log_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(&lc->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->clear_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)
 {
     struct log_c *lc = log->context;
     struct {
         region_t r;
         int64_t i;
     } pkg;
 
     pkg.r = region;
     pkg.i = (int64_t)in_sync;
 
     (void) 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 enough 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;
     char *table_args;
     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;
         table_args = strchr(lc->usr_argv_str, ' ');
         BUG_ON(!table_args); /* There will always be a ' ' */
         table_args++;
 
         DMEMIT("%s %u %s ", log->type->name, lc->usr_argc, lc->uuid);
         if (lc->integrated_flush)
             DMEMIT("integrated_flush ");
         DMEMIT("%s ", table_args);
         break;
     case STATUSTYPE_IMA:
         *result = '\0';
         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 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 (time_after(limit, jiffies))
         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_cache = KMEM_CACHE(dm_dirty_log_flush_entry, 0);
     if (!_flush_entry_cache) {
         DMWARN("Unable to create flush_entry_cache: No memory.");
         return -ENOMEM;
     }
 
     r = dm_ulog_tfr_init();
     if (r) {
         DMWARN("Unable to initialize userspace log communications");
         kmem_cache_destroy(_flush_entry_cache);
         return r;
     }
 
     r = dm_dirty_log_type_register(&_userspace_type);
     if (r) {
         DMWARN("Couldn't register userspace dirty log type");
         dm_ulog_tfr_exit();
         kmem_cache_destroy(_flush_entry_cache);
         return r;
     }
 
     DMINFO("version " DM_LOG_USERSPACE_VSN " loaded");
     return 0;
 }
 
 static void __exit userspace_dirty_log_exit(void)
 {
     dm_dirty_log_type_unregister(&_userspace_type);
     dm_ulog_tfr_exit();
     kmem_cache_destroy(_flush_entry_cache);
 
     DMINFO("version " DM_LOG_USERSPACE_VSN " 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");

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