Merge branch 'stable/for-jens-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus
Pull Xen block driver fixes from Konrad: "Fix for flushing out persistent pages at a deterministic rate" * 'stable/for-jens-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen/blkback: remove unused pers_gnts_lock from struct xen_blkif_ring xen/blkback: move persistent grants flags to bool xen/blkfront: reorder tests in xlblk_init() xen/blkfront: cleanup stale persistent grants xen/blkback: don't keep persistent grants too long
This commit is contained in:
Jens Axboe
commit
057d3ccf93
@ -15,3 +15,13 @@ Description:
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blkback. If the frontend tries to use more than
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max_persistent_grants, the LRU kicks in and starts
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removing 5% of max_persistent_grants every 100ms.
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What: /sys/module/xen_blkback/parameters/persistent_grant_unused_seconds
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Date: August 2018
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KernelVersion: 4.19
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Contact: Roger Pau Monné <roger.pau@citrix.com>
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Description:
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How long a persistent grant is allowed to remain
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allocated without being in use. The time is in
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seconds, 0 means indefinitely long.
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The default is 60 seconds.
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@ -83,6 +83,18 @@ module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644);
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MODULE_PARM_DESC(max_persistent_grants,
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"Maximum number of grants to map persistently");
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/*
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* How long a persistent grant is allowed to remain allocated without being in
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* use. The time is in seconds, 0 means indefinitely long.
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*/
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static unsigned int xen_blkif_pgrant_timeout = 60;
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module_param_named(persistent_grant_unused_seconds, xen_blkif_pgrant_timeout,
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uint, 0644);
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MODULE_PARM_DESC(persistent_grant_unused_seconds,
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"Time in seconds an unused persistent grant is allowed to "
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"remain allocated. Default is 60, 0 means unlimited.");
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/*
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* Maximum number of rings/queues blkback supports, allow as many queues as there
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* are CPUs if user has not specified a value.
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@ -123,6 +135,13 @@ module_param(log_stats, int, 0644);
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/* Number of free pages to remove on each call to gnttab_free_pages */
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#define NUM_BATCH_FREE_PAGES 10
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static inline bool persistent_gnt_timeout(struct persistent_gnt *persistent_gnt)
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{
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return xen_blkif_pgrant_timeout &&
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(jiffies - persistent_gnt->last_used >=
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HZ * xen_blkif_pgrant_timeout);
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}
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static inline int get_free_page(struct xen_blkif_ring *ring, struct page **page)
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{
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unsigned long flags;
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@ -236,8 +255,7 @@ static int add_persistent_gnt(struct xen_blkif_ring *ring,
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}
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}
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bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE);
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set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
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persistent_gnt->active = true;
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/* Add new node and rebalance tree. */
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rb_link_node(&(persistent_gnt->node), parent, new);
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rb_insert_color(&(persistent_gnt->node), &ring->persistent_gnts);
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@ -261,11 +279,11 @@ static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring,
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else if (gref > data->gnt)
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node = node->rb_right;
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else {
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if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) {
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if (data->active) {
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pr_alert_ratelimited("requesting a grant already in use\n");
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return NULL;
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}
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set_bit(PERSISTENT_GNT_ACTIVE, data->flags);
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data->active = true;
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atomic_inc(&ring->persistent_gnt_in_use);
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return data;
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}
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@ -276,10 +294,10 @@ static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring,
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static void put_persistent_gnt(struct xen_blkif_ring *ring,
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struct persistent_gnt *persistent_gnt)
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{
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if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
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if (!persistent_gnt->active)
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pr_alert_ratelimited("freeing a grant already unused\n");
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set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
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clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
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persistent_gnt->last_used = jiffies;
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persistent_gnt->active = false;
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atomic_dec(&ring->persistent_gnt_in_use);
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}
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@ -371,26 +389,26 @@ static void purge_persistent_gnt(struct xen_blkif_ring *ring)
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struct persistent_gnt *persistent_gnt;
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struct rb_node *n;
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unsigned int num_clean, total;
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bool scan_used = false, clean_used = false;
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bool scan_used = false;
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struct rb_root *root;
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if (ring->persistent_gnt_c < xen_blkif_max_pgrants ||
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(ring->persistent_gnt_c == xen_blkif_max_pgrants &&
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!ring->blkif->vbd.overflow_max_grants)) {
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goto out;
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}
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if (work_busy(&ring->persistent_purge_work)) {
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pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n");
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goto out;
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}
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num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
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num_clean = ring->persistent_gnt_c - xen_blkif_max_pgrants + num_clean;
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num_clean = min(ring->persistent_gnt_c, num_clean);
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if ((num_clean == 0) ||
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(num_clean > (ring->persistent_gnt_c - atomic_read(&ring->persistent_gnt_in_use))))
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goto out;
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if (ring->persistent_gnt_c < xen_blkif_max_pgrants ||
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(ring->persistent_gnt_c == xen_blkif_max_pgrants &&
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!ring->blkif->vbd.overflow_max_grants)) {
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num_clean = 0;
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} else {
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num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
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num_clean = ring->persistent_gnt_c - xen_blkif_max_pgrants +
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num_clean;
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num_clean = min(ring->persistent_gnt_c, num_clean);
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pr_debug("Going to purge at least %u persistent grants\n",
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num_clean);
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}
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/*
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* At this point, we can assure that there will be no calls
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@ -401,9 +419,7 @@ static void purge_persistent_gnt(struct xen_blkif_ring *ring)
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* number of grants.
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*/
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total = num_clean;
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pr_debug("Going to purge %u persistent grants\n", num_clean);
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total = 0;
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BUG_ON(!list_empty(&ring->persistent_purge_list));
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root = &ring->persistent_gnts;
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@ -412,47 +428,38 @@ purge_list:
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BUG_ON(persistent_gnt->handle ==
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BLKBACK_INVALID_HANDLE);
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if (clean_used) {
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clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
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if (persistent_gnt->active)
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continue;
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}
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if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
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if (!scan_used && !persistent_gnt_timeout(persistent_gnt))
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continue;
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if (!scan_used &&
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(test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags)))
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if (scan_used && total >= num_clean)
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continue;
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rb_erase(&persistent_gnt->node, root);
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list_add(&persistent_gnt->remove_node,
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&ring->persistent_purge_list);
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if (--num_clean == 0)
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goto finished;
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total++;
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}
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/*
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* If we get here it means we also need to start cleaning
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* Check whether we also need to start cleaning
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* grants that were used since last purge in order to cope
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* with the requested num
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*/
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if (!scan_used && !clean_used) {
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pr_debug("Still missing %u purged frames\n", num_clean);
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if (!scan_used && total < num_clean) {
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pr_debug("Still missing %u purged frames\n", num_clean - total);
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scan_used = true;
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goto purge_list;
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}
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finished:
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if (!clean_used) {
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pr_debug("Finished scanning for grants to clean, removing used flag\n");
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clean_used = true;
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goto purge_list;
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if (total) {
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ring->persistent_gnt_c -= total;
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ring->blkif->vbd.overflow_max_grants = 0;
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/* We can defer this work */
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schedule_work(&ring->persistent_purge_work);
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pr_debug("Purged %u/%u\n", num_clean, total);
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}
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ring->persistent_gnt_c -= (total - num_clean);
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ring->blkif->vbd.overflow_max_grants = 0;
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/* We can defer this work */
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schedule_work(&ring->persistent_purge_work);
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pr_debug("Purged %u/%u\n", (total - num_clean), total);
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out:
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return;
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}
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@ -233,16 +233,6 @@ struct xen_vbd {
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struct backend_info;
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/* Number of available flags */
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#define PERSISTENT_GNT_FLAGS_SIZE 2
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/* This persistent grant is currently in use */
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#define PERSISTENT_GNT_ACTIVE 0
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/*
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* This persistent grant has been used, this flag is set when we remove the
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* PERSISTENT_GNT_ACTIVE, to know that this grant has been used recently.
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*/
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#define PERSISTENT_GNT_WAS_ACTIVE 1
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/* Number of requests that we can fit in a ring */
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#define XEN_BLKIF_REQS_PER_PAGE 32
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@ -250,7 +240,8 @@ struct persistent_gnt {
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struct page *page;
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grant_ref_t gnt;
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grant_handle_t handle;
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DECLARE_BITMAP(flags, PERSISTENT_GNT_FLAGS_SIZE);
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unsigned long last_used;
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bool active;
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struct rb_node node;
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struct list_head remove_node;
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};
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@ -278,7 +269,6 @@ struct xen_blkif_ring {
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wait_queue_head_t pending_free_wq;
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/* Tree to store persistent grants. */
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spinlock_t pers_gnts_lock;
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struct rb_root persistent_gnts;
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unsigned int persistent_gnt_c;
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atomic_t persistent_gnt_in_use;
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@ -46,6 +46,7 @@
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#include <linux/scatterlist.h>
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#include <linux/bitmap.h>
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#include <linux/list.h>
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#include <linux/workqueue.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
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@ -121,6 +122,8 @@ static inline struct blkif_req *blkif_req(struct request *rq)
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static DEFINE_MUTEX(blkfront_mutex);
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static const struct block_device_operations xlvbd_block_fops;
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static struct delayed_work blkfront_work;
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static LIST_HEAD(info_list);
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/*
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* Maximum number of segments in indirect requests, the actual value used by
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@ -216,6 +219,7 @@ struct blkfront_info
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/* Save uncomplete reqs and bios for migration. */
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struct list_head requests;
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struct bio_list bio_list;
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struct list_head info_list;
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};
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static unsigned int nr_minors;
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@ -1759,6 +1763,12 @@ abort_transaction:
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return err;
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}
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static void free_info(struct blkfront_info *info)
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{
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list_del(&info->info_list);
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kfree(info);
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}
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/* Common code used when first setting up, and when resuming. */
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static int talk_to_blkback(struct xenbus_device *dev,
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struct blkfront_info *info)
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@ -1880,7 +1890,10 @@ again:
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destroy_blkring:
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blkif_free(info, 0);
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kfree(info);
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mutex_lock(&blkfront_mutex);
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free_info(info);
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mutex_unlock(&blkfront_mutex);
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dev_set_drvdata(&dev->dev, NULL);
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return err;
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@ -1991,6 +2004,10 @@ static int blkfront_probe(struct xenbus_device *dev,
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info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
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dev_set_drvdata(&dev->dev, info);
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mutex_lock(&blkfront_mutex);
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list_add(&info->info_list, &info_list);
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mutex_unlock(&blkfront_mutex);
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return 0;
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}
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@ -2301,6 +2318,12 @@ static void blkfront_gather_backend_features(struct blkfront_info *info)
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if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
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indirect_segments = 0;
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info->max_indirect_segments = indirect_segments;
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if (info->feature_persistent) {
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mutex_lock(&blkfront_mutex);
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schedule_delayed_work(&blkfront_work, HZ * 10);
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mutex_unlock(&blkfront_mutex);
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}
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}
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|
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/*
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@ -2482,7 +2505,9 @@ static int blkfront_remove(struct xenbus_device *xbdev)
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mutex_unlock(&info->mutex);
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if (!bdev) {
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kfree(info);
|
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mutex_lock(&blkfront_mutex);
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free_info(info);
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mutex_unlock(&blkfront_mutex);
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return 0;
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}
|
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|
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@ -2502,7 +2527,9 @@ static int blkfront_remove(struct xenbus_device *xbdev)
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if (info && !bdev->bd_openers) {
|
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xlvbd_release_gendisk(info);
|
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disk->private_data = NULL;
|
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kfree(info);
|
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mutex_lock(&blkfront_mutex);
|
||||
free_info(info);
|
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mutex_unlock(&blkfront_mutex);
|
||||
}
|
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|
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mutex_unlock(&bdev->bd_mutex);
|
||||
@ -2585,7 +2612,7 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
|
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dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
|
||||
xlvbd_release_gendisk(info);
|
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disk->private_data = NULL;
|
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kfree(info);
|
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free_info(info);
|
||||
}
|
||||
|
||||
out:
|
||||
@ -2618,6 +2645,61 @@ static struct xenbus_driver blkfront_driver = {
|
||||
.is_ready = blkfront_is_ready,
|
||||
};
|
||||
|
||||
static void purge_persistent_grants(struct blkfront_info *info)
|
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{
|
||||
unsigned int i;
|
||||
unsigned long flags;
|
||||
|
||||
for (i = 0; i < info->nr_rings; i++) {
|
||||
struct blkfront_ring_info *rinfo = &info->rinfo[i];
|
||||
struct grant *gnt_list_entry, *tmp;
|
||||
|
||||
spin_lock_irqsave(&rinfo->ring_lock, flags);
|
||||
|
||||
if (rinfo->persistent_gnts_c == 0) {
|
||||
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
|
||||
continue;
|
||||
}
|
||||
|
||||
list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
|
||||
node) {
|
||||
if (gnt_list_entry->gref == GRANT_INVALID_REF ||
|
||||
gnttab_query_foreign_access(gnt_list_entry->gref))
|
||||
continue;
|
||||
|
||||
list_del(&gnt_list_entry->node);
|
||||
gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
|
||||
rinfo->persistent_gnts_c--;
|
||||
__free_page(gnt_list_entry->page);
|
||||
kfree(gnt_list_entry);
|
||||
}
|
||||
|
||||
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
|
||||
}
|
||||
}
|
||||
|
||||
static void blkfront_delay_work(struct work_struct *work)
|
||||
{
|
||||
struct blkfront_info *info;
|
||||
bool need_schedule_work = false;
|
||||
|
||||
mutex_lock(&blkfront_mutex);
|
||||
|
||||
list_for_each_entry(info, &info_list, info_list) {
|
||||
if (info->feature_persistent) {
|
||||
need_schedule_work = true;
|
||||
mutex_lock(&info->mutex);
|
||||
purge_persistent_grants(info);
|
||||
mutex_unlock(&info->mutex);
|
||||
}
|
||||
}
|
||||
|
||||
if (need_schedule_work)
|
||||
schedule_delayed_work(&blkfront_work, HZ * 10);
|
||||
|
||||
mutex_unlock(&blkfront_mutex);
|
||||
}
|
||||
|
||||
static int __init xlblk_init(void)
|
||||
{
|
||||
int ret;
|
||||
@ -2626,6 +2708,15 @@ static int __init xlblk_init(void)
|
||||
if (!xen_domain())
|
||||
return -ENODEV;
|
||||
|
||||
if (!xen_has_pv_disk_devices())
|
||||
return -ENODEV;
|
||||
|
||||
if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
|
||||
pr_warn("xen_blk: can't get major %d with name %s\n",
|
||||
XENVBD_MAJOR, DEV_NAME);
|
||||
return -ENODEV;
|
||||
}
|
||||
|
||||
if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
|
||||
xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
|
||||
|
||||
@ -2641,14 +2732,7 @@ static int __init xlblk_init(void)
|
||||
xen_blkif_max_queues = nr_cpus;
|
||||
}
|
||||
|
||||
if (!xen_has_pv_disk_devices())
|
||||
return -ENODEV;
|
||||
|
||||
if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
|
||||
printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
|
||||
XENVBD_MAJOR, DEV_NAME);
|
||||
return -ENODEV;
|
||||
}
|
||||
INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
|
||||
|
||||
ret = xenbus_register_frontend(&blkfront_driver);
|
||||
if (ret) {
|
||||
@ -2663,6 +2747,8 @@ module_init(xlblk_init);
|
||||
|
||||
static void __exit xlblk_exit(void)
|
||||
{
|
||||
cancel_delayed_work_sync(&blkfront_work);
|
||||
|
||||
xenbus_unregister_driver(&blkfront_driver);
|
||||
unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
|
||||
kfree(minors);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user