From 3cb5977c5214c219b2859f926ed547480d53fdde Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Tue, 2 Nov 2021 15:17:18 -0400 Subject: [PATCH] fs: dlm: ls_count busy wait to event based wait This patch changes the ls_count busy wait to use atomic counter values and wait_event() to wait until ls_count reach zero. It will slightly reduce the number of holding lslist_lock. At remove lockspace we need to retry the wait because it a lockspace get could interefere between wait_event() and holding the lock which deletes the lockspace list entry. Signed-off-by: Alexander Aring Signed-off-by: David Teigland --- fs/dlm/dlm_internal.h | 3 ++- fs/dlm/lockspace.c | 33 +++++++++++++++++---------------- fs/dlm/requestqueue.c | 2 +- 3 files changed, 20 insertions(+), 18 deletions(-) diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h index fd1c7a8c4485..019931804af9 100644 --- a/fs/dlm/dlm_internal.h +++ b/fs/dlm/dlm_internal.h @@ -548,8 +548,9 @@ struct dlm_ls { uint32_t ls_generation; uint32_t ls_exflags; int ls_lvblen; - int ls_count; /* refcount of processes in + atomic_t ls_count; /* refcount of processes in the dlm using this ls */ + wait_queue_head_t ls_count_wait; int ls_create_count; /* create/release refcount */ unsigned long ls_flags; /* LSFL_ */ unsigned long ls_scan_time; diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c index 4e4181304ca1..2e51bd2bdacc 100644 --- a/fs/dlm/lockspace.c +++ b/fs/dlm/lockspace.c @@ -314,7 +314,7 @@ struct dlm_ls *dlm_find_lockspace_global(uint32_t id) list_for_each_entry(ls, &lslist, ls_list) { if (ls->ls_global_id == id) { - ls->ls_count++; + atomic_inc(&ls->ls_count); goto out; } } @@ -331,7 +331,7 @@ struct dlm_ls *dlm_find_lockspace_local(dlm_lockspace_t *lockspace) spin_lock(&lslist_lock); list_for_each_entry(ls, &lslist, ls_list) { if (ls->ls_local_handle == lockspace) { - ls->ls_count++; + atomic_inc(&ls->ls_count); goto out; } } @@ -348,7 +348,7 @@ struct dlm_ls *dlm_find_lockspace_device(int minor) spin_lock(&lslist_lock); list_for_each_entry(ls, &lslist, ls_list) { if (ls->ls_device.minor == minor) { - ls->ls_count++; + atomic_inc(&ls->ls_count); goto out; } } @@ -360,24 +360,24 @@ struct dlm_ls *dlm_find_lockspace_device(int minor) void dlm_put_lockspace(struct dlm_ls *ls) { - spin_lock(&lslist_lock); - ls->ls_count--; - spin_unlock(&lslist_lock); + if (atomic_dec_and_test(&ls->ls_count)) + wake_up(&ls->ls_count_wait); } static void remove_lockspace(struct dlm_ls *ls) { - for (;;) { - spin_lock(&lslist_lock); - if (ls->ls_count == 0) { - WARN_ON(ls->ls_create_count != 0); - list_del(&ls->ls_list); - spin_unlock(&lslist_lock); - return; - } +retry: + wait_event(ls->ls_count_wait, atomic_read(&ls->ls_count) == 0); + + spin_lock(&lslist_lock); + if (atomic_read(&ls->ls_count) != 0) { spin_unlock(&lslist_lock); - ssleep(1); + goto retry; } + + WARN_ON(ls->ls_create_count != 0); + list_del(&ls->ls_list); + spin_unlock(&lslist_lock); } static int threads_start(void) @@ -481,7 +481,8 @@ static int new_lockspace(const char *name, const char *cluster, memcpy(ls->ls_name, name, namelen); ls->ls_namelen = namelen; ls->ls_lvblen = lvblen; - ls->ls_count = 0; + atomic_set(&ls->ls_count, 0); + init_waitqueue_head(&ls->ls_count_wait); ls->ls_flags = 0; ls->ls_scan_time = jiffies; diff --git a/fs/dlm/requestqueue.c b/fs/dlm/requestqueue.c index d0cf68570dcf..ccb5307c21e9 100644 --- a/fs/dlm/requestqueue.c +++ b/fs/dlm/requestqueue.c @@ -127,7 +127,7 @@ static int purge_request(struct dlm_ls *ls, struct dlm_message *ms, int nodeid) uint32_t type = ms->m_type; /* the ls is being cleaned up and freed by release_lockspace */ - if (!ls->ls_count) + if (!atomic_read(&ls->ls_count)) return 1; if (dlm_is_removed(ls, nodeid))