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fs/locks: Replace lg_local with a per-cpu spinlock

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As Oleg suggested, replace file_lock_list with a structure containing
the hlist head and a spinlock.

This completely removes the lglock from fs/locks.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: der.herr@hofr.at
Cc: paulmck@linux.vnet.ibm.com
Cc: riel@redhat.com
Cc: tj@kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2015-06-22 14:16:34 +02:00 committed by Ingo Molnar
parent aba3766073
commit 7c3f654d8e
2 changed files with 30 additions and 18 deletions
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1
fs/Kconfig
View File

@ -79,6 +79,7 @@ config EXPORTFS_BLOCK_OPS
config FILE_LOCKING config FILE_LOCKING
bool "Enable POSIX file locking API" if EXPERT bool "Enable POSIX file locking API" if EXPERT
default y default y
select PERCPU_RWSEM
help help
This option enables standard file locking support, required This option enables standard file locking support, required
for filesystems like NFS and for the flock() system for filesystems like NFS and for the flock() system

47
fs/locks.c
View File

@ -127,7 +127,6 @@
#include <linux/pid_namespace.h> #include <linux/pid_namespace.h>
#include <linux/hashtable.h> #include <linux/hashtable.h>
#include <linux/percpu.h> #include <linux/percpu.h>
#include <linux/lglock.h>
#define CREATE_TRACE_POINTS #define CREATE_TRACE_POINTS
#include <trace/events/filelock.h> #include <trace/events/filelock.h>
@ -158,12 +157,17 @@ int lease_break_time = 45;
/* /*
* The global file_lock_list is only used for displaying /proc/locks, so we * The global file_lock_list is only used for displaying /proc/locks, so we
* keep a list on each CPU, with each list protected by its own spinlock via * keep a list on each CPU, with each list protected by its own spinlock.
* the file_lock_lglock. Note that alterations to the list also require that * Global serialization is done using file_rwsem.
* the relevant flc_lock is held. *
* Note that alterations to the list also require that the relevant flc_lock is
* held.
*/ */
DEFINE_STATIC_LGLOCK(file_lock_lglock); struct file_lock_list_struct {
static DEFINE_PER_CPU(struct hlist_head, file_lock_list); spinlock_t lock;
struct hlist_head hlist;
};
static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
DEFINE_STATIC_PERCPU_RWSEM(file_rwsem); DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
/* /*
@ -588,17 +592,21 @@ static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
/* Must be called with the flc_lock held! */ /* Must be called with the flc_lock held! */
static void locks_insert_global_locks(struct file_lock *fl) static void locks_insert_global_locks(struct file_lock *fl)
{ {
struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
percpu_rwsem_assert_held(&file_rwsem); percpu_rwsem_assert_held(&file_rwsem);
lg_local_lock(&file_lock_lglock); spin_lock(&fll->lock);
fl->fl_link_cpu = smp_processor_id(); fl->fl_link_cpu = smp_processor_id();
hlist_add_head(&fl->fl_link, this_cpu_ptr(&file_lock_list)); hlist_add_head(&fl->fl_link, &fll->hlist);
lg_local_unlock(&file_lock_lglock); spin_unlock(&fll->lock);
} }
/* Must be called with the flc_lock held! */ /* Must be called with the flc_lock held! */
static void locks_delete_global_locks(struct file_lock *fl) static void locks_delete_global_locks(struct file_lock *fl)
{ {
struct file_lock_list_struct *fll;
percpu_rwsem_assert_held(&file_rwsem); percpu_rwsem_assert_held(&file_rwsem);
/* /*
@ -608,9 +616,11 @@ static void locks_delete_global_locks(struct file_lock *fl)
*/ */
if (hlist_unhashed(&fl->fl_link)) if (hlist_unhashed(&fl->fl_link))
return; return;
lg_local_lock_cpu(&file_lock_lglock, fl->fl_link_cpu);
fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu);
spin_lock(&fll->lock);
hlist_del_init(&fl->fl_link); hlist_del_init(&fl->fl_link);
lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu); spin_unlock(&fll->lock);
} }
static unsigned long static unsigned long
@ -2723,9 +2733,8 @@ static void *locks_start(struct seq_file *f, loff_t *pos)
iter->li_pos = *pos + 1; iter->li_pos = *pos + 1;
percpu_down_write(&file_rwsem); percpu_down_write(&file_rwsem);
lg_global_lock(&file_lock_lglock);
spin_lock(&blocked_lock_lock); spin_lock(&blocked_lock_lock);
return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos); return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
} }
static void *locks_next(struct seq_file *f, void *v, loff_t *pos) static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
@ -2733,14 +2742,13 @@ static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
struct locks_iterator *iter = f->private; struct locks_iterator *iter = f->private;
++iter->li_pos; ++iter->li_pos;
return seq_hlist_next_percpu(v, &file_lock_list, &iter->li_cpu, pos); return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
} }
static void locks_stop(struct seq_file *f, void *v) static void locks_stop(struct seq_file *f, void *v)
__releases(&blocked_lock_lock) __releases(&blocked_lock_lock)
{ {
spin_unlock(&blocked_lock_lock); spin_unlock(&blocked_lock_lock);
lg_global_unlock(&file_lock_lglock);
percpu_up_write(&file_rwsem); percpu_up_write(&file_rwsem);
} }
@ -2782,10 +2790,13 @@ static int __init filelock_init(void)
filelock_cache = kmem_cache_create("file_lock_cache", filelock_cache = kmem_cache_create("file_lock_cache",
sizeof(struct file_lock), 0, SLAB_PANIC, NULL); sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
lg_lock_init(&file_lock_lglock, "file_lock_lglock");
for_each_possible_cpu(i) for_each_possible_cpu(i) {
INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i)); struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
spin_lock_init(&fll->lock);
INIT_HLIST_HEAD(&fll->hlist);
}
return 0; return 0;
} }