Commit-ID: 7c3f654d8e18942295eeda42f7d75494443980e0
Gitweb: http://git.kernel.org/tip/7c3f654d8e18942295eeda42f7d75494443980e0
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 22 Jun 2015 14:16:34 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 22 Sep 2016 15:25:53 +0200
fs/locks: Replace lg_local with a per-cpu spinlock
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@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: dave@xxxxxxxxxxxx
Cc: der.herr@xxxxxxx
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Cc: riel@xxxxxxxxxx
Cc: tj@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
fs/Kconfig | 1 +
fs/locks.c | 47 +++++++++++++++++++++++++++++------------------
2 files changed, 30 insertions(+), 18 deletions(-)
diff --git a/fs/Kconfig b/fs/Kconfig
index 2bc7ad7..3ef62ba 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -79,6 +79,7 @@ config EXPORTFS_BLOCK_OPS
config FILE_LOCKING
bool "Enable POSIX file locking API" if EXPERT
default y
+ select PERCPU_RWSEM
help
This option enables standard file locking support, required
for filesystems like NFS and for the flock() system
diff --git a/fs/locks.c b/fs/locks.c
index 8f609ec..c33aa77 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -127,7 +127,6 @@
#include <linux/pid_namespace.h>
#include <linux/hashtable.h>
#include <linux/percpu.h>
-#include <linux/lglock.h>
#define CREATE_TRACE_POINTS
#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
- * keep a list on each CPU, with each list protected by its own spinlock via
- * the file_lock_lglock. Note that alterations to the list also require that
- * the relevant flc_lock is held.
+ * keep a list on each CPU, with each list protected by its own spinlock.
+ * Global serialization is done using file_rwsem.
+ *
+ * Note that alterations to the list also require that the relevant flc_lock is
+ * held.
*/
-DEFINE_STATIC_LGLOCK(file_lock_lglock);
-static DEFINE_PER_CPU(struct hlist_head, file_lock_list);
+struct file_lock_list_struct {
+ 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);
/*
@@ -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! */
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);
- lg_local_lock(&file_lock_lglock);
+ spin_lock(&fll->lock);
fl->fl_link_cpu = smp_processor_id();
- hlist_add_head(&fl->fl_link, this_cpu_ptr(&file_lock_list));
- lg_local_unlock(&file_lock_lglock);
+ hlist_add_head(&fl->fl_link, &fll->hlist);
+ spin_unlock(&fll->lock);
}
/* Must be called with the flc_lock held! */
static void locks_delete_global_locks(struct file_lock *fl)
{
+ struct file_lock_list_struct *fll;
+
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))
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);
- lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu);
+ spin_unlock(&fll->lock);
}
static unsigned long
@@ -2723,9 +2733,8 @@ static void *locks_start(struct seq_file *f, loff_t *pos)
iter->li_pos = *pos + 1;
percpu_down_write(&file_rwsem);
- lg_global_lock(&file_lock_lglock);
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)
@@ -2733,14 +2742,13 @@ static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
struct locks_iterator *iter = f->private;
++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)
__releases(&blocked_lock_lock)
{
spin_unlock(&blocked_lock_lock);
- lg_global_unlock(&file_lock_lglock);
percpu_up_write(&file_rwsem);
}
@@ -2782,10 +2790,13 @@ static int __init filelock_init(void)
filelock_cache = kmem_cache_create("file_lock_cache",
sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
- lg_lock_init(&file_lock_lglock, "file_lock_lglock");
- for_each_possible_cpu(i)
- INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i));
+ for_each_possible_cpu(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;
}
--
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