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.
Cc: Al Viro <v...@zeniv.linux.org.uk>
Suggested-by: Oleg Nesterov <o...@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
fs/Kconfig | 1 +
fs/locks.c | 47 +++++++++++++++++++++++++++++------------------
2 files changed, 30 insertions(+), 18 deletions(-)
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -65,6 +65,7 @@ config EXPORTFS
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
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -128,7 +128,6 @@
#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>
@@ -159,12 +158,17 @@ 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);
static struct percpu_rw_semaphore file_rwsem;
/*
@@ -557,17 +561,21 @@ static int posix_same_owner(struct file_
/* 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);
+
lockdep_assert_held_percpu_rwsem(&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;
+
lockdep_assert_held_percpu_rwsem(&file_rwsem);
/*
@@ -577,9 +585,11 @@ static void locks_delete_global_locks(st
*/
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
@@ -2650,9 +2660,8 @@ static void *locks_start(struct seq_file
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)
@@ -2660,14 +2669,13 @@ static void *locks_next(struct seq_file
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);
}
@@ -2709,11 +2717,14 @@ 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");
percpu_init_rwsem(&file_rwsem);
- 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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