fs/locks.c: prepare for BKL removal
This prepares the removal of the big kernel lock from the
file locking code. We still use the BKL as long as fs/lockd
uses it and ceph might sleep, but we can flip the definition
to a private spinlock as soon as that's done.
All users outside of fs/lockd get converted to use
lock_flocks() instead of lock_kernel() where appropriate.
Based on an earlier patch to use a spinlock from Matthew
Wilcox, who has attempted this a few times before, the
earliest patch from over 10 years ago turned it into
a semaphore, which ended up being slower than the BKL
and was subsequently reverted.
Someone should do some serious performance testing when
this becomes a spinlock, since this has caused problems
before. Using a spinlock should be at least as good
as the BKL in theory, but who knows...
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Sage Weil <sage@newdream.net>
Cc: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 3e2f19b..96524c5 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -40,7 +40,7 @@
#include <linux/kernel.h>
#include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/fs.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_idmap.h>
#include <linux/kthread.h>
@@ -970,13 +970,13 @@
/* Guard against delegation returns and new lock/unlock calls */
down_write(&nfsi->rwsem);
/* Protect inode->i_flock using the BKL */
- lock_kernel();
+ lock_flocks();
for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
continue;
if (nfs_file_open_context(fl->fl_file)->state != state)
continue;
- unlock_kernel();
+ unlock_flocks();
status = ops->recover_lock(state, fl);
switch (status) {
case 0:
@@ -1003,9 +1003,9 @@
/* kill_proc(fl->fl_pid, SIGLOST, 1); */
status = 0;
}
- lock_kernel();
+ lock_flocks();
}
- unlock_kernel();
+ unlock_flocks();
out:
up_write(&nfsi->rwsem);
return status;