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Commit b89f4321 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

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: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarMatthew 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
parent 2e54eb96

fs/afs/flock.c

+2 −3
Original line number Diff line number Diff line
@@ -9,7 +9,6 @@ 
 * 2 of the License, or (at your option) any later version.

 */



#include <linux/smp_lock.h>

#include "internal.h"



#define AFS_LOCK_GRANTED	0
@@ -274,7 +273,7 @@ static int afs_do_setlk(struct file *file, struct file_lock *fl) 


	type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;



	lock_kernel();

	lock_flocks();



	/* make sure we've got a callback on this file and that our view of the

	 * data version is up to date */
@@ -421,7 +420,7 @@ static int afs_do_setlk(struct file *file, struct file_lock *fl) 
	afs_vnode_fetch_status(vnode, NULL, key);



error:

	unlock_kernel();

	unlock_flocks();

	_leave(" = %d", ret);

	return ret;

fs/cifs/cifsfs.c

+2 −2
Original line number Diff line number Diff line
@@ -562,8 +562,8 @@ static loff_t cifs_llseek(struct file *file, loff_t offset, int origin) 


static int cifs_setlease(struct file *file, long arg, struct file_lock **lease)

{

	/* note that this is called by vfs setlease with the BKL held

	   although I doubt that BKL is needed here in cifs */

	/* note that this is called by vfs setlease with lock_flocks held

	   to protect *lease from going away */

	struct inode *inode = file->f_path.dentry->d_inode;



	if (!(S_ISREG(inode->i_mode)))

fs/gfs2/file.c

+2 −0
Original line number Diff line number Diff line
@@ -620,6 +620,8 @@ static ssize_t gfs2_file_aio_write(struct kiocb *iocb, const struct iovec *iov, 
 * cluster; until we do, disable leases (by just returning -EINVAL),

 * unless the administrator has requested purely local locking.

 *

 * Locking: called under lock_flocks

 *

 * Returns: errno

 */

fs/locks.c

+68 −44
Original line number Diff line number Diff line
@@ -143,6 +143,22 @@ int lease_break_time = 45; 
static LIST_HEAD(file_lock_list);

static LIST_HEAD(blocked_list);



/*

 * Protects the two list heads above, plus the inode->i_flock list

 * FIXME: should use a spinlock, once lockd and ceph are ready.

 */

void lock_flocks(void)

{

	lock_kernel();

}

EXPORT_SYMBOL_GPL(lock_flocks);



void unlock_flocks(void)

{

	unlock_kernel();

}

EXPORT_SYMBOL_GPL(unlock_flocks);



static struct kmem_cache *filelock_cache __read_mostly;



/* Allocate an empty lock structure. */
@@ -511,9 +527,9 @@ static void __locks_delete_block(struct file_lock *waiter) 
 */

static void locks_delete_block(struct file_lock *waiter)

{

	lock_kernel();

	lock_flocks();

	__locks_delete_block(waiter);

	unlock_kernel();

	unlock_flocks();

}



/* Insert waiter into blocker's block list.
@@ -644,7 +660,7 @@ posix_test_lock(struct file *filp, struct file_lock *fl) 
{

	struct file_lock *cfl;



	lock_kernel();

	lock_flocks();

	for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {

		if (!IS_POSIX(cfl))

			continue;
@@ -657,7 +673,7 @@ posix_test_lock(struct file *filp, struct file_lock *fl) 
			fl->fl_pid = pid_vnr(cfl->fl_nspid);

	} else

		fl->fl_type = F_UNLCK;

	unlock_kernel();

	unlock_flocks();

	return;

}

EXPORT_SYMBOL(posix_test_lock);
@@ -730,18 +746,16 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) 
	int error = 0;

	int found = 0;



	lock_kernel();

	if (request->fl_flags & FL_ACCESS)

		goto find_conflict;



	if (request->fl_type != F_UNLCK) {

		error = -ENOMEM;

	if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {

		new_fl = locks_alloc_lock();

		if (new_fl == NULL)

			goto out;

		error = 0;

		if (!new_fl)

			return -ENOMEM;

	}



	lock_flocks();

	if (request->fl_flags & FL_ACCESS)

		goto find_conflict;



	for_each_lock(inode, before) {

		struct file_lock *fl = *before;

		if (IS_POSIX(fl))
@@ -767,8 +781,11 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) 
	 * If a higher-priority process was blocked on the old file lock,

	 * give it the opportunity to lock the file.

	 */

	if (found)

	if (found) {

		unlock_flocks();

		cond_resched();

		lock_flocks();

	}



find_conflict:

	for_each_lock(inode, before) {
@@ -794,7 +811,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) 
	error = 0;



out:

	unlock_kernel();

	unlock_flocks();

	if (new_fl)

		locks_free_lock(new_fl);

	return error;
@@ -823,7 +840,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str 
		new_fl2 = locks_alloc_lock();

	}



	lock_kernel();

	lock_flocks();

	if (request->fl_type != F_UNLCK) {

		for_each_lock(inode, before) {

			fl = *before;
@@ -991,7 +1008,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str 
		locks_wake_up_blocks(left);

	}

 out:

	unlock_kernel();

	unlock_flocks();

	/*

	 * Free any unused locks.

	 */
@@ -1066,14 +1083,14 @@ int locks_mandatory_locked(struct inode *inode) 
	/*

	 * Search the lock list for this inode for any POSIX locks.

	 */

	lock_kernel();

	lock_flocks();

	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {

		if (!IS_POSIX(fl))

			continue;

		if (fl->fl_owner != owner)

			break;

	}

	unlock_kernel();

	unlock_flocks();

	return fl ? -EAGAIN : 0;

}
@@ -1186,7 +1203,7 @@ int __break_lease(struct inode *inode, unsigned int mode) 


	new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);



	lock_kernel();

	lock_flocks();



	time_out_leases(inode);
@@ -1247,8 +1264,10 @@ int __break_lease(struct inode *inode, unsigned int mode) 
			break_time++;

	}

	locks_insert_block(flock, new_fl);

	unlock_flocks();

	error = wait_event_interruptible_timeout(new_fl->fl_wait,

						!new_fl->fl_next, break_time);

	lock_flocks();

	__locks_delete_block(new_fl);

	if (error >= 0) {

		if (error == 0)
@@ -1263,7 +1282,7 @@ int __break_lease(struct inode *inode, unsigned int mode) 
	}



out:

	unlock_kernel();

	unlock_flocks();

	if (!IS_ERR(new_fl))

		locks_free_lock(new_fl);

	return error;
@@ -1319,7 +1338,7 @@ int fcntl_getlease(struct file *filp) 
	struct file_lock *fl;

	int type = F_UNLCK;



	lock_kernel();

	lock_flocks();

	time_out_leases(filp->f_path.dentry->d_inode);

	for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);

			fl = fl->fl_next) {
@@ -1328,7 +1347,7 @@ int fcntl_getlease(struct file *filp) 
			break;

		}

	}

	unlock_kernel();

	unlock_flocks();

	return type;

}
@@ -1341,7 +1360,7 @@ int fcntl_getlease(struct file *filp) 
 *	The (input) flp->fl_lmops->fl_break function is required

 *	by break_lease().

 *

 *	Called with kernel lock held.

 *	Called with file_lock_lock held.

 */

int generic_setlease(struct file *filp, long arg, struct file_lock **flp)

{
@@ -1436,6 +1455,14 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp) 
}

EXPORT_SYMBOL(generic_setlease);



static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)

{

	if (filp->f_op && filp->f_op->setlease)

		return filp->f_op->setlease(filp, arg, lease);

	else

		return generic_setlease(filp, arg, lease);

}



/**

 *	vfs_setlease        -       sets a lease on an open file

 *	@filp: file pointer
@@ -1467,12 +1494,9 @@ int vfs_setlease(struct file *filp, long arg, struct file_lock **lease) 
{

	int error;



	lock_kernel();

	if (filp->f_op && filp->f_op->setlease)

		error = filp->f_op->setlease(filp, arg, lease);

	else

		error = generic_setlease(filp, arg, lease);

	unlock_kernel();

	lock_flocks();

	error = __vfs_setlease(filp, arg, lease);

	unlock_flocks();



	return error;

}
@@ -1499,9 +1523,9 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg) 
	if (error)

		return error;



	lock_kernel();

	lock_flocks();



	error = vfs_setlease(filp, arg, &flp);

	error = __vfs_setlease(filp, arg, &flp);

	if (error || arg == F_UNLCK)

		goto out_unlock;
@@ -1516,7 +1540,7 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg) 


	error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);

out_unlock:

	unlock_kernel();

	unlock_flocks();

	return error;

}
@@ -2020,7 +2044,7 @@ void locks_remove_flock(struct file *filp) 
			fl.fl_ops->fl_release_private(&fl);

	}



	lock_kernel();

	lock_flocks();

	before = &inode->i_flock;



	while ((fl = *before) != NULL) {
@@ -2038,7 +2062,7 @@ void locks_remove_flock(struct file *filp) 
 		}

		before = &fl->fl_next;

	}

	unlock_kernel();

	unlock_flocks();

}



/**
@@ -2053,12 +2077,12 @@ posix_unblock_lock(struct file *filp, struct file_lock *waiter) 
{

	int status = 0;



	lock_kernel();

	lock_flocks();

	if (waiter->fl_next)

		__locks_delete_block(waiter);

	else

		status = -ENOENT;

	unlock_kernel();

	unlock_flocks();

	return status;

}
@@ -2172,7 +2196,7 @@ static int locks_show(struct seq_file *f, void *v) 


static void *locks_start(struct seq_file *f, loff_t *pos)

{

	lock_kernel();

	lock_flocks();

	f->private = (void *)1;

	return seq_list_start(&file_lock_list, *pos);

}
@@ -2184,7 +2208,7 @@ static void *locks_next(struct seq_file *f, void *v, loff_t *pos) 


static void locks_stop(struct seq_file *f, void *v)

{

	unlock_kernel();

	unlock_flocks();

}



static const struct seq_operations locks_seq_operations = {
@@ -2231,7 +2255,7 @@ int lock_may_read(struct inode *inode, loff_t start, unsigned long len) 
{

	struct file_lock *fl;

	int result = 1;

	lock_kernel();

	lock_flocks();

	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {

		if (IS_POSIX(fl)) {

			if (fl->fl_type == F_RDLCK)
@@ -2248,7 +2272,7 @@ int lock_may_read(struct inode *inode, loff_t start, unsigned long len) 
		result = 0;

		break;

	}

	unlock_kernel();

	unlock_flocks();

	return result;

}
@@ -2271,7 +2295,7 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len) 
{

	struct file_lock *fl;

	int result = 1;

	lock_kernel();

	lock_flocks();

	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {

		if (IS_POSIX(fl)) {

			if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
@@ -2286,7 +2310,7 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len) 
		result = 0;

		break;

	}

	unlock_kernel();

	unlock_flocks();

	return result;

}

fs/nfs/delegation.c

+5 −5
Original line number Diff line number Diff line
@@ -71,20 +71,20 @@ static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_ 
	if (inode->i_flock == NULL)

		goto out;



	/* Protect inode->i_flock using the BKL */

	lock_kernel();

	/* Protect inode->i_flock using the file locks lock */

	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) != ctx)

			continue;

		unlock_kernel();

		unlock_flocks();

		status = nfs4_lock_delegation_recall(state, fl);

		if (status < 0)

			goto out;

		lock_kernel();

		lock_flocks();

	}

	unlock_kernel();

	unlock_flocks();

out:

	return status;

}