Skip to content

Commit

Permalink
fs/locks.c: prepare for BKL removal
Browse files Browse the repository at this point in the history 
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 <[email protected]>
Acked-by: Matthew Wilcox <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: "J. Bruce Fields" <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Miklos Szeredi <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Sage Weil <[email protected]>
Cc: [email protected]
Cc: [email protected]
  • Loading branch information
@arndb
arndb committed Oct 5, 2010
1 parent 2e54eb9 commit b89f432
Show file tree
Hide file tree
Showing 8 changed files with 97 additions and 66 deletions.
5 changes: 2 additions & 3 deletions fs/afs/flock.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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;

Expand Down
4 changes: 2 additions & 2 deletions fs/cifs/cifsfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)))
Expand Down
2 changes: 2 additions & 0 deletions fs/gfs2/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
*/

Expand Down
112 changes: 68 additions & 44 deletions fs/locks.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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. */
Expand Down Expand Up @@ -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.
Expand Down Expand Up @@ -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;
Expand All @@ -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);
Expand Down Expand Up @@ -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))
Expand All @@ -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) {
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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.
*/
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -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);

Expand Down Expand Up @@ -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)
Expand All @@ -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;
Expand Down Expand Up @@ -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) {
Expand All @@ -1328,7 +1347,7 @@ int fcntl_getlease(struct file *filp)
break;
}
}
unlock_kernel();
unlock_flocks();
return type;
}

Expand All @@ -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)
{
Expand Down Expand Up @@ -1436,7 +1455,15 @@ 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
* @arg: type of lease to obtain
Expand Down Expand Up @@ -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;
}
Expand All @@ -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;

Expand All @@ -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;
}

Expand Down Expand Up @@ -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) {
Expand All @@ -2038,7 +2062,7 @@ void locks_remove_flock(struct file *filp)
}
before = &fl->fl_next;
}
unlock_kernel();
unlock_flocks();
}

/**
Expand All @@ -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;
}

Expand Down Expand Up @@ -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);
}
Expand All @@ -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 = {
Expand Down Expand Up @@ -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)
Expand All @@ -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;
}

Expand All @@ -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)))
Expand All @@ -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;
}

Expand Down
Loading

0 comments on commit b89f432

Please sign in to comment.