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fs/locks.c: prepare for BKL removal

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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
This commit is contained in:
Arnd Bergmann 2010-09-18 15:09:31 +02:00
parent 2e54eb96e2
commit b89f432133
8 changed files with 97 additions and 66 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
fs/afs/flock.c
View File

@ -9,7 +9,6 @@
* 2 of the License, or (at your option) any later version. * 2 of the License, or (at your option) any later version.
*/ */
#include <linux/smp_lock.h>
#include "internal.h" #include "internal.h"
#define AFS_LOCK_GRANTED 0 #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; 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 /* make sure we've got a callback on this file and that our view of the
* data version is up to date */ * data version is up to date */
@ -421,7 +420,7 @@ given_lock:
afs_vnode_fetch_status(vnode, NULL, key); afs_vnode_fetch_status(vnode, NULL, key);
error: error:
unlock_kernel(); unlock_flocks();
_leave(" = %d", ret); _leave(" = %d", ret);
return ret; return ret;

4
fs/cifs/cifsfs.c
View File

@ -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) 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 /* note that this is called by vfs setlease with lock_flocks held
although I doubt that BKL is needed here in cifs */ to protect *lease from going away */
struct inode *inode = file->f_path.dentry->d_inode; struct inode *inode = file->f_path.dentry->d_inode;
if (!(S_ISREG(inode->i_mode))) if (!(S_ISREG(inode->i_mode)))

2
fs/gfs2/file.c
View File

@ -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), * cluster; until we do, disable leases (by just returning -EINVAL),
* unless the administrator has requested purely local locking. * unless the administrator has requested purely local locking.
* *
* Locking: called under lock_flocks
*
* Returns: errno * Returns: errno
*/ */

112
fs/locks.c
View File

@ -143,6 +143,22 @@ int lease_break_time = 45;
static LIST_HEAD(file_lock_list); static LIST_HEAD(file_lock_list);
static LIST_HEAD(blocked_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; static struct kmem_cache *filelock_cache __read_mostly;
/* Allocate an empty lock structure. */ /* 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) static void locks_delete_block(struct file_lock *waiter)
{ {
lock_kernel(); lock_flocks();
__locks_delete_block(waiter); __locks_delete_block(waiter);
unlock_kernel(); unlock_flocks();
} }
/* Insert waiter into blocker's block list. /* 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; struct file_lock *cfl;
lock_kernel(); lock_flocks();
for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
if (!IS_POSIX(cfl)) if (!IS_POSIX(cfl))
continue; continue;
@ -657,7 +673,7 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
fl->fl_pid = pid_vnr(cfl->fl_nspid); fl->fl_pid = pid_vnr(cfl->fl_nspid);
} else } else
fl->fl_type = F_UNLCK; fl->fl_type = F_UNLCK;
unlock_kernel(); unlock_flocks();
return; return;
} }
EXPORT_SYMBOL(posix_test_lock); 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 error = 0;
int found = 0; int found = 0;
lock_kernel(); if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
new_fl = locks_alloc_lock();
if (!new_fl)
return -ENOMEM;
}
lock_flocks();
if (request->fl_flags & FL_ACCESS) if (request->fl_flags & FL_ACCESS)
goto find_conflict; goto find_conflict;
if (request->fl_type != F_UNLCK) {
error = -ENOMEM;
new_fl = locks_alloc_lock();
if (new_fl == NULL)
goto out;
error = 0;
}
for_each_lock(inode, before) { for_each_lock(inode, before) {
struct file_lock *fl = *before; struct file_lock *fl = *before;
if (IS_POSIX(fl)) 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, * If a higher-priority process was blocked on the old file lock,
* give it the opportunity to lock the file. * give it the opportunity to lock the file.
*/ */
if (found) if (found) {
unlock_flocks();
cond_resched(); cond_resched();
lock_flocks();
}
find_conflict: find_conflict:
for_each_lock(inode, before) { for_each_lock(inode, before) {
@ -794,7 +811,7 @@ find_conflict:
error = 0; error = 0;
out: out:
unlock_kernel(); unlock_flocks();
if (new_fl) if (new_fl)
locks_free_lock(new_fl); locks_free_lock(new_fl);
return error; return error;
@ -823,7 +840,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
new_fl2 = locks_alloc_lock(); new_fl2 = locks_alloc_lock();
} }
lock_kernel(); lock_flocks();
if (request->fl_type != F_UNLCK) { if (request->fl_type != F_UNLCK) {
for_each_lock(inode, before) { for_each_lock(inode, before) {
fl = *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); locks_wake_up_blocks(left);
} }
out: out:
unlock_kernel(); unlock_flocks();
/* /*
* Free any unused locks. * 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. * 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) { for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (!IS_POSIX(fl)) if (!IS_POSIX(fl))
continue; continue;
if (fl->fl_owner != owner) if (fl->fl_owner != owner)
break; break;
} }
unlock_kernel(); unlock_flocks();
return fl ? -EAGAIN : 0; 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); new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
lock_kernel(); lock_flocks();
time_out_leases(inode); time_out_leases(inode);
@ -1247,8 +1264,10 @@ restart:
break_time++; break_time++;
} }
locks_insert_block(flock, new_fl); locks_insert_block(flock, new_fl);
unlock_flocks();
error = wait_event_interruptible_timeout(new_fl->fl_wait, error = wait_event_interruptible_timeout(new_fl->fl_wait,
!new_fl->fl_next, break_time); !new_fl->fl_next, break_time);
lock_flocks();
__locks_delete_block(new_fl); __locks_delete_block(new_fl);
if (error >= 0) { if (error >= 0) {
if (error == 0) if (error == 0)
@ -1263,7 +1282,7 @@ restart:
} }
out: out:
unlock_kernel(); unlock_flocks();
if (!IS_ERR(new_fl)) if (!IS_ERR(new_fl))
locks_free_lock(new_fl); locks_free_lock(new_fl);
return error; return error;
@ -1319,7 +1338,7 @@ int fcntl_getlease(struct file *filp)
struct file_lock *fl; struct file_lock *fl;
int type = F_UNLCK; int type = F_UNLCK;
lock_kernel(); lock_flocks();
time_out_leases(filp->f_path.dentry->d_inode); time_out_leases(filp->f_path.dentry->d_inode);
for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl); for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
fl = fl->fl_next) { fl = fl->fl_next) {
@ -1328,7 +1347,7 @@ int fcntl_getlease(struct file *filp)
break; break;
} }
} }
unlock_kernel(); unlock_flocks();
return type; return type;
} }
@ -1341,7 +1360,7 @@ int fcntl_getlease(struct file *filp)
* The (input) flp->fl_lmops->fl_break function is required * The (input) flp->fl_lmops->fl_break function is required
* by break_lease(). * 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) int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
{ {
@ -1436,7 +1455,15 @@ out:
} }
EXPORT_SYMBOL(generic_setlease); 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 * vfs_setlease - sets a lease on an open file
* @filp: file pointer * @filp: file pointer
* @arg: type of lease to obtain * @arg: type of lease to obtain
@ -1467,12 +1494,9 @@ int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
{ {
int error; int error;
lock_kernel(); lock_flocks();
if (filp->f_op && filp->f_op->setlease) error = __vfs_setlease(filp, arg, lease);
error = filp->f_op->setlease(filp, arg, lease); unlock_flocks();
else
error = generic_setlease(filp, arg, lease);
unlock_kernel();
return error; return error;
} }
@ -1499,9 +1523,9 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
if (error) if (error)
return error; return error;
lock_kernel(); lock_flocks();
error = vfs_setlease(filp, arg, &flp); error = __vfs_setlease(filp, arg, &flp);
if (error || arg == F_UNLCK) if (error || arg == F_UNLCK)
goto out_unlock; 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); error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
out_unlock: out_unlock:
unlock_kernel(); unlock_flocks();
return error; return error;
} }
@ -2020,7 +2044,7 @@ void locks_remove_flock(struct file *filp)
fl.fl_ops->fl_release_private(&fl); fl.fl_ops->fl_release_private(&fl);
} }
lock_kernel(); lock_flocks();
before = &inode->i_flock; before = &inode->i_flock;
while ((fl = *before) != NULL) { while ((fl = *before) != NULL) {
@ -2038,7 +2062,7 @@ void locks_remove_flock(struct file *filp)
} }
before = &fl->fl_next; 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; int status = 0;
lock_kernel(); lock_flocks();
if (waiter->fl_next) if (waiter->fl_next)
__locks_delete_block(waiter); __locks_delete_block(waiter);
else else
status = -ENOENT; status = -ENOENT;
unlock_kernel(); unlock_flocks();
return status; 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) static void *locks_start(struct seq_file *f, loff_t *pos)
{ {
lock_kernel(); lock_flocks();
f->private = (void *)1; f->private = (void *)1;
return seq_list_start(&file_lock_list, *pos); 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) static void locks_stop(struct seq_file *f, void *v)
{ {
unlock_kernel(); unlock_flocks();
} }
static const struct seq_operations locks_seq_operations = { 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; struct file_lock *fl;
int result = 1; int result = 1;
lock_kernel(); lock_flocks();
for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (IS_POSIX(fl)) { if (IS_POSIX(fl)) {
if (fl->fl_type == F_RDLCK) 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; result = 0;
break; break;
} }
unlock_kernel(); unlock_flocks();
return result; return result;
} }
@ -2271,7 +2295,7 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
{ {
struct file_lock *fl; struct file_lock *fl;
int result = 1; int result = 1;
lock_kernel(); lock_flocks();
for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (IS_POSIX(fl)) { if (IS_POSIX(fl)) {
if ((fl->fl_end < start) || (fl->fl_start > (start + len))) 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; result = 0;
break; break;
} }
unlock_kernel(); unlock_flocks();
return result; return result;
} }

10
fs/nfs/delegation.c
View File

@ -71,20 +71,20 @@ static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_
if (inode->i_flock == NULL) if (inode->i_flock == NULL)
goto out; goto out;
/* Protect inode->i_flock using the BKL */ /* Protect inode->i_flock using the file locks lock */
lock_kernel(); lock_flocks();
for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK))) if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
continue; continue;
if (nfs_file_open_context(fl->fl_file) != ctx) if (nfs_file_open_context(fl->fl_file) != ctx)
continue; continue;
unlock_kernel(); unlock_flocks();
status = nfs4_lock_delegation_recall(state, fl); status = nfs4_lock_delegation_recall(state, fl);
if (status < 0) if (status < 0)
goto out; goto out;
lock_kernel(); lock_flocks();
} }
unlock_kernel(); unlock_flocks();
out: out:
return status; return status;
} }

10
fs/nfs/nfs4state.c
View File

@ -40,7 +40,7 @@
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/smp_lock.h> #include <linux/fs.h>
#include <linux/nfs_fs.h> #include <linux/nfs_fs.h>
#include <linux/nfs_idmap.h> #include <linux/nfs_idmap.h>
#include <linux/kthread.h> #include <linux/kthread.h>
@ -970,13 +970,13 @@ static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_
/* Guard against delegation returns and new lock/unlock calls */ /* Guard against delegation returns and new lock/unlock calls */
down_write(&nfsi->rwsem); down_write(&nfsi->rwsem);
/* Protect inode->i_flock using the BKL */ /* Protect inode->i_flock using the BKL */
lock_kernel(); lock_flocks();
for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK))) if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
continue; continue;
if (nfs_file_open_context(fl->fl_file)->state != state) if (nfs_file_open_context(fl->fl_file)->state != state)
continue; continue;
unlock_kernel(); unlock_flocks();
status = ops->recover_lock(state, fl); status = ops->recover_lock(state, fl);
switch (status) { switch (status) {
case 0: case 0:
@ -1003,9 +1003,9 @@ static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_
/* kill_proc(fl->fl_pid, SIGLOST, 1); */ /* kill_proc(fl->fl_pid, SIGLOST, 1); */
status = 0; status = 0;
} }
lock_kernel(); lock_flocks();
} }
unlock_kernel(); unlock_flocks();
out: out:
up_write(&nfsi->rwsem); up_write(&nfsi->rwsem);
return status; return status;

6
fs/nfsd/nfs4state.c
View File

@ -33,7 +33,7 @@
*/ */
#include <linux/file.h> #include <linux/file.h>
#include <linux/smp_lock.h> #include <linux/fs.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/namei.h> #include <linux/namei.h>
#include <linux/swap.h> #include <linux/swap.h>
@ -3895,7 +3895,7 @@ check_for_locks(struct nfs4_file *filp, struct nfs4_stateowner *lowner)
struct inode *inode = filp->fi_inode; struct inode *inode = filp->fi_inode;
int status = 0; int status = 0;
lock_kernel(); lock_flocks();
for (flpp = &inode->i_flock; *flpp != NULL; flpp = &(*flpp)->fl_next) { for (flpp = &inode->i_flock; *flpp != NULL; flpp = &(*flpp)->fl_next) {
if ((*flpp)->fl_owner == (fl_owner_t)lowner) { if ((*flpp)->fl_owner == (fl_owner_t)lowner) {
status = 1; status = 1;
@ -3903,7 +3903,7 @@ check_for_locks(struct nfs4_file *filp, struct nfs4_stateowner *lowner)
} }
} }
out: out:
unlock_kernel(); unlock_flocks();
return status; return status;
} }

14
include/linux/fs.h
View File

@ -1093,10 +1093,6 @@ struct file_lock {
#include <linux/fcntl.h> #include <linux/fcntl.h>
/* temporary stubs for BKL removal */
#define lock_flocks() lock_kernel()
#define unlock_flocks() unlock_kernel()
extern void send_sigio(struct fown_struct *fown, int fd, int band); extern void send_sigio(struct fown_struct *fown, int fd, int band);
#ifdef CONFIG_FILE_LOCKING #ifdef CONFIG_FILE_LOCKING
@ -1135,6 +1131,8 @@ extern int vfs_setlease(struct file *, long, struct file_lock **);
extern int lease_modify(struct file_lock **, int); extern int lease_modify(struct file_lock **, int);
extern int lock_may_read(struct inode *, loff_t start, unsigned long count); extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
extern int lock_may_write(struct inode *, loff_t start, unsigned long count); extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
extern void lock_flocks(void);
extern void unlock_flocks(void);
#else /* !CONFIG_FILE_LOCKING */ #else /* !CONFIG_FILE_LOCKING */
static inline int fcntl_getlk(struct file *file, struct flock __user *user) static inline int fcntl_getlk(struct file *file, struct flock __user *user)
{ {
@ -1277,6 +1275,14 @@ static inline int lock_may_write(struct inode *inode, loff_t start,
return 1; return 1;
} }
static inline void lock_flocks(void)
{
}
static inline void unlock_flocks(void)
{
}
#endif /* !CONFIG_FILE_LOCKING */ #endif /* !CONFIG_FILE_LOCKING */