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Date: Thu, 08 May 2008 11:24:59 +0800
From: "Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
To: Matthew Wilcox <matthew@....cx>
Cc: Ingo Molnar <mingo@...e.hu>,
"J. Bruce Fields" <bfields@...i.umich.edu>,
LKML <linux-kernel@...r.kernel.org>,
Alexander Viro <viro@....linux.org.uk>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-fsdevel@...r.kernel.org
Subject: Re: AIM7 40% regression with 2.6.26-rc1
On Tue, 2008-05-06 at 10:23 -0600, Matthew Wilcox wrote:
> On Tue, May 06, 2008 at 06:09:34AM -0600, Matthew Wilcox wrote:
> > So the only likely things I can see are:
> >
> > - file locks
> > - fasync
>
> I've wanted to fix file locks for a while. Here's a first attempt.
> It was done quickly, so I concede that it may well have bugs in it.
> I found (and fixed) one with LTP.
>
> It takes *no account* of nfsd, nor remote filesystems. We need to have
> a serious discussion about their requirements.
I tested it on 8-core stoakley. aim7 result becomes 23% worse than the one of
pure 2.6.26-rc1.
I replied this email in case you have many patches and I might test what you don't
expect.
-yanmin
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 663c069..cb09765 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -140,6 +140,8 @@ int lease_break_time = 45;
> #define for_each_lock(inode, lockp) \
> for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
>
> +static DEFINE_SPINLOCK(file_lock_lock);
> +
> static LIST_HEAD(file_lock_list);
> static LIST_HEAD(blocked_list);
>
> @@ -510,9 +512,9 @@ static void __locks_delete_block(struct file_lock *waiter)
> */
> static void locks_delete_block(struct file_lock *waiter)
> {
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> __locks_delete_block(waiter);
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> }
>
> /* Insert waiter into blocker's block list.
> @@ -649,7 +651,7 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
> {
> struct file_lock *cfl;
>
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
> if (!IS_POSIX(cfl))
> continue;
> @@ -662,7 +664,7 @@ 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();
> + spin_unlock(&file_lock_lock);
> return;
> }
> EXPORT_SYMBOL(posix_test_lock);
> @@ -735,18 +737,21 @@ 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)
> + if (request->fl_flags & FL_ACCESS) {
> + spin_lock(&file_lock_lock);
> goto find_conflict;
> + }
>
> if (request->fl_type != F_UNLCK) {
> error = -ENOMEM;
> +
> new_fl = locks_alloc_lock();
> if (new_fl == NULL)
> - goto out;
> + goto out_unlocked;
> error = 0;
> }
>
> + spin_lock(&file_lock_lock);
> for_each_lock(inode, before) {
> struct file_lock *fl = *before;
> if (IS_POSIX(fl))
> @@ -772,10 +777,13 @@ 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) {
> + spin_unlock(&file_lock_lock);
> cond_resched();
> + spin_lock(&file_lock_lock);
> + }
>
> -find_conflict:
> + find_conflict:
> for_each_lock(inode, before) {
> struct file_lock *fl = *before;
> if (IS_POSIX(fl))
> @@ -796,8 +804,9 @@ find_conflict:
> new_fl = NULL;
> error = 0;
>
> -out:
> - unlock_kernel();
> + out:
> + spin_unlock(&file_lock_lock);
> + out_unlocked:
> if (new_fl)
> locks_free_lock(new_fl);
> return error;
> @@ -826,7 +835,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
> new_fl2 = locks_alloc_lock();
> }
>
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> if (request->fl_type != F_UNLCK) {
> for_each_lock(inode, before) {
> fl = *before;
> @@ -994,7 +1003,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
> locks_wake_up_blocks(left);
> }
> out:
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> /*
> * Free any unused locks.
> */
> @@ -1069,14 +1078,14 @@ int locks_mandatory_locked(struct inode *inode)
> /*
> * Search the lock list for this inode for any POSIX locks.
> */
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
> if (!IS_POSIX(fl))
> continue;
> if (fl->fl_owner != owner)
> break;
> }
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> return fl ? -EAGAIN : 0;
> }
>
> @@ -1190,7 +1199,7 @@ int __break_lease(struct inode *inode, unsigned int mode)
>
> new_fl = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK);
>
> - lock_kernel();
> + spin_lock(&file_lock_lock);
>
> time_out_leases(inode);
>
> @@ -1251,8 +1260,10 @@ restart:
> break_time++;
> }
> locks_insert_block(flock, new_fl);
> + spin_unlock(&file_lock_lock);
> error = wait_event_interruptible_timeout(new_fl->fl_wait,
> !new_fl->fl_next, break_time);
> + spin_lock(&file_lock_lock);
> __locks_delete_block(new_fl);
> if (error >= 0) {
> if (error == 0)
> @@ -1266,8 +1277,8 @@ restart:
> error = 0;
> }
>
> -out:
> - unlock_kernel();
> + out:
> + spin_unlock(&file_lock_lock);
> if (!IS_ERR(new_fl))
> locks_free_lock(new_fl);
> return error;
> @@ -1323,7 +1334,7 @@ int fcntl_getlease(struct file *filp)
> struct file_lock *fl;
> int type = F_UNLCK;
>
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> 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) {
> @@ -1332,7 +1343,7 @@ int fcntl_getlease(struct file *filp)
> break;
> }
> }
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> return type;
> }
>
> @@ -1363,6 +1374,7 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
> if (error)
> return error;
>
> + spin_lock(&file_lock_lock);
> time_out_leases(inode);
>
> BUG_ON(!(*flp)->fl_lmops->fl_break);
> @@ -1370,10 +1382,11 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
> lease = *flp;
>
> if (arg != F_UNLCK) {
> + spin_unlock(&file_lock_lock);
> error = -ENOMEM;
> new_fl = locks_alloc_lock();
> if (new_fl == NULL)
> - goto out;
> + goto out_unlocked;
>
> error = -EAGAIN;
> if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
> @@ -1382,6 +1395,7 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
> && ((atomic_read(&dentry->d_count) > 1)
> || (atomic_read(&inode->i_count) > 1)))
> goto out;
> + spin_lock(&file_lock_lock);
> }
>
> /*
> @@ -1429,11 +1443,14 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
>
> locks_copy_lock(new_fl, lease);
> locks_insert_lock(before, new_fl);
> + spin_unlock(&file_lock_lock);
>
> *flp = new_fl;
> return 0;
>
> -out:
> + out:
> + spin_unlock(&file_lock_lock);
> + out_unlocked:
> if (new_fl != NULL)
> locks_free_lock(new_fl);
> return error;
> @@ -1471,12 +1488,10 @@ 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();
>
> return error;
> }
> @@ -1503,12 +1518,11 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
> if (error)
> return error;
>
> - lock_kernel();
> -
> error = vfs_setlease(filp, arg, &flp);
> if (error || arg == F_UNLCK)
> - goto out_unlock;
> + return error;
>
> + lock_kernel();
> error = fasync_helper(fd, filp, 1, &flp->fl_fasync);
> if (error < 0) {
> /* remove lease just inserted by setlease */
> @@ -1519,7 +1533,7 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
> }
>
> error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
> -out_unlock:
> + out_unlock:
> unlock_kernel();
> return error;
> }
> @@ -2024,7 +2038,7 @@ void locks_remove_flock(struct file *filp)
> fl.fl_ops->fl_release_private(&fl);
> }
>
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> before = &inode->i_flock;
>
> while ((fl = *before) != NULL) {
> @@ -2042,7 +2056,7 @@ void locks_remove_flock(struct file *filp)
> }
> before = &fl->fl_next;
> }
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> }
>
> /**
> @@ -2057,12 +2071,12 @@ posix_unblock_lock(struct file *filp, struct file_lock *waiter)
> {
> int status = 0;
>
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> if (waiter->fl_next)
> __locks_delete_block(waiter);
> else
> status = -ENOENT;
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> return status;
> }
>
> @@ -2175,7 +2189,7 @@ static int locks_show(struct seq_file *f, void *v)
>
> static void *locks_start(struct seq_file *f, loff_t *pos)
> {
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> f->private = (void *)1;
> return seq_list_start(&file_lock_list, *pos);
> }
> @@ -2187,7 +2201,7 @@ 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();
> + spin_unlock(&file_lock_lock);
> }
>
> struct seq_operations locks_seq_operations = {
> @@ -2215,7 +2229,7 @@ int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
> {
> struct file_lock *fl;
> int result = 1;
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
> if (IS_POSIX(fl)) {
> if (fl->fl_type == F_RDLCK)
> @@ -2232,7 +2246,7 @@ int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
> result = 0;
> break;
> }
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> return result;
> }
>
> @@ -2255,7 +2269,7 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
> {
> struct file_lock *fl;
> int result = 1;
> - lock_kernel();
> + spin_lock(&file_lock_lock);
> 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)))
> @@ -2270,7 +2284,7 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
> result = 0;
> break;
> }
> - unlock_kernel();
> + spin_unlock(&file_lock_lock);
> return result;
> }
>
>
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