diff options
| -rw-r--r-- | fs/afs/flock.c | 126 |
1 files changed, 79 insertions, 47 deletions
diff --git a/fs/afs/flock.c b/fs/afs/flock.c index 4f77f3caee9..af6952e39a1 100644 --- a/fs/afs/flock.c +++ b/fs/afs/flock.c @@ -19,6 +19,7 @@ static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl); static void afs_fl_release_private(struct file_lock *fl); static struct workqueue_struct *afs_lock_manager; +static DEFINE_MUTEX(afs_lock_manager_mutex); static struct file_lock_operations afs_lock_ops = { .fl_copy_lock = afs_fl_copy_lock, @@ -30,12 +31,20 @@ static struct file_lock_operations afs_lock_ops = { */ static int afs_init_lock_manager(void) { + int ret; + + ret = 0; if (!afs_lock_manager) { - afs_lock_manager = create_singlethread_workqueue("kafs_lockd"); - if (!afs_lock_manager) - return -ENOMEM; + mutex_lock(&afs_lock_manager_mutex); + if (!afs_lock_manager) { + afs_lock_manager = + create_singlethread_workqueue("kafs_lockd"); + if (!afs_lock_manager) + ret = -ENOMEM; + } + mutex_unlock(&afs_lock_manager_mutex); } - return 0; + return ret; } /* @@ -68,6 +77,29 @@ static void afs_schedule_lock_extension(struct afs_vnode *vnode) } /* + * grant one or more locks (readlocks are allowed to jump the queue if the + * first lock in the queue is itself a readlock) + * - the caller must hold the vnode lock + */ +static void afs_grant_locks(struct afs_vnode *vnode, struct file_lock *fl) +{ + struct file_lock *p, *_p; + + list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks); + if (fl->fl_type == F_RDLCK) { + list_for_each_entry_safe(p, _p, &vnode->pending_locks, + fl_u.afs.link) { + if (p->fl_type == F_RDLCK) { + p->fl_u.afs.state = AFS_LOCK_GRANTED; + list_move_tail(&p->fl_u.afs.link, + &vnode->granted_locks); + wake_up(&p->fl_wait); + } + } + } +} + +/* * do work for a lock, including: * - probing for a lock we're waiting on but didn't get immediately * - extending a lock that's close to timing out @@ -172,8 +204,7 @@ void afs_lock_work(struct work_struct *work) struct file_lock, fl_u.afs.link) == fl) { fl->fl_u.afs.state = ret; if (ret == AFS_LOCK_GRANTED) - list_move_tail(&fl->fl_u.afs.link, - &vnode->granted_locks); + afs_grant_locks(vnode, fl); else list_del_init(&fl->fl_u.afs.link); wake_up(&fl->fl_wait); @@ -258,49 +289,50 @@ static int afs_do_setlk(struct file *file, struct file_lock *fl) spin_lock(&vnode->lock); - if (list_empty(&vnode->pending_locks)) { - /* if there's no-one else with a lock on this vnode, then we - * need to ask the server for a lock */ - if (list_empty(&vnode->granted_locks)) { - _debug("not locked"); - ASSERTCMP(vnode->flags & - ((1 << AFS_VNODE_LOCKING) | - (1 << AFS_VNODE_READLOCKED) | - (1 << AFS_VNODE_WRITELOCKED)), ==, 0); - list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks); - set_bit(AFS_VNODE_LOCKING, &vnode->flags); - spin_unlock(&vnode->lock); + /* if we've already got a readlock on the server then we can instantly + * grant another readlock, irrespective of whether there are any + * pending writelocks */ + if (type == AFS_LOCK_READ && + vnode->flags & (1 << AFS_VNODE_READLOCKED)) { + _debug("instant readlock"); + ASSERTCMP(vnode->flags & + ((1 << AFS_VNODE_LOCKING) | + (1 << AFS_VNODE_WRITELOCKED)), ==, 0); + ASSERT(!list_empty(&vnode->granted_locks)); + goto sharing_existing_lock; + } - ret = afs_vnode_set_lock(vnode, key, type); - clear_bit(AFS_VNODE_LOCKING, &vnode->flags); - switch (ret) { - case 0: - goto acquired_server_lock; - case -EWOULDBLOCK: - spin_lock(&vnode->lock); - ASSERT(list_empty(&vnode->granted_locks)); - ASSERTCMP(vnode->pending_locks.next, ==, - &fl->fl_u.afs.link); - goto wait; - default: - spin_lock(&vnode->lock); - list_del_init(&fl->fl_u.afs.link); - spin_unlock(&vnode->lock); - goto error; - } - } + /* if there's no-one else with a lock on this vnode, then we need to + * ask the server for a lock */ + if (list_empty(&vnode->pending_locks) && + list_empty(&vnode->granted_locks)) { + _debug("not locked"); + ASSERTCMP(vnode->flags & + ((1 << AFS_VNODE_LOCKING) | + (1 << AFS_VNODE_READLOCKED) | + (1 << AFS_VNODE_WRITELOCKED)), ==, 0); + list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks); + set_bit(AFS_VNODE_LOCKING, &vnode->flags); + spin_unlock(&vnode->lock); - /* if we've already got a readlock on the server and no waiting - * writelocks, then we might be able to instantly grant another - * readlock */ - if (type == AFS_LOCK_READ && - vnode->flags & (1 << AFS_VNODE_READLOCKED)) { - _debug("instant readlock"); - ASSERTCMP(vnode->flags & - ((1 << AFS_VNODE_LOCKING) | - (1 << AFS_VNODE_WRITELOCKED)), ==, 0); - ASSERT(!list_empty(&vnode->granted_locks)); - goto sharing_existing_lock; + ret = afs_vnode_set_lock(vnode, key, type); + clear_bit(AFS_VNODE_LOCKING, &vnode->flags); + switch (ret) { + case 0: + _debug("acquired"); + goto acquired_server_lock; + case -EWOULDBLOCK: + _debug("would block"); + spin_lock(&vnode->lock); + ASSERT(list_empty(&vnode->granted_locks)); + ASSERTCMP(vnode->pending_locks.next, ==, + &fl->fl_u.afs.link); + goto wait; + default: + spin_lock(&vnode->lock); + list_del_init(&fl->fl_u.afs.link); + spin_unlock(&vnode->lock); + goto error; } } |