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0c3a5ac281
Store the data version number indicated by an FS.FetchData op into the read request structure so that it's accessible by the page reader. Signed-off-by: David Howells <dhowells@redhat.com>
717 lines
19 KiB
C
717 lines
19 KiB
C
/* AFS file locking support
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include "internal.h"
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#define AFS_LOCK_GRANTED 0
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#define AFS_LOCK_PENDING 1
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struct workqueue_struct *afs_lock_manager;
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static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl);
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static void afs_fl_release_private(struct file_lock *fl);
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static const struct file_lock_operations afs_lock_ops = {
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.fl_copy_lock = afs_fl_copy_lock,
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.fl_release_private = afs_fl_release_private,
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};
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/*
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* if the callback is broken on this vnode, then the lock may now be available
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*/
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void afs_lock_may_be_available(struct afs_vnode *vnode)
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{
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_enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
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queue_delayed_work(afs_lock_manager, &vnode->lock_work, 0);
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}
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/*
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* the lock will time out in 5 minutes unless we extend it, so schedule
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* extension in a bit less than that time
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*/
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static void afs_schedule_lock_extension(struct afs_vnode *vnode)
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{
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queue_delayed_work(afs_lock_manager, &vnode->lock_work,
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AFS_LOCKWAIT * HZ / 2);
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}
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/*
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* grant one or more locks (readlocks are allowed to jump the queue if the
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* first lock in the queue is itself a readlock)
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* - the caller must hold the vnode lock
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*/
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static void afs_grant_locks(struct afs_vnode *vnode, struct file_lock *fl)
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{
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struct file_lock *p, *_p;
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list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
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if (fl->fl_type == F_RDLCK) {
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list_for_each_entry_safe(p, _p, &vnode->pending_locks,
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fl_u.afs.link) {
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if (p->fl_type == F_RDLCK) {
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p->fl_u.afs.state = AFS_LOCK_GRANTED;
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list_move_tail(&p->fl_u.afs.link,
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&vnode->granted_locks);
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wake_up(&p->fl_wait);
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}
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}
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}
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}
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/*
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* Get a lock on a file
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*/
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static int afs_set_lock(struct afs_vnode *vnode, struct key *key,
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afs_lock_type_t type)
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{
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struct afs_fs_cursor fc;
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int ret;
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_enter("%s{%x:%u.%u},%x,%u",
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vnode->volume->name,
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vnode->fid.vid,
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vnode->fid.vnode,
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vnode->fid.unique,
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key_serial(key), type);
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ret = -ERESTARTSYS;
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if (afs_begin_vnode_operation(&fc, vnode, key)) {
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while (afs_select_fileserver(&fc)) {
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fc.cb_break = vnode->cb_break + vnode->cb_s_break;
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afs_fs_set_lock(&fc, type);
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}
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afs_check_for_remote_deletion(&fc, fc.vnode);
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afs_vnode_commit_status(&fc, vnode, fc.cb_break);
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ret = afs_end_vnode_operation(&fc);
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}
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* Extend a lock on a file
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*/
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static int afs_extend_lock(struct afs_vnode *vnode, struct key *key)
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{
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struct afs_fs_cursor fc;
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int ret;
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_enter("%s{%x:%u.%u},%x",
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vnode->volume->name,
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vnode->fid.vid,
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vnode->fid.vnode,
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vnode->fid.unique,
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key_serial(key));
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ret = -ERESTARTSYS;
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if (afs_begin_vnode_operation(&fc, vnode, key)) {
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while (afs_select_current_fileserver(&fc)) {
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fc.cb_break = vnode->cb_break + vnode->cb_s_break;
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afs_fs_extend_lock(&fc);
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}
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afs_check_for_remote_deletion(&fc, fc.vnode);
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afs_vnode_commit_status(&fc, vnode, fc.cb_break);
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ret = afs_end_vnode_operation(&fc);
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}
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* Release a lock on a file
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*/
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static int afs_release_lock(struct afs_vnode *vnode, struct key *key)
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{
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struct afs_fs_cursor fc;
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int ret;
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_enter("%s{%x:%u.%u},%x",
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vnode->volume->name,
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vnode->fid.vid,
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vnode->fid.vnode,
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vnode->fid.unique,
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key_serial(key));
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ret = -ERESTARTSYS;
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if (afs_begin_vnode_operation(&fc, vnode, key)) {
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while (afs_select_current_fileserver(&fc)) {
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fc.cb_break = vnode->cb_break + vnode->cb_s_break;
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afs_fs_release_lock(&fc);
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}
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afs_check_for_remote_deletion(&fc, fc.vnode);
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afs_vnode_commit_status(&fc, vnode, fc.cb_break);
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ret = afs_end_vnode_operation(&fc);
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}
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* do work for a lock, including:
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* - probing for a lock we're waiting on but didn't get immediately
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* - extending a lock that's close to timing out
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*/
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void afs_lock_work(struct work_struct *work)
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{
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struct afs_vnode *vnode =
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container_of(work, struct afs_vnode, lock_work.work);
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struct file_lock *fl, *next;
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afs_lock_type_t type;
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struct key *key;
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int ret;
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_enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
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spin_lock(&vnode->lock);
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again:
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_debug("wstate %u for %p", vnode->lock_state, vnode);
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switch (vnode->lock_state) {
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case AFS_VNODE_LOCK_NEED_UNLOCK:
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_debug("unlock");
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vnode->lock_state = AFS_VNODE_LOCK_UNLOCKING;
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spin_unlock(&vnode->lock);
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/* attempt to release the server lock; if it fails, we just
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* wait 5 minutes and it'll expire anyway */
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ret = afs_release_lock(vnode, vnode->lock_key);
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if (ret < 0)
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printk(KERN_WARNING "AFS:"
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" Failed to release lock on {%x:%x} error %d\n",
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vnode->fid.vid, vnode->fid.vnode, ret);
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spin_lock(&vnode->lock);
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key_put(vnode->lock_key);
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vnode->lock_key = NULL;
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vnode->lock_state = AFS_VNODE_LOCK_NONE;
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if (list_empty(&vnode->pending_locks)) {
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spin_unlock(&vnode->lock);
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return;
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}
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/* The new front of the queue now owns the state variables. */
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next = list_entry(vnode->pending_locks.next,
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struct file_lock, fl_u.afs.link);
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vnode->lock_key = afs_file_key(next->fl_file);
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vnode->lock_type = (next->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
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vnode->lock_state = AFS_VNODE_LOCK_WAITING_FOR_CB;
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goto again;
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/* If we've already got a lock, then it must be time to extend that
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* lock as AFS locks time out after 5 minutes.
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*/
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case AFS_VNODE_LOCK_GRANTED:
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_debug("extend");
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ASSERT(!list_empty(&vnode->granted_locks));
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key = key_get(vnode->lock_key);
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vnode->lock_state = AFS_VNODE_LOCK_EXTENDING;
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spin_unlock(&vnode->lock);
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ret = afs_extend_lock(vnode, key); /* RPC */
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key_put(key);
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if (ret < 0)
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pr_warning("AFS: Failed to extend lock on {%x:%x} error %d\n",
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vnode->fid.vid, vnode->fid.vnode, ret);
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spin_lock(&vnode->lock);
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if (vnode->lock_state != AFS_VNODE_LOCK_EXTENDING)
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goto again;
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vnode->lock_state = AFS_VNODE_LOCK_GRANTED;
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if (ret == 0)
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afs_schedule_lock_extension(vnode);
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else
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queue_delayed_work(afs_lock_manager, &vnode->lock_work,
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HZ * 10);
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spin_unlock(&vnode->lock);
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_leave(" [ext]");
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return;
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/* If we don't have a granted lock, then we must've been called
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* back by the server, and so if might be possible to get a
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* lock we're currently waiting for.
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*/
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case AFS_VNODE_LOCK_WAITING_FOR_CB:
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_debug("get");
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key = key_get(vnode->lock_key);
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type = vnode->lock_type;
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vnode->lock_state = AFS_VNODE_LOCK_SETTING;
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spin_unlock(&vnode->lock);
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ret = afs_set_lock(vnode, key, type); /* RPC */
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key_put(key);
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spin_lock(&vnode->lock);
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switch (ret) {
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case -EWOULDBLOCK:
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_debug("blocked");
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break;
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case 0:
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_debug("acquired");
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vnode->lock_state = AFS_VNODE_LOCK_GRANTED;
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/* Fall through */
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default:
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/* Pass the lock or the error onto the first locker in
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* the list - if they're looking for this type of lock.
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* If they're not, we assume that whoever asked for it
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* took a signal.
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*/
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if (list_empty(&vnode->pending_locks)) {
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_debug("withdrawn");
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vnode->lock_state = AFS_VNODE_LOCK_NEED_UNLOCK;
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goto again;
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}
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fl = list_entry(vnode->pending_locks.next,
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struct file_lock, fl_u.afs.link);
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type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
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if (vnode->lock_type != type) {
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_debug("changed");
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vnode->lock_state = AFS_VNODE_LOCK_NEED_UNLOCK;
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goto again;
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}
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fl->fl_u.afs.state = ret;
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if (ret == 0)
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afs_grant_locks(vnode, fl);
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else
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list_del_init(&fl->fl_u.afs.link);
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wake_up(&fl->fl_wait);
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spin_unlock(&vnode->lock);
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_leave(" [granted]");
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return;
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}
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default:
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/* Looks like a lock request was withdrawn. */
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spin_unlock(&vnode->lock);
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_leave(" [no]");
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return;
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}
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}
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/*
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* pass responsibility for the unlocking of a vnode on the server to the
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* manager thread, lest a pending signal in the calling thread interrupt
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* AF_RXRPC
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* - the caller must hold the vnode lock
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*/
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static void afs_defer_unlock(struct afs_vnode *vnode)
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{
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_enter("");
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if (vnode->lock_state == AFS_VNODE_LOCK_GRANTED ||
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vnode->lock_state == AFS_VNODE_LOCK_EXTENDING) {
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cancel_delayed_work(&vnode->lock_work);
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vnode->lock_state = AFS_VNODE_LOCK_NEED_UNLOCK;
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afs_lock_may_be_available(vnode);
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}
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}
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/*
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* Check that our view of the file metadata is up to date and check to see
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* whether we think that we have a locking permit.
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*/
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static int afs_do_setlk_check(struct afs_vnode *vnode, struct key *key,
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afs_lock_type_t type, bool can_sleep)
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{
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afs_access_t access;
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int ret;
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/* Make sure we've got a callback on this file and that our view of the
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* data version is up to date.
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*/
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ret = afs_validate(vnode, key);
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if (ret < 0)
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return ret;
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/* Check the permission set to see if we're actually going to be
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* allowed to get a lock on this file.
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*/
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ret = afs_check_permit(vnode, key, &access);
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if (ret < 0)
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return ret;
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/* At a rough estimation, you need LOCK, WRITE or INSERT perm to
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* read-lock a file and WRITE or INSERT perm to write-lock a file.
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*
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* We can't rely on the server to do this for us since if we want to
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* share a read lock that we already have, we won't go the server.
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*/
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if (type == AFS_LOCK_READ) {
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if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE | AFS_ACE_LOCK)))
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return -EACCES;
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if (vnode->status.lock_count == -1 && !can_sleep)
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return -EAGAIN; /* Write locked */
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} else {
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if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE)))
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return -EACCES;
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if (vnode->status.lock_count != 0 && !can_sleep)
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return -EAGAIN; /* Locked */
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}
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return 0;
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}
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/*
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* Remove the front runner from the pending queue.
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* - The caller must hold vnode->lock.
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*/
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static void afs_dequeue_lock(struct afs_vnode *vnode, struct file_lock *fl)
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{
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struct file_lock *next;
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_enter("");
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/* ->lock_type, ->lock_key and ->lock_state only belong to this
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* file_lock if we're at the front of the pending queue or if we have
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* the lock granted or if the lock_state is NEED_UNLOCK or UNLOCKING.
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*/
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if (vnode->granted_locks.next == &fl->fl_u.afs.link &&
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vnode->granted_locks.prev == &fl->fl_u.afs.link) {
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list_del_init(&fl->fl_u.afs.link);
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afs_defer_unlock(vnode);
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return;
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}
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if (!list_empty(&vnode->granted_locks) ||
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vnode->pending_locks.next != &fl->fl_u.afs.link) {
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list_del_init(&fl->fl_u.afs.link);
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return;
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}
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list_del_init(&fl->fl_u.afs.link);
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key_put(vnode->lock_key);
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vnode->lock_key = NULL;
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vnode->lock_state = AFS_VNODE_LOCK_NONE;
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if (list_empty(&vnode->pending_locks))
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return;
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/* The new front of the queue now owns the state variables. */
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next = list_entry(vnode->pending_locks.next,
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struct file_lock, fl_u.afs.link);
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vnode->lock_key = afs_file_key(next->fl_file);
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vnode->lock_type = (next->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
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vnode->lock_state = AFS_VNODE_LOCK_WAITING_FOR_CB;
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afs_lock_may_be_available(vnode);
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}
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/*
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* request a lock on a file on the server
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*/
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static int afs_do_setlk(struct file *file, struct file_lock *fl)
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{
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struct inode *inode = locks_inode(file);
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struct afs_vnode *vnode = AFS_FS_I(inode);
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afs_lock_type_t type;
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struct key *key = afs_file_key(file);
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int ret;
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_enter("{%x:%u},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
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/* only whole-file locks are supported */
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if (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX)
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return -EINVAL;
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fl->fl_ops = &afs_lock_ops;
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INIT_LIST_HEAD(&fl->fl_u.afs.link);
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fl->fl_u.afs.state = AFS_LOCK_PENDING;
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type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
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ret = afs_do_setlk_check(vnode, key, type, fl->fl_flags & FL_SLEEP);
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if (ret < 0)
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return ret;
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spin_lock(&vnode->lock);
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/* If we've already got a readlock on the server then we instantly
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* grant another readlock, irrespective of whether there are any
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* pending writelocks.
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*/
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if (type == AFS_LOCK_READ &&
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vnode->lock_state == AFS_VNODE_LOCK_GRANTED &&
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vnode->lock_type == AFS_LOCK_READ) {
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_debug("instant readlock");
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ASSERT(!list_empty(&vnode->granted_locks));
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goto share_existing_lock;
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}
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list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
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if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
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goto need_to_wait;
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/* We don't have a lock on this vnode and we aren't currently waiting
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* for one either, so ask the server for a lock.
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*
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* Note that we need to be careful if we get interrupted by a signal
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* after dispatching the request as we may still get the lock, even
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* though we don't wait for the reply (it's not too bad a problem - the
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* lock will expire in 10 mins anyway).
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*/
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_debug("not locked");
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vnode->lock_key = key_get(key);
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vnode->lock_type = type;
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vnode->lock_state = AFS_VNODE_LOCK_SETTING;
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spin_unlock(&vnode->lock);
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ret = afs_set_lock(vnode, key, type); /* RPC */
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spin_lock(&vnode->lock);
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switch (ret) {
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default:
|
|
goto abort_attempt;
|
|
|
|
case -EWOULDBLOCK:
|
|
/* The server doesn't have a lock-waiting queue, so the client
|
|
* will have to retry. The server will break the outstanding
|
|
* callbacks on a file when a lock is released.
|
|
*/
|
|
_debug("would block");
|
|
ASSERT(list_empty(&vnode->granted_locks));
|
|
ASSERTCMP(vnode->pending_locks.next, ==, &fl->fl_u.afs.link);
|
|
vnode->lock_state = AFS_VNODE_LOCK_WAITING_FOR_CB;
|
|
goto need_to_wait;
|
|
|
|
case 0:
|
|
_debug("acquired");
|
|
break;
|
|
}
|
|
|
|
/* we've acquired a server lock, but it needs to be renewed after 5
|
|
* mins */
|
|
vnode->lock_state = AFS_VNODE_LOCK_GRANTED;
|
|
afs_schedule_lock_extension(vnode);
|
|
|
|
share_existing_lock:
|
|
/* the lock has been granted as far as we're concerned... */
|
|
fl->fl_u.afs.state = AFS_LOCK_GRANTED;
|
|
list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
|
|
|
|
given_lock:
|
|
/* ... but we do still need to get the VFS's blessing */
|
|
spin_unlock(&vnode->lock);
|
|
|
|
ret = posix_lock_file(file, fl, NULL);
|
|
if (ret < 0)
|
|
goto vfs_rejected_lock;
|
|
|
|
/* Again, make sure we've got a callback on this file and, again, make
|
|
* sure that our view of the data version is up to date (we ignore
|
|
* errors incurred here and deal with the consequences elsewhere).
|
|
*/
|
|
afs_validate(vnode, key);
|
|
_leave(" = 0");
|
|
return 0;
|
|
|
|
need_to_wait:
|
|
/* We're going to have to wait. Either this client doesn't have a lock
|
|
* on the server yet and we need to wait for a callback to occur, or
|
|
* the client does have a lock on the server, but it belongs to some
|
|
* other process(es) and is incompatible with the lock we want.
|
|
*/
|
|
ret = -EAGAIN;
|
|
if (fl->fl_flags & FL_SLEEP) {
|
|
spin_unlock(&vnode->lock);
|
|
|
|
_debug("sleep");
|
|
ret = wait_event_interruptible(fl->fl_wait,
|
|
fl->fl_u.afs.state != AFS_LOCK_PENDING);
|
|
|
|
spin_lock(&vnode->lock);
|
|
}
|
|
|
|
if (fl->fl_u.afs.state == AFS_LOCK_GRANTED)
|
|
goto given_lock;
|
|
if (fl->fl_u.afs.state < 0)
|
|
ret = fl->fl_u.afs.state;
|
|
|
|
abort_attempt:
|
|
/* we aren't going to get the lock, either because we're unwilling to
|
|
* wait, or because some signal happened */
|
|
_debug("abort");
|
|
afs_dequeue_lock(vnode, fl);
|
|
|
|
error_unlock:
|
|
spin_unlock(&vnode->lock);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
|
|
vfs_rejected_lock:
|
|
/* The VFS rejected the lock we just obtained, so we have to discard
|
|
* what we just got. We defer this to the lock manager work item to
|
|
* deal with.
|
|
*/
|
|
_debug("vfs refused %d", ret);
|
|
spin_lock(&vnode->lock);
|
|
list_del_init(&fl->fl_u.afs.link);
|
|
if (list_empty(&vnode->granted_locks))
|
|
afs_defer_unlock(vnode);
|
|
goto error_unlock;
|
|
}
|
|
|
|
/*
|
|
* unlock on a file on the server
|
|
*/
|
|
static int afs_do_unlk(struct file *file, struct file_lock *fl)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
|
|
int ret;
|
|
|
|
_enter("{%x:%u},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
|
|
|
|
/* Flush all pending writes before doing anything with locks. */
|
|
vfs_fsync(file, 0);
|
|
|
|
/* only whole-file unlocks are supported */
|
|
if (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX)
|
|
return -EINVAL;
|
|
|
|
ret = posix_lock_file(file, fl, NULL);
|
|
_leave(" = %d [%u]", ret, vnode->lock_state);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* return information about a lock we currently hold, if indeed we hold one
|
|
*/
|
|
static int afs_do_getlk(struct file *file, struct file_lock *fl)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
|
|
struct key *key = afs_file_key(file);
|
|
int ret, lock_count;
|
|
|
|
_enter("");
|
|
|
|
fl->fl_type = F_UNLCK;
|
|
|
|
/* check local lock records first */
|
|
posix_test_lock(file, fl);
|
|
if (fl->fl_type == F_UNLCK) {
|
|
/* no local locks; consult the server */
|
|
ret = afs_fetch_status(vnode, key, false);
|
|
if (ret < 0)
|
|
goto error;
|
|
|
|
lock_count = READ_ONCE(vnode->status.lock_count);
|
|
if (lock_count > 0)
|
|
fl->fl_type = F_RDLCK;
|
|
else
|
|
fl->fl_type = F_WRLCK;
|
|
fl->fl_start = 0;
|
|
fl->fl_end = OFFSET_MAX;
|
|
}
|
|
|
|
ret = 0;
|
|
error:
|
|
_leave(" = %d [%hd]", ret, fl->fl_type);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* manage POSIX locks on a file
|
|
*/
|
|
int afs_lock(struct file *file, int cmd, struct file_lock *fl)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
|
|
|
|
_enter("{%x:%u},%d,{t=%x,fl=%x,r=%Ld:%Ld}",
|
|
vnode->fid.vid, vnode->fid.vnode, cmd,
|
|
fl->fl_type, fl->fl_flags,
|
|
(long long) fl->fl_start, (long long) fl->fl_end);
|
|
|
|
/* AFS doesn't support mandatory locks */
|
|
if (__mandatory_lock(&vnode->vfs_inode) && fl->fl_type != F_UNLCK)
|
|
return -ENOLCK;
|
|
|
|
if (IS_GETLK(cmd))
|
|
return afs_do_getlk(file, fl);
|
|
if (fl->fl_type == F_UNLCK)
|
|
return afs_do_unlk(file, fl);
|
|
return afs_do_setlk(file, fl);
|
|
}
|
|
|
|
/*
|
|
* manage FLOCK locks on a file
|
|
*/
|
|
int afs_flock(struct file *file, int cmd, struct file_lock *fl)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
|
|
|
|
_enter("{%x:%u},%d,{t=%x,fl=%x}",
|
|
vnode->fid.vid, vnode->fid.vnode, cmd,
|
|
fl->fl_type, fl->fl_flags);
|
|
|
|
/*
|
|
* No BSD flocks over NFS allowed.
|
|
* Note: we could try to fake a POSIX lock request here by
|
|
* using ((u32) filp | 0x80000000) or some such as the pid.
|
|
* Not sure whether that would be unique, though, or whether
|
|
* that would break in other places.
|
|
*/
|
|
if (!(fl->fl_flags & FL_FLOCK))
|
|
return -ENOLCK;
|
|
|
|
/* we're simulating flock() locks using posix locks on the server */
|
|
if (fl->fl_type == F_UNLCK)
|
|
return afs_do_unlk(file, fl);
|
|
return afs_do_setlk(file, fl);
|
|
}
|
|
|
|
/*
|
|
* the POSIX lock management core VFS code copies the lock record and adds the
|
|
* copy into its own list, so we need to add that copy to the vnode's lock
|
|
* queue in the same place as the original (which will be deleted shortly
|
|
* after)
|
|
*/
|
|
static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
|
|
|
|
_enter("");
|
|
|
|
spin_lock(&vnode->lock);
|
|
list_add(&new->fl_u.afs.link, &fl->fl_u.afs.link);
|
|
spin_unlock(&vnode->lock);
|
|
}
|
|
|
|
/*
|
|
* need to remove this lock from the vnode queue when it's removed from the
|
|
* VFS's list
|
|
*/
|
|
static void afs_fl_release_private(struct file_lock *fl)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
|
|
|
|
_enter("");
|
|
|
|
spin_lock(&vnode->lock);
|
|
afs_dequeue_lock(vnode, fl);
|
|
_debug("state %u for %p", vnode->lock_state, vnode);
|
|
spin_unlock(&vnode->lock);
|
|
}
|