AFS: implement file locking

Implement file locking for AFS.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

13 files changed, 881 insertions, 15 deletions

diff --git a/fs/afs/Makefile b/fs/afs/Makefile
index 73ce561f3ea..a66671082cf 100644
--- a/fs/afs/Makefile
+++ b/fs/afs/Makefile
@@ -8,6 +8,7 @@ kafs-objs := \
         cmservice.o \
         dir.o \
         file.o \
+        flock.o \
         fsclient.o \
         inode.o \
         main.o \
diff --git a/fs/afs/afs.h b/fs/afs/afs.h
index 24525794814..c548aa346f0 100644
--- a/fs/afs/afs.h
+++ b/fs/afs/afs.h
@@ -37,6 +37,13 @@ typedef enum {
         AFS_FTYPE_SYMLINK       = 3,
 } afs_file_type_t;
 
+typedef enum {
+        AFS_LOCK_READ           = 0,    /* read lock request */
+        AFS_LOCK_WRITE          = 1,    /* write lock request */
+} afs_lock_type_t;
+
+#define AFS_LOCKWAIT            (5 * 60) /* time until a lock times out (seconds) */
+
 /*
  * AFS file identifier
  */
@@ -120,6 +127,7 @@ struct afs_file_status {
         struct afs_fid          parent;         /* parent dir ID for non-dirs only */
         time_t                  mtime_client;   /* last time client changed data */
         time_t                  mtime_server;   /* last time server changed data */
+        s32                     lock_count;     /* file lock count (0=UNLK -1=WRLCK +ve=#RDLCK */
 };
 
 /*
diff --git a/fs/afs/afs_fs.h b/fs/afs/afs_fs.h
index a18c374ebe0..eb647323d8f 100644
--- a/fs/afs/afs_fs.h
+++ b/fs/afs/afs_fs.h
@@ -31,6 +31,9 @@ enum AFS_FS_Operations {
         FSGETVOLUMEINFO         = 148,  /* AFS Get information about a volume */
         FSGETVOLUMESTATUS       = 149,  /* AFS Get volume status information */
         FSGETROOTVOLUME         = 151,  /* AFS Get root volume name */
+        FSSETLOCK               = 156,  /* AFS Request a file lock */
+        FSEXTENDLOCK            = 157,  /* AFS Extend a file lock */
+        FSRELEASELOCK           = 158,  /* AFS Release a file lock */
         FSLOOKUP                = 161,  /* AFS lookup file in directory */
         FSFETCHDATA64           = 65537, /* AFS Fetch file data */
         FSSTOREDATA64           = 65538, /* AFS Store file data */
diff --git a/fs/afs/callback.c b/fs/afs/callback.c
index bacf518c6fa..b8243945818 100644
--- a/fs/afs/callback.c
+++ b/fs/afs/callback.c
@@ -125,6 +125,9 @@ static void afs_break_callback(struct afs_server *server,
                 spin_unlock(&server->cb_lock);
 
                 queue_work(afs_callback_update_worker, &vnode->cb_broken_work);
+                if (list_empty(&vnode->granted_locks) &&
+                    !list_empty(&vnode->pending_locks))
+                        afs_lock_may_be_available(vnode);
                 spin_unlock(&vnode->lock);
         }
 }
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 546c59522eb..33fe39ad4e0 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -44,6 +44,7 @@ const struct file_operations afs_dir_file_operations = {
         .open           = afs_dir_open,
         .release        = afs_release,
         .readdir        = afs_readdir,
+        .lock           = afs_lock,
 };
 
 const struct inode_operations afs_dir_inode_operations = {
diff --git a/fs/afs/file.c b/fs/afs/file.c
index aede7eb66dd..525f7c56e06 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -34,6 +34,8 @@ const struct file_operations afs_file_operations = {
         .mmap           = generic_file_readonly_mmap,
         .splice_read    = generic_file_splice_read,
         .fsync          = afs_fsync,
+        .lock           = afs_lock,
+        .flock          = afs_flock,
 };
 
 const struct inode_operations afs_file_inode_operations = {
diff --git a/fs/afs/flock.c b/fs/afs/flock.c
new file mode 100644
index 00000000000..8f07f8d1bfa
--- /dev/null
+++ b/fs/afs/flock.c
@@ -0,0 +1,558 @@
+/* AFS file locking support
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/smp_lock.h>
+#include "internal.h"
+
+#define AFS_LOCK_GRANTED        0
+#define AFS_LOCK_PENDING        1
+
+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 struct file_lock_operations afs_lock_ops = {
+        .fl_copy_lock           = afs_fl_copy_lock,
+        .fl_release_private     = afs_fl_release_private,
+};
+
+/*
+ * initialise the lock manager thread if it isn't already running
+ */
+static int afs_init_lock_manager(void)
+{
+        if (!afs_lock_manager) {
+                afs_lock_manager = create_singlethread_workqueue("kafs_lockd");
+                if (!afs_lock_manager)
+                        return -ENOMEM;
+        }
+        return 0;
+}
+
+/*
+ * destroy the lock manager thread if it's running
+ */
+void __exit afs_kill_lock_manager(void)
+{
+        if (afs_lock_manager)
+                destroy_workqueue(afs_lock_manager);
+}
+
+/*
+ * if the callback is broken on this vnode, then the lock may now be available
+ */
+void afs_lock_may_be_available(struct afs_vnode *vnode)
+{
+        _enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
+
+        queue_delayed_work(afs_lock_manager, &vnode->lock_work, 0);
+}
+
+/*
+ * the lock will time out in 5 minutes unless we extend it, so schedule
+ * extension in a bit less than that time
+ */
+static void afs_schedule_lock_extension(struct afs_vnode *vnode)
+{
+        queue_delayed_work(afs_lock_manager, &vnode->lock_work,
+                           AFS_LOCKWAIT * HZ / 2);
+}
+
+/*
+ * 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
+ */
+void afs_lock_work(struct work_struct *work)
+{
+        struct afs_vnode *vnode =
+                container_of(work, struct afs_vnode, lock_work.work);
+        struct file_lock *fl;
+        afs_lock_type_t type;
+        struct key *key;
+        int ret;
+
+        _enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
+
+        spin_lock(&vnode->lock);
+
+        if (test_bit(AFS_VNODE_UNLOCKING, &vnode->flags)) {
+                _debug("unlock");
+                spin_unlock(&vnode->lock);
+
+                /* attempt to release the server lock; if it fails, we just
+                 * wait 5 minutes and it'll time out anyway */
+                ret = afs_vnode_release_lock(vnode, vnode->unlock_key);
+                if (ret < 0)
+                        printk(KERN_WARNING "AFS:"
+                               " Failed to release lock on {%x:%x} error %d\n",
+                               vnode->fid.vid, vnode->fid.vnode, ret);
+
+                spin_lock(&vnode->lock);
+                key_put(vnode->unlock_key);
+                vnode->unlock_key = NULL;
+                clear_bit(AFS_VNODE_UNLOCKING, &vnode->flags);
+        }
+
+        /* if we've got a lock, then it must be time to extend that lock as AFS
+         * locks time out after 5 minutes */
+        if (!list_empty(&vnode->granted_locks)) {
+                _debug("extend");
+
+                if (test_and_set_bit(AFS_VNODE_LOCKING, &vnode->flags))
+                        BUG();
+                fl = list_entry(vnode->granted_locks.next,
+                                struct file_lock, fl_u.afs.link);
+                key = key_get(fl->fl_file->private_data);
+                spin_unlock(&vnode->lock);
+
+                ret = afs_vnode_extend_lock(vnode, key);
+                clear_bit(AFS_VNODE_LOCKING, &vnode->flags);
+                key_put(key);
+                switch (ret) {
+                case 0:
+                        afs_schedule_lock_extension(vnode);
+                        break;
+                default:
+                        /* ummm... we failed to extend the lock - retry
+                         * extension shortly */
+                        printk(KERN_WARNING "AFS:"
+                               " Failed to extend lock on {%x:%x} error %d\n",
+                               vnode->fid.vid, vnode->fid.vnode, ret);
+                        queue_delayed_work(afs_lock_manager, &vnode->lock_work,
+                                           HZ * 10);
+                        break;
+                }
+                _leave(" [extend]");
+                return;
+        }
+
+        /* if we don't have a granted lock, then we must've been called back by
+         * the server, and so if might be possible to get a lock we're
+         * currently waiting for */
+        if (!list_empty(&vnode->pending_locks)) {
+                _debug("get");
+
+                if (test_and_set_bit(AFS_VNODE_LOCKING, &vnode->flags))
+                        BUG();
+                fl = list_entry(vnode->pending_locks.next,
+                                struct file_lock, fl_u.afs.link);
+                key = key_get(fl->fl_file->private_data);
+                type = (fl->fl_type == F_RDLCK) ?
+                        AFS_LOCK_READ : AFS_LOCK_WRITE;
+                spin_unlock(&vnode->lock);
+
+                ret = afs_vnode_set_lock(vnode, key, type);
+                clear_bit(AFS_VNODE_LOCKING, &vnode->flags);
+                switch (ret) {
+                case -EWOULDBLOCK:
+                        _debug("blocked");
+                        break;
+                case 0:
+                        _debug("acquired");
+                        if (type == AFS_LOCK_READ)
+                                set_bit(AFS_VNODE_READLOCKED, &vnode->flags);
+                        else
+                                set_bit(AFS_VNODE_WRITELOCKED, &vnode->flags);
+                        ret = AFS_LOCK_GRANTED;
+                default:
+                        spin_lock(&vnode->lock);
+                        /* the pending lock may have been withdrawn due to a
+                         * signal */
+                        if (list_entry(vnode->pending_locks.next,
+                                       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);
+                                else
+                                        list_del_init(&fl->fl_u.afs.link);
+                                wake_up(&fl->fl_wait);
+                                spin_unlock(&vnode->lock);
+                        } else {
+                                _debug("withdrawn");
+                                clear_bit(AFS_VNODE_READLOCKED, &vnode->flags);
+                                clear_bit(AFS_VNODE_WRITELOCKED, &vnode->flags);
+                                spin_unlock(&vnode->lock);
+                                afs_vnode_release_lock(vnode, key);
+                                if (!list_empty(&vnode->pending_locks))
+                                        afs_lock_may_be_available(vnode);
+                        }
+                        break;
+                }
+                key_put(key);
+                _leave(" [pend]");
+                return;
+        }
+
+        /* looks like the lock request was withdrawn on a signal */
+        spin_unlock(&vnode->lock);
+        _leave(" [no locks]");
+}
+
+/*
+ * pass responsibility for the unlocking of a vnode on the server to the
+ * manager thread, lest a pending signal in the calling thread interrupt
+ * AF_RXRPC
+ * - the caller must hold the vnode lock
+ */
+static void afs_defer_unlock(struct afs_vnode *vnode, struct key *key)
+{
+        cancel_delayed_work(&vnode->lock_work);
+        if (!test_and_clear_bit(AFS_VNODE_READLOCKED, &vnode->flags) &&
+            !test_and_clear_bit(AFS_VNODE_WRITELOCKED, &vnode->flags))
+                BUG();
+        if (test_and_set_bit(AFS_VNODE_UNLOCKING, &vnode->flags))
+                BUG();
+        vnode->unlock_key = key_get(key);
+        afs_lock_may_be_available(vnode);
+}
+
+/*
+ * request a lock on a file on the server
+ */
+static int afs_do_setlk(struct file *file, struct file_lock *fl)
+{
+        struct afs_vnode *vnode = AFS_FS_I(file->f_mapping->host);
+        afs_lock_type_t type;
+        struct key *key = file->private_data;
+        int ret;
+
+        _enter("{%x:%u},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
+
+        /* only whole-file locks are supported */
+        if (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX)
+                return -EINVAL;
+
+        ret = afs_init_lock_manager();
+        if (ret < 0)
+                return ret;
+
+        fl->fl_ops = &afs_lock_ops;
+        INIT_LIST_HEAD(&fl->fl_u.afs.link);
+        fl->fl_u.afs.state = AFS_LOCK_PENDING;
+
+        type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
+
+        lock_kernel();
+
+        /* make sure we've got a callback on this file and that our view of the
+         * data version is up to date */
+        ret = afs_vnode_fetch_status(vnode, NULL, key);
+        if (ret < 0)
+                goto error;
+
+        if (vnode->status.lock_count != 0 && !(fl->fl_flags & FL_SLEEP)) {
+                ret = -EAGAIN;
+                goto error;
+        }
+
+        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);
+
+                        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 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;
+                }
+        }
+
+        /* otherwise, we need to wait for a local lock to become available */
+        _debug("wait local");
+        list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
+wait:
+        if (!(fl->fl_flags & FL_SLEEP)) {
+                _debug("noblock");
+                ret = -EAGAIN;
+                goto abort_attempt;
+        }
+        spin_unlock(&vnode->lock);
+
+        /* now we need to sleep and wait for the lock manager thread to get the
+         * lock from the server */
+        _debug("sleep");
+        ret = wait_event_interruptible(fl->fl_wait,
+                                       fl->fl_u.afs.state <= AFS_LOCK_GRANTED);
+        if (fl->fl_u.afs.state <= AFS_LOCK_GRANTED) {
+                ret = fl->fl_u.afs.state;
+                if (ret < 0)
+                        goto error;
+                spin_lock(&vnode->lock);
+                goto given_lock;
+        }
+
+        /* we were interrupted, but someone may still be in the throes of
+         * giving us the lock */
+        _debug("intr");
+        ASSERTCMP(ret, ==, -ERESTARTSYS);
+
+        spin_lock(&vnode->lock);
+        if (fl->fl_u.afs.state <= AFS_LOCK_GRANTED) {
+                ret = fl->fl_u.afs.state;
+                if (ret < 0) {
+                        spin_unlock(&vnode->lock);
+                        goto error;
+                }
+                goto given_lock;
+        }
+
+abort_attempt:
+        /* we aren't going to get the lock, either because we're unwilling to
+         * wait, or because some signal happened */
+        _debug("abort");
+        if (list_empty(&vnode->granted_locks) &&
+            vnode->pending_locks.next == &fl->fl_u.afs.link) {
+                if (vnode->pending_locks.prev != &fl->fl_u.afs.link) {
+                        /* kick the next pending lock into having a go */
+                        list_del_init(&fl->fl_u.afs.link);
+                        afs_lock_may_be_available(vnode);
+                }
+        } else {
+                list_del_init(&fl->fl_u.afs.link);
+        }
+        spin_unlock(&vnode->lock);
+        goto error;
+
+acquired_server_lock:
+        /* we've acquired a server lock, but it needs to be renewed after 5
+         * mins */
+        spin_lock(&vnode->lock);
+        afs_schedule_lock_extension(vnode);
+        if (type == AFS_LOCK_READ)
+                set_bit(AFS_VNODE_READLOCKED, &vnode->flags);
+        else
+                set_bit(AFS_VNODE_WRITELOCKED, &vnode->flags);
+sharing_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 */
+        ASSERT(!(vnode->flags & (1 << AFS_VNODE_LOCKING)));
+        ASSERT((vnode->flags & ((1 << AFS_VNODE_READLOCKED) |
+                                (1 << AFS_VNODE_WRITELOCKED))) != 0);
+        ret = posix_lock_file(file, fl, NULL);
+        if (ret < 0)
+                goto vfs_rejected_lock;
+        spin_unlock(&vnode->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_vnode_fetch_status(vnode, NULL, key);
+
+error:
+        unlock_kernel();
+        _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 */
+        _debug("vfs refused %d", ret);
+        list_del_init(&fl->fl_u.afs.link);
+        if (list_empty(&vnode->granted_locks))
+                afs_defer_unlock(vnode, key);
+        spin_unlock(&vnode->lock);
+        goto abort_attempt;
+}
+
+/*
+ * 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(file->f_mapping->host);
+        struct key *key = file->private_data;
+        int ret;
+
+        _enter("{%x:%u},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
+
+        /* only whole-file unlocks are supported */
+        if (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX)
+                return -EINVAL;
+
+        fl->fl_ops = &afs_lock_ops;
+        INIT_LIST_HEAD(&fl->fl_u.afs.link);
+        fl->fl_u.afs.state = AFS_LOCK_PENDING;
+
+        spin_lock(&vnode->lock);
+        ret = posix_lock_file(file, fl, NULL);
+        if (ret < 0) {
+                spin_unlock(&vnode->lock);
+                _leave(" = %d [vfs]", ret);
+                return ret;
+        }
+
+        /* discard the server lock only if all granted locks are gone */
+        if (list_empty(&vnode->granted_locks))
+                afs_defer_unlock(vnode, key);
+        spin_unlock(&vnode->lock);
+        _leave(" = 0");
+        return 0;
+}
+
+/*
+ * 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(file->f_mapping->host);
+        struct key *key = file->private_data;
+        int ret, lock_count;
+
+        _enter("");
+
+        fl->fl_type = F_UNLCK;
+
+        mutex_lock(&vnode->vfs_inode.i_mutex);
+
+        /* check local lock records first */
+        ret = 0;
+        if (posix_test_lock(file, fl) == 0) {
+                /* no local locks; consult the server */
+                ret = afs_vnode_fetch_status(vnode, NULL, key);
+                if (ret < 0)
+                        goto error;
+                lock_count = vnode->status.lock_count;
+                if (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;
+                }
+        }
+
+error:
+        mutex_unlock(&vnode->vfs_inode.i_mutex);
+        _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(file->f_dentry->d_inode);
+
+        _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 ((vnode->vfs_inode.i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
+            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(file->f_dentry->d_inode);
+
+        _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 */
+        fl->fl_owner = (fl_owner_t) file;
+        fl->fl_start = 0;
+        fl->fl_end = OFFSET_MAX;
+
+        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)
+{
+        _enter("");
+
+        list_add(&new->fl_u.afs.link, &fl->fl_u.afs.link);
+}
+
+/*
+ * 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)
+{
+        _enter("");
+
+        list_del_init(&fl->fl_u.afs.link);
+}
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 5dff1308b6f..023b95b0d9d 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -67,7 +67,7 @@ static void xdr_decode_AFSFetchStatus(const __be32 **_bp,
         EXTRACT(status->group);
         bp++; /* sync counter */
         data_version |= (u64) ntohl(*bp++) << 32;
-        bp++; /* lock count */
+        EXTRACT(status->lock_count);
         size |= (u64) ntohl(*bp++) << 32;
         bp++; /* spare 4 */
         *_bp = bp;
@@ -1748,3 +1748,156 @@ int afs_fs_get_volume_status(struct afs_server *server,
 
         return afs_make_call(&server->addr, call, GFP_NOFS, wait_mode);
 }
+
+/*
+ * deliver reply data to an FS.SetLock, FS.ExtendLock or FS.ReleaseLock
+ */
+static int afs_deliver_fs_xxxx_lock(struct afs_call *call,
+                                    struct sk_buff *skb, bool last)
+{
+        const __be32 *bp;
+
+        _enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
+
+        afs_transfer_reply(call, skb);
+        if (!last)
+                return 0;
+
+        if (call->reply_size != call->reply_max)
+                return -EBADMSG;
+
+        /* unmarshall the reply once we've received all of it */
+        bp = call->buffer;
+        /* xdr_decode_AFSVolSync(&bp, call->replyX); */
+
+        _leave(" = 0 [done]");
+        return 0;
+}
+
+/*
+ * FS.SetLock operation type
+ */
+static const struct afs_call_type afs_RXFSSetLock = {
+        .name           = "FS.SetLock",
+        .deliver        = afs_deliver_fs_xxxx_lock,
+        .abort_to_error = afs_abort_to_error,
+        .destructor     = afs_flat_call_destructor,
+};
+
+/*
+ * FS.ExtendLock operation type
+ */
+static const struct afs_call_type afs_RXFSExtendLock = {
+        .name           = "FS.ExtendLock",
+        .deliver        = afs_deliver_fs_xxxx_lock,
+        .abort_to_error = afs_abort_to_error,
+        .destructor     = afs_flat_call_destructor,
+};
+
+/*
+ * FS.ReleaseLock operation type
+ */
+static const struct afs_call_type afs_RXFSReleaseLock = {
+        .name           = "FS.ReleaseLock",
+        .deliver        = afs_deliver_fs_xxxx_lock,
+        .abort_to_error = afs_abort_to_error,
+        .destructor     = afs_flat_call_destructor,
+};
+
+/*
+ * get a lock on a file
+ */
+int afs_fs_set_lock(struct afs_server *server,
+                    struct key *key,
+                    struct afs_vnode *vnode,
+                    afs_lock_type_t type,
+                    const struct afs_wait_mode *wait_mode)
+{
+        struct afs_call *call;
+        __be32 *bp;
+
+        _enter("");
+
+        call = afs_alloc_flat_call(&afs_RXFSSetLock, 5 * 4, 6 * 4);
+        if (!call)
+                return -ENOMEM;
+
+        call->key = key;
+        call->reply = vnode;
+        call->service_id = FS_SERVICE;
+        call->port = htons(AFS_FS_PORT);
+
+        /* marshall the parameters */
+        bp = call->request;
+        *bp++ = htonl(FSSETLOCK);
+        *bp++ = htonl(vnode->fid.vid);
+        *bp++ = htonl(vnode->fid.vnode);
+        *bp++ = htonl(vnode->fid.unique);
+        *bp++ = htonl(type);
+
+        return afs_make_call(&server->addr, call, GFP_NOFS, wait_mode);
+}
+
+/*
+ * extend a lock on a file
+ */
+int afs_fs_extend_lock(struct afs_server *server,
+                       struct key *key,
+                       struct afs_vnode *vnode,
+                       const struct afs_wait_mode *wait_mode)
+{
+        struct afs_call *call;
+        __be32 *bp;
+
+        _enter("");
+
+        call = afs_alloc_flat_call(&afs_RXFSExtendLock, 4 * 4, 6 * 4);
+        if (!call)
+                return -ENOMEM;
+
+        call->key = key;
+        call->reply = vnode;
+        call->service_id = FS_SERVICE;
+        call->port = htons(AFS_FS_PORT);
+
+        /* marshall the parameters */
+        bp = call->request;
+        *bp++ = htonl(FSEXTENDLOCK);
+        *bp++ = htonl(vnode->fid.vid);
+        *bp++ = htonl(vnode->fid.vnode);
+        *bp++ = htonl(vnode->fid.unique);
+
+        return afs_make_call(&server->addr, call, GFP_NOFS, wait_mode);
+}
+
+/*
+ * release a lock on a file
+ */
+int afs_fs_release_lock(struct afs_server *server,
+                        struct key *key,
+                        struct afs_vnode *vnode,
+                        const struct afs_wait_mode *wait_mode)
+{
+        struct afs_call *call;
+        __be32 *bp;
+
+        _enter("");
+
+        call = afs_alloc_flat_call(&afs_RXFSReleaseLock, 4 * 4, 6 * 4);
+        if (!call)
+                return -ENOMEM;
+
+        call->key = key;
+        call->reply = vnode;
+        call->service_id = FS_SERVICE;
+        call->port = htons(AFS_FS_PORT);
+
+        /* marshall the parameters */
+        bp = call->request;
+        *bp++ = htonl(FSRELEASELOCK);
+        *bp++ = htonl(vnode->fid.vid);
+        *bp++ = htonl(vnode->fid.vnode);
+        *bp++ = htonl(vnode->fid.unique);
+
+        return afs_make_call(&server->addr, call, GFP_NOFS, wait_mode);
+}
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 2c55dd94a1d..6306438f331 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -351,10 +351,18 @@ struct afs_vnode {
 #define AFS_VNODE_ZAP_DATA      3               /* set if vnode's data should be invalidated */
 #define AFS_VNODE_DELETED       4               /* set if vnode deleted on server */
 #define AFS_VNODE_MOUNTPOINT    5               /* set if vnode is a mountpoint symlink */
+#define AFS_VNODE_LOCKING       6               /* set if waiting for lock on vnode */
+#define AFS_VNODE_READLOCKED    7               /* set if vnode is read-locked on the server */
+#define AFS_VNODE_WRITELOCKED   8               /* set if vnode is write-locked on the server */
+#define AFS_VNODE_UNLOCKING     9               /* set if vnode is being unlocked on the server */
 
         long                    acl_order;      /* ACL check count (callback break count) */
 
         struct list_head        writebacks;     /* alterations in pagecache that need writing */
+        struct list_head        pending_locks;  /* locks waiting to be granted */
+        struct list_head        granted_locks;  /* locks granted on this file */
+        struct delayed_work     lock_work;      /* work to be done in locking */
+        struct key              *unlock_key;    /* key to be used in unlocking */
 
         /* outstanding callback notification on this file */
         struct rb_node          server_rb;      /* link in server->fs_vnodes */
@@ -474,6 +482,15 @@ extern int afs_open(struct inode *, struct file *);
 extern int afs_release(struct inode *, struct file *);
 
 /*
+ * flock.c
+ */
+extern void __exit afs_kill_lock_manager(void);
+extern void afs_lock_work(struct work_struct *);
+extern void afs_lock_may_be_available(struct afs_vnode *);
+extern int afs_lock(struct file *, int, struct file_lock *);
+extern int afs_flock(struct file *, int, struct file_lock *);
+
+/*
  * fsclient.c
  */
 extern int afs_fs_fetch_file_status(struct afs_server *, struct key *,
@@ -513,6 +530,15 @@ extern int afs_fs_get_volume_status(struct afs_server *, struct key *,
                                     struct afs_vnode *,
                                     struct afs_volume_status *,
                                     const struct afs_wait_mode *);
+extern int afs_fs_set_lock(struct afs_server *, struct key *,
+                           struct afs_vnode *, afs_lock_type_t,
+                           const struct afs_wait_mode *);
+extern int afs_fs_extend_lock(struct afs_server *, struct key *,
+                              struct afs_vnode *,
+                              const struct afs_wait_mode *);
+extern int afs_fs_release_lock(struct afs_server *, struct key *,
+                               struct afs_vnode *,
+                               const struct afs_wait_mode *);
 
 /*
  * inode.c
@@ -681,6 +707,10 @@ extern int afs_vnode_store_data(struct afs_writeback *, pgoff_t, pgoff_t,
 extern int afs_vnode_setattr(struct afs_vnode *, struct key *, struct iattr *);
 extern int afs_vnode_get_volume_status(struct afs_vnode *, struct key *,
                                        struct afs_volume_status *);
+extern int afs_vnode_set_lock(struct afs_vnode *, struct key *,
+                              afs_lock_type_t);
+extern int afs_vnode_extend_lock(struct afs_vnode *, struct key *);
+extern int afs_vnode_release_lock(struct afs_vnode *, struct key *);
 
 /*
  * volume.c
diff --git a/fs/afs/main.c b/fs/afs/main.c
index cd21195bbb2..0f60f6b3576 100644
--- a/fs/afs/main.c
+++ b/fs/afs/main.c
@@ -168,6 +168,7 @@ static void __exit afs_exit(void)
         printk(KERN_INFO "kAFS: Red Hat AFS client v0.1 unregistering.\n");
 
         afs_fs_exit();
+        afs_kill_lock_manager();
         afs_close_socket();
         afs_purge_servers();
         afs_callback_update_kill();
diff --git a/fs/afs/misc.c b/fs/afs/misc.c
index d1a889c4074..2d33a5f7d21 100644
--- a/fs/afs/misc.c
+++ b/fs/afs/misc.c
@@ -35,6 +35,7 @@ int afs_abort_to_error(u32 abort_code)
         case VOVERQUOTA:        return -EDQUOT;
         case VBUSY:             return -EBUSY;
         case VMOVED:            return -ENXIO;
+        case 0x2f6df0a:         return -EWOULDBLOCK;
         case 0x2f6df0c:         return -EACCES;
         case 0x2f6df0f:         return -EBUSY;
         case 0x2f6df10:         return -EEXIST;
diff --git a/fs/afs/super.c b/fs/afs/super.c
index 2e8496ba120..993cdf1cce3 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -460,6 +460,9 @@ static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
         spin_lock_init(&vnode->writeback_lock);
         spin_lock_init(&vnode->lock);
         INIT_LIST_HEAD(&vnode->writebacks);
+        INIT_LIST_HEAD(&vnode->pending_locks);
+        INIT_LIST_HEAD(&vnode->granted_locks);
+        INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
         INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 }
 
diff --git a/fs/afs/vnode.c b/fs/afs/vnode.c
index 232c55dc245..ac811e445b2 100644
--- a/fs/afs/vnode.c
+++ b/fs/afs/vnode.c
@@ -887,11 +887,6 @@ int afs_vnode_get_volume_status(struct afs_vnode *vnode, struct key *key,
                vnode->fid.unique,
                key_serial(key));
 
-        /* this op will fetch the status */
-        spin_lock(&vnode->lock);
-        vnode->update_cnt++;
-        spin_unlock(&vnode->lock);
-
         do {
                 /* pick a server to query */
                 server = afs_volume_pick_fileserver(vnode);
@@ -905,20 +900,127 @@ int afs_vnode_get_volume_status(struct afs_vnode *vnode, struct key *key,
         } while (!afs_volume_release_fileserver(vnode, server, ret));
 
         /* adjust the flags */
-        if (ret == 0) {
-                afs_vnode_finalise_status_update(vnode, server);
+        if (ret == 0)
+                afs_put_server(server);
+
+        _leave(" = %d", ret);
+        return ret;
+
+no_server:
+        return PTR_ERR(server);
+}
+
+/*
+ * get a lock on a file
+ */
+int afs_vnode_set_lock(struct afs_vnode *vnode, struct key *key,
+                       afs_lock_type_t type)
+{
+        struct afs_server *server;
+        int ret;
+
+        _enter("%s{%x:%u.%u},%x,%u",
+               vnode->volume->vlocation->vldb.name,
+               vnode->fid.vid,
+               vnode->fid.vnode,
+               vnode->fid.unique,
+               key_serial(key), type);
+
+        do {
+                /* pick a server to query */
+                server = afs_volume_pick_fileserver(vnode);
+                if (IS_ERR(server))
+                        goto no_server;
+
+                _debug("USING SERVER: %08x\n", ntohl(server->addr.s_addr));
+
+                ret = afs_fs_set_lock(server, key, vnode, type, &afs_sync_call);
+
+        } while (!afs_volume_release_fileserver(vnode, server, ret));
+
+        /* adjust the flags */
+        if (ret == 0)
+                afs_put_server(server);
+
+        _leave(" = %d", ret);
+        return ret;
+
+no_server:
+        return PTR_ERR(server);
+}
+
+/*
+ * extend a lock on a file
+ */
+int afs_vnode_extend_lock(struct afs_vnode *vnode, struct key *key)
+{
+        struct afs_server *server;
+        int ret;
+
+        _enter("%s{%x:%u.%u},%x",
+               vnode->volume->vlocation->vldb.name,
+               vnode->fid.vid,
+               vnode->fid.vnode,
+               vnode->fid.unique,
+               key_serial(key));
+
+        do {
+                /* pick a server to query */
+                server = afs_volume_pick_fileserver(vnode);
+                if (IS_ERR(server))
+                        goto no_server;
+
+                _debug("USING SERVER: %08x\n", ntohl(server->addr.s_addr));
+
+                ret = afs_fs_extend_lock(server, key, vnode, &afs_sync_call);
+
+        } while (!afs_volume_release_fileserver(vnode, server, ret));
+
+        /* adjust the flags */
+        if (ret == 0)
+                afs_put_server(server);
+
+        _leave(" = %d", ret);
+        return ret;
+
+no_server:
+        return PTR_ERR(server);
+}
+
+/*
+ * release a lock on a file
+ */
+int afs_vnode_release_lock(struct afs_vnode *vnode, struct key *key)
+{
+        struct afs_server *server;
+        int ret;
+
+        _enter("%s{%x:%u.%u},%x",
+               vnode->volume->vlocation->vldb.name,
+               vnode->fid.vid,
+               vnode->fid.vnode,
+               vnode->fid.unique,
+               key_serial(key));
+
+        do {
+                /* pick a server to query */
+                server = afs_volume_pick_fileserver(vnode);
+                if (IS_ERR(server))
+                        goto no_server;
+
+                _debug("USING SERVER: %08x\n", ntohl(server->addr.s_addr));
+
+                ret = afs_fs_release_lock(server, key, vnode, &afs_sync_call);
+
+        } while (!afs_volume_release_fileserver(vnode, server, ret));
+
+        /* adjust the flags */
+        if (ret == 0)
                 afs_put_server(server);
-        } else {
-                afs_vnode_status_update_failed(vnode, ret);
-        }
 
         _leave(" = %d", ret);
         return ret;
 
 no_server:
-        spin_lock(&vnode->lock);
-        vnode->update_cnt--;
-        ASSERTCMP(vnode->update_cnt, >=, 0);
-        spin_unlock(&vnode->lock);
         return PTR_ERR(server);
 }