2 files changed, 104 insertions, 10 deletions

diff --git a/fs/gfs2/locking/dlm/plock.c b/fs/gfs2/locking/dlm/plock.c
index 1dd4215b83d0..f82495e18c2d 100644
--- a/fs/gfs2/locking/dlm/plock.c
+++ b/fs/gfs2/locking/dlm/plock.c
@@ -25,6 +25,15 @@ struct plock_op {
         struct gdlm_plock_info info;
 };
 
+struct plock_xop {
+        struct plock_op xop;
+        void *callback;
+        void *fl;
+        void *file;
+        struct file_lock flc;
+};
+
+
 static inline void set_version(struct gdlm_plock_info *info)
 {
         info->version[0] = GDLM_PLOCK_VERSION_MAJOR;
@@ -64,12 +73,14 @@ int gdlm_plock(void *lockspace, struct lm_lockname *name,
 {
         struct gdlm_ls *ls = lockspace;
         struct plock_op *op;
+        struct plock_xop *xop;
         int rv;
 
-        op = kzalloc(sizeof(*op), GFP_KERNEL);
-        if (!op)
+        xop = kzalloc(sizeof(*xop), GFP_KERNEL);
+        if (!xop)
                 return -ENOMEM;
 
+        op = &xop->xop;
         op->info.optype         = GDLM_PLOCK_OP_LOCK;
         op->info.pid            = fl->fl_pid;
         op->info.ex             = (fl->fl_type == F_WRLCK);
@@ -79,9 +90,21 @@ int gdlm_plock(void *lockspace, struct lm_lockname *name,
         op->info.start          = fl->fl_start;
         op->info.end            = fl->fl_end;
         op->info.owner          = (__u64)(long) fl->fl_owner;
+        if (fl->fl_lmops && fl->fl_lmops->fl_grant) {
+                xop->callback   = fl->fl_lmops->fl_grant;
+                locks_init_lock(&xop->flc);
+                locks_copy_lock(&xop->flc, fl);
+                xop->fl         = fl;
+                xop->file       = file;
+        } else
+                xop->callback   = NULL;
 
         send_op(op);
-        wait_event(recv_wq, (op->done != 0));
+
+        if (xop->callback == NULL)
+                wait_event(recv_wq, (op->done != 0));
+        else
+                return -EINPROGRESS;
 
         spin_lock(&ops_lock);
         if (!list_empty(&op->list)) {
@@ -99,7 +122,63 @@ int gdlm_plock(void *lockspace, struct lm_lockname *name,
                                   (unsigned long long)name->ln_number);
         }
 
-        kfree(op);
+        kfree(xop);
+        return rv;
+}
+
+/* Returns failure iff a succesful lock operation should be canceled */
+static int gdlm_plock_callback(struct plock_op *op)
+{
+        struct file *file;
+        struct file_lock *fl;
+        struct file_lock *flc;
+        int (*notify)(void *, void *, int) = NULL;
+        struct plock_xop *xop = (struct plock_xop *)op;
+        int rv = 0;
+
+        spin_lock(&ops_lock);
+        if (!list_empty(&op->list)) {
+                printk(KERN_INFO "plock op on list\n");
+                list_del(&op->list);
+        }
+        spin_unlock(&ops_lock);
+
+        /* check if the following 2 are still valid or make a copy */
+        file = xop->file;
+        flc = &xop->flc;
+        fl = xop->fl;
+        notify = xop->callback;
+
+        if (op->info.rv) {
+                notify(flc, NULL, op->info.rv);
+                goto out;
+        }
+
+        /* got fs lock; bookkeep locally as well: */
+        flc->fl_flags &= ~FL_SLEEP;
+        if (posix_lock_file(file, flc, NULL)) {
+                /*
+                 * This can only happen in the case of kmalloc() failure.
+                 * The filesystem's own lock is the authoritative lock,
+                 * so a failure to get the lock locally is not a disaster.
+                 * As long as GFS cannot reliably cancel locks (especially
+                 * in a low-memory situation), we're better off ignoring
+                 * this failure than trying to recover.
+                 */
+                log_error("gdlm_plock: vfs lock error file %p fl %p",
+                                file, fl);
+        }
+
+        rv = notify(flc, NULL, 0);
+        if (rv) {
+                /* XXX: We need to cancel the fs lock here: */
+                printk("gfs2 lock granted after lock request failed;"
+                                                " dangling lock!\n");
+                goto out;
+        }
+
+out:
+        kfree(xop);
         return rv;
 }
 
@@ -138,6 +217,9 @@ int gdlm_punlock(void *lockspace, struct lm_lockname *name,
 
         rv = op->info.rv;
 
+        if (rv == -ENOENT)
+                rv = 0;
+
         kfree(op);
         return rv;
 }
@@ -161,6 +243,7 @@ int gdlm_plock_get(void *lockspace, struct lm_lockname *name,
         op->info.start          = fl->fl_start;
         op->info.end            = fl->fl_end;
 
+
         send_op(op);
         wait_event(recv_wq, (op->done != 0));
 
@@ -173,9 +256,10 @@ int gdlm_plock_get(void *lockspace, struct lm_lockname *name,
 
         rv = op->info.rv;
 
-        if (rv == 0)
-                fl->fl_type = F_UNLCK;
-        else if (rv > 0) {
+        fl->fl_type = F_UNLCK;
+        if (rv == -ENOENT)
+                rv = 0;
+        else if (rv == 0 && op->info.pid != fl->fl_pid) {
                 fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
                 fl->fl_pid = op->info.pid;
                 fl->fl_start = op->info.start;
@@ -243,9 +327,14 @@ static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
         }
         spin_unlock(&ops_lock);
 
-        if (found)
-                wake_up(&recv_wq);
-        else
+        if (found) {
+                struct plock_xop *xop;
+                xop = (struct plock_xop *)op;
+                if (xop->callback)
+                        count = gdlm_plock_callback(op);
+                else
+                        wake_up(&recv_wq);
+        } else
                 printk(KERN_INFO "gdlm dev_write no op %x %llx\n", info.fsid,
                         (unsigned long long)info.number);
         return count;
diff --git a/fs/gfs2/ops_file.c b/fs/gfs2/ops_file.c
index 48b248d7c823..329c4dcdecdb 100644
--- a/fs/gfs2/ops_file.c
+++ b/fs/gfs2/ops_file.c
@@ -520,6 +520,11 @@ static int gfs2_lock(struct file *file, int cmd, struct file_lock *fl)
                 }
         }
 
+        if (cmd == F_CANCELLK) {
+                /* Hack: */
+                cmd = F_SETLK;
+                fl->fl_type = F_UNLCK;
+        }
         if (IS_GETLK(cmd))
                 return gfs2_lm_plock_get(sdp, &name, file, fl);
         else if (fl->fl_type == F_UNLCK)