[DLM] canceling deadlocked lock

Add a function that can be used through libdlm by a system daemon to cancel
another process's deadlocked lock.  A completion ast with EDEADLK is returned
to the process waiting for the lock.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index a7435a8..a006fa5 100644 (file)
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -216,6 +216,7 @@ struct dlm_args {
 #define DLM_IFL_ENDOFLIFE      0x00200000
 #define DLM_IFL_WATCH_TIMEWARN 0x00400000
 #define DLM_IFL_TIMEOUT_CANCEL 0x00800000
+#define DLM_IFL_DEADLOCK_CANCEL        0x01000000
 #define DLM_IFL_USER           0x00000001
 #define DLM_IFL_ORPHAN         0x00000002
 

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index df91578..de943af 100644 (file)
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -300,6 +300,11 @@ static void queue_cast(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv)
                rv = -ETIMEDOUT;
        }
 
+       if (rv == -DLM_ECANCEL && (lkb->lkb_flags & DLM_IFL_DEADLOCK_CANCEL)) {
+               lkb->lkb_flags &= ~DLM_IFL_DEADLOCK_CANCEL;
+               rv = -EDEADLK;
+       }
+
        lkb->lkb_lksb->sb_status = rv;
        lkb->lkb_lksb->sb_flags = lkb->lkb_sbflags;
 
@@ -4450,6 +4455,54 @@ int dlm_user_cancel(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
        return error;
 }
 
+int dlm_user_deadlock(struct dlm_ls *ls, uint32_t flags, uint32_t lkid)
+{
+       struct dlm_lkb *lkb;
+       struct dlm_args args;
+       struct dlm_user_args *ua;
+       struct dlm_rsb *r;
+       int error;
+
+       dlm_lock_recovery(ls);
+
+       error = find_lkb(ls, lkid, &lkb);
+       if (error)
+               goto out;
+
+       ua = (struct dlm_user_args *)lkb->lkb_astparam;
+
+       error = set_unlock_args(flags, ua, &args);
+       if (error)
+               goto out_put;
+
+       /* same as cancel_lock(), but set DEADLOCK_CANCEL after lock_rsb */
+
+       r = lkb->lkb_resource;
+       hold_rsb(r);
+       lock_rsb(r);
+
+       error = validate_unlock_args(lkb, &args);
+       if (error)
+               goto out_r;
+       lkb->lkb_flags |= DLM_IFL_DEADLOCK_CANCEL;
+
+       error = _cancel_lock(r, lkb);
+ out_r:
+       unlock_rsb(r);
+       put_rsb(r);
+
+       if (error == -DLM_ECANCEL)
+               error = 0;
+       /* from validate_unlock_args() */
+       if (error == -EBUSY)
+               error = 0;
+ out_put:
+       dlm_put_lkb(lkb);
+ out:
+       dlm_unlock_recovery(ls);
+       return error;
+}
+
 /* lkb's that are removed from the waiters list by revert are just left on the
    orphans list with the granted orphan locks, to be freed by purge */
 

diff --git a/fs/dlm/lock.h b/fs/dlm/lock.h
index 99ab463..1720313 100644 (file)
--- a/fs/dlm/lock.h
+++ b/fs/dlm/lock.h
@@ -49,6 +49,7 @@ int dlm_user_cancel(struct dlm_ls *ls,  struct dlm_user_args *ua_tmp,
        uint32_t flags, uint32_t lkid);
 int dlm_user_purge(struct dlm_ls *ls, struct dlm_user_proc *proc,
        int nodeid, int pid);
+int dlm_user_deadlock(struct dlm_ls *ls, uint32_t flags, uint32_t lkid);
 void dlm_clear_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc);
 
 static inline int is_master(struct dlm_rsb *r)

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 329da1b..6438941 100644 (file)
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -156,6 +156,7 @@ static int lkb_is_endoflife(struct dlm_lkb *lkb, int sb_status, int type)
                return 1;
        case -DLM_ECANCEL:
        case -ETIMEDOUT:
+       case -EDEADLK:
                if (lkb->lkb_grmode == DLM_LOCK_IV)
                        return 1;
                break;
@@ -320,6 +321,22 @@ static int device_user_unlock(struct dlm_user_proc *proc,
        return error;
 }
 
+static int device_user_deadlock(struct dlm_user_proc *proc,
+                               struct dlm_lock_params *params)
+{
+       struct dlm_ls *ls;
+       int error;
+
+       ls = dlm_find_lockspace_local(proc->lockspace);
+       if (!ls)
+               return -ENOENT;
+
+       error = dlm_user_deadlock(ls, params->flags, params->lkid);
+
+       dlm_put_lockspace(ls);
+       return error;
+}
+
 static int create_misc_device(struct dlm_ls *ls, char *name)
 {
        int error, len;
@@ -545,6 +562,14 @@ static ssize_t device_write(struct file *file, const char __user *buf,
                error = device_user_unlock(proc, &kbuf->i.lock);
                break;
 
+       case DLM_USER_DEADLOCK:
+               if (!proc) {
+                       log_print("no locking on control device");
+                       goto out_sig;
+               }
+               error = device_user_deadlock(proc, &kbuf->i.lock);
+               break;
+
        case DLM_USER_CREATE_LOCKSPACE:
                if (proc) {
                        log_print("create/remove only on control device");

diff --git a/include/linux/dlm_device.h b/include/linux/dlm_device.h
index f7b9b57..9642277 100644 (file)
--- a/include/linux/dlm_device.h
+++ b/include/linux/dlm_device.h
@@ -92,6 +92,7 @@ struct dlm_lock_result {
 #define DLM_USER_CREATE_LOCKSPACE  4
 #define DLM_USER_REMOVE_LOCKSPACE  5
 #define DLM_USER_PURGE        6
+#define DLM_USER_DEADLOCK     7
 
 /* Arbitrary length restriction */
 #define MAX_LS_NAME_LEN 64