6 files changed, 44 insertions, 17 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 63981e2fb835..d636b3e80f5d 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -764,7 +764,7 @@ static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
 {
         struct gfs2_sbd *sdp = gl->gl_sbd;
-        const struct gfs2_glock_operations *glops = gl->gl_ops;
+        struct gfs2_holder *gh = gl->gl_req_gh;
 
         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
         gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
@@ -772,8 +772,14 @@ static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
 
         state_change(gl, LM_ST_UNLOCKED);
 
-        if (glops->go_inval)
-                glops->go_inval(gl, DIO_METADATA);
+        if (test_and_clear_bit(GLF_CONV_DEADLK, &gl->gl_flags)) {
+                spin_lock(&gl->gl_spin);
+                gh->gh_error = 0;
+                spin_unlock(&gl->gl_spin);
+                gfs2_glock_xmote_th(gl, gl->gl_req_gh);
+                gfs2_glock_put(gl);
+                return;
+        }
 
         spin_lock(&gl->gl_spin);
         gfs2_demote_wake(gl);
@@ -794,7 +800,6 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
         struct gfs2_sbd *sdp = gl->gl_sbd;
         const struct gfs2_glock_operations *glops = gl->gl_ops;
         struct gfs2_holder *gh = gl->gl_req_gh;
-        int prev_state = gl->gl_state;
         int op_done = 1;
 
         if (!gh && (ret & LM_OUT_ST_MASK) == LM_ST_UNLOCKED) {
@@ -808,16 +813,6 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
 
         state_change(gl, ret & LM_OUT_ST_MASK);
 
-        if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
-                if (glops->go_inval)
-                        glops->go_inval(gl, DIO_METADATA);
-        } else if (gl->gl_state == LM_ST_DEFERRED) {
-                /* We might not want to do this here.
-                   Look at moving to the inode glops. */
-                if (glops->go_inval)
-                        glops->go_inval(gl, 0);
-        }
-
         /*  Deal with each possible exit condition  */
 
         if (!gh) {
@@ -837,6 +832,14 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
                 }
         } else {
                 spin_lock(&gl->gl_spin);
+                if (ret & LM_OUT_CONV_DEADLK) {
+                        gh->gh_error = 0;
+                        set_bit(GLF_CONV_DEADLK, &gl->gl_flags);
+                        spin_unlock(&gl->gl_spin);
+                        gfs2_glock_drop_th(gl);
+                        gfs2_glock_put(gl);
+                        return;
+                }
                 list_del_init(&gh->gh_list);
                 gh->gh_error = -EIO;
                 if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) 
@@ -910,6 +913,8 @@ static void gfs2_glock_xmote_th(struct gfs2_glock *gl, struct gfs2_holder *gh)
 
         if (glops->go_xmote_th)
                 glops->go_xmote_th(gl);
+        if (state == LM_ST_DEFERRED && glops->go_inval)
+                glops->go_inval(gl, DIO_METADATA);
 
         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
         gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
@@ -952,6 +957,8 @@ static void gfs2_glock_drop_th(struct gfs2_glock *gl)
 
         if (glops->go_xmote_th)
                 glops->go_xmote_th(gl);
+        if (glops->go_inval)
+                glops->go_inval(gl, DIO_METADATA);
 
         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
         gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 4ba2ea63119d..9c2c0b90b22a 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -167,6 +167,7 @@ enum {
         GLF_DEMOTE_IN_PROGRESS  = 6,
         GLF_LFLUSH              = 7,
         GLF_WAITERS2            = 8,
+        GLF_CONV_DEADLK         = 9,
 };
 
 struct gfs2_glock {
diff --git a/fs/gfs2/locking/dlm/lock.c b/fs/gfs2/locking/dlm/lock.c
index 542a797ac89a..53a6ab3c0919 100644
--- a/fs/gfs2/locking/dlm/lock.c
+++ b/fs/gfs2/locking/dlm/lock.c
@@ -137,7 +137,8 @@ static inline unsigned int make_flags(struct gdlm_lock *lp,
 
                 /* Conversion deadlock avoidance by DLM */
 
-                if (!test_bit(LFL_FORCE_PROMOTE, &lp->flags) &&
+                if (!(lp->ls->fsflags & LM_MFLAG_CONV_NODROP) &&
+                    !test_bit(LFL_FORCE_PROMOTE, &lp->flags) &&
                     !(lkf & DLM_LKF_NOQUEUE) &&
                     cur > DLM_LOCK_NL && req > DLM_LOCK_NL && cur != req)
                         lkf |= DLM_LKF_CONVDEADLK;
diff --git a/fs/gfs2/locking/dlm/thread.c b/fs/gfs2/locking/dlm/thread.c
index 521694fc19d6..e53db6fd28ab 100644
--- a/fs/gfs2/locking/dlm/thread.c
+++ b/fs/gfs2/locking/dlm/thread.c
@@ -135,7 +135,15 @@ static void process_complete(struct gdlm_lock *lp)
                          lp->lksb.sb_status, lp->lockname.ln_type,
                          (unsigned long long)lp->lockname.ln_number,
                          lp->flags);
-                return;
+                if (lp->lksb.sb_status == -EDEADLOCK &&
+                    lp->ls->fsflags & LM_MFLAG_CONV_NODROP) {
+                        lp->req = lp->cur;
+                        acb.lc_ret |= LM_OUT_CONV_DEADLK;
+                        if (lp->cur == DLM_LOCK_IV)
+                                lp->lksb.sb_lkid = 0;
+                        goto out;
+                } else
+                        return;
         }
 
         /*
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 5b518f73497a..ef9c6c4f80f6 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -723,7 +723,7 @@ static int gfs2_lm_mount(struct gfs2_sbd *sdp, int silent)
 {
         char *proto = sdp->sd_proto_name;
         char *table = sdp->sd_table_name;
-        int flags = 0;
+        int flags = LM_MFLAG_CONV_NODROP;
         int error;
 
         if (sdp->sd_args.ar_spectator)
diff --git a/include/linux/lm_interface.h b/include/linux/lm_interface.h
index 1418fdc9ac02..f274997bc283 100644
--- a/include/linux/lm_interface.h
+++ b/include/linux/lm_interface.h
@@ -21,9 +21,15 @@ typedef void (*lm_callback_t) (void *ptr, unsigned int type, void *data);
  * modify the filesystem.  The lock module shouldn't assign a journal to the FS
  * mount.  It shouldn't send recovery callbacks to the FS mount.  If the node
  * dies or withdraws, all locks can be wiped immediately.
+ *
+ * LM_MFLAG_CONV_NODROP
+ * Do not allow the dlm to internally resolve conversion deadlocks by demoting
+ * the lock to unlocked and then reacquiring it in the requested mode. Instead,
+ * it should cancel the request and return LM_OUT_CONV_DEADLK.
  */
 
 #define LM_MFLAG_SPECTATOR      0x00000001
+#define LM_MFLAG_CONV_NODROP    0x00000002
 
 /*
  * lm_lockstruct flags
@@ -110,6 +116,9 @@ typedef void (*lm_callback_t) (void *ptr, unsigned int type, void *data);
  *
  * LM_OUT_ASYNC
  * The result of the request will be returned in an LM_CB_ASYNC callback.
+ *
+ * LM_OUT_CONV_DEADLK
+ * The lock request was canceled do to a conversion deadlock.
  */
 
 #define LM_OUT_ST_MASK          0x00000003
@@ -117,6 +126,7 @@ typedef void (*lm_callback_t) (void *ptr, unsigned int type, void *data);
 #define LM_OUT_CANCELED         0x00000008
 #define LM_OUT_ASYNC            0x00000080
 #define LM_OUT_ERROR            0x00000100
+#define LM_OUT_CONV_DEADLK      0x00000200
 
 /*
  * lm_callback_t types