mount/fuse: Add support for multi-threaded fuse readers

Usage: Use 'reader-thread-count=<NUM>' as command line option to
set the thread count at the time of mounting the volume.

Next task is to make these threads auto-scale based on the load,
instead of having the user remount the volume everytime to change
the thread count.

Updates #412

Change-Id: I94aa1505e5ae6a133683d473e0e4e0edd139b76b
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>

5 files changed, 168 insertions, 83 deletions

diff --git a/xlators/mount/fuse/src/fuse-bridge.c b/xlators/mount/fuse/src/fuse-bridge.c
index dee9b16abf3..9e9fb815080 100644
--- a/xlators/mount/fuse/src/fuse-bridge.c
+++ b/xlators/mount/fuse/src/fuse-bridge.c
@@ -690,7 +690,8 @@ fuse_lookup_resume (fuse_state_t *state)
 }
 
 static void
-fuse_lookup (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_lookup (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
         char           *name     = msg;
         fuse_state_t   *state    = NULL;
@@ -718,7 +719,8 @@ do_forget(xlator_t *this, uint64_t unique, uint64_t nodeid, uint64_t nlookup)
 }
 
 static void
-fuse_forget (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_forget (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 
 {
         struct fuse_forget_in *ffi        = msg;
@@ -739,7 +741,8 @@ fuse_forget (xlator_t *this, fuse_in_header_t *finh, void *msg)
 
 #if FUSE_KERNEL_MINOR_VERSION >= 16
 static void
-fuse_batch_forget(xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_batch_forget(xlator_t *this, fuse_in_header_t *finh, void *msg,
+                  struct iobuf *iobuf)
 {
 	struct fuse_batch_forget_in *fbfi = msg;
 	struct fuse_forget_one *ffo = (struct fuse_forget_one *) (fbfi + 1);
@@ -957,7 +960,8 @@ fuse_getattr_resume (fuse_state_t *state)
 }
 
 static void
-fuse_getattr (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_getattr (xlator_t *this, fuse_in_header_t *finh, void *msg,
+              struct iobuf *iobuf)
 {
 #if FUSE_KERNEL_MINOR_VERSION >= 9
         struct fuse_getattr_in *fgi  = msg;
@@ -1287,7 +1291,8 @@ fuse_setattr_resume (fuse_state_t *state)
 }
 
 static void
-fuse_setattr (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_setattr (xlator_t *this, fuse_in_header_t *finh, void *msg,
+              struct iobuf *iobuf)
 {
         struct fuse_setattr_in *fsi = msg;
 
@@ -1514,7 +1519,8 @@ fuse_access_resume (fuse_state_t *state)
 }
 
 static void
-fuse_access (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_access (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
         struct fuse_access_in *fai = msg;
         fuse_state_t *state = NULL;
@@ -1588,7 +1594,8 @@ fuse_readlink_resume (fuse_state_t *state)
 }
 
 static void
-fuse_readlink (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_readlink (xlator_t *this, fuse_in_header_t *finh, void *msg,
+               struct iobuf *iobuf)
 {
         fuse_state_t *state = NULL;
 
@@ -1638,7 +1645,8 @@ fuse_mknod_resume (fuse_state_t *state)
 }
 
 static void
-fuse_mknod (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_mknod (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_mknod_in *fmi = msg;
         char         *name = (char *)(fmi + 1);
@@ -1708,7 +1716,8 @@ fuse_mkdir_resume (fuse_state_t *state)
 }
 
 static void
-fuse_mkdir (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_mkdir (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_mkdir_in *fmi = msg;
         char *name = (char *)(fmi + 1);
@@ -1760,7 +1769,8 @@ fuse_unlink_resume (fuse_state_t *state)
 }
 
 static void
-fuse_unlink (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_unlink (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
         char         *name = msg;
         fuse_state_t *state = NULL;
@@ -1797,7 +1807,8 @@ fuse_rmdir_resume (fuse_state_t *state)
 }
 
 static void
-fuse_rmdir (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_rmdir (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         char         *name = msg;
         fuse_state_t *state = NULL;
@@ -1847,7 +1858,8 @@ fuse_symlink_resume (fuse_state_t *state)
 }
 
 static void
-fuse_symlink (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_symlink (xlator_t *this, fuse_in_header_t *finh, void *msg,
+              struct iobuf *iobuf)
 {
         char         *name = msg;
         char         *linkname = name + strlen (name) + 1;
@@ -1969,7 +1981,8 @@ fuse_rename_resume (fuse_state_t *state)
 }
 
 static void
-fuse_rename (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_rename (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
         struct fuse_rename_in  *fri = msg;
         char *oldname = (char *)(fri + 1);
@@ -2019,7 +2032,8 @@ fuse_link_resume (fuse_state_t *state)
 }
 
 static void
-fuse_link (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_link (xlator_t *this, fuse_in_header_t *finh, void *msg,
+           struct iobuf *iobuf)
 {
         struct fuse_link_in *fli = msg;
         char         *name = (char *)(fli + 1);
@@ -2208,7 +2222,8 @@ fuse_create_resume (fuse_state_t *state)
 }
 
 static void
-fuse_create (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_create (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
 #if FUSE_KERNEL_MINOR_VERSION >= 12
         struct fuse_create_in *fci = msg;
@@ -2298,7 +2313,8 @@ fuse_open_resume (fuse_state_t *state)
 }
 
 static void
-fuse_open (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_open (xlator_t *this, fuse_in_header_t *finh, void *msg,
+           struct iobuf *iobuf)
 {
         struct fuse_open_in *foi = msg;
         fuse_state_t *state = NULL;
@@ -2375,7 +2391,8 @@ fuse_readv_resume (fuse_state_t *state)
 }
 
 static void
-fuse_readv (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_readv (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_read_in *fri = msg;
 
@@ -2451,8 +2468,6 @@ void
 fuse_write_resume (fuse_state_t *state)
 {
         struct iobref *iobref = NULL;
-        struct iobuf  *iobuf = NULL;
-
 
         iobref = iobref_new ();
         if (!iobref) {
@@ -2465,8 +2480,7 @@ fuse_write_resume (fuse_state_t *state)
                 return;
         }
 
-        iobuf = ((fuse_private_t *) (state->this->private))->iobuf;
-        iobref_add (iobref, iobuf);
+        iobref_add (iobref, state->iobuf);
 
         gf_log ("glusterfs-fuse", GF_LOG_TRACE,
                 "%"PRIu64": WRITE (%p, size=%"GF_PRI_SIZET", offset=%"PRId64")",
@@ -2480,7 +2494,8 @@ fuse_write_resume (fuse_state_t *state)
 }
 
 static void
-fuse_write (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_write (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         /* WRITE is special, metadata is attached to in_header,
          * and msg is the payload as-is.
@@ -2523,6 +2538,7 @@ fuse_write (xlator_t *this, fuse_in_header_t *finh, void *msg)
 
         state->vector.iov_base = msg;
         state->vector.iov_len  = fwi->size;
+        state->iobuf = iobuf;
 
         fuse_resolve_and_resume (state, fuse_write_resume);
 
@@ -2561,7 +2577,8 @@ fuse_lseek_resume (fuse_state_t *state)
 }
 
 static void
-fuse_lseek (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_lseek (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_lseek_in *ffi   = msg;
         fuse_state_t         *state = NULL;
@@ -2597,7 +2614,8 @@ fuse_flush_resume (fuse_state_t *state)
 }
 
 static void
-fuse_flush (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_flush (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_flush_in *ffi = msg;
 
@@ -2633,7 +2651,8 @@ fuse_internal_release (xlator_t *this, fd_t *fd)
 }
 
 static void
-fuse_release (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_release (xlator_t *this, fuse_in_header_t *finh, void *msg,
+              struct iobuf *iobuf)
 {
         struct fuse_release_in *fri       = msg;
         fd_t                   *fd        = NULL;
@@ -2678,7 +2697,8 @@ fuse_fsync_resume (fuse_state_t *state)
 }
 
 static void
-fuse_fsync (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_fsync (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_fsync_in *fsi = msg;
 
@@ -2748,7 +2768,8 @@ fuse_opendir_resume (fuse_state_t *state)
 }
 
 static void
-fuse_opendir (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_opendir (xlator_t *this, fuse_in_header_t *finh, void *msg,
+              struct iobuf *iobuf)
 {
         /*
         struct fuse_open_in *foi = msg;
@@ -2890,7 +2911,8 @@ fuse_readdir_resume (fuse_state_t *state)
 }
 
 static void
-fuse_readdir (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_readdir (xlator_t *this, fuse_in_header_t *finh, void *msg,
+              struct iobuf *iobuf)
 {
         struct fuse_read_in *fri = msg;
 
@@ -3041,7 +3063,8 @@ fuse_readdirp_resume (fuse_state_t *state)
 
 
 static void
-fuse_readdirp (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_readdirp (xlator_t *this, fuse_in_header_t *finh, void *msg,
+               struct iobuf *iobuf)
 {
 	struct fuse_read_in *fri = msg;
 
@@ -3088,7 +3111,8 @@ fuse_fallocate_resume(fuse_state_t *state)
 }
 
 static void
-fuse_fallocate(xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_fallocate(xlator_t *this, fuse_in_header_t *finh, void *msg,
+               struct iobuf *iobuf)
 {
 	struct fuse_fallocate_in *ffi = msg;
 	fuse_state_t *state = NULL;
@@ -3106,7 +3130,8 @@ fuse_fallocate(xlator_t *this, fuse_in_header_t *finh, void *msg)
 #endif /* FUSE minor version >= 19 */
 
 static void
-fuse_releasedir (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_releasedir (xlator_t *this, fuse_in_header_t *finh, void *msg,
+                 struct iobuf *iobuf)
 {
         struct fuse_release_in *fri       = msg;
         fuse_state_t           *state     = NULL;
@@ -3147,7 +3172,8 @@ fuse_fsyncdir_resume (fuse_state_t *state)
 }
 
 static void
-fuse_fsyncdir (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_fsyncdir (xlator_t *this, fuse_in_header_t *finh, void *msg,
+               struct iobuf *iobuf)
 {
         struct fuse_fsync_in *fsi = msg;
 
@@ -3247,7 +3273,8 @@ fuse_statfs_resume (fuse_state_t *state)
 
 
 static void
-fuse_statfs (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_statfs (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
         fuse_state_t *state = NULL;
 
@@ -3299,7 +3326,8 @@ fuse_setxattr_resume (fuse_state_t *state)
 
 
 static void
-fuse_setxattr (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_setxattr (xlator_t *this, fuse_in_header_t *finh, void *msg,
+               struct iobuf *iobuf)
 {
         struct fuse_setxattr_in *fsi = msg;
         char         *name = (char *)(fsi + 1);
@@ -3630,7 +3658,8 @@ fuse_getxattr_resume (fuse_state_t *state)
 
 
 static void
-fuse_getxattr (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_getxattr (xlator_t *this, fuse_in_header_t *finh, void *msg,
+               struct iobuf *iobuf)
 {
         struct fuse_getxattr_in *fgxi     = msg;
         char                    *name     = (char *)(fgxi + 1);
@@ -3736,7 +3765,8 @@ fuse_listxattr_resume (fuse_state_t *state)
 
 
 static void
-fuse_listxattr (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_listxattr (xlator_t *this, fuse_in_header_t *finh, void *msg,
+                struct iobuf *iobuf)
 {
         struct fuse_getxattr_in *fgxi = msg;
         fuse_state_t *state = NULL;
@@ -3792,7 +3822,8 @@ fuse_removexattr_resume (fuse_state_t *state)
 
 
 static void
-fuse_removexattr (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_removexattr (xlator_t *this, fuse_in_header_t *finh, void *msg,
+                  struct iobuf *iobuf)
 {
         char *name = msg;
 
@@ -3891,7 +3922,8 @@ fuse_getlk_resume (fuse_state_t *state)
 
 
 static void
-fuse_getlk (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_getlk (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_lk_in *fli = msg;
 
@@ -3983,7 +4015,8 @@ fuse_setlk_resume (fuse_state_t *state)
 
 
 static void
-fuse_setlk (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_setlk (xlator_t *this, fuse_in_header_t *finh, void *msg,
+            struct iobuf *iobuf)
 {
         struct fuse_lk_in *fli = msg;
 
@@ -4086,7 +4119,8 @@ notify_kernel_loop (void *data)
 #endif
 
 static void
-fuse_init (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_init (xlator_t *this, fuse_in_header_t *finh, void *msg,
+           struct iobuf *iobuf)
 {
         struct fuse_init_in  *fini      = msg;
         struct fuse_init_out  fino      = {0,};
@@ -4257,7 +4291,8 @@ fuse_init (xlator_t *this, fuse_in_header_t *finh, void *msg)
 
 
 static void
-fuse_enosys (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_enosys (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
         send_fuse_err (this, finh, ENOSYS);
 
@@ -4266,7 +4301,8 @@ fuse_enosys (xlator_t *this, fuse_in_header_t *finh, void *msg)
 
 
 static void
-fuse_destroy (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_destroy (xlator_t *this, fuse_in_header_t *finh, void *msg,
+              struct iobuf *iobuf)
 {
         send_fuse_err (this, finh, 0);
 
@@ -4857,6 +4893,7 @@ fuse_graph_sync (xlator_t *this)
                 new_graph_id = priv->next_graph->id;
                 priv->next_graph = NULL;
                 need_first_lookup = 1;
+                priv->handle_graph_switch = _gf_true;
 
                 while (!priv->event_recvd) {
                         ret = pthread_cond_wait (&priv->sync_cond,
@@ -4885,6 +4922,8 @@ unlock:
                 {
                         old_subvol->switched = 1;
                         winds_on_old_subvol = old_subvol->winds;
+                        priv->handle_graph_switch = _gf_false;
+                        pthread_cond_broadcast (&priv->migrate_cond);
                 }
                 pthread_mutex_unlock (&priv->sync_mutex);
 
@@ -4892,6 +4931,13 @@ unlock:
                         xlator_notify (old_subvol, GF_EVENT_PARENT_DOWN,
                                        old_subvol, NULL);
                 }
+        } else {
+                pthread_mutex_lock (&priv->sync_mutex);
+                {
+                        priv->handle_graph_switch = _gf_false;
+                        pthread_cond_broadcast (&priv->migrate_cond);
+                }
+                pthread_mutex_unlock (&priv->sync_mutex);
         }
 
         return 0;
@@ -4928,7 +4974,6 @@ fuse_thread_proc (void *data)
         const size_t              msg0_size = sizeof (*finh) + 128;
         fuse_handler_t          **fuse_ops = NULL;
         struct pollfd             pfd[2] = {{0,}};
-        gf_boolean_t              mount_finished = _gf_false;
 
         this = data;
         priv = this->private;
@@ -4945,32 +4990,40 @@ fuse_thread_proc (void *data)
                 /* THIS has to be reset here */
                 THIS = this;
 
-                if (!mount_finished) {
-                        memset(pfd,0,sizeof(pfd));
-                        pfd[0].fd = priv->status_pipe[0];
-                        pfd[0].events = POLLIN | POLLHUP | POLLERR;
-                        pfd[1].fd = priv->fd;
-                        pfd[1].events = POLLIN | POLLHUP | POLLERR;
-                        if (poll(pfd,2,-1) < 0) {
-                                gf_log (this->name, GF_LOG_ERROR,
-                                        "poll error %s", strerror(errno));
-                                break;
-                        }
-                        if (pfd[0].revents & POLLIN) {
-                                if (fuse_get_mount_status(this) != 0) {
+                pthread_mutex_lock (&priv->sync_mutex);
+                {
+                        if (!priv->mount_finished) {
+                                memset(pfd, 0, sizeof(pfd));
+                                pfd[0].fd = priv->status_pipe[0];
+                                pfd[0].events = POLLIN | POLLHUP | POLLERR;
+                                pfd[1].fd = priv->fd;
+                                pfd[1].events = POLLIN | POLLHUP | POLLERR;
+                                if (poll(pfd, 2, -1) < 0) {
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "poll error %s",
+                                                strerror(errno));
+                                        pthread_mutex_unlock (&priv->sync_mutex);
                                         break;
                                 }
-                                mount_finished = _gf_true;
-                        }
-                        else if (pfd[0].revents) {
-                                gf_log (this->name, GF_LOG_ERROR,
-                                        "mount pipe closed without status");
-                                break;
-                        }
-                        if (!pfd[1].revents) {
-                                continue;
+                                if (pfd[0].revents & POLLIN) {
+                                        if (fuse_get_mount_status(this) != 0) {
+                                                pthread_mutex_unlock (&priv->sync_mutex);
+                                                break;
+                                        }
+                                        priv->mount_finished = _gf_true;
+                                } else if (pfd[0].revents) {
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "mount pipe closed without status");
+                                        pthread_mutex_unlock (&priv->sync_mutex);
+                                        break;
+                                }
+                                if (!pfd[1].revents) {
+                                        pthread_mutex_unlock (&priv->sync_mutex);
+                                        continue;
+                                }
                         }
                 }
+                pthread_mutex_unlock (&priv->sync_mutex);
 
                 /*
                  * We don't want to block on readv while we're still waiting
@@ -5065,8 +5118,6 @@ fuse_thread_proc (void *data)
                         break;
                 }
 
-                priv->iobuf = iobuf;
-
                 /*
                  * This can be moved around a bit, but it's important to do it
                  * *after* the readv.  Otherwise, a graph switch could occur
@@ -5109,9 +5160,9 @@ fuse_thread_proc (void *data)
 
                 if (finh->opcode >= FUSE_OP_HIGH)
                         /* turn down MacFUSE specific messages */
-                        fuse_enosys (this, finh, msg);
+                        fuse_enosys (this, finh, msg, NULL);
                 else
-                        fuse_ops[finh->opcode] (this, finh, msg);
+                        fuse_ops[finh->opcode] (this, finh, msg, iobuf);
 
                 iobuf_unref (iobuf);
                 continue;
@@ -5183,8 +5234,6 @@ fuse_priv_dump (xlator_t  *this)
                             private->volfile_size);
         gf_proc_dump_write("mount_point", "%s",
                             private->mount_point);
-        gf_proc_dump_write("iobuf", "%u",
-                            private->iobuf);
         gf_proc_dump_write("fuse_thread_started", "%d",
                             (int)private->fuse_thread_started);
         gf_proc_dump_write("direct_io_mode", "%d",
@@ -5310,6 +5359,7 @@ unlock:
 int
 notify (xlator_t *this, int32_t event, void *data, ...)
 {
+        int                 i       = 0;
         int32_t             ret     = 0;
         fuse_private_t     *private = NULL;
         gf_boolean_t        start_thread = _gf_false;
@@ -5358,14 +5408,21 @@ notify (xlator_t *this, int32_t event, void *data, ...)
                 pthread_mutex_unlock (&private->sync_mutex);
 
                 if (start_thread) {
-                        ret = gf_thread_create (&private->fuse_thread, NULL,
-                                                fuse_thread_proc, this,
-                                                "fuseproc");
-                        if (ret != 0) {
-                                gf_log (this->name, GF_LOG_DEBUG,
-                                        "pthread_create() failed (%s)",
-                                        strerror (errno));
-                                break;
+                        private->fuse_thread = GF_CALLOC (private->reader_thread_count,
+                                                          sizeof (pthread_t),
+                                                          gf_fuse_mt_pthread_t);
+                        for (i = 0; i < private->reader_thread_count; i++) {
+
+                                ret = gf_thread_create (&private->fuse_thread[i],
+                                                        NULL,
+                                                        fuse_thread_proc, this,
+                                                        "fuseproc");
+                                if (ret != 0) {
+                                        gf_log (this->name, GF_LOG_DEBUG,
+                                                "pthread_create() failed (%s)",
+                                                strerror (errno));
+                                        break;
+                                }
                         }
                 }
 
@@ -5472,7 +5529,8 @@ static fuse_handler_t *fuse_dump_ops[FUSE_OP_HIGH];
 
 
 static void
-fuse_dumper (xlator_t *this, fuse_in_header_t *finh, void *msg)
+fuse_dumper (xlator_t *this, fuse_in_header_t *finh, void *msg,
+             struct iobuf *iobuf)
 {
         fuse_private_t *priv = NULL;
         struct iovec diov[6]           = {{0,},};
@@ -5504,7 +5562,7 @@ fuse_dumper (xlator_t *this, fuse_in_header_t *finh, void *msg)
                         "failed to dump fuse message (R): %s",
                         strerror (errno));
 
-        priv->fuse_ops0[finh->opcode] (this, finh, msg);
+        priv->fuse_ops0[finh->opcode] (this, finh, msg, NULL);
 }
 
 
@@ -5609,6 +5667,9 @@ init (xlator_t *this_xl)
         GF_OPTION_INIT (ZR_ATTR_TIMEOUT_OPT, priv->attribute_timeout, double,
                         cleanup_exit);
 
+        GF_OPTION_INIT ("reader-thread-count", priv->reader_thread_count, uint32,
+                        cleanup_exit);
+
         GF_OPTION_INIT (ZR_ENTRY_TIMEOUT_OPT, priv->entry_timeout, double,
                         cleanup_exit);
 
@@ -5830,6 +5891,7 @@ init (xlator_t *this_xl)
 
         pthread_mutex_init (&priv->fuse_dump_mutex, NULL);
         pthread_cond_init (&priv->sync_cond, NULL);
+        pthread_cond_init (&priv->migrate_cond, NULL);
         pthread_mutex_init (&priv->sync_mutex, NULL);
         priv->event_recvd = 0;
 
@@ -6034,5 +6096,12 @@ struct volume_options options[] = {
           .default_value = "false",
           .description = "Enables thin mount and connects via gfproxyd daemon.",
         },
+        { .key = {"reader-thread-count"},
+          .type = GF_OPTION_TYPE_INT,
+          .default_value = "4",
+          .min = 1,
+          .max = 64,
+          .description = "Sets fuse reader thread count.",
+        },
         { .key = {NULL} },
 };
diff --git a/xlators/mount/fuse/src/fuse-bridge.h b/xlators/mount/fuse/src/fuse-bridge.h
index 52718161c24..6cf9d2f7cf8 100644
--- a/xlators/mount/fuse/src/fuse-bridge.h
+++ b/xlators/mount/fuse/src/fuse-bridge.h
@@ -52,7 +52,7 @@
 
 typedef struct fuse_in_header fuse_in_header_t;
 typedef void (fuse_handler_t) (xlator_t *this, fuse_in_header_t *finh,
-                               void *msg);
+                               void *msg, struct iobuf *iobuf);
 
 struct fuse_private {
         int                  fd;
@@ -62,7 +62,8 @@ struct fuse_private {
         char                *mount_point;
         struct iobuf        *iobuf;
 
-        pthread_t            fuse_thread;
+        pthread_t            *fuse_thread;
+        uint32_t              reader_thread_count;
         char                 fuse_thread_started;
 
         uint32_t             direct_io_mode;
@@ -143,6 +144,9 @@ struct fuse_private {
 
         /* Load the thin volfile, and connect to gfproxyd*/
         gf_boolean_t         thin_client;
+        gf_boolean_t         mount_finished;
+        gf_boolean_t         handle_graph_switch;
+        pthread_cond_t       migrate_cond;
 };
 typedef struct fuse_private fuse_private_t;
 
@@ -394,6 +398,7 @@ typedef struct {
         int32_t        fd_no;
 
         gf_seek_what_t whence;
+        struct iobuf *iobuf;
 } fuse_state_t;
 
 typedef struct {
diff --git a/xlators/mount/fuse/src/fuse-helpers.c b/xlators/mount/fuse/src/fuse-helpers.c
index c59ff772cb8..c2d4d0cc9d8 100644
--- a/xlators/mount/fuse/src/fuse-helpers.c
+++ b/xlators/mount/fuse/src/fuse-helpers.c
@@ -123,6 +123,9 @@ get_fuse_state (xlator_t *this, fuse_in_header_t *finh)
 
         pthread_mutex_lock (&priv->sync_mutex);
         {
+                while (priv->handle_graph_switch)
+                        pthread_cond_wait (&priv->migrate_cond,
+                                           &priv->sync_mutex);
                 active_subvol = fuse_active_subvol (state->this);
                 active_subvol->winds++;
         }
diff --git a/xlators/mount/fuse/src/fuse-mem-types.h b/xlators/mount/fuse/src/fuse-mem-types.h
index 2b4b473813d..721b9a347cf 100644
--- a/xlators/mount/fuse/src/fuse-mem-types.h
+++ b/xlators/mount/fuse/src/fuse-mem-types.h
@@ -23,6 +23,7 @@ enum gf_fuse_mem_types_ {
         gf_fuse_mt_graph_switch_args_t,
 	gf_fuse_mt_gids_t,
         gf_fuse_mt_invalidate_node_t,
+        gf_fuse_mt_pthread_t,
         gf_fuse_mt_end
 };
 #endif
diff --git a/xlators/mount/fuse/utils/mount.glusterfs.in b/xlators/mount/fuse/utils/mount.glusterfs.in
index fd616844d65..6890ff00121 100755
--- a/xlators/mount/fuse/utils/mount.glusterfs.in
+++ b/xlators/mount/fuse/utils/mount.glusterfs.in
@@ -225,6 +225,10 @@ start_glusterfs ()
         cmd_line=$(echo "$cmd_line --event-history=$event_history");
     fi
 
+    if [ -n "$reader_thread_count" ]; then
+        cmd_line=$(echo "$cmd_line --reader-thread-count=$reader_thread_count");
+    fi
+
     if [ -n "$volume_name" ]; then
         cmd_line=$(echo "$cmd_line --volume-name=$volume_name");
     fi
@@ -499,6 +503,9 @@ with_options()
         "event-history")
             event_history=$value
             ;;
+        "reader-thread-count")
+            reader_thread_count=$value
+            ;;
         "no-root-squash")
             if [ $value = "yes" ] ||
                 [ $value = "on" ] ||