8.1-STABLE: zfs and sendfile: problem still exists

[Artemiev Igor]

On Sat, Oct 30, 2010 at 01:33:00PM +0300, Andriy Gapon wrote:
> on 30/10/2010 13:12 Artemiev Igor said the following:
> > On Sat, Oct 30, 2010 at 12:52:54PM +0300, Andriy Gapon wrote:
> > 
> >> Heh, next try.
> > 
> > Got a panic, "vm_page_unwire: invalid wire count: 0"
> 
> Oh, thank you for testing - forgot another piece (VM_ALLOC_WIRE for vm_page_alloc):

Yep, it work. But VM_ALLOC_WIRE not exists in RELENG_8, therefore i slightly modified your patch:

--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c.orig     2010-10-30 11:56:41.621138440 +0200
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c  2010-10-30 12:49:32.858692096 +0200
@@ -67,6 +67,7 @@
 #include <sys/sf_buf.h>
 #include <sys/sched.h>
 #include <sys/acl.h>
+#include <vm/vm_pageout.h>

 /*
  * Programming rules.
@@ -464,7 +465,7 @@
                                uiomove_fromphys(&m, off, bytes, uio);
                        VM_OBJECT_LOCK(obj);
                        vm_page_wakeup(m);
-               } else if (m != NULL && uio->uio_segflg == UIO_NOCOPY) {
+               } else if (uio->uio_segflg == UIO_NOCOPY) {
                        /*
                         * The code below is here to make sendfile(2) work
                         * correctly with ZFS. As pointed out by ups@
@@ -474,9 +475,23 @@
                         */
                        KASSERT(off == 0,
                            ("unexpected offset in mappedread for sendfile"));
-                       if (vm_page_sleep_if_busy(m, FALSE, "zfsmrb"))
+                        if (m != NULL && vm_page_sleep_if_busy(m, FALSE, "zfsmrb"))
                                goto again;
-                       vm_page_busy(m);
+                        if (m == NULL) {
+                                m = vm_page_alloc(obj, OFF_TO_IDX(start),
+                                    VM_ALLOC_NOBUSY | VM_ALLOC_NORMAL);
+                                if (m == NULL) {
+                                        VM_OBJECT_UNLOCK(obj);
+                                        VM_WAIT;
+                                        VM_OBJECT_LOCK(obj);
+                                        goto again;
+                                }
+                       }
+                        vm_page_lock_queues();
+                        vm_page_wire(m);
+                        vm_page_unlock_queues();
+
+                        vm_page_io_start(m);
                        VM_OBJECT_UNLOCK(obj);
                        if (dirbytes > 0) {
                                error = dmu_read_uio(os, zp->z_id, uio,
@@ -494,6 +509,10 @@
                        VM_OBJECT_LOCK(obj);
                        if (error == 0)
                                m->valid = VM_PAGE_BITS_ALL;
+                        vm_page_io_finish(m);
+                        vm_page_lock_queues();
+                        vm_page_unwire(m, 0);
+                        vm_page_unlock_queues();
                        vm_page_wakeup(m);
                        if (error == 0) {
                                uio->uio_resid -= bytes;