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Date:      Sat, 14 Jan 2012 23:04:28 +0000 (UTC)
From:      Alan Cox <alc@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r230120 - head/sys/fs/tmpfs
Message-ID:  <201201142304.q0EN4SEJ052635@svn.freebsd.org>
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Author: alc
Date: Sat Jan 14 23:04:27 2012
New Revision: 230120
URL: http://svn.freebsd.org/changeset/base/230120

Log:
  Neither tmpfs_nocacheread() nor tmpfs_mappedwrite() needs to call
  vm_object_pip_{add,subtract}() on the swap object because the swap
  object can't be destroyed while the vnode is exclusively locked.
  Moreover, even if the swap object could have been destroyed during
  tmpfs_nocacheread() and tmpfs_mappedwrite() this code is broken
  because vm_object_pip_subtract() does not wake up the sleeping thread
  that is trying to destroy the swap object.
  
  Free invalid pages after an I/O error.  There is no virtue in keeping
  them around in the swap object creating more work for the page daemon.
  (I believe that any non-busy page in the swap object will now always
  be valid.)
  
  vm_pager_get_pages() does not return a standard errno, so its return
  value should not be returned by tmpfs without translation to an errno
  value.
  
  There is no reason for the wakeup on vpg in tmpfs_mappedwrite() to
  occur with the swap object locked.
  
  Eliminate printf()s from tmpfs_nocacheread() and tmpfs_mappedwrite().
  (The swap pager already spam your console if data corruption is
  imminent.)
  
  Reviewed by:	kib
  MFC after:	3 weeks

Modified:
  head/sys/fs/tmpfs/tmpfs_subr.c
  head/sys/fs/tmpfs/tmpfs_vnops.c

Modified: head/sys/fs/tmpfs/tmpfs_subr.c
==============================================================================
--- head/sys/fs/tmpfs/tmpfs_subr.c	Sat Jan 14 22:51:34 2012	(r230119)
+++ head/sys/fs/tmpfs/tmpfs_subr.c	Sat Jan 14 23:04:27 2012	(r230120)
@@ -929,6 +929,7 @@ retry:
 					vm_page_sleep(m, "tmfssz");
 					goto retry;
 				}
+				MPASS(m->valid == VM_PAGE_BITS_ALL);
 			} else if (vm_pager_has_page(uobj, idx, NULL, NULL)) {
 				m = vm_page_alloc(uobj, idx, VM_ALLOC_NORMAL);
 				if (m == NULL) {
@@ -957,7 +958,6 @@ retry:
 			}
 			if (m != NULL) {
 				pmap_zero_page_area(m, base, PAGE_SIZE - base);
-				MPASS(m->valid == VM_PAGE_BITS_ALL);
 				vm_page_dirty(m);
 				vm_pager_page_unswapped(m);
 			}

Modified: head/sys/fs/tmpfs/tmpfs_vnops.c
==============================================================================
--- head/sys/fs/tmpfs/tmpfs_vnops.c	Sat Jan 14 22:51:34 2012	(r230119)
+++ head/sys/fs/tmpfs/tmpfs_vnops.c	Sat Jan 14 23:04:27 2012	(r230120)
@@ -437,18 +437,20 @@ tmpfs_nocacheread(vm_object_t tobj, vm_p
     vm_offset_t offset, size_t tlen, struct uio *uio)
 {
 	vm_page_t	m;
-	int		error;
+	int		error, rv;
 
 	VM_OBJECT_LOCK(tobj);
-	vm_object_pip_add(tobj, 1);
 	m = vm_page_grab(tobj, idx, VM_ALLOC_WIRED |
 	    VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
 	if (m->valid != VM_PAGE_BITS_ALL) {
 		if (vm_pager_has_page(tobj, idx, NULL, NULL)) {
-			error = vm_pager_get_pages(tobj, &m, 1, 0);
-			if (error != 0) {
-				printf("tmpfs get pages from pager error [read]\n");
-				goto out;
+			rv = vm_pager_get_pages(tobj, &m, 1, 0);
+			if (rv != VM_PAGER_OK) {
+				vm_page_lock(m);
+				vm_page_free(m);
+				vm_page_unlock(m);
+				VM_OBJECT_UNLOCK(tobj);
+				return (EIO);
 			}
 		} else
 			vm_page_zero_invalid(m, TRUE);
@@ -456,12 +458,10 @@ tmpfs_nocacheread(vm_object_t tobj, vm_p
 	VM_OBJECT_UNLOCK(tobj);
 	error = uiomove_fromphys(&m, offset, tlen, uio);
 	VM_OBJECT_LOCK(tobj);
-out:
 	vm_page_lock(m);
 	vm_page_unwire(m, TRUE);
 	vm_page_unlock(m);
 	vm_page_wakeup(m);
-	vm_object_pip_subtract(tobj, 1);
 	VM_OBJECT_UNLOCK(tobj);
 
 	return (error);
@@ -624,7 +624,7 @@ tmpfs_mappedwrite(vm_object_t vobj, vm_o
 	vm_offset_t	offset;
 	off_t		addr;
 	size_t		tlen;
-	int		error;
+	int		error, rv;
 
 	error = 0;
 	
@@ -664,14 +664,16 @@ lookupvpg:
 	}
 nocache:
 	VM_OBJECT_LOCK(tobj);
-	vm_object_pip_add(tobj, 1);
 	tpg = vm_page_grab(tobj, idx, VM_ALLOC_WIRED |
 	    VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
 	if (tpg->valid != VM_PAGE_BITS_ALL) {
 		if (vm_pager_has_page(tobj, idx, NULL, NULL)) {
-			error = vm_pager_get_pages(tobj, &tpg, 1, 0);
-			if (error != 0) {
-				printf("tmpfs get pages from pager error [write]\n");
+			rv = vm_pager_get_pages(tobj, &tpg, 1, 0);
+			if (rv != VM_PAGER_OK) {
+				vm_page_lock(tpg);
+				vm_page_free(tpg);
+				vm_page_unlock(tpg);
+				error = EIO;
 				goto out;
 			}
 		} else
@@ -685,9 +687,6 @@ nocache:
 		pmap_copy_page(vpg, tpg);
 	}
 	VM_OBJECT_LOCK(tobj);
-out:
-	if (vobj != NULL)
-		VM_OBJECT_LOCK(vobj);
 	if (error == 0) {
 		KASSERT(tpg->valid == VM_PAGE_BITS_ALL,
 		    ("parts of tpg invalid"));
@@ -697,12 +696,13 @@ out:
 	vm_page_unwire(tpg, TRUE);
 	vm_page_unlock(tpg);
 	vm_page_wakeup(tpg);
-	if (vpg != NULL)
+out:
+	VM_OBJECT_UNLOCK(tobj);
+	if (vpg != NULL) {
+		VM_OBJECT_LOCK(vobj);
 		vm_page_wakeup(vpg);
-	if (vobj != NULL)
 		VM_OBJECT_UNLOCK(vobj);
-	vm_object_pip_subtract(tobj, 1);
-	VM_OBJECT_UNLOCK(tobj);
+	}
 
 	return	(error);
 }

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