Distinguish between two distinct kinds of errors from VOP_BMAP() in

vnode_pager_generic_getpages(): (1) that VOP_BMAP() is unsupported by the
underlying file system and (2) an error in performing the VOP_BMAP().
Previously, vnode_pager_generic_getpages() assumed that all errors were
of the first type.  If, in fact, the error was of the second type, the
likely outcome was for the process to become permanently blocked on a busy
page.

MFC after: 3 weeks
Reviewed by: tegge

1 files changed, 12 insertions, 2 deletions

diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index e683a84..b4a9bf6 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -701,7 +701,7 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 	int runend;
 	struct buf *bp;
 	int count;
-	int error = 0;
+	int error;
 
 	object = vp->v_object;
 	count = bytecount / PAGE_SIZE;
@@ -724,7 +724,8 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 	/*
 	 * if we can't bmap, use old VOP code
 	 */
-	if (VOP_BMAP(vp, foff / bsize, &bo, &reqblock, NULL, NULL)) {
+	error = VOP_BMAP(vp, foff / bsize, &bo, &reqblock, NULL, NULL);
+	if (error == EOPNOTSUPP) {
 		VM_OBJECT_LOCK(object);
 		vm_page_lock_queues();
 		for (i = 0; i < count; i++)
@@ -736,6 +737,15 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 		error = vnode_pager_input_old(object, m[reqpage]);
 		VM_OBJECT_UNLOCK(object);
 		return (error);
+	} else if (error != 0) {
+		VM_OBJECT_LOCK(object);
+		vm_page_lock_queues();
+		for (i = 0; i < count; i++)
+			if (i != reqpage)
+				vm_page_free(m[i]);
+		vm_page_unlock_queues();
+		VM_OBJECT_UNLOCK(object);
+		return (VM_PAGER_ERROR);
 
 		/*
 		 * if the blocksize is smaller than a page size, then use