Re: hugetlbfs not working

[Marcelo Tosatti <marcelo@kvack.org>]

On Fri, Mar 28, 2008 at 09:41:06AM +0300, Avi Kivity wrote:
> >mmap() should fail if anything goes wrong with ftruncate and the file
> >length is not extented on tmpfs.
> >
> >--- vl.c.orig   2008-03-27 18:51:31.000000000 -0300
> >+++ vl.c        2008-03-27 18:52:40.000000000 -0300
> >@@ -8749,11 +8749,7 @@
> >
> >     memory = (memory+hpagesize-1) & ~(hpagesize-1);
> >
> >-    if (ftruncate(fd, memory) == -1) {
> >-       perror("ftruncate");
> >-       close(fd);
> >-       return NULL;
> >-    }
> >+    ftruncate(fd, memory);
> >  
> 
> I'm sure a patch will follow to add a missing error check, so how about 
> a comment here?
> 
> btw, we use signoffs on kvm-userspace, too.

QEMU/KVM: ftruncate() is not supported by hugetlbfs on older hosts

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/qemu/vl.c b/qemu/vl.c
index 5627862..6a240bf 100644
--- a/qemu/vl.c
+++ b/qemu/vl.c
@@ -8739,11 +8739,13 @@ void *alloc_mem_area(unsigned long memory, const char *path)
 
     memory = (memory+hpagesize-1) & ~(hpagesize-1);
 
-    if (ftruncate(fd, memory) == -1) {
-	perror("ftruncate");
-	close(fd);
-	return NULL;
-    }
+    /*
+     * ftruncate is not supported by hugetlbfs in older 
+     * hosts, so don't bother checking for errors.
+     * If anything goes wrong with it under other filesystems,
+     * mmap will fail.
+     */
+    ftruncate(fd, memory);
 
     area = mmap(0, memory, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
     if (area == MAP_FAILED) {


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