[Xen-devel] [BLOCK] blkback: Fix potential grant entry leaks on error

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Hi Keir:

This patch is similar to the corresponding patch for blktap.

[BLOCK] blkback: Fix potential grant entry leaks on error

As it stands grant entries for the actual data are mapped in bulk.
If one of the earlier entries fail to be mapped, it can cause all
subsequent entries to be leaked if they were successfully mapped.

This patch changes it so that we will continue to reap grant entries
even when an error is detected.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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--
diff -r 29b02d929b7e linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c        Mon Oct 23 
14:42:52 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c        Tue Oct 24 
16:31:07 2006 +1000
@@ -392,16 +392,24 @@ static void dispatch_rw_block_io(blkif_t
        for (i = 0; i < nseg; i++) {
                if (unlikely(map[i].status != 0)) {
                        DPRINTK("invalid buffer -- could not remap it\n");
-                       goto fail_flush;
+                       map[i].handle = BLKBACK_INVALID_HANDLE;
+                       ret |= 1;
                }
 
                pending_handle(pending_req, i) = map[i].handle;
+
+               if (ret)
+                       continue;
+
                set_phys_to_machine(__pa(vaddr(
                        pending_req, i)) >> PAGE_SHIFT,
                        FOREIGN_FRAME(map[i].dev_bus_addr >> PAGE_SHIFT));
                seg[i].buf  = map[i].dev_bus_addr | 
                        (req->seg[i].first_sect << 9);
        }
+
+       if (ret)
+               goto fail_flush;
 
        if (vbd_translate(&preq, blkif, operation) != 0) {
                DPRINTK("access denied: %s of [%llu,%llu] on dev=%04x\n", 

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