[Xen-changelog] [xen-unstable] [BLOCK] blkback: Fix potential grant entry leaks on error

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID ffbd9e4668a6cfd3c936c7344c194afe368f2642
# Parent  4be49a3be040f0951a9be971e9b4cf0a399589ec
[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>
---
 linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletion(-)

diff -r 4be49a3be040 -r ffbd9e4668a6 
linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c        Wed Oct 25 
10:56:50 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c        Wed Oct 25 
10:59:00 2006 +0100
@@ -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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