[Xen-changelog] [qemu-xen master] qcow2: Make qcow2_cache_table_release() work only in Linux

[patchbot@xxxxxxx]

commit 2f2c8d6b371cfc6689affb0b7e463fa2160c9e5b
Author:     Alberto Garcia <berto@xxxxxxxxxx>
AuthorDate: Fri Nov 25 13:27:43 2016 +0200
Commit:     Kevin Wolf <kwolf@xxxxxxxxxx>
CommitDate: Fri Nov 25 13:51:30 2016 +0100

    qcow2: Make qcow2_cache_table_release() work only in Linux
    
    We are using QEMU_MADV_DONTNEED to discard the memory of individual L2
    cache tables. The problem with this is that those semantics are
    specific to the Linux madvise() system call. Other implementations of
    madvise() (including the very Linux implementation of posix_madvise())
    don't do that, so we cannot use them for the same purpose.
    
    This patch makes the code Linux-specific and uses madvise() directly
    since there's no point in going through qemu_madvise() for this.
    
    Signed-off-by: Alberto Garcia <berto@xxxxxxxxxx>
    Signed-off-by: Kevin Wolf <kwolf@xxxxxxxxxx>
---
 block/qcow2-cache.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 6eaefed..ab8ee2d 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -66,7 +66,8 @@ static inline int qcow2_cache_get_table_idx(BlockDriverState 
*bs,
 static void qcow2_cache_table_release(BlockDriverState *bs, Qcow2Cache *c,
                                       int i, int num_tables)
 {
-#if QEMU_MADV_DONTNEED != QEMU_MADV_INVALID
+/* Using MADV_DONTNEED to discard memory is a Linux-specific feature */
+#ifdef CONFIG_LINUX
     BDRVQcow2State *s = bs->opaque;
     void *t = qcow2_cache_get_table_addr(bs, c, i);
     int align = getpagesize();
@@ -74,7 +75,7 @@ static void qcow2_cache_table_release(BlockDriverState *bs, 
Qcow2Cache *c,
     size_t offset = QEMU_ALIGN_UP((uintptr_t) t, align) - (uintptr_t) t;
     size_t length = QEMU_ALIGN_DOWN(mem_size - offset, align);
     if (length > 0) {
-        qemu_madvise((uint8_t *) t + offset, length, QEMU_MADV_DONTNEED);
+        madvise((uint8_t *) t + offset, length, MADV_DONTNEED);
     }
 #endif
 }
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#master

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
https://lists.xenproject.org/xen-changelog