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authorAlberto Garcia <berto@igalia.com>2016-11-25 13:27:43 +0200
committerKevin Wolf <kwolf@redhat.com>2016-11-25 13:51:30 +0100
commit2f2c8d6b371cfc6689affb0b7e463fa2160c9e5b (patch)
tree2d49c8f653f2cfb0a11d1e8f21a92eaac79f0996
parent00227fefd2059464cd2f59aed29944874c630e2f (diff)
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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@igalia.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--block/qcow2-cache.c5
1 files 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
}