On 27/01/15 20:57, Max Reitz wrote:
On 2015-01-27 at 08:51, Denis V. Lunev wrote:
There is a possibility that we are extending our image and thus
writing
zeroes beyond the end of the file. In this case we do not need to care
about the hole to make sure that there is no data in the file under
this offset (pre-condition to fallocate(0) to work). We could
simply call
fallocate(0).
This improves the performance of writing zeroes even on really old
platforms which do not have even FALLOC_FL_PUNCH_HOLE.
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Kevin Wolf <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
CC: Peter Lieven <address@hidden>
CC: Fam Zheng <address@hidden>
---
block/raw-posix.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index c039bef..fa05239 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -60,7 +60,7 @@
#define FS_NOCOW_FL 0x00800000 /* Do not cow
file */
#endif
#endif
-#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) ||
defined(CONFIG_FALLOCATE_ZERO_RANGE)
+#ifdef CONFIG_FALLOCATE
This change doesn't seem right; CONFIG_FALLOCATE is set if
posix_fallocate() is available, not for the Linux-specific
fallocate() from linux/falloc.h.
here is a check for fallocate and posix_fallocate in configure script
# check for fallocate
fallocate=no
cat > $TMPC << EOF
#include <fcntl.h>
int main(void)
{
fallocate(0, 0, 0, 0);
return 0;
}
EOF
if compile_prog "" "" ; then
fallocate=yes
fi
...
# check for posix_fallocate
posix_fallocate=no
cat > $TMPC << EOF
#include <fcntl.h>
int main(void)
{
posix_fallocate(0, 0, 0);
return 0;
}
EOF
if compile_prog "" "" ; then
posix_fallocate=yes
fi
...
if test "$fallocate" = "yes" ; then
echo "CONFIG_FALLOCATE=y" >> $config_host_mak
fi
...
if test "$posix_fallocate" = "yes" ; then
echo "CONFIG_POSIX_FALLOCATE=y" >> $config_host_mak
fi
Thus my check looks correct to me.