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[Qemu-devel] [PATCH 4/7] block: use fallocate(FALLOC_FL_ZERO_RANGE) in h
From: |
Denis V. Lunev |
Subject: |
[Qemu-devel] [PATCH 4/7] block: use fallocate(FALLOC_FL_ZERO_RANGE) in handle_aiocb_write_zeroes |
Date: |
Wed, 28 Jan 2015 21:38:55 +0300 |
This efficiently writes zeroes on Linux if the kernel is capable enough.
FALLOC_FL_ZERO_RANGE correctly handles all cases, including and not
including file expansion.
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Max Reitz <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 | 15 +++++++++++++--
configure | 19 +++++++++++++++++++
2 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index d3910fd..5a777e7 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
-#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
+#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) ||
defined(CONFIG_FALLOCATE_ZERO_RANGE)
#include <linux/falloc.h>
#endif
#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
@@ -902,7 +902,7 @@ static int translate_err(int err)
return err;
}
-#if defined(CONFIG_FALLOCATE_PUNCH_HOLE)
+#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) ||
defined(CONFIG_FALLOCATE_ZERO_RANGE)
static int do_fallocate(int fd, int mode, off_t offset, off_t len)
{
do {
@@ -954,6 +954,17 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData
*aiocb)
}
#endif
+#ifdef CONFIG_FALLOCATE_ZERO_RANGE
+ if (s->has_write_zeroes) {
+ int ret = do_fallocate(s->fd, FALLOC_FL_ZERO_RANGE,
+ aiocb->aio_offset, aiocb->aio_nbytes);
+ if (ret == 0 || ret != -ENOTSUP) {
+ return ret;
+ }
+ s->has_write_zeroes = false;
+ }
+#endif
+
return -ENOTSUP;
}
diff --git a/configure b/configure
index f185dd0..e00e03a 100755
--- a/configure
+++ b/configure
@@ -3335,6 +3335,22 @@ if compile_prog "" "" ; then
fallocate_punch_hole=yes
fi
+# check that fallocate supports range zeroing inside the file
+fallocate_zero_range=no
+cat > $TMPC << EOF
+#include <fcntl.h>
+#include <linux/falloc.h>
+
+int main(void)
+{
+ fallocate(0, FALLOC_FL_ZERO_RANGE, 0, 0);
+ return 0;
+}
+EOF
+if compile_prog "" "" ; then
+ fallocate_zero_range=yes
+fi
+
# check for posix_fallocate
posix_fallocate=no
cat > $TMPC << EOF
@@ -4567,6 +4583,9 @@ fi
if test "$fallocate_punch_hole" = "yes" ; then
echo "CONFIG_FALLOCATE_PUNCH_HOLE=y" >> $config_host_mak
fi
+if test "$fallocate_zero_range" = "yes" ; then
+ echo "CONFIG_FALLOCATE_ZERO_RANGE=y" >> $config_host_mak
+fi
if test "$posix_fallocate" = "yes" ; then
echo "CONFIG_POSIX_FALLOCATE=y" >> $config_host_mak
fi
--
1.9.1
- [Qemu-devel] [PATCH v5 0/7] eliminate data write in bdrv_write_zeroes on Linux in raw-posix.c, Denis V. Lunev, 2015/01/28
- [Qemu-devel] [PATCH 7/7] block/raw-posix: set max_write_zeroes to INT_MAX for regular files, Denis V. Lunev, 2015/01/28
- [Qemu-devel] [PATCH 3/7] block/raw-posix: refactor handle_aiocb_write_zeroes a bit, Denis V. Lunev, 2015/01/28
- [Qemu-devel] [PATCH 5/7] block: use fallocate(FALLOC_FL_PUNCH_HOLE) & fallocate(0) to write zeroes, Denis V. Lunev, 2015/01/28
- [Qemu-devel] [PATCH 6/7] block/raw-posix: call plain fallocate in handle_aiocb_write_zeroes, Denis V. Lunev, 2015/01/28
- [Qemu-devel] [PATCH 2/7] block/raw-posix: create do_fallocate helper, Denis V. Lunev, 2015/01/28
- [Qemu-devel] [PATCH 4/7] block: use fallocate(FALLOC_FL_ZERO_RANGE) in handle_aiocb_write_zeroes,
Denis V. Lunev <=
- [Qemu-devel] [PATCH 1/7] block/raw-posix: create translate_err helper to merge errno values, Denis V. Lunev, 2015/01/28