fallocate() works fine and could handle properly with arbitrary size
requests. There is no sense to reduce the amount of space to fallocate.
The bigger is the size, the better is the performance as the amount of
journal updates is reduced.
The patch changes behavior for both generic filesystem and XFS codepaths,
which are different in handle_aiocb_write_zeroes. The implementation
of fallocate and xfsctl(XFS_IOC_ZERO_RANGE) for XFS are exactly the same
thus the change is fine for both ways.
Signed-off-by: Denis V. Lunev <address@hidden>
Reviewed-by: 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 | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 7b42f37..933c778 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -293,6 +293,20 @@ static void raw_probe_alignment(BlockDriverState *bs, int
fd, Error **errp)
}
}
+static void raw_probe_max_write_zeroes(BlockDriverState *bs)
+{
+ BDRVRawState *s = bs->opaque;
+ struct stat st;
+
+ if (fstat(s->fd, &st) < 0) {
+ return; /* no problem, keep default value */
+ }
+ if (!S_ISREG(st.st_mode) || !s->discard_zeroes) {
+ return;
+ }
+ bs->bl.max_write_zeroes = INT_MAX;
+}