@@ -968,6 +968,23 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb)
#endif
s->has_write_zeroes = false;
+
+#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
+ if (s->has_discard) {
+ int ret;
+ ret = do_fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+ aiocb->aio_offset, aiocb->aio_nbytes);
+ if (ret < 0) {
+ if (ret == -ENOTSUP) {
+ s->has_discard = false;
+ }
+ return ret;
+ }
+ return do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes);
+ }
+#endif
+
+ s->has_discard = false;
return -ENOTSUP;
}
This sequence works efficiently if FALLOC_FL_ZERO_RANGE is not supported. Simple fallocate(0) will extend file with zeroes when appropriate in the middle of the file if there is a hole there and at the end of the file. Unfortunately fallocate(0) does not drop the content of the file if there is a data on this offset. Therefore to make the situation consistent we should drop the data beforehand. This is done using FALLOC_FL_PUNCH_HOLE This should increase the performance a bit for not-so-modern kernels or for filesystems which do not support FALLOC_FL_ZERO_RANGE. Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Kevin Wolf <kwolf@redhat.com> CC: Stefan Hajnoczi <stefanha@redhat.com> --- block/raw-posix.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)