From d50d82221934696633296975aa433fe8aeeac714 Mon Sep 17 00:00:00 2001 From: "Denis V. Lunev" Date: Fri, 30 Jan 2015 11:42:15 +0300 Subject: [PATCH] block/raw-posix: call plain fallocate in handle_aiocb_write_zeroes 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. Before the patch do_fallocate was used when either CONFIG_FALLOCATE_PUNCH_HOLE or CONFIG_FALLOCATE_ZERO_RANGE are defined. Now the story is different. CONFIG_FALLOCATE is defined when Linux fallocate is defined, posix_fallocate is completely different story (CONFIG_POSIX_FALLOCATE). CONFIG_FALLOCATE is mandatory prerequite for both CONFIG_FALLOCATE_PUNCH_HOLE and CONFIG_FALLOCATE_ZERO_RANGE thus we are on the safe side. CC: Max Reitz CC: Kevin Wolf CC: Stefan Hajnoczi CC: Peter Lieven CC: Fam Zheng Signed-off-by: Denis V. Lunev Reviewed-by: Max Reitz Signed-off-by: Kevin Wolf --- block/raw-posix.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/block/raw-posix.c b/block/raw-posix.c index 5a777e7137..1c88ad89d8 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -147,6 +147,7 @@ typedef struct BDRVRawState { bool has_discard:1; bool has_write_zeroes:1; bool discard_zeroes:1; + bool has_fallocate; bool needs_alignment; } BDRVRawState; @@ -452,6 +453,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, } if (S_ISREG(st.st_mode)) { s->discard_zeroes = true; + s->has_fallocate = true; } if (S_ISBLK(st.st_mode)) { #ifdef BLKDISCARDZEROES @@ -902,7 +904,7 @@ static int translate_err(int err) return err; } -#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || defined(CONFIG_FALLOCATE_ZERO_RANGE) +#ifdef CONFIG_FALLOCATE static int do_fallocate(int fd, int mode, off_t offset, off_t len) { do { @@ -965,6 +967,16 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) } #endif +#ifdef CONFIG_FALLOCATE + if (s->has_fallocate && aiocb->aio_offset >= bdrv_getlength(aiocb->bs)) { + int ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes); + if (ret == 0 || ret != -ENOTSUP) { + return ret; + } + s->has_fallocate = false; + } +#endif + return -ENOTSUP; }