| Message ID | 20170804151013.13057-2-den@openvz.org |
|---|---|
| State | New |
| Headers | show |
On 08/04/2017 10:10 AM, Denis V. Lunev wrote: > Original idea beyond the code in question was the following: we have failed > to write zeroes with fallocate(FALLOC_FL_ZERO_RANGE) as the simplest > approach and via fallocate(FALLOC_FL_PUNCH_HOLE)/fallocate(0). We have the > only chance now: if the request comes beyond end of the file. Thus we > should calculate file length and respect the error code from that op. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Markus Armbruster <armbru@redhat.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Max Reitz <mreitz@redhat.com> > CC: Stefan Hajnoczi <stefanha@redhat.com> > --- > block/file-posix.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/block/file-posix.c b/block/file-posix.c index cfbb236f6f..f4de022ae0 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1339,6 +1339,9 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) #if defined(CONFIG_FALLOCATE) || defined(CONFIG_XFS) BDRVRawState *s = aiocb->bs->opaque; #endif +#ifdef CONFIG_FALLOCATE + int64_t len; +#endif if (aiocb->aio_type & QEMU_AIO_BLKDEV) { return handle_aiocb_write_zeroes_block(aiocb); @@ -1381,7 +1384,10 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) #endif #ifdef CONFIG_FALLOCATE - if (s->has_fallocate && aiocb->aio_offset >= bdrv_getlength(aiocb->bs)) { + /* Last resort: we are trying to extend the file with zeroed data. This + * can be done via fallocate(fd, 0) */ + len = bdrv_getlength(aiocb->bs); + if (s->has_fallocate && len >= 0 && aiocb->aio_offset >= len) { int ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes); if (ret == 0 || ret != -ENOTSUP) { return ret;
Original idea beyond the code in question was the following: we have failed to write zeroes with fallocate(FALLOC_FL_ZERO_RANGE) as the simplest approach and via fallocate(FALLOC_FL_PUNCH_HOLE)/fallocate(0). We have the only chance now: if the request comes beyond end of the file. Thus we should calculate file length and respect the error code from that op. Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Markus Armbruster <armbru@redhat.com> CC: Kevin Wolf <kwolf@redhat.com> CC: Max Reitz <mreitz@redhat.com> CC: Stefan Hajnoczi <stefanha@redhat.com> --- block/file-posix.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)