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| author | Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> | 2020-04-08 22:29:58 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-04-08 09:23:42 -0600 |
| commit | 45097daea2f4e89bdb1c98359f78d0d6feb8e5c8 (patch) | |
| tree | 97a91059f9973494c0a08c2e3923ffe69dff336e /fs | |
| parent | 08a1d26eb894a9dcf79f674558a284ad1ffef517 (diff) | |
| download | lwn-45097daea2f4e89bdb1c98359f78d0d6feb8e5c8.tar.gz lwn-45097daea2f4e89bdb1c98359f78d0d6feb8e5c8.zip | |
io_uring: do not always copy iovec in io_req_map_rw()
In io_read_prep() or io_write_prep(), io_req_map_rw() takes
struct io_async_rw's fast_iov as argument to call io_import_iovec(),
and if io_import_iovec() uses struct io_async_rw's fast_iov as
valid iovec array, later indeed io_req_map_rw() does not need
to do the memcpy operation, because they are same pointers.
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io_uring.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index e71aa42e102a..b06188a50af4 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2493,8 +2493,9 @@ static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size, req->io->rw.iov = iovec; if (!req->io->rw.iov) { req->io->rw.iov = req->io->rw.fast_iov; - memcpy(req->io->rw.iov, fast_iov, - sizeof(struct iovec) * iter->nr_segs); + if (req->io->rw.iov != fast_iov) + memcpy(req->io->rw.iov, fast_iov, + sizeof(struct iovec) * iter->nr_segs); } else { req->flags |= REQ_F_NEED_CLEANUP; } |