aio: use iovec array rather than the single one

Previously, we only offer a single iovec to handle all the read/write cases, so
the PREADV/PWRITEV request always need to alloc more iovec buffer when copying
user vectors.
If we use a tmp iovec array rather than the single one, some small PREADV/PWRITEV
workloads(vector size small than the tmp buffer) will not need to alloc more
iovec buffer when copying user vectors.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>

diff --git a/fs/aio.c b/fs/aio.c
index d6d9520..0fd9181 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1243,12 +1243,12 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
        if (compat)
                ret = compat_rw_copy_check_uvector(rw,
                                (struct compat_iovec __user *)buf,
-                               *nr_segs, 1, *iovec, iovec);
+                               *nr_segs, UIO_FASTIOV, *iovec, iovec);
        else
 #endif
                ret = rw_copy_check_uvector(rw,
                                (struct iovec __user *)buf,
-                               *nr_segs, 1, *iovec, iovec);
+                               *nr_segs, UIO_FASTIOV, *iovec, iovec);
        if (ret < 0)
                return ret;
 
@@ -1285,7 +1285,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
        fmode_t mode;
        aio_rw_op *rw_op;
        rw_iter_op *iter_op;
-       struct iovec inline_vec, *iovec = &inline_vec;
+       struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
        struct iov_iter iter;
 
        switch (opcode) {
@@ -1320,7 +1320,7 @@ rw_common:
                if (!ret)
                        ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
                if (ret < 0) {
-                       if (iovec != &inline_vec)
+                       if (iovec != inline_vecs)
                                kfree(iovec);
                        return ret;
                }
@@ -1367,7 +1367,7 @@ rw_common:
                return -EINVAL;
        }
 
-       if (iovec != &inline_vec)
+       if (iovec != inline_vecs)
                kfree(iovec);
 
        if (ret != -EIOCBQUEUED) {