From: piaojun <piaojun@huawei.com>

Date: Mon, 27 Jan 2020 19:02:17 +0000

Subject: [PATCH] virtiofsd: add definition of fuse_buf_writev()

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Define fuse_buf_writev() which use pwritev and writev to improve io

bandwidth. Especially, the src bufs with 0 size should be skipped as

their mems are not *block_size* aligned which will cause writev failed

in direct io mode.

Signed-off-by: Jun Piao <piaojun@huawei.com>

Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

(cherry picked from commit 9ceaaa15cf21073c2b23058c374f61c30cd39c31)

---

 tools/virtiofsd/buffer.c | 38 ++++++++++++++++++++++++++++++++++++++

 1 file changed, 38 insertions(+)

diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c

index 42a608f6bd..37befebac2 100644

--- a/tools/virtiofsd/buffer.c

+++ b/tools/virtiofsd/buffer.c

@@ -14,6 +14,7 @@

 #include "fuse_lowlevel.h"

 #include <assert.h>

 #include <errno.h>

+#include <stdlib.h>

 #include <string.h>

 #include <unistd.h>

@@ -33,6 +34,43 @@ size_t fuse_buf_size(const struct fuse_bufvec *bufv)

     return size;

 }

+__attribute__((unused))

+static ssize_t fuse_buf_writev(struct fuse_buf *out_buf,

+                               struct fuse_bufvec *in_buf)

+{

+    ssize_t res, i, j;

+    size_t iovcnt = in_buf->count;

+    struct iovec *iov;

+    int fd = out_buf->fd;

+

+    iov = calloc(iovcnt, sizeof(struct iovec));

+    if (!iov) {

+        return -ENOMEM;

+    }

+

+    for (i = 0, j = 0; i < iovcnt; i++) {

+        /* Skip the buf with 0 size */

+        if (in_buf->buf[i].size) {

+            iov[j].iov_base = in_buf->buf[i].mem;

+            iov[j].iov_len = in_buf->buf[i].size;

+            j++;

+        }

+    }

+

+    if (out_buf->flags & FUSE_BUF_FD_SEEK) {

+        res = pwritev(fd, iov, iovcnt, out_buf->pos);

+    } else {

+        res = writev(fd, iov, iovcnt);

+    }

+

+    if (res == -1) {

+        res = -errno;

+    }

+

+    free(iov);

+    return res;

+}

+

 static size_t min_size(size_t s1, size_t s2)

 {

     return s1 < s2 ? s1 : s2;