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From: piaojun <piaojun@huawei.com>
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Date: Mon, 27 Jan 2020 19:02:18 +0000
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Subject: [PATCH] virtiofsd: use fuse_buf_writev to replace fuse_buf_write for
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better performance
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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fuse_buf_writev() only handles the normal write in which src is buffer
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and dest is fd. Specially if src buffer represents guest physical
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address that can't be mapped by the daemon process, IO must be bounced
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back to the VMM to do it by fuse_buf_copy().
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Signed-off-by: Jun Piao <piaojun@huawei.com>
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Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit c465bba2c90a810f6e71e4f2646b1b4ee4b478de)
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---
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tools/virtiofsd/buffer.c | 20 ++++++++++++++++++--
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1 file changed, 18 insertions(+), 2 deletions(-)
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diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c
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index 37befebac2..27c1377f22 100644
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--- a/tools/virtiofsd/buffer.c
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+++ b/tools/virtiofsd/buffer.c
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@@ -34,7 +34,6 @@ size_t fuse_buf_size(const struct fuse_bufvec *bufv)
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return size;
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}
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-__attribute__((unused))
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static ssize_t fuse_buf_writev(struct fuse_buf *out_buf,
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struct fuse_bufvec *in_buf)
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{
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@@ -262,12 +261,29 @@ static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len)
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ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv)
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{
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- size_t copied = 0;
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+ size_t copied = 0, i;
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if (dstv == srcv) {
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return fuse_buf_size(dstv);
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}
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+ /*
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+ * use writev to improve bandwidth when all the
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+ * src buffers already mapped by the daemon
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+ * process
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+ */
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+ for (i = 0; i < srcv->count; i++) {
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+ if (srcv->buf[i].flags & FUSE_BUF_IS_FD) {
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+ break;
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+ }
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+ }
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+ if ((i == srcv->count) && (dstv->count == 1) &&
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+ (dstv->idx == 0) &&
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+ (dstv->buf[0].flags & FUSE_BUF_IS_FD)) {
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+ dstv->buf[0].pos += dstv->off;
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+ return fuse_buf_writev(&dstv->buf[0], srcv);
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+ }
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+
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for (;;) {
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const struct fuse_buf *src = fuse_bufvec_current(srcv);
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const struct fuse_buf *dst = fuse_bufvec_current(dstv);
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