Blame 0108-virtiofsd-add-definition-of-fuse_buf_writev.patch

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From: piaojun <piaojun@huawei.com>
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Date: Mon, 27 Jan 2020 19:02:17 +0000
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Subject: [PATCH] virtiofsd: add definition of fuse_buf_writev()
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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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Define fuse_buf_writev() which use pwritev and writev to improve io
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bandwidth. Especially, the src bufs with 0 size should be skipped as
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their mems are not *block_size* aligned which will cause writev failed
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in direct io mode.
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Signed-off-by: Jun Piao <piaojun@huawei.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 9ceaaa15cf21073c2b23058c374f61c30cd39c31)
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---
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 tools/virtiofsd/buffer.c | 38 ++++++++++++++++++++++++++++++++++++++
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 1 file changed, 38 insertions(+)
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diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c
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index 42a608f6bd..37befebac2 100644
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--- a/tools/virtiofsd/buffer.c
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+++ b/tools/virtiofsd/buffer.c
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@@ -14,6 +14,7 @@
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 #include "fuse_lowlevel.h"
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 #include <assert.h>
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 #include <errno.h>
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+#include <stdlib.h>
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 #include <string.h>
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 #include <unistd.h>
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@@ -33,6 +34,43 @@ 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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+    ssize_t res, i, j;
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+    size_t iovcnt = in_buf->count;
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+    struct iovec *iov;
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+    int fd = out_buf->fd;
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+
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+    iov = calloc(iovcnt, sizeof(struct iovec));
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+    if (!iov) {
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+        return -ENOMEM;
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+    }
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+
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+    for (i = 0, j = 0; i < iovcnt; i++) {
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+        /* Skip the buf with 0 size */
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+        if (in_buf->buf[i].size) {
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+            iov[j].iov_base = in_buf->buf[i].mem;
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+            iov[j].iov_len = in_buf->buf[i].size;
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+            j++;
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+        }
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+    }
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+
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+    if (out_buf->flags & FUSE_BUF_FD_SEEK) {
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+        res = pwritev(fd, iov, iovcnt, out_buf->pos);
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+    } else {
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+        res = writev(fd, iov, iovcnt);
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+    }
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+
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+    if (res == -1) {
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+        res = -errno;
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+    }
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+
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+    free(iov);
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+    return res;
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+}
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+
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 static size_t min_size(size_t s1, size_t s2)
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 {
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     return s1 < s2 ? s1 : s2;