Blame SOURCES/kvm-virtiofsd-Plumb-fuse_bufvec-through-to-do_write_buf.patch

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From 9e4320eec5204da851ac95fb7a7e6520c9ccee7d Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:01:19 +0100
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Subject: [PATCH 048/116] virtiofsd: Plumb fuse_bufvec through to do_write_buf
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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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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20200127190227.40942-45-dgilbert@redhat.com>
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Patchwork-id: 93499
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O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 044/112] virtiofsd: Plumb fuse_bufvec through to do_write_buf
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Bugzilla: 1694164
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Let fuse_session_process_buf_int take a fuse_bufvec * instead of a
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fuse_buf;  and then through to do_write_buf - where in the best
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case it can pass that straight through to op.write_buf without copying
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(other than skipping a header).
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 469f9d2fc405b0508e6cf1b4b5bbcadfc82064e5)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 tools/virtiofsd/fuse_i.h        |  2 +-
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 tools/virtiofsd/fuse_lowlevel.c | 61 +++++++++++++++++++++++++++--------------
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 tools/virtiofsd/fuse_virtio.c   |  3 +-
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 3 files changed, 44 insertions(+), 22 deletions(-)
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diff --git a/tools/virtiofsd/fuse_i.h b/tools/virtiofsd/fuse_i.h
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index 45995f3..a20854f 100644
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--- a/tools/virtiofsd/fuse_i.h
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+++ b/tools/virtiofsd/fuse_i.h
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@@ -100,7 +100,7 @@ int fuse_send_reply_iov_nofree(fuse_req_t req, int error, struct iovec *iov,
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 void fuse_free_req(fuse_req_t req);
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 void fuse_session_process_buf_int(struct fuse_session *se,
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-                                  const struct fuse_buf *buf,
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+                                  struct fuse_bufvec *bufv,
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                                   struct fuse_chan *ch);
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diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
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index 95f4db8..7e10995 100644
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--- a/tools/virtiofsd/fuse_lowlevel.c
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+++ b/tools/virtiofsd/fuse_lowlevel.c
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@@ -1004,11 +1004,12 @@ static void do_write(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
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 }
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 static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid, const void *inarg,
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-                         const struct fuse_buf *ibuf)
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+                         struct fuse_bufvec *ibufv)
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 {
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     struct fuse_session *se = req->se;
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-    struct fuse_bufvec bufv = {
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-        .buf[0] = *ibuf,
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+    struct fuse_bufvec *pbufv = ibufv;
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+    struct fuse_bufvec tmpbufv = {
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+        .buf[0] = ibufv->buf[0],
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         .count = 1,
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     };
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     struct fuse_write_in *arg = (struct fuse_write_in *)inarg;
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@@ -1018,22 +1019,31 @@ static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid, const void *inarg,
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     fi.fh = arg->fh;
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     fi.writepage = arg->write_flags & FUSE_WRITE_CACHE;
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-    fi.lock_owner = arg->lock_owner;
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-    fi.flags = arg->flags;
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-    if (!(bufv.buf[0].flags & FUSE_BUF_IS_FD)) {
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-        bufv.buf[0].mem = PARAM(arg);
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-    }
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-
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-    bufv.buf[0].size -=
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-        sizeof(struct fuse_in_header) + sizeof(struct fuse_write_in);
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-    if (bufv.buf[0].size < arg->size) {
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-        fuse_log(FUSE_LOG_ERR, "fuse: do_write_buf: buffer size too small\n");
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-        fuse_reply_err(req, EIO);
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-        return;
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+    if (ibufv->count == 1) {
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+        fi.lock_owner = arg->lock_owner;
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+        fi.flags = arg->flags;
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+        if (!(tmpbufv.buf[0].flags & FUSE_BUF_IS_FD)) {
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+            tmpbufv.buf[0].mem = PARAM(arg);
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+        }
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+        tmpbufv.buf[0].size -=
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+            sizeof(struct fuse_in_header) + sizeof(struct fuse_write_in);
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+        if (tmpbufv.buf[0].size < arg->size) {
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+            fuse_log(FUSE_LOG_ERR,
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+                     "fuse: do_write_buf: buffer size too small\n");
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+            fuse_reply_err(req, EIO);
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+            return;
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+        }
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+        tmpbufv.buf[0].size = arg->size;
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+        pbufv = &tmpbufv;
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+    } else {
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+        /*
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+         *  Input bufv contains the headers in the first element
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+         * and the data in the rest, we need to skip that first element
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+         */
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+        ibufv->buf[0].size = 0;
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     }
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-    bufv.buf[0].size = arg->size;
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-    se->op.write_buf(req, nodeid, &bufv, arg->offset, &fi);
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+    se->op.write_buf(req, nodeid, pbufv, arg->offset, &fi);
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 }
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 static void do_flush(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
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@@ -2024,13 +2034,24 @@ static const char *opname(enum fuse_opcode opcode)
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 void fuse_session_process_buf(struct fuse_session *se,
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                               const struct fuse_buf *buf)
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 {
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-    fuse_session_process_buf_int(se, buf, NULL);
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+    struct fuse_bufvec bufv = { .buf[0] = *buf, .count = 1 };
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+    fuse_session_process_buf_int(se, &bufv, NULL);
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 }
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+/*
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+ * Restriction:
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+ *   bufv is normally a single entry buffer, except for a write
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+ *   where (if it's in memory) then the bufv may be multiple entries,
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+ *   where the first entry contains all headers and subsequent entries
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+ *   contain data
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+ *   bufv shall not use any offsets etc to make the data anything
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+ *   other than contiguous starting from 0.
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+ */
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 void fuse_session_process_buf_int(struct fuse_session *se,
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-                                  const struct fuse_buf *buf,
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+                                  struct fuse_bufvec *bufv,
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                                   struct fuse_chan *ch)
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 {
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+    const struct fuse_buf *buf = bufv->buf;
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     struct fuse_in_header *in;
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     const void *inarg;
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     struct fuse_req *req;
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@@ -2108,7 +2129,7 @@ void fuse_session_process_buf_int(struct fuse_session *se,
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     inarg = (void *)&in[1];
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     if (in->opcode == FUSE_WRITE && se->op.write_buf) {
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-        do_write_buf(req, in->nodeid, inarg, buf);
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+        do_write_buf(req, in->nodeid, inarg, bufv);
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     } else {
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         fuse_ll_ops[in->opcode].func(req, in->nodeid, inarg);
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     }
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diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
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index 635f877..fd588a4 100644
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--- a/tools/virtiofsd/fuse_virtio.c
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+++ b/tools/virtiofsd/fuse_virtio.c
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@@ -501,7 +501,8 @@ static void *fv_queue_thread(void *opaque)
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             /* TODO! Endianness of header */
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             /* TODO: Add checks for fuse_session_exited */
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-            fuse_session_process_buf_int(se, &fbuf, &ch);
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+            struct fuse_bufvec bufv = { .buf[0] = fbuf, .count = 1 };
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+            fuse_session_process_buf_int(se, &bufv, &ch);
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             if (!qi->reply_sent) {
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                 fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n",
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-- 
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1.8.3.1
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