[PATCH v2 21/25] DAX/unmap virtiofsd: route unmappable write to slave command

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

When a fuse_buf_copy is performed on an element with FUSE_BUF_PHYS_ADDR
route it to a fuse_virtio_write request that does a slave command to
perform the write.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 tools/virtiofsd/buffer.c         | 14 +++++++++++---
 tools/virtiofsd/fuse_common.h    |  6 +++++-
 tools/virtiofsd/fuse_lowlevel.h  |  3 ---
 tools/virtiofsd/passthrough_ll.c |  2 +-
 4 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c
index 1a050aa441..8135d52d2a 100644
--- a/tools/virtiofsd/buffer.c
+++ b/tools/virtiofsd/buffer.c
@@ -200,13 +200,20 @@ static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off,
     return copied;
 }
 
-static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off,
+static ssize_t fuse_buf_copy_one(fuse_req_t req,
+                                 const struct fuse_buf *dst, size_t dst_off,
                                  const struct fuse_buf *src, size_t src_off,
                                  size_t len)
 {
     int src_is_fd = src->flags & FUSE_BUF_IS_FD;
     int dst_is_fd = dst->flags & FUSE_BUF_IS_FD;
+    int src_is_phys = src->flags & FUSE_BUF_PHYS_ADDR;
+    int dst_is_phys = src->flags & FUSE_BUF_PHYS_ADDR;
 
+    if (src_is_phys && !src_is_fd && dst_is_fd) {
+        return fuse_virtio_write(req, dst, dst_off, src, src_off, len);
+    }
+    assert(!src_is_phys && !dst_is_phys);
     if (!src_is_fd && !dst_is_fd) {
         char *dstmem = (char *)dst->mem + dst_off;
         char *srcmem = (char *)src->mem + src_off;
@@ -259,7 +266,8 @@ static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len)
     return 1;
 }
 
-ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv)
+ssize_t fuse_buf_copy(fuse_req_t req, struct fuse_bufvec *dstv,
+                      struct fuse_bufvec *srcv)
 {
     size_t copied = 0, i;
 
@@ -301,7 +309,7 @@ ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv)
         dst_len = dst->size - dstv->off;
         len = min_size(src_len, dst_len);
 
-        res = fuse_buf_copy_one(dst, dstv->off, src, srcv->off, len);
+        res = fuse_buf_copy_one(req, dst, dstv->off, src, srcv->off, len);
         if (res < 0) {
             if (!copied) {
                 return res;
diff --git a/tools/virtiofsd/fuse_common.h b/tools/virtiofsd/fuse_common.h
index af43cf19f9..beed03aa93 100644
--- a/tools/virtiofsd/fuse_common.h
+++ b/tools/virtiofsd/fuse_common.h
@@ -510,6 +510,8 @@ struct fuse_conn_info {
 struct fuse_session;
 struct fuse_pollhandle;
 struct fuse_conn_info_opts;
+struct fuse_req;
+typedef struct fuse_req *fuse_req_t;
 
 /**
  * This function parses several command-line options that can be used
@@ -728,11 +730,13 @@ size_t fuse_buf_size(const struct fuse_bufvec *bufv);
 /**
  * Copy data from one buffer vector to another
  *
+ * @param req The request this copy is part of
  * @param dst destination buffer vector
  * @param src source buffer vector
  * @return actual number of bytes copied or -errno on error
  */
-ssize_t fuse_buf_copy(struct fuse_bufvec *dst, struct fuse_bufvec *src);
+ssize_t fuse_buf_copy(fuse_req_t req,
+                      struct fuse_bufvec *dst, struct fuse_bufvec *src);
 
 /**
  * Memory buffer iterator
diff --git a/tools/virtiofsd/fuse_lowlevel.h b/tools/virtiofsd/fuse_lowlevel.h
index 757cdae49b..24e580aafe 100644
--- a/tools/virtiofsd/fuse_lowlevel.h
+++ b/tools/virtiofsd/fuse_lowlevel.h
@@ -42,9 +42,6 @@
 /** Inode number type */
 typedef uint64_t fuse_ino_t;
 
-/** Request pointer type */
-typedef struct fuse_req *fuse_req_t;
-
 /**
  * Session
  *
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 726343677e..b3954376b3 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -2301,7 +2301,7 @@ static void lo_write_buf(fuse_req_t req, fuse_ino_t ino,
         }
     }
 
-    res = fuse_buf_copy(&out_buf, in_buf);
+    res = fuse_buf_copy(req, &out_buf, in_buf);
     if (res < 0) {
         fuse_reply_err(req, -res);
     } else {
-- 
2.31.1