virtiofsd: Parse flag FUSE_WRITE_KILL_PRIV

Caller can set FUSE_WRITE_KILL_PRIV in write_flags. Parse it and pass it
to the filesystem.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

tools/virtiofsd/fuse_common.h

@@ -93,8 +93,12 @@ struct fuse_file_info {
      */
     unsigned int cache_readdir:1;
 
+    /* Indicates that suid/sgid bits should be removed upon write */
+    unsigned int kill_priv:1;
+
+
     /** Padding.  Reserved for future use*/
-    unsigned int padding:25;
+    unsigned int padding:24;
     unsigned int padding2:32;
 
     /*

tools/virtiofsd/fuse_lowlevel.c

@@ -1142,6 +1142,7 @@ static void do_write(fuse_req_t req, fuse_ino_t nodeid,
     memset(&fi, 0, sizeof(fi));
     fi.fh = arg->fh;
     fi.writepage = (arg->write_flags & FUSE_WRITE_CACHE) != 0;
+    fi.kill_priv = !!(arg->write_flags & FUSE_WRITE_KILL_PRIV);
 
     fi.lock_owner = arg->lock_owner;
     fi.flags = arg->flags;
@@ -1177,7 +1178,8 @@ static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid,
     fi.lock_owner = arg->lock_owner;
     fi.flags = arg->flags;
     fi.fh = arg->fh;
-    fi.writepage = arg->write_flags & FUSE_WRITE_CACHE;
+    fi.writepage = !!(arg->write_flags & FUSE_WRITE_CACHE);
+    fi.kill_priv = !!(arg->write_flags & FUSE_WRITE_KILL_PRIV);
 
     if (ibufv->count == 1) {
         assert(!(tmpbufv.buf[0].flags & FUSE_BUF_IS_FD));