Merge #6422 from ZyX-I/fix-6420

eval,fileio: Omit additional fsync() call

src/nvim/eval.c

@@ -17289,7 +17289,7 @@ static bool write_list(FileDescriptor *const fp, const list_T *const list,
       }
     }
   }
-  if ((error = file_fsync(fp)) != 0) {
+  if ((error = file_flush(fp)) != 0) {
     goto write_list_error;
   }
   return true;
@@ -17439,21 +17439,21 @@ static void f_writefile(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   if (fname == NULL) {
     return;
   }
-  FileDescriptor *fp;
+  FileDescriptor fp;
   int error;
   rettv->vval.v_number = -1;
   if (*fname == NUL) {
     EMSG(_("E482: Can't open file with an empty name"));
-  } else if ((fp = file_open_new(&error, fname,
+  } else if ((error = file_open(&fp, fname,
-                                 ((append ? kFileAppend : kFileTruncate)
+                                ((append ? kFileAppend : kFileTruncate)
-                                  | kFileCreate), 0666)) == NULL) {
+                                 | kFileCreate), 0666)) != 0) {
     emsgf(_("E482: Can't open file %s for writing: %s"),
           fname, os_strerror(error));
   } else {
-    if (write_list(fp, argvars[0].vval.v_list, binary)) {
+    if (write_list(&fp, argvars[0].vval.v_list, binary)) {
       rettv->vval.v_number = 0;
     }
-    if ((error = file_free(fp)) != 0) {
+    if ((error = file_close(&fp)) != 0) {
       emsgf(_("E80: Error when closing file %s: %s"),
             fname, os_strerror(error));
     }

src/nvim/os/fileio.c

@@ -143,21 +143,36 @@ int file_free(FileDescriptor *const fp) FUNC_ATTR_NONNULL_ALL
 /// @param[in,out]  fp  File to work with.
 ///
 /// @return 0 or error code.
-int file_fsync(FileDescriptor *const fp)
+int file_flush(FileDescriptor *const fp)
   FUNC_ATTR_NONNULL_ALL
 {
   if (!fp->wr) {
     return 0;
   }
   file_rb_write_full_cb(fp->rv, fp);
-  if (fp->_error != 0) {
+  const int error = fp->_error;
-    const int error = fp->_error;
+  fp->_error = 0;
-    fp->_error = 0;
+  return error;
-    return error;
+}
+
+/// Flush file modifications to disk and run fsync()
+///
+/// @param[in,out]  fp  File to work with.
+///
+/// @return 0 or error code.
+int file_fsync(FileDescriptor *const fp)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (!fp->wr) {
+    return 0;
   }
-  const int error = os_fsync(fp->fd);
+  const int flush_error = file_flush(fp);
-  if (error != UV_EINVAL && error != UV_EROFS) {
+  if (flush_error != 0) {
-    return error;
+    return flush_error;
+  }
+  const int fsync_error = os_fsync(fp->fd);
+  if (fsync_error != UV_EINVAL && fsync_error != UV_EROFS) {
+    return fsync_error;
   }
   return 0;
 }

test/unit/os/fileio_spec.lua

@@ -80,6 +80,10 @@ local function file_read(fp, size)
   return ret1, ret2
 end
 
+local function file_flush(fp)
+  return m.file_flush(fp)
+end
+
 local function file_fsync(fp)
   return m.file_fsync(fp)
 end
@@ -244,6 +248,21 @@ describe('file_fsync', function()
   end)
 end)
 
+describe('file_flush', function()
+  itp('can flush writes to disk', function()
+    local err, fp = file_open(filec, m.kFileCreateOnly, 384)
+    eq(0, file_flush(fp))
+    eq(0, err)
+    eq(0, lfs.attributes(filec).size)
+    local wsize = file_write(fp, 'test')
+    eq(4, wsize)
+    eq(0, lfs.attributes(filec).size)
+    eq(0, file_flush(fp))
+    eq(wsize, lfs.attributes(filec).size)
+    eq(0, m.file_close(fp))
+  end)
+end)
+
 describe('file_read', function()
   itp('can read small chunks of input until eof', function()
     local err, fp = file_open(file1, 0, 384)