rename the generic fsync implementations

We don't name our generic fsync implementations very well currently.
The no-op implementation for in-memory filesystems currently is called
simple_sync_file which doesn't make too much sense to start with,
the the generic one for simple filesystems is called simple_fsync
which can lead to some confusion.

This patch renames the generic file fsync method to generic_file_fsync
to match the other generic_file_* routines it is supposed to be used
with, and the no-op implementation to noop_fsync to make it obvious
what to expect.  In addition add some documentation for both methods.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 21 insertions, 9 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index e57ea58bda6..b84d0a7a220 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -58,11 +58,6 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct na
         return NULL;
 }
 
-int simple_sync_file(struct file *file, int datasync)
-{
-        return 0;
-}
- 
 int dcache_dir_open(struct inode *inode, struct file *file)
 {
         static struct qstr cursor_name = {.len = 1, .name = "."};
@@ -190,7 +185,7 @@ const struct file_operations simple_dir_operations = {
         .llseek         = dcache_dir_lseek,
         .read           = generic_read_dir,
         .readdir        = dcache_readdir,
-        .fsync          = simple_sync_file,
+        .fsync          = noop_fsync,
 };
 
 const struct inode_operations simple_dir_inode_operations = {
@@ -851,7 +846,16 @@ struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
 }
 EXPORT_SYMBOL_GPL(generic_fh_to_parent);
 
-int simple_fsync(struct file *file, int datasync)
+/**
+ * generic_file_fsync - generic fsync implementation for simple filesystems
+ * @file:       file to synchronize
+ * @datasync:   only synchronize essential metadata if true
+ *
+ * This is a generic implementation of the fsync method for simple
+ * filesystems which track all non-inode metadata in the buffers list
+ * hanging off the address_space structure.
+ */
+int generic_file_fsync(struct file *file, int datasync)
 {
         struct writeback_control wbc = {
                 .sync_mode = WB_SYNC_ALL,
@@ -872,7 +876,15 @@ int simple_fsync(struct file *file, int datasync)
                 ret = err;
         return ret;
 }
-EXPORT_SYMBOL(simple_fsync);
+EXPORT_SYMBOL(generic_file_fsync);
+
+/*
+ * No-op implementation of ->fsync for in-memory filesystems.
+ */
+int noop_fsync(struct file *file, int datasync)
+{
+        return 0;
+}
 
 EXPORT_SYMBOL(dcache_dir_close);
 EXPORT_SYMBOL(dcache_dir_lseek);
@@ -895,7 +907,7 @@ EXPORT_SYMBOL(simple_release_fs);
 EXPORT_SYMBOL(simple_rename);
 EXPORT_SYMBOL(simple_rmdir);
 EXPORT_SYMBOL(simple_statfs);
-EXPORT_SYMBOL(simple_sync_file);
+EXPORT_SYMBOL(noop_fsync);
 EXPORT_SYMBOL(simple_unlink);
 EXPORT_SYMBOL(simple_read_from_buffer);
 EXPORT_SYMBOL(simple_write_to_buffer);