cifs: add comments explaining cifs_new_fileinfo behavior

The comments make it clear the otherwise subtle behavior of cifs_new_fileinfo().

Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Reviewed-by: Shirish Pargaonkar <shirishp@us.ibm.com>
--
 fs/cifs/dir.c |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index d791d0763a9c..bd363df19b3f 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -129,6 +129,12 @@ cifs_bp_rename_retry:
         return full_path;
 }
 
+/*
+ * When called with struct file pointer set to NULL, there is no way we could
+ * update file->private_data, but getting it stuck on openFileList provides a
+ * way to access it from cifs_fill_filedata and thereby set file->private_data
+ * from cifs_open.
+ */
 struct cifsFileInfo *
 cifs_new_fileinfo(struct inode *newinode, __u16 fileHandle,
                   struct file *file, struct vfsmount *mnt, unsigned int oflags)
@@ -251,6 +257,10 @@ int cifs_posix_open(char *full_path, struct inode **pinode,
                 cifs_fattr_to_inode(*pinode, &fattr);
         }
 
+        /*
+         * cifs_fill_filedata() takes care of setting cifsFileInfo pointer to
+         * file->private_data.
+         */
         if (mnt)
                 cifs_new_fileinfo(*pinode, *pnetfid, NULL, mnt, oflags);
 
@@ -466,8 +476,12 @@ cifs_create_set_dentry:
                 /* mknod case - do not leave file open */
                 CIFSSMBClose(xid, tcon, fileHandle);
         } else if (!(posix_create) && (newinode)) {
-                        cifs_new_fileinfo(newinode, fileHandle, NULL,
-                                                nd->path.mnt, oflags);
+                /*
+                 * cifs_fill_filedata() takes care of setting cifsFileInfo
+                 * pointer to file->private_data.
+                 */
+                cifs_new_fileinfo(newinode, fileHandle, NULL, nd->path.mnt,
+                                  oflags);
         }
 cifs_create_out:
         kfree(buf);