fs: stream_open - opener for stream-like files so that read and write can run simulta...

[linux-block.git] / fs / open.c

diff --git a/fs/open.c b/fs/open.c
index f1c2f855fd43c7664a739c2172f83be2f93944e4..a00350018a4792e758d5749e6294902cf32f2174 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -1215,3 +1215,21 @@ int nonseekable_open(struct inode *inode, struct file *filp)
 }
 
 EXPORT_SYMBOL(nonseekable_open);
+
+/*
+ * stream_open is used by subsystems that want stream-like file descriptors.
+ * Such file descriptors are not seekable and don't have notion of position
+ * (file.f_pos is always 0). Contrary to file descriptors of other regular
+ * files, .read() and .write() can run simultaneously.
+ *
+ * stream_open never fails and is marked to return int so that it could be
+ * directly used as file_operations.open .
+ */
+int stream_open(struct inode *inode, struct file *filp)
+{
+       filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
+       filp->f_mode |= FMODE_STREAM;
+       return 0;
+}
+
+EXPORT_SYMBOL(stream_open);