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Subject[char-misc-next 5/5] mei: implement fsync
Date
From: Alexander Usyskin <alexander.usyskin@intel.com>

When write() returns successfully, it is only assumed that a message
was successfully queued. Add fsync syscall implementation to help
user-space ensure that all data is written.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
---
drivers/misc/mei/main.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 72 insertions(+)

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 9802c5930c10..e825f013e54e 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -586,6 +586,77 @@ static unsigned int mei_poll(struct file *file, poll_table *wait)
}

/**
+ * mei_cl_is_write_queued - check if the client has pending writes.
+ *
+ * @cl: writing host client
+ *
+ * Return: true if client is writing, false otherwise.
+ */
+static bool mei_cl_is_write_queued(struct mei_cl *cl)
+{
+ struct mei_device *dev = cl->dev;
+ struct mei_cl_cb *cb;
+
+ list_for_each_entry(cb, &dev->write_list, list)
+ if (cb->cl == cl)
+ return true;
+ list_for_each_entry(cb, &dev->write_waiting_list, list)
+ if (cb->cl == cl)
+ return true;
+ return false;
+}
+
+/**
+ * mei_fsync - the fsync handler
+ *
+ * @fp: pointer to file structure
+ * @start: unused
+ * @end: unused
+ * @datasync: unused
+ *
+ * Return: 0 on success, -ENODEV if client is not connected
+ */
+static int mei_fsync(struct file *fp, loff_t start, loff_t end, int datasync)
+{
+ struct mei_cl *cl = fp->private_data;
+ struct mei_device *dev;
+ int rets;
+
+ if (WARN_ON(!cl || !cl->dev))
+ return -ENODEV;
+
+ dev = cl->dev;
+
+ mutex_lock(&dev->device_lock);
+
+ if (dev->dev_state != MEI_DEV_ENABLED || !mei_cl_is_connected(cl)) {
+ rets = -ENODEV;
+ goto out;
+ }
+
+ while (mei_cl_is_write_queued(cl)) {
+ mutex_unlock(&dev->device_lock);
+ rets = wait_event_interruptible(cl->tx_wait,
+ cl->writing_state == MEI_WRITE_COMPLETE ||
+ !mei_cl_is_connected(cl));
+ mutex_lock(&dev->device_lock);
+ if (rets) {
+ if (signal_pending(current))
+ rets = -EINTR;
+ goto out;
+ }
+ if (!mei_cl_is_connected(cl)) {
+ rets = -ENODEV;
+ goto out;
+ }
+ }
+ rets = 0;
+out:
+ mutex_unlock(&dev->device_lock);
+ return rets;
+}
+
+/**
* mei_fasync - asynchronous io support
*
* @fd: file descriptor
@@ -700,6 +771,7 @@ static const struct file_operations mei_fops = {
.release = mei_release,
.write = mei_write,
.poll = mei_poll,
+ .fsync = mei_fsync,
.fasync = mei_fasync,
.llseek = no_llseek
};
--
2.9.3
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