NFS: add comments clarifying the use of nfs_post_op_update()
Comments-only change to clarify a detail of the NFS protocol and how it is
implemented in Linux.
Test plan:
None.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 38ba5c0..c12effb 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1253,7 +1253,13 @@
dprintk("NFS: %4d nfs_writeback_done (status %d)\n",
task->tk_pid, task->tk_status);
- /* Call the NFS version-specific code */
+ /*
+ * ->write_done will attempt to use post-op attributes to detect
+ * conflicting writes by other clients. A strict interpretation
+ * of close-to-open would allow us to continue caching even if
+ * another writer had changed the file, but some applications
+ * depend on tighter cache coherency when writing.
+ */
status = NFS_PROTO(data->inode)->write_done(task, data);
if (status != 0)
return status;