fs/9p: Add fid to inode in cached mode

The fid attached to inode will be opened O_RDWR mode and is used
for dirty page writeback only.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index b00223c99d70..9d6a5d3bfe15 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -261,3 +261,29 @@ struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
         ret = p9_client_walk(fid, 0, NULL, 1);
         return ret;
 }
+
+
+struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
+{
+        int err;
+        struct p9_fid *fid;
+
+        fid = v9fs_fid_clone(dentry);
+        if (IS_ERR(fid))
+                goto error_out;
+        /*
+         * writeback fid will only be used to write back the
+         * dirty pages. We always request for the open fid in read-write
+         * mode so that a partial page write which result in page
+         * read can work.
+         * FIXME!!: we should make the fid owned by uid = 0
+         */
+        err = p9_client_open(fid, O_RDWR);
+        if (err < 0) {
+                p9_client_clunk(fid);
+                fid = ERR_PTR(err);
+                goto error_out;
+        }
+error_out:
+        return fid;
+}