[patch 19/33] nfsd: Ensure nfsv4 calls the underlying filesystemon LOCKT

From: Greg KH
Date: Wed Feb 04 2009 - 13:44:17 EST


2.6.28-stable review patch. If anyone has any objections, please let us know.

------------------

From: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>

commit 55ef1274dddd4de387c54d110e354ffbb6cdc706 upstream.

Since nfsv4 allows LOCKT without an open, but the ->lock() method is a
file method, we fake up a struct file in the nfsv4 code with just the
fields we need initialized. But we forgot to initialize the file
operations, with the result that LOCKT never results in a call to the
filesystem's ->lock() method (if it exists).

We could just add that one more initialization. But this hack of faking
up a struct file with only some fields initialized seems the kind of
thing that might cause more problems in the future. We should either do
an open and get a real struct file, or make lock-testing an inode (not a
file) method.

This patch does the former.

Reported-by: Marc Eshel <eshel@xxxxxxxxxxxxxxx>
Tested-by: Marc Eshel <eshel@xxxxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
fs/nfsd/nfs4state.c | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)

--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2769,6 +2769,25 @@ out:
}

/*
+ * The NFSv4 spec allows a client to do a LOCKT without holding an OPEN,
+ * so we do a temporary open here just to get an open file to pass to
+ * vfs_test_lock. (Arguably perhaps test_lock should be done with an
+ * inode operation.)
+ */
+static int nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file_lock *lock)
+{
+ struct file *file;
+ int err;
+
+ err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_READ, &file);
+ if (err)
+ return err;
+ err = vfs_test_lock(file, lock);
+ nfsd_close(file);
+ return err;
+}
+
+/*
* LOCKT operation
*/
__be32
@@ -2776,7 +2795,6 @@ nfsd4_lockt(struct svc_rqst *rqstp, stru
struct nfsd4_lockt *lockt)
{
struct inode *inode;
- struct file file;
struct file_lock file_lock;
int error;
__be32 status;
@@ -2833,16 +2851,8 @@ nfsd4_lockt(struct svc_rqst *rqstp, stru

nfs4_transform_lock_offset(&file_lock);

- /* vfs_test_lock uses the struct file _only_ to resolve the inode.
- * since LOCKT doesn't require an OPEN, and therefore a struct
- * file may not exist, pass vfs_test_lock a struct file with
- * only the dentry:inode set.
- */
- memset(&file, 0, sizeof (struct file));
- file.f_path.dentry = cstate->current_fh.fh_dentry;
-
status = nfs_ok;
- error = vfs_test_lock(&file, &file_lock);
+ error = nfsd_test_lock(rqstp, &cstate->current_fh, &file_lock);
if (error) {
status = nfserrno(error);
goto out;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/