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Subject[PATCH] nfsd: Ensure nfsv4 calls the underlying filesystem on LOCKT
From
From: J. Bruce Fields <bfields@citi.umich.edu>

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@almaden.ibm.com>
Tested-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
---
fs/nfsd/nfs4state.c | 30 ++++++++++++++++++++----------
1 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 06b89df..e62d0e3 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2782,6 +2782,25 @@ 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
@@ -2789,7 +2808,6 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
struct nfsd4_lockt *lockt)
{
struct inode *inode;
- struct file file;
struct file_lock file_lock;
int error;
__be32 status;
@@ -2847,16 +2865,8 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,

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;
--
1.5.6.3


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