NFS: clean up NFS client's a_ops->direct_IO method
The NFS client's a_ops->direct_IO method, nfs_direct_IO, is required to
be present to allow NFS files to be opened with O_DIRECT, but is never
called because the NFS client shunts reads and writes to files opened
with O_DIRECT directly to its own routines.
Gut the nfs_direct_IO function. This eliminates the only part of the
NFS client's direct I/O path that requires support for multi-segment
iovs, allowing further simplification in subsequent patches.
Test plan:
Compile the kernel with CONFIG_NFS and CONFIG_NFS_DIRECTIO enabled. Millions
of fsx-odirect ops. OraSim.
Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 3f87a72..8096d32 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -79,6 +79,29 @@
/**
+ * nfs_direct_IO - NFS address space operation for direct I/O
+ * @rw: direction (read or write)
+ * @iocb: target I/O control block
+ * @iov: array of vectors that define I/O buffer
+ * @pos: offset in file to begin the operation
+ * @nr_segs: size of iovec array
+ *
+ * The presence of this routine in the address space ops vector means
+ * the NFS client supports direct I/O. However, we shunt off direct
+ * read and write requests before the VFS gets them, so this method
+ * should never be called.
+ */
+ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
+{
+ struct dentry *dentry = iocb->ki_filp->f_dentry;
+
+ dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
+ dentry->d_name.name, (long long) pos, nr_segs);
+
+ return -EINVAL;
+}
+
+/**
* nfs_get_user_pages - find and set up pages underlying user's buffer
* rw: direction (read or write)
* user_addr: starting address of this segment of user's buffer
@@ -606,53 +629,6 @@
}
/**
- * nfs_direct_IO - NFS address space operation for direct I/O
- * rw: direction (read or write)
- * @iocb: target I/O control block
- * @iov: array of vectors that define I/O buffer
- * file_offset: offset in file to begin the operation
- * nr_segs: size of iovec array
- *
- */
-ssize_t
-nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
- loff_t file_offset, unsigned long nr_segs)
-{
- ssize_t result = -EINVAL;
- struct file *file = iocb->ki_filp;
- struct nfs_open_context *ctx;
- struct dentry *dentry = file->f_dentry;
- struct inode *inode = dentry->d_inode;
-
- /*
- * No support for async yet
- */
- if (!is_sync_kiocb(iocb))
- return result;
-
- ctx = (struct nfs_open_context *)file->private_data;
- switch (rw) {
- case READ:
- dprintk("NFS: direct_IO(read) (%s) off/no(%Lu/%lu)\n",
- dentry->d_name.name, file_offset, nr_segs);
-
- result = nfs_direct_read(inode, ctx, iov,
- file_offset, nr_segs);
- break;
- case WRITE:
- dprintk("NFS: direct_IO(write) (%s) off/no(%Lu/%lu)\n",
- dentry->d_name.name, file_offset, nr_segs);
-
- result = nfs_direct_write(inode, ctx, iov,
- file_offset, nr_segs);
- break;
- default:
- break;
- }
- return result;
-}
-
-/**
* nfs_file_direct_read - file direct read operation for NFS files
* @iocb: target I/O control block
* @buf: user's buffer into which to read data