fs/nfs/export.c

Source file repositories/reference/linux-study-clean/fs/nfs/export.c

File Facts

System
Linux kernel
Corpus path
fs/nfs/export.c
Extension
.c
Size
4240 bytes
Lines
167
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2015, Primary Data, Inc. All rights reserved.
 *
 * Tao Peng <bergwolf@primarydata.com>
 */
#include <linux/dcache.h>
#include <linux/exportfs.h>
#include <linux/nfs.h>
#include <linux/nfs_fs.h>

#include "internal.h"
#include "nfstrace.h"

#define NFSDBG_FACILITY		NFSDBG_VFS

enum {
	FILEID_HIGH_OFF = 0,	/* inode fileid high */
	FILEID_LOW_OFF,		/* inode fileid low */
	FILE_I_TYPE_OFF,	/* inode type */
	EMBED_FH_OFF		/* embeded server fh */
};


static struct nfs_fh *nfs_exp_embedfh(__u32 *p)
{
	return (struct nfs_fh *)(p + EMBED_FH_OFF);
}

/*
 * Let's break subtree checking for now... otherwise we'll have to embed parent fh
 * but there might not be enough space.
 */
static int
nfs_encode_fh(struct inode *inode, __u32 *p, int *max_len, struct inode *parent)
{
	struct nfs_fh *server_fh = NFS_FH(inode);
	struct nfs_fh *clnt_fh = nfs_exp_embedfh(p);
	size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
	int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);

	dprintk("%s: max fh len %d inode %p parent %p",
		__func__, *max_len, inode, parent);

	if (*max_len < len) {
		dprintk("%s: fh len %d too small, required %d\n",
			__func__, *max_len, len);
		*max_len = len;
		return FILEID_INVALID;
	}

	p[FILEID_HIGH_OFF] = NFS_FILEID(inode) >> 32;
	p[FILEID_LOW_OFF] = NFS_FILEID(inode);
	p[FILE_I_TYPE_OFF] = inode->i_mode & S_IFMT;
	p[len - 1] = 0; /* Padding */
	nfs_copy_fh(clnt_fh, server_fh);
	*max_len = len;
	dprintk("%s: result fh fileid %llu mode %u size %d\n",
		__func__, NFS_FILEID(inode), inode->i_mode, *max_len);
	return *max_len;
}

static struct dentry *
nfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
		 int fh_len, int fh_type)
{
	struct nfs_fattr *fattr = NULL;
	struct nfs_fh *server_fh = nfs_exp_embedfh(fid->raw);
	size_t fh_size = offsetof(struct nfs_fh, data);
	const struct nfs_rpc_ops *rpc_ops;
	struct dentry *dentry;
	struct inode *inode;
	int len = EMBED_FH_OFF;
	u32 *p = fid->raw;
	int ret;

	/* Initial check of bounds */
	if (fh_len < len + XDR_QUADLEN(fh_size) ||
	    fh_len > XDR_QUADLEN(NFS_MAXFHSIZE))
		return NULL;
	/* Calculate embedded filehandle size */
	fh_size += server_fh->size;
	len += XDR_QUADLEN(fh_size);
	/* NULL translates to ESTALE */
	if (fh_len < len || fh_type != len)
		return NULL;

	fattr = nfs_alloc_fattr_with_label(NFS_SB(sb));
	if (fattr == NULL) {
		dentry = ERR_PTR(-ENOMEM);

Annotation

Implementation Notes