inode.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

/*
 *  linux/fs/nfs/inode.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  nfs inode and superblock handling functions
 *
 *  Modularised by Alan Cox <[e-mail]>, while hacking some
 *  experimental NFS changes. Modularisation taken straight from SYS5 fs.
 *
 *  Change to nfs_read_super() to permit NFS mounts to multi-homed hosts.
 *  [e-mail]
 *
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/locks.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs_flushd.h>
#include <linux/lockd/bind.h>
#include <linux/smp_lock.h>
#include <linux/seq_file.h>

#include <asm/system.h>
#include <asm/uaccess.h>

#define CONFIG_NFS_SNAPSHOT 1
#define NFSDBG_FACILITY		NFSDBG_VFS
#define NFS_PARANOIA 1

static struct inode * __nfs_fhget(struct super_block *, struct nfs_fh *, struct nfs_fattr *);
void nfs_zap_caches(struct inode *);
static void nfs_invalidate_inode(struct inode *);

static void nfs_read_inode(struct inode *);
static void nfs_write_inode(struct inode *,int);
static void nfs_delete_inode(struct inode *);
static void nfs_put_super(struct super_block *);
static void nfs_clear_inode(struct inode *);
static void nfs_umount_begin(struct super_block *);
static int  nfs_statfs(struct super_block *, struct statfs *);
static int  nfs_show_options(struct seq_file *, struct vfsmount *);

static struct super_operations nfs_sops = { 
	read_inode:	nfs_read_inode,
	write_inode:	nfs_write_inode,
	delete_inode:	nfs_delete_inode,
	put_super:	nfs_put_super,
	statfs:		nfs_statfs,
	clear_inode:	nfs_clear_inode,
	umount_begin:	nfs_umount_begin,
	show_options:	nfs_show_options,
};

/*
 * RPC cruft for NFS
 */
struct rpc_stat			nfs_rpcstat = { &nfs_program };
static struct rpc_version *	nfs_version[] = {
	NULL,
	NULL,
	&nfs_version2,
#ifdef CONFIG_NFS_V3
	&nfs_version3,
#endif
};

struct rpc_program		nfs_program = {
	"nfs",
	NFS_PROGRAM,
	sizeof(nfs_version) / sizeof(nfs_version[0]),
	nfs_version,
	&nfs_rpcstat,
};

static inline unsigned long
nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
{
	return nfs_fileid_to_ino_t(fattr->fileid);
}

/*
 * The "read_inode" function doesn't actually do anything:
 * the real data is filled in later in nfs_fhget. Here we
 * just mark the cache times invalid, and zero out i_mode
 * (the latter makes "nfs_refresh_inode" do the right thing
 * wrt pipe inodes)
 */
static void
nfs_read_inode(struct inode * inode)
{
	inode->i_blksize = inode->i_sb->s_blocksize;
	inode->i_mode = 0;
	inode->i_rdev = 0;
	/* We can't support UPDATE_ATIME(), since the server will reset it */
	inode->i_flags |= S_NOATIME;
	INIT_LIST_HEAD(&inode->u.nfs_i.read);
	INIT_LIST_HEAD(&inode->u.nfs_i.dirty);
	INIT_LIST_HEAD(&inode->u.nfs_i.commit);
	INIT_LIST_HEAD(&inode->u.nfs_i.writeback);
	NFS_CACHEINV(inode);
	NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
	NFS_ATTRTIMEO_UPDATE(inode) = jiffies;
}

static void
nfs_write_inode(struct inode *inode, int sync)
{
	int flags = sync ? FLUSH_WAIT : 0;

	nfs_sync_file(inode, NULL, 0, 0, flags);
}

static void
nfs_delete_inode(struct inode * inode)
{
	dprintk("NFS: delete_inode(%x/%ld)\n", inode->i_dev, inode->i_ino);

	/*
	 * The following can never actually happen...
	 */
	if (nfs_have_writebacks(inode) || nfs_have_read(inode)) {
		printk(KERN_ERR "nfs_delete_inode: inode %ld has pending RPC requests\n", inode->i_ino);
	}

	clear_inode(inode);
}

/*
 * For the moment, the only task for the NFS clear_inode method is to
 * release the mmap credential
 */
static void
nfs_clear_inode(struct inode *inode)
{
	struct rpc_cred *cred = NFS_I(inode)->mm_cred;

	if (cred)
		put_rpccred(cred);
}

void
nfs_put_super(struct super_block *sb)
{
	struct nfs_server *server = &sb->u.nfs_sb.s_server;
	struct rpc_clnt	*rpc;

	/*
	 * First get rid of the request flushing daemon.
	 * Relies on rpc_shutdown_client() waiting on all
	 * client tasks to finish.
	 */
	nfs_reqlist_exit(server);

	if ((rpc = server->client) != NULL)
		rpc_shutdown_client(rpc);

	nfs_reqlist_free(server);

	if (!(server->flags & NFS_MOUNT_NONLM))
		lockd_down();	/* release rpc.lockd */
	rpciod_down();		/* release rpciod */

	kfree(server->hostname);
}

void
nfs_umount_begin(struct super_block *sb)
{
	struct nfs_server *server = &sb->u.nfs_sb.s_server;
	struct rpc_clnt	*rpc;

	/* -EIO all pending I/O */
	if ((rpc = server->client) != NULL)
		rpc_killall_tasks(rpc);
}


static inline unsigned long
nfs_block_bits(unsigned long bsize, unsigned char *nrbitsp)
{
	/* make sure blocksize is a power of two */
	if ((bsize & (bsize - 1)) || nrbitsp) {
		unsigned char	nrbits;

		for (nrbits = 31; nrbits && !(bsize & (1 << nrbits)); nrbits--)
			;
		bsize = 1 << nrbits;
		if (nrbitsp)
			*nrbitsp = nrbits;
	}

	return bsize;
}

/*
 * Calculate the number of 512byte blocks used.
 */
static inline unsigned long
nfs_calc_block_size(u64 tsize)
{
	loff_t used = (tsize + 511) >> 9;
	return (used > ULONG_MAX) ? ULONG_MAX : used;
}

/*
 * Compute and set NFS server blocksize
 */
static inline unsigned long
nfs_block_size(unsigned long bsize, unsigned char *nrbitsp)
{
	if (bsize < 1024)
		bsize = NFS_DEF_FILE_IO_BUFFER_SIZE;
	else if (bsize >= NFS_MAX_FILE_IO_BUFFER_SIZE)
		bsize = NFS_MAX_FILE_IO_BUFFER_SIZE;

	return nfs_block_bits(bsize, nrbitsp);
}

/*
 * Obtain the root inode of the file system.
 */
static struct inode *
nfs_get_root(struct super_block *sb, struct nfs_fh *rootfh)
{
	struct nfs_server	*server = &sb->u.nfs_sb.s_server;
	struct nfs_fattr	fattr;
	struct inode		*inode;
	int			error;

	if ((error = server->rpc_ops->getroot(server, rootfh, &fattr)) < 0) {
		printk(KERN_NOTICE "nfs_get_root: getattr error = %d\n", -error);
		return NULL;
	}

	inode = __nfs_fhget(sb, rootfh, &fattr);
	return inode;
}

/*
 * The way this works is that the mount process passes a structure
 * in the data argument which contains the server's IP address
 * and the root file handle obtained from the server's mount
 * daemon. We stash these away in the private superblock fields.
 */
struct super_block *
nfs_read_super(struct super_block *sb, void *raw_data, int silent)
{
	struct nfs_mount_data	*data = (struct nfs_mount_data *) raw_data;
	struct nfs_server	*server;
	struct rpc_xprt		*xprt = NULL;
	struct rpc_clnt		*clnt = NULL;
	struct nfs_fh		*root = &data->root, fh;
	struct inode		*root_inode = NULL;
	unsigned int		authflavor;
	struct sockaddr_in	srvaddr;
	struct rpc_timeout	timeparms;
	struct nfs_fsinfo	fsinfo;
	int			tcp, version, maxlen;

	memset(&sb->u.nfs_sb, 0, sizeof(sb->u.nfs_sb));
	if (!data)
		goto out_miss_args;

	memset(&fh, 0, sizeof(fh));
	if (data->version != NFS_MOUNT_VERSION) {
		printk("nfs warning: mount version %s than kernel\n",
			data->version < NFS_MOUNT_VERSION ? "older" : "newer");
		if (data->version < 2)
			data->namlen = 0;
		if (data->version < 3)
			data->bsize  = 0;
		if (data->version < 4) {
			data->flags &= ~NFS_MOUNT_VER3;
			root = &fh;
			root->size = NFS2_FHSIZE;
			memcpy(root->data, data->old_root.data, NFS2_FHSIZE);
		}
	}

	/* We now require that the mount process passes the remote address */
	memcpy(&srvaddr, &data->addr, sizeof(srvaddr));
	if (srvaddr.sin_addr.s_addr == INADDR_ANY)
		goto out_no_remote;

	sb->s_magic      = NFS_SUPER_MAGIC;
	sb->s_op         = &nfs_sops;
	sb->s_blocksize_bits = 0;
	sb->s_blocksize  = nfs_block_size(data->bsize, &sb->s_blocksize_bits);
	server           = &sb->u.nfs_sb.s_server;
	server->rsize    = nfs_block_size(data->rsize, NULL);
	server->wsize    = nfs_block_size(data->wsize, NULL);
	server->flags    = data->flags & NFS_MOUNT_FLAGMASK;

	if (data->flags & NFS_MOUNT_NOAC) {
		data->acregmin = data->acregmax = 0;
		data->acdirmin = data->acdirmax = 0;
		sb->s_flags |= MS_SYNCHRONOUS;
	}
	server->acregmin = data->acregmin*HZ;
	server->acregmax = data->acregmax*HZ;
	server->acdirmin = data->acdirmin*HZ;
	server->acdirmax = data->acdirmax*HZ;

	server->namelen  = data->namlen;
	server->hostname = kmalloc(strlen(data->hostname) + 1, GFP_KERNEL);
	if (!server->hostname)
		goto out_unlock;
	strcpy(server->hostname, data->hostname);
	INIT_LIST_HEAD(&server->lru_read);
	INIT_LIST_HEAD(&server->lru_dirty);
	INIT_LIST_HEAD(&server->lru_commit);
	INIT_LIST_HEAD(&server->lru_busy);

 nfsv3_try_again:
	/* Check NFS protocol revision and initialize RPC op vector
	 * and file handle pool. */
	if (data->flags & NFS_MOUNT_VER3) {
#ifdef CONFIG_NFS_V3
		server->rpc_ops = &nfs_v3_clientops;
		version = 3;
		if (data->version < 4) {
			printk(KERN_NOTICE "NFS: NFSv3 not supported by mount program.\n");
			goto out_unlock;
		}
#else
		printk(KERN_NOTICE "NFS: NFSv3 not supported.\n");
		goto out_unlock;
#endif
	} else {
		server->rpc_ops = &nfs_v2_clientops;
		version = 2;
        }

	/* Which protocol do we use? */
	tcp   = (data->flags & NFS_MOUNT_TCP);

	/* Initialize timeout values */
	timeparms.to_initval = data->timeo * HZ / 10;
	timeparms.to_retries = data->retrans;
	timeparms.to_maxval  = tcp? RPC_MAX_TCP_TIMEOUT : RPC_MAX_UDP_TIMEOUT;
	timeparms.to_exponential = 1;

	if (!timeparms.to_initval)
		timeparms.to_initval = (tcp ? 600 : 11) * HZ / 10;
	if (!timeparms.to_retries)
		timeparms.to_retries = 5;

	/* Now create transport and client */
	xprt = xprt_create_proto(tcp? IPPROTO_TCP : IPPROTO_UDP,
						&srvaddr, &timeparms);
	if (xprt == NULL)
		goto out_no_xprt;

	/* Choose authentication flavor */
	authflavor = RPC_AUTH_UNIX;
	if (data->flags & NFS_MOUNT_SECURE)
		authflavor = RPC_AUTH_DES;
	else if (data->flags & NFS_MOUNT_KERBEROS)
		authflavor = RPC_AUTH_KRB;

	clnt = rpc_create_client(xprt, server->hostname, &nfs_program,
				 version, authflavor);
	if (clnt == NULL)
		goto out_no_client;

	clnt->cl_intr     = (data->flags & NFS_MOUNT_INTR)? 1 : 0;
	clnt->cl_softrtry = (data->flags & NFS_MOUNT_SOFT)? 1 : 0;
	clnt->cl_droppriv = (data->flags & NFS_MOUNT_BROKEN_SUID) ? 1 : 0;
	clnt->cl_chatty   = 1;
	server->client    = clnt;

	/* Fire up rpciod if not yet running */
	if (rpciod_up() != 0)
		goto out_no_iod;

	/*
	 * Keep the super block locked while we try to get 
	 * the root fh attributes.
	 */
	/* Did getting the root inode fail? */
	if (!(root_inode = nfs_get_root(sb, root))
	    && (data->flags & NFS_MOUNT_VER3)) {
		data->flags &= ~NFS_MOUNT_VER3;
		rpciod_down();