inode.c

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 */
static void
nfs_fill_inode(struct inode *inode, struct nfs_fh *fh, struct nfs_fattr *fattr)
{
	/*
	 * Check whether the mode has been set, as we only want to
	 * do this once. (We don't allow inodes to change types.)
	 */
	if (inode->i_mode == 0) {
		NFS_FILEID(inode) = fattr->fileid;
		NFS_FSID(inode) = fattr->fsid;
		inode->i_mode = fattr->mode;
		/* Why so? Because we want revalidate for devices/FIFOs, and
		 * that's precisely what we have in nfs_file_inode_operations.
		 */
		inode->i_op = &nfs_file_inode_operations;
		if (S_ISREG(inode->i_mode)) {
			inode->i_fop = &nfs_file_operations;
			inode->i_data.a_ops = &nfs_file_aops;
		} else if (S_ISDIR(inode->i_mode)) {
			inode->i_op = &nfs_dir_inode_operations;
			inode->i_fop = &nfs_dir_operations;
		} else if (S_ISLNK(inode->i_mode))
			inode->i_op = &nfs_symlink_inode_operations;
		else
			init_special_inode(inode, inode->i_mode, fattr->rdev);
		/*
		 * Preset the size and mtime, as there's no need
		 * to invalidate the caches.
		 */ 
		inode->i_size  = nfs_size_to_loff_t(fattr->size);
		inode->i_mtime = nfs_time_to_secs(fattr->mtime);
		inode->i_atime = nfs_time_to_secs(fattr->atime);
		inode->i_ctime = nfs_time_to_secs(fattr->ctime);
		NFS_CACHE_CTIME(inode) = fattr->ctime;
		NFS_CACHE_MTIME(inode) = fattr->mtime;
		NFS_CACHE_ATIME(inode) = fattr->atime;
		NFS_CACHE_ISIZE(inode) = fattr->size;
		NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
		NFS_ATTRTIMEO_UPDATE(inode) = jiffies;
		memcpy(&inode->u.nfs_i.fh, fh, sizeof(inode->u.nfs_i.fh));
	}
	nfs_refresh_inode(inode, fattr);
}

struct nfs_find_desc {
	struct nfs_fh		*fh;
	struct nfs_fattr	*fattr;
};

/*
 * In NFSv3 we can have 64bit inode numbers. In order to support
 * this, and re-exported directories (also seen in NFSv2)
 * we are forced to allow 2 different inodes to have the same
 * i_ino.
 */
static int
nfs_find_actor(struct inode *inode, unsigned long ino, void *opaque)
{
	struct nfs_find_desc	*desc = (struct nfs_find_desc *)opaque;
	struct nfs_fh		*fh = desc->fh;
	struct nfs_fattr	*fattr = desc->fattr;

	if (NFS_FSID(inode) != fattr->fsid)
		return 0;
	if (NFS_FILEID(inode) != fattr->fileid)
		return 0;
	if (memcmp(&inode->u.nfs_i.fh, fh, sizeof(inode->u.nfs_i.fh)) != 0)
		return 0;
	return 1;
}

int
nfs_inode_is_stale(struct inode *inode, struct nfs_fh *fh, struct nfs_fattr *fattr)
{
	/* Empty inodes are not stale */
	if (!inode->i_mode)
		return 0;

	if ((fattr->mode & S_IFMT) != (inode->i_mode & S_IFMT))
		return 1;

	if (is_bad_inode(inode))
		return 1;

	/* Has the filehandle changed? If so is the old one stale? */
	if (memcmp(&inode->u.nfs_i.fh, fh, sizeof(inode->u.nfs_i.fh)) != 0 &&
	    __nfs_revalidate_inode(NFS_SERVER(inode),inode) == -ESTALE)
		return 1;

	return 0;
}

/*
 * This is our own version of iget that looks up inodes by file handle
 * instead of inode number.  We use this technique instead of using
 * the vfs read_inode function because there is no way to pass the
 * file handle or current attributes into the read_inode function.
 *
 */
struct inode *
nfs_fhget(struct dentry *dentry, struct nfs_fh *fhandle,
				 struct nfs_fattr *fattr)
{
	struct super_block *sb = dentry->d_sb;

	dprintk("NFS: nfs_fhget(%s/%s fileid=%Ld)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,
		(long long)fattr->fileid);
	return __nfs_fhget(sb, fhandle, fattr);
}

/*
 * Look up the inode by super block and fattr->fileid.
 */
static struct inode *
__nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
{
	struct nfs_find_desc desc = { fh, fattr };
	struct inode *inode = NULL;
	unsigned long ino;

	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
		goto out_no_inode;

	if (!fattr->nlink) {
		printk("NFS: Buggy server - nlink == 0!\n");
		goto out_no_inode;
	}

	ino = nfs_fattr_to_ino_t(fattr);

	if (!(inode = iget4(sb, ino, nfs_find_actor, &desc)))
		goto out_no_inode;

	nfs_fill_inode(inode, fh, fattr);
	dprintk("NFS: __nfs_fhget(%x/%Ld ct=%d)\n",
		inode->i_dev, (long long)NFS_FILEID(inode),
		atomic_read(&inode->i_count));

out:
	return inode;

out_no_inode:
	printk("__nfs_fhget: iget failed\n");
	goto out;
}

int
nfs_notify_change(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;
	struct nfs_fattr fattr;
	int error;

	/*
	 * Make sure the inode is up-to-date.
	 */
	error = nfs_revalidate(dentry);
	if (error) {
#ifdef NFS_PARANOIA
printk("nfs_notify_change: revalidate failed, error=%d\n", error);
#endif
		goto out;
	}

	if (!S_ISREG(inode->i_mode))
		attr->ia_valid &= ~ATTR_SIZE;

	error = nfs_wb_all(inode);
	if (error)
		goto out;

	error = NFS_PROTO(inode)->setattr(inode, &fattr, attr);
	if (error)
		goto out;
	/*
	 * If we changed the size or mtime, update the inode
	 * now to avoid invalidating the page cache.
	 */
	if (attr->ia_valid & ATTR_SIZE) {
		if (attr->ia_size != fattr.size)
			printk("nfs_notify_change: attr=%Ld, fattr=%Ld??\n",
			       (long long) attr->ia_size, (long long)fattr.size);
		vmtruncate(inode, attr->ia_size);
	}

	/*
	 * If we changed the size or mtime, update the inode
	 * now to avoid invalidating the page cache.
	 */
	if (!(fattr.valid & NFS_ATTR_WCC)) {
		fattr.pre_size = NFS_CACHE_ISIZE(inode);
		fattr.pre_mtime = NFS_CACHE_MTIME(inode);
		fattr.pre_ctime = NFS_CACHE_CTIME(inode);
		fattr.valid |= NFS_ATTR_WCC;
	}
	error = nfs_refresh_inode(inode, &fattr);
out:
	return error;
}

/*
 * Wait for the inode to get unlocked.
 * (Used for NFS_INO_LOCKED and NFS_INO_REVALIDATING).
 */
int
nfs_wait_on_inode(struct inode *inode, int flag)
{
	struct rpc_clnt	*clnt = NFS_CLIENT(inode);
	int error;
	if (!(NFS_FLAGS(inode) & flag))
		return 0;
	atomic_inc(&inode->i_count);
	error = nfs_wait_event(clnt, inode->i_wait, !(NFS_FLAGS(inode) & flag));
	iput(inode);
	return error;
}

/*
 * Externally visible revalidation function
 */
int
nfs_revalidate(struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;
	return nfs_revalidate_inode(NFS_SERVER(inode), inode);
}

/*
 * These are probably going to contain hooks for
 * allocating and releasing RPC credentials for
 * the file. I'll have to think about Tronds patch
 * a bit more..
 */
int nfs_open(struct inode *inode, struct file *filp)
{
	struct rpc_auth *auth;
	struct rpc_cred *cred;

	lock_kernel();
	auth = NFS_CLIENT(inode)->cl_auth;
	cred = rpcauth_lookupcred(auth, 0);
	filp->private_data = cred;
	unlock_kernel();
	return 0;
}

int nfs_release(struct inode *inode, struct file *filp)
{
	struct rpc_auth *auth;
	struct rpc_cred *cred;

	lock_kernel();
	auth = NFS_CLIENT(inode)->cl_auth;
	cred = nfs_file_cred(filp);
	if (cred)
		rpcauth_releasecred(auth, cred);
	unlock_kernel();
	return 0;
}

/*
 * This function is called whenever some part of NFS notices that
 * the cached attributes have to be refreshed.
 */
int
__nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
{
	int		 status = 0;
	struct nfs_fattr fattr;

	dfprintk(PAGECACHE, "NFS: revalidating (%x/%Ld)\n",
		inode->i_dev, (long long)NFS_FILEID(inode));

	lock_kernel();
	if (!inode || is_bad_inode(inode) || NFS_STALE(inode)) {
		unlock_kernel();
		return -ESTALE;
	}

	while (NFS_REVALIDATING(inode)) {
		status = nfs_wait_on_inode(inode, NFS_INO_REVALIDATING);
		if (status < 0) {
			unlock_kernel();
			return status;
		}
		if (time_before(jiffies,NFS_READTIME(inode)+NFS_ATTRTIMEO(inode))) {
			status = NFS_STALE(inode) ? -ESTALE : 0;
			goto out_nowait;
		}
	}
	NFS_FLAGS(inode) |= NFS_INO_REVALIDATING;

	status = NFS_PROTO(inode)->getattr(inode, &fattr);
	if (status) {
		dfprintk(PAGECACHE, "nfs_revalidate_inode: (%x/%Ld) getattr failed, error=%d\n",
			 inode->i_dev, (long long)NFS_FILEID(inode), status);
		if (status == -ESTALE) {
			NFS_FLAGS(inode) |= NFS_INO_STALE;
			remove_inode_hash(inode);
		}
		goto out;
	}

	status = nfs_refresh_inode(inode, &fattr);
	if (status) {
		dfprintk(PAGECACHE, "nfs_revalidate_inode: (%x/%Ld) refresh failed, error=%d\n",
			 inode->i_dev, (long long)NFS_FILEID(inode), status);
		goto out;
	}
	dfprintk(PAGECACHE, "NFS: (%x/%Ld) revalidation complete\n",
		inode->i_dev, (long long)NFS_FILEID(inode));
out:
	NFS_FLAGS(inode) &= ~NFS_INO_REVALIDATING;
	wake_up(&inode->i_wait);
 out_nowait:
	unlock_kernel();
	return status;
}

/*
 * Many nfs protocol calls return the new file attributes after
 * an operation.  Here we update the inode to reflect the state
 * of the server's inode.
 *
 * This is a bit tricky because we have to make sure all dirty pages
 * have been sent off to the server before calling invalidate_inode_pages.
 * To make sure no other process adds more write requests while we try
 * our best to flush them, we make them sleep during the attribute refresh.
 *
 * A very similar scenario holds for the dir cache.
 */
int
nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
{
	__u64		new_size, new_mtime;
	loff_t		new_isize;
	int		invalid = 0;
	int		error = -EIO;

	if (!inode || !fattr) {
		printk(KERN_ERR "nfs_refresh_inode: inode or fattr is NULL\n");
		goto out;
	}
	if (inode->i_mode == 0) {
		printk(KERN_ERR "nfs_refresh_inode: empty inode\n");
		goto out;
	}

	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
		goto out;

	if (is_bad_inode(inode))
		goto out;

	dfprintk(VFS, "NFS: refresh_inode(%x/%ld ct=%d info=0x%x)\n",
			inode->i_dev, inode->i_ino,
			atomic_read(&inode->i_count), fattr->valid);


	if (NFS_FSID(inode) != fattr->fsid ||
	    NFS_FILEID(inode) != fattr->fileid) {
		printk(KERN_ERR "nfs_refresh_inode: inode number mismatch\n"
		       "expected (0x%Lx/0x%Lx), got (0x%Lx/0x%Lx)\n",
		       (long long)NFS_FSID(inode), (long long)NFS_FILEID(inode),
		       (long long)fattr->fsid, (long long)fattr->fileid);
		goto out;
	}

	/*
	 * Make sure the inode's type hasn't changed.
	 */
	if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
		goto out_changed;

 	new_mtime = fattr->mtime;
	new_size = fattr->size;
 	new_isize = nfs_size_to_loff_t(fattr->size);

	error = 0;

	/*
	 * Update the read time so we don't revalidate too often.
	 */
	NFS_READTIME(inode) = jiffies;

	/*
	 * Note: NFS_CACHE_ISIZE(inode) reflects the state of the cache.
	 *       NOT inode->i_size!!!
	 */
	if (NFS_CACHE_ISIZE(inode) != new_size) {
#ifdef NFS_DEBUG_VERBOSE
		printk(KERN_DEBUG "NFS: isize change on %x/%ld\n", inode->i_dev, inode->i_ino);
#endif
		invalid = 1;
	}

	/*
	 * Note: we don't check inode->i_mtime since pipes etc.
	 *       can change this value in VFS without requiring a
	 *	 cache revalidation.
	 */
	if (NFS_CACHE_MTIME(inode) != new_mtime) {
#ifdef NFS_DEBUG_VERBOSE
		printk(KERN_DEBUG "NFS: mtime change on %x/%ld\n", inode->i_dev, inode->i_ino);
#endif
		invalid = 1;
	}

	/* Check Weak Cache Consistency data.
	 * If size and mtime match the pre-operation values, we can
	 * assume that any attribute changes were caused by our NFS
         * operation, so there's no need to invalidate the caches.
         */
        if ((fattr->valid & NFS_ATTR_WCC)
	    && NFS_CACHE_ISIZE(inode) == fattr->pre_size
	    && NFS_CACHE_MTIME(inode) == fattr->pre_mtime) {
		invalid = 0;
	}

	/*
	 * If we have pending writebacks, things can get
	 * messy.
	 */
	if (nfs_have_writebacks(inode) && new_isize < inode->i_size)
		new_isize = inode->i_size;

	NFS_CACHE_CTIME(inode) = fattr->ctime;
	inode->i_ctime = nfs_time_to_secs(fattr->ctime);
	/* If we've been messing around with atime, don't
	 * update it. Save the server value in NFS_CACHE_ATIME.
	 */
	NFS_CACHE_ATIME(inode) = fattr->atime;
	if (time_before(inode->i_atime, nfs_time_to_secs(fattr->atime)))
		inode->i_atime = nfs_time_to_secs(fattr->atime);

	NFS_CACHE_MTIME(inode) = new_mtime;
	inode->i_mtime = nfs_time_to_secs(new_mtime);

	NFS_CACHE_ISIZE(inode) = new_size;
	inode->i_size = new_isize;

	inode->i_mode = fattr->mode;
	inode->i_nlink = fattr->nlink;
	inode->i_uid = fattr->uid;
	inode->i_gid = fattr->gid;

	if (fattr->valid & NFS_ATTR_FATTR_V3) {
		/*
		 * report the blocks in 512byte units
		 */
		inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
		inode->i_blksize = inode->i_sb->s_blocksize;
 	} else {
 		inode->i_blocks = fattr->du.nfs2.blocks;
 		inode->i_blksize = fattr->du.nfs2.blocksize;
 	}
 	inode->i_rdev = 0;
 	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
 		inode->i_rdev = to_kdev_t(fattr->rdev);
 
	/* Update attrtimeo value */
	if (!invalid && time_after(jiffies, NFS_ATTRTIMEO_UPDATE(inode)+NFS_ATTRTIMEO(inode))) {
		if ((NFS_ATTRTIMEO(inode) <<= 1) > NFS_MAXATTRTIMEO(inode))
			NFS_ATTRTIMEO(inode) = NFS_MAXATTRTIMEO(inode);
		NFS_ATTRTIMEO_UPDATE(inode) = jiffies;
	}

	if (invalid)
		nfs_zap_caches(inode);

out:
	return error;

out_changed:
	/*
	 * Big trouble! The inode has become a different object.
	 */
#ifdef NFS_PARANOIA
	printk(KERN_DEBUG "nfs_refresh_inode: inode %ld mode changed, %07o to %07o\n",
	       inode->i_ino, inode->i_mode, fattr->mode);
#endif
	/*
	 * No need to worry about unhashing the dentry, as the
	 * lookup validation will know that the inode is bad.
	 * (But we fall through to invalidate the caches.)
	 */
	nfs_invalidate_inode(inode);
	goto out;
}

/*
 * File system information
 */
static DECLARE_FSTYPE(nfs_fs_type, "nfs", nfs_read_super, FS_ODD_RENAME);

extern int nfs_init_nfspagecache(void);
extern void nfs_destroy_nfspagecache(void);
extern int nfs_init_readpagecache(void);
extern int nfs_destroy_readpagecache(void);

/*
 * Initialize NFS
 */
int
init_nfs_fs(void)
{
	int err;

	err = nfs_init_nfspagecache();
	if (err)
		return err;

	err = nfs_init_readpagecache();
	if (err)
		return err;

#ifdef CONFIG_PROC_FS
	rpc_proc_register(&nfs_rpcstat);
#endif
        return register_filesystem(&nfs_fs_type);
}

/*
 * Every kernel module contains stuff like this.
 */
#ifdef MODULE

EXPORT_NO_SYMBOLS;
/* Not quite true; I just maintain it */
MODULE_AUTHOR("Olaf Kirch <[e-mail]>");

int
init_module(void)
{
	return init_nfs_fs();
}

void
cleanup_module(void)
{
	nfs_destroy_readpagecache();
	nfs_destroy_nfspagecache();
#ifdef CONFIG_PROC_FS
	rpc_proc_unregister("nfs");
#endif
	unregister_filesystem(&nfs_fs_type);
}
#endif