[mirror_ubuntu-bionic-kernel.git] / fs / nfs / symlink.c

/*
 *  linux/fs/nfs/symlink.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  Optimization changes Copyright (C) 1994 Florian La Roche
 *
 *  Jun 7 1999, cache symlink lookups in the page cache.  -DaveM
 *
 *  nfs symlink handling code
 */

#include <linux/time.h>
#include <linux/errno.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs.h>
#include <linux/nfs2.h>
#include <linux/nfs_fs.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/string.h>

/* Symlink caching in the page cache is even more simplistic
 * and straight-forward than readdir caching.
 */

static int nfs_symlink_filler(struct inode *inode, struct page *page)
{
	int error;

	error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
	if (error < 0)
		goto error;
	SetPageUptodate(page);
	unlock_page(page);
	return 0;

error:
	SetPageError(page);
	unlock_page(page);
	return -EIO;
}

static const char *nfs_get_link(struct dentry *dentry,
				struct inode *inode,
				struct delayed_call *done)
{
	struct page *page;
	void *err;

	if (!dentry) {
		err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
		if (err)
			return err;
		page = find_get_page(inode->i_mapping, 0);
		if (!page)
			return ERR_PTR(-ECHILD);
		if (!PageUptodate(page)) {
			put_page(page);
			return ERR_PTR(-ECHILD);
		}
	} else {
		err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
		if (err)
			return err;
		page = read_cache_page(&inode->i_data, 0,
					(filler_t *)nfs_symlink_filler, inode);
		if (IS_ERR(page))
			return ERR_CAST(page);
	}
	set_delayed_call(done, page_put_link, page);
	return page_address(page);
}

/*
 * symlinks can't do much...
 */
const struct inode_operations nfs_symlink_inode_operations = {
	.readlink	= generic_readlink,
	.get_link	= nfs_get_link,
	.getattr	= nfs_getattr,
	.setattr	= nfs_setattr,
};
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/nfs/symlink.c
	3	*
	4	* Copyright (C) 1992 Rick Sladkey
	5	*
	6	* Optimization changes Copyright (C) 1994 Florian La Roche
	7	*
	8	* Jun 7 1999, cache symlink lookups in the page cache. -DaveM
	9	*
	10	* nfs symlink handling code
	11	*/
	12
1da177e4 LT	13	#include <linux/time.h>
	14	#include <linux/errno.h>
	15	#include <linux/sunrpc/clnt.h>
	16	#include <linux/nfs.h>
	17	#include <linux/nfs2.h>
	18	#include <linux/nfs_fs.h>
	19	#include <linux/pagemap.h>
	20	#include <linux/stat.h>
	21	#include <linux/mm.h>
1da177e4	22	#include <linux/string.h>
1da177e4 LT	23
	24	/* Symlink caching in the page cache is even more simplistic
	25	* and straight-forward than readdir caching.
1da177e4 LT	26	*/
1da177e4 LT	27
1da177e4 LT	28	static int nfs_symlink_filler(struct inode inode, struct page page)
1da177e4 LT	29	{
1da177e4 LT	30	int error;
1da177e4 LT	31
cc314eef	32	error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
1da177e4 LT	33	if (error < 0)
	34	goto error;
	35	SetPageUptodate(page);
	36	unlock_page(page);
	37	return 0;
	38
	39	error:
	40	SetPageError(page);
	41	unlock_page(page);
	42	return -EIO;
	43	}
	44
6b255391	45	static const char nfs_get_link(struct dentry dentry,
fceef393 AV	46	struct inode *inode,
fceef393 AV	47	struct delayed_call *done)
1da177e4	48	{
1da177e4	49	struct page *page;
717d44e8 TM	50	void *err;
717d44e8 TM	51
0d0def49 AV	52	if (!dentry) {
	53	err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
	54	if (err)
	55	return err;
	56	page = find_get_page(inode->i_mapping, 0);
	57	if (!page)
	58	return ERR_PTR(-ECHILD);
	59	if (!PageUptodate(page)) {
	60	put_page(page);
	61	return ERR_PTR(-ECHILD);
	62	}
	63	} else {
	64	err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
	65	if (err)
	66	return err;
	67	page = read_cache_page(&inode->i_data, 0,
	68	(filler_t *)nfs_symlink_filler, inode);
	69	if (IS_ERR(page))
	70	return ERR_CAST(page);
	71	}
fceef393	72	set_delayed_call(done, page_put_link, page);
21fc61c7	73	return page_address(page);
1da177e4 LT	74	}
1da177e4 LT	75
1da177e4 LT	76	/*
	77	* symlinks can't do much...
	78	*/
92e1d5be	79	const struct inode_operations nfs_symlink_inode_operations = {
1da177e4	80	.readlink = generic_readlink,
6b255391	81	.get_link = nfs_get_link,
1da177e4 LT	82	.getattr = nfs_getattr,
	83	.setattr = nfs_setattr,
	84	};