1 /*
2  * Copyright (c) 2000-2001 Christoph Hellwig.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions, and the following disclaimer,
10  *    without modification.
11  * 2. The name of the author may not be used to endorse or promote products
12  *    derived from this software without specific prior written permission.
13  *
14  * Alternatively, this software may be distributed under the terms of the
15  * GNU General Public License ("GPL").
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
21  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 /*
31  * Veritas filesystem driver - shared subroutines.
32  */
33 #include <linux/fs.h>
34 #include <linux/buffer_head.h>
35 #include <linux/kernel.h>
36 #include <linux/pagemap.h>
37 
38 #include "vxfs_extern.h"
39 
40 
41 static int		vxfs_readpage(struct file *, struct page *);
42 static sector_t		vxfs_bmap(struct address_space *, sector_t);
43 
44 const struct address_space_operations vxfs_aops = {
45 	.readpage =		vxfs_readpage,
46 	.bmap =			vxfs_bmap,
47 };
48 
49 inline void
vxfs_put_page(struct page * pp)50 vxfs_put_page(struct page *pp)
51 {
52 	kunmap(pp);
53 	put_page(pp);
54 }
55 
56 /**
57  * vxfs_get_page - read a page into memory.
58  * @ip:		inode to read from
59  * @n:		page number
60  *
61  * Description:
62  *   vxfs_get_page reads the @n th page of @ip into the pagecache.
63  *
64  * Returns:
65  *   The wanted page on success, else a NULL pointer.
66  */
67 struct page *
vxfs_get_page(struct address_space * mapping,u_long n)68 vxfs_get_page(struct address_space *mapping, u_long n)
69 {
70 	struct page *			pp;
71 
72 	pp = read_mapping_page(mapping, n, NULL);
73 
74 	if (!IS_ERR(pp)) {
75 		kmap(pp);
76 		/** if (!PageChecked(pp)) **/
77 			/** vxfs_check_page(pp); **/
78 		if (PageError(pp))
79 			goto fail;
80 	}
81 
82 	return (pp);
83 
84 fail:
85 	vxfs_put_page(pp);
86 	return ERR_PTR(-EIO);
87 }
88 
89 /**
90  * vxfs_bread - read buffer for a give inode,block tuple
91  * @ip:		inode
92  * @block:	logical block
93  *
94  * Description:
95  *   The vxfs_bread function reads block no @block  of
96  *   @ip into the buffercache.
97  *
98  * Returns:
99  *   The resulting &struct buffer_head.
100  */
101 struct buffer_head *
vxfs_bread(struct inode * ip,int block)102 vxfs_bread(struct inode *ip, int block)
103 {
104 	struct buffer_head	*bp;
105 	daddr_t			pblock;
106 
107 	pblock = vxfs_bmap1(ip, block);
108 	bp = sb_bread(ip->i_sb, pblock);
109 
110 	return (bp);
111 }
112 
113 /**
114  * vxfs_get_block - locate buffer for given inode,block tuple
115  * @ip:		inode
116  * @iblock:	logical block
117  * @bp:		buffer skeleton
118  * @create:	%TRUE if blocks may be newly allocated.
119  *
120  * Description:
121  *   The vxfs_get_block function fills @bp with the right physical
122  *   block and device number to perform a lowlevel read/write on
123  *   it.
124  *
125  * Returns:
126  *   Zero on success, else a negativ error code (-EIO).
127  */
128 static int
vxfs_getblk(struct inode * ip,sector_t iblock,struct buffer_head * bp,int create)129 vxfs_getblk(struct inode *ip, sector_t iblock,
130 	    struct buffer_head *bp, int create)
131 {
132 	daddr_t			pblock;
133 
134 	pblock = vxfs_bmap1(ip, iblock);
135 	if (pblock != 0) {
136 		map_bh(bp, ip->i_sb, pblock);
137 		return 0;
138 	}
139 
140 	return -EIO;
141 }
142 
143 /**
144  * vxfs_readpage - read one page synchronously into the pagecache
145  * @file:	file context (unused)
146  * @page:	page frame to fill in.
147  *
148  * Description:
149  *   The vxfs_readpage routine reads @page synchronously into the
150  *   pagecache.
151  *
152  * Returns:
153  *   Zero on success, else a negative error code.
154  *
155  * Locking status:
156  *   @page is locked and will be unlocked.
157  */
158 static int
vxfs_readpage(struct file * file,struct page * page)159 vxfs_readpage(struct file *file, struct page *page)
160 {
161 	return block_read_full_page(page, vxfs_getblk);
162 }
163 
164 /**
165  * vxfs_bmap - perform logical to physical block mapping
166  * @mapping:	logical to physical mapping to use
167  * @block:	logical block (relative to @mapping).
168  *
169  * Description:
170  *   Vxfs_bmap find out the corresponding phsical block to the
171  *   @mapping, @block pair.
172  *
173  * Returns:
174  *   Physical block number on success, else Zero.
175  *
176  * Locking status:
177  *   We are under the bkl.
178  */
179 static sector_t
vxfs_bmap(struct address_space * mapping,sector_t block)180 vxfs_bmap(struct address_space *mapping, sector_t block)
181 {
182 	return generic_block_bmap(mapping, block, vxfs_getblk);
183 }
184