1/*
2 *  linux/fs/hpfs/buffer.c
3 *
4 *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
5 *
6 *  general buffer i/o
7 */
8#include <linux/sched.h>
9#include <linux/slab.h>
10#include <linux/blkdev.h>
11#include "hpfs_fn.h"
12
13void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n)
14{
15	struct buffer_head *bh;
16	struct blk_plug plug;
17
18	if (n <= 0 || unlikely(secno >= hpfs_sb(s)->sb_fs_size))
19		return;
20
21	bh = sb_find_get_block(s, secno);
22	if (bh) {
23		if (buffer_uptodate(bh)) {
24			brelse(bh);
25			return;
26		}
27		brelse(bh);
28	};
29
30	blk_start_plug(&plug);
31	while (n > 0) {
32		if (unlikely(secno >= hpfs_sb(s)->sb_fs_size))
33			break;
34		sb_breadahead(s, secno);
35		secno++;
36		n--;
37	}
38	blk_finish_plug(&plug);
39}
40
41/* Map a sector into a buffer and return pointers to it and to the buffer. */
42
43void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp,
44		 int ahead)
45{
46	struct buffer_head *bh;
47
48	hpfs_lock_assert(s);
49
50	hpfs_prefetch_sectors(s, secno, ahead);
51
52	cond_resched();
53
54	*bhp = bh = sb_bread(s, secno);
55	if (bh != NULL)
56		return bh->b_data;
57	else {
58		pr_err("%s(): read error\n", __func__);
59		return NULL;
60	}
61}
62
63/* Like hpfs_map_sector but don't read anything */
64
65void *hpfs_get_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp)
66{
67	struct buffer_head *bh;
68	/*return hpfs_map_sector(s, secno, bhp, 0);*/
69
70	hpfs_lock_assert(s);
71
72	cond_resched();
73
74	if ((*bhp = bh = sb_getblk(s, secno)) != NULL) {
75		if (!buffer_uptodate(bh)) wait_on_buffer(bh);
76		set_buffer_uptodate(bh);
77		return bh->b_data;
78	} else {
79		pr_err("%s(): getblk failed\n", __func__);
80		return NULL;
81	}
82}
83
84/* Map 4 sectors into a 4buffer and return pointers to it and to the buffer. */
85
86void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffer_head *qbh,
87		   int ahead)
88{
89	char *data;
90
91	hpfs_lock_assert(s);
92
93	cond_resched();
94
95	if (secno & 3) {
96		pr_err("%s(): unaligned read\n", __func__);
97		return NULL;
98	}
99
100	hpfs_prefetch_sectors(s, secno, 4 + ahead);
101
102	if (!(qbh->bh[0] = sb_bread(s, secno + 0))) goto bail0;
103	if (!(qbh->bh[1] = sb_bread(s, secno + 1))) goto bail1;
104	if (!(qbh->bh[2] = sb_bread(s, secno + 2))) goto bail2;
105	if (!(qbh->bh[3] = sb_bread(s, secno + 3))) goto bail3;
106
107	if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
108	    likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
109	    likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
110		return qbh->data = qbh->bh[0]->b_data;
111	}
112
113	qbh->data = data = kmalloc(2048, GFP_NOFS);
114	if (!data) {
115		pr_err("%s(): out of memory\n", __func__);
116		goto bail4;
117	}
118
119	memcpy(data + 0 * 512, qbh->bh[0]->b_data, 512);
120	memcpy(data + 1 * 512, qbh->bh[1]->b_data, 512);
121	memcpy(data + 2 * 512, qbh->bh[2]->b_data, 512);
122	memcpy(data + 3 * 512, qbh->bh[3]->b_data, 512);
123
124	return data;
125
126 bail4:
127	brelse(qbh->bh[3]);
128 bail3:
129	brelse(qbh->bh[2]);
130 bail2:
131	brelse(qbh->bh[1]);
132 bail1:
133	brelse(qbh->bh[0]);
134 bail0:
135	return NULL;
136}
137
138/* Don't read sectors */
139
140void *hpfs_get_4sectors(struct super_block *s, unsigned secno,
141                          struct quad_buffer_head *qbh)
142{
143	cond_resched();
144
145	hpfs_lock_assert(s);
146
147	if (secno & 3) {
148		pr_err("%s(): unaligned read\n", __func__);
149		return NULL;
150	}
151
152	if (!hpfs_get_sector(s, secno + 0, &qbh->bh[0])) goto bail0;
153	if (!hpfs_get_sector(s, secno + 1, &qbh->bh[1])) goto bail1;
154	if (!hpfs_get_sector(s, secno + 2, &qbh->bh[2])) goto bail2;
155	if (!hpfs_get_sector(s, secno + 3, &qbh->bh[3])) goto bail3;
156
157	if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
158	    likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
159	    likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
160		return qbh->data = qbh->bh[0]->b_data;
161	}
162
163	if (!(qbh->data = kmalloc(2048, GFP_NOFS))) {
164		pr_err("%s(): out of memory\n", __func__);
165		goto bail4;
166	}
167	return qbh->data;
168
169bail4:
170	brelse(qbh->bh[3]);
171bail3:
172	brelse(qbh->bh[2]);
173bail2:
174	brelse(qbh->bh[1]);
175bail1:
176	brelse(qbh->bh[0]);
177bail0:
178	return NULL;
179}
180
181
182void hpfs_brelse4(struct quad_buffer_head *qbh)
183{
184	if (unlikely(qbh->data != qbh->bh[0]->b_data))
185		kfree(qbh->data);
186	brelse(qbh->bh[0]);
187	brelse(qbh->bh[1]);
188	brelse(qbh->bh[2]);
189	brelse(qbh->bh[3]);
190}
191
192void hpfs_mark_4buffers_dirty(struct quad_buffer_head *qbh)
193{
194	if (unlikely(qbh->data != qbh->bh[0]->b_data)) {
195		memcpy(qbh->bh[0]->b_data, qbh->data + 0 * 512, 512);
196		memcpy(qbh->bh[1]->b_data, qbh->data + 1 * 512, 512);
197		memcpy(qbh->bh[2]->b_data, qbh->data + 2 * 512, 512);
198		memcpy(qbh->bh[3]->b_data, qbh->data + 3 * 512, 512);
199	}
200	mark_buffer_dirty(qbh->bh[0]);
201	mark_buffer_dirty(qbh->bh[1]);
202	mark_buffer_dirty(qbh->bh[2]);
203	mark_buffer_dirty(qbh->bh[3]);
204}
205