1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  linux/fs/hpfs/buffer.c
4 *
5 *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
6 *
7 *  general buffer i/o
8 */
9#include <linux/sched.h>
10#include <linux/slab.h>
11#include <linux/blkdev.h>
12#include "hpfs_fn.h"
13
14secno hpfs_search_hotfix_map(struct super_block *s, secno sec)
15{
16	unsigned i;
17	struct hpfs_sb_info *sbi = hpfs_sb(s);
18	for (i = 0; unlikely(i < sbi->n_hotfixes); i++) {
19		if (sbi->hotfix_from[i] == sec) {
20			return sbi->hotfix_to[i];
21		}
22	}
23	return sec;
24}
25
26unsigned hpfs_search_hotfix_map_for_range(struct super_block *s, secno sec, unsigned n)
27{
28	unsigned i;
29	struct hpfs_sb_info *sbi = hpfs_sb(s);
30	for (i = 0; unlikely(i < sbi->n_hotfixes); i++) {
31		if (sbi->hotfix_from[i] >= sec && sbi->hotfix_from[i] < sec + n) {
32			n = sbi->hotfix_from[i] - sec;
33		}
34	}
35	return n;
36}
37
38void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n)
39{
40	struct buffer_head *bh;
41	struct blk_plug plug;
42
43	if (n <= 0 || unlikely(secno >= hpfs_sb(s)->sb_fs_size))
44		return;
45
46	if (unlikely(hpfs_search_hotfix_map_for_range(s, secno, n) != n))
47		return;
48
49	bh = sb_find_get_block(s, secno);
50	if (bh) {
51		if (buffer_uptodate(bh)) {
52			brelse(bh);
53			return;
54		}
55		brelse(bh);
56	}
57
58	blk_start_plug(&plug);
59	while (n > 0) {
60		if (unlikely(secno >= hpfs_sb(s)->sb_fs_size))
61			break;
62		sb_breadahead(s, secno);
63		secno++;
64		n--;
65	}
66	blk_finish_plug(&plug);
67}
68
69/* Map a sector into a buffer and return pointers to it and to the buffer. */
70
71void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp,
72		 int ahead)
73{
74	struct buffer_head *bh;
75
76	hpfs_lock_assert(s);
77
78	hpfs_prefetch_sectors(s, secno, ahead);
79
80	cond_resched();
81
82	*bhp = bh = sb_bread(s, hpfs_search_hotfix_map(s, secno));
83	if (bh != NULL)
84		return bh->b_data;
85	else {
86		pr_err("%s(): read error\n", __func__);
87		return NULL;
88	}
89}
90
91/* Like hpfs_map_sector but don't read anything */
92
93void *hpfs_get_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp)
94{
95	struct buffer_head *bh;
96	/*return hpfs_map_sector(s, secno, bhp, 0);*/
97
98	hpfs_lock_assert(s);
99
100	cond_resched();
101
102	if ((*bhp = bh = sb_getblk(s, hpfs_search_hotfix_map(s, secno))) != NULL) {
103		if (!buffer_uptodate(bh)) wait_on_buffer(bh);
104		set_buffer_uptodate(bh);
105		return bh->b_data;
106	} else {
107		pr_err("%s(): getblk failed\n", __func__);
108		return NULL;
109	}
110}
111
112/* Map 4 sectors into a 4buffer and return pointers to it and to the buffer. */
113
114void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffer_head *qbh,
115		   int ahead)
116{
117	char *data;
118
119	hpfs_lock_assert(s);
120
121	cond_resched();
122
123	if (secno & 3) {
124		pr_err("%s(): unaligned read\n", __func__);
125		return NULL;
126	}
127
128	hpfs_prefetch_sectors(s, secno, 4 + ahead);
129
130	if (!hpfs_map_sector(s, secno + 0, &qbh->bh[0], 0)) goto bail0;
131	if (!hpfs_map_sector(s, secno + 1, &qbh->bh[1], 0)) goto bail1;
132	if (!hpfs_map_sector(s, secno + 2, &qbh->bh[2], 0)) goto bail2;
133	if (!hpfs_map_sector(s, secno + 3, &qbh->bh[3], 0)) goto bail3;
134
135	if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
136	    likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
137	    likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
138		return qbh->data = qbh->bh[0]->b_data;
139	}
140
141	qbh->data = data = kmalloc(2048, GFP_NOFS);
142	if (!data) {
143		pr_err("%s(): out of memory\n", __func__);
144		goto bail4;
145	}
146
147	memcpy(data + 0 * 512, qbh->bh[0]->b_data, 512);
148	memcpy(data + 1 * 512, qbh->bh[1]->b_data, 512);
149	memcpy(data + 2 * 512, qbh->bh[2]->b_data, 512);
150	memcpy(data + 3 * 512, qbh->bh[3]->b_data, 512);
151
152	return data;
153
154 bail4:
155	brelse(qbh->bh[3]);
156 bail3:
157	brelse(qbh->bh[2]);
158 bail2:
159	brelse(qbh->bh[1]);
160 bail1:
161	brelse(qbh->bh[0]);
162 bail0:
163	return NULL;
164}
165
166/* Don't read sectors */
167
168void *hpfs_get_4sectors(struct super_block *s, unsigned secno,
169                          struct quad_buffer_head *qbh)
170{
171	cond_resched();
172
173	hpfs_lock_assert(s);
174
175	if (secno & 3) {
176		pr_err("%s(): unaligned read\n", __func__);
177		return NULL;
178	}
179
180	if (!hpfs_get_sector(s, secno + 0, &qbh->bh[0])) goto bail0;
181	if (!hpfs_get_sector(s, secno + 1, &qbh->bh[1])) goto bail1;
182	if (!hpfs_get_sector(s, secno + 2, &qbh->bh[2])) goto bail2;
183	if (!hpfs_get_sector(s, secno + 3, &qbh->bh[3])) goto bail3;
184
185	if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
186	    likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
187	    likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
188		return qbh->data = qbh->bh[0]->b_data;
189	}
190
191	if (!(qbh->data = kmalloc(2048, GFP_NOFS))) {
192		pr_err("%s(): out of memory\n", __func__);
193		goto bail4;
194	}
195	return qbh->data;
196
197bail4:
198	brelse(qbh->bh[3]);
199bail3:
200	brelse(qbh->bh[2]);
201bail2:
202	brelse(qbh->bh[1]);
203bail1:
204	brelse(qbh->bh[0]);
205bail0:
206	return NULL;
207}
208
209
210void hpfs_brelse4(struct quad_buffer_head *qbh)
211{
212	if (unlikely(qbh->data != qbh->bh[0]->b_data))
213		kfree(qbh->data);
214	brelse(qbh->bh[0]);
215	brelse(qbh->bh[1]);
216	brelse(qbh->bh[2]);
217	brelse(qbh->bh[3]);
218}
219
220void hpfs_mark_4buffers_dirty(struct quad_buffer_head *qbh)
221{
222	if (unlikely(qbh->data != qbh->bh[0]->b_data)) {
223		memcpy(qbh->bh[0]->b_data, qbh->data + 0 * 512, 512);
224		memcpy(qbh->bh[1]->b_data, qbh->data + 1 * 512, 512);
225		memcpy(qbh->bh[2]->b_data, qbh->data + 2 * 512, 512);
226		memcpy(qbh->bh[3]->b_data, qbh->data + 3 * 512, 512);
227	}
228	mark_buffer_dirty(qbh->bh[0]);
229	mark_buffer_dirty(qbh->bh[1]);
230	mark_buffer_dirty(qbh->bh[2]);
231	mark_buffer_dirty(qbh->bh[3]);
232}
233