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2023-12-11 072de836f53be56a70cecf70b43ae43b7ce17376 
 kernel/fs/squashfs/block.c
....@@ -1,22 +1,9 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
12 /*
23  * Squashfs - a compressed read only filesystem for Linux
34  *
45  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
56  * Phillip Lougher <phillip@squashfs.org.uk>
6
- *
7
- * This program is free software; you can redistribute it and/or
8
- * modify it under the terms of the GNU General Public License
9
- * as published by the Free Software Foundation; either version 2,
10
- * or (at your option) any later version.
11
- *
12
- * This program is distributed in the hope that it will be useful,
13
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
14
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15
- * GNU General Public License for more details.
16
- *
17
- * You should have received a copy of the GNU General Public License
18
- * along with this program; if not, write to the Free Software
19
- * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
207  *
218  * block.c
229  */
....@@ -26,6 +13,7 @@
2613  * datablocks and metadata blocks.
2714  */
2815 
16
+#include <linux/blkdev.h>
2917 #include <linux/fs.h>
3018 #include <linux/vfs.h>
3119 #include <linux/slab.h>
....@@ -40,44 +28,107 @@
4028 #include "page_actor.h"
4129 
4230 /*
43
- * Read the metadata block length, this is stored in the first two
44
- * bytes of the metadata block.
31
+ * Returns the amount of bytes copied to the page actor.
4532  */
46
-static struct buffer_head *get_block_length(struct super_block *sb,
47
-			u64 *cur_index, int *offset, int *length)
33
+static int copy_bio_to_actor(struct bio *bio,
34
+			     struct squashfs_page_actor *actor,
35
+			     int offset, int req_length)
4836 {
49
-	struct squashfs_sb_info *msblk = sb->s_fs_info;
50
-	struct buffer_head *bh;
37
+	void *actor_addr = squashfs_first_page(actor);
38
+	struct bvec_iter_all iter_all = {};
39
+	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
40
+	int copied_bytes = 0;
41
+	int actor_offset = 0;
5142 
52
-	bh = sb_bread(sb, *cur_index);
53
-	if (bh == NULL)
54
-		return NULL;
43
+	if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all)))
44
+		return 0;
5545 
56
-	if (msblk->devblksize - *offset == 1) {
57
-		*length = (unsigned char) bh->b_data[*offset];
58
-		put_bh(bh);
59
-		bh = sb_bread(sb, ++(*cur_index));
60
-		if (bh == NULL)
61
-			return NULL;
62
-		*length |= (unsigned char) bh->b_data[0] << 8;
63
-		*offset = 1;
64
-	} else {
65
-		*length = (unsigned char) bh->b_data[*offset] |
66
-			(unsigned char) bh->b_data[*offset + 1] << 8;
67
-		*offset += 2;
46
+	while (copied_bytes < req_length) {
47
+		int bytes_to_copy = min_t(int, bvec->bv_len - offset,
48
+					  PAGE_SIZE - actor_offset);
6849 
69
-		if (*offset == msblk->devblksize) {
70
-			put_bh(bh);
71
-			bh = sb_bread(sb, ++(*cur_index));
72
-			if (bh == NULL)
73
-				return NULL;
74
-			*offset = 0;
50
+		bytes_to_copy = min_t(int, bytes_to_copy,
51
+				      req_length - copied_bytes);
52
+		memcpy(actor_addr + actor_offset,
53
+		       page_address(bvec->bv_page) + bvec->bv_offset + offset,
54
+		       bytes_to_copy);
55
+
56
+		actor_offset += bytes_to_copy;
57
+		copied_bytes += bytes_to_copy;
58
+		offset += bytes_to_copy;
59
+
60
+		if (actor_offset >= PAGE_SIZE) {
61
+			actor_addr = squashfs_next_page(actor);
62
+			if (!actor_addr)
63
+				break;
64
+			actor_offset = 0;
65
+		}
66
+		if (offset >= bvec->bv_len) {
67
+			if (!bio_next_segment(bio, &iter_all))
68
+				break;
69
+			offset = 0;
7570 		}
7671 	}
77
-
78
-	return bh;
72
+	squashfs_finish_page(actor);
73
+	return copied_bytes;
7974 }
8075 
76
+static int squashfs_bio_read(struct super_block *sb, u64 index, int length,
77
+			     struct bio **biop, int *block_offset)
78
+{
79
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
80
+	const u64 read_start = round_down(index, msblk->devblksize);
81
+	const sector_t block = read_start >> msblk->devblksize_log2;
82
+	const u64 read_end = round_up(index + length, msblk->devblksize);
83
+	const sector_t block_end = read_end >> msblk->devblksize_log2;
84
+	int offset = read_start - round_down(index, PAGE_SIZE);
85
+	int total_len = (block_end - block) << msblk->devblksize_log2;
86
+	const int page_count = DIV_ROUND_UP(total_len + offset, PAGE_SIZE);
87
+	int error, i;
88
+	struct bio *bio;
89
+
90
+	if (page_count <= BIO_MAX_PAGES)
91
+		bio = bio_alloc(GFP_NOIO, page_count);
92
+	else
93
+		bio = bio_kmalloc(GFP_NOIO, page_count);
94
+
95
+	if (!bio)
96
+		return -ENOMEM;
97
+
98
+	bio_set_dev(bio, sb->s_bdev);
99
+	bio->bi_opf = READ;
100
+	bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT);
101
+
102
+	for (i = 0; i < page_count; ++i) {
103
+		unsigned int len =
104
+			min_t(unsigned int, PAGE_SIZE - offset, total_len);
105
+		struct page *page = alloc_page(GFP_NOIO);
106
+
107
+		if (!page) {
108
+			error = -ENOMEM;
109
+			goto out_free_bio;
110
+		}
111
+		if (!bio_add_page(bio, page, len, offset)) {
112
+			error = -EIO;
113
+			goto out_free_bio;
114
+		}
115
+		offset = 0;
116
+		total_len -= len;
117
+	}
118
+
119
+	error = submit_bio_wait(bio);
120
+	if (error)
121
+		goto out_free_bio;
122
+
123
+	*biop = bio;
124
+	*block_offset = index & ((1 << msblk->devblksize_log2) - 1);
125
+	return 0;
126
+
127
+out_free_bio:
128
+	bio_free_pages(bio);
129
+	bio_put(bio);
130
+	return error;
131
+}
81132 
82133 /*
83134  * Read and decompress a metadata block or datablock.  Length is non-zero
....@@ -89,129 +140,94 @@
89140  * algorithms).
90141  */
91142 int squashfs_read_data(struct super_block *sb, u64 index, int length,
92
-		u64 *next_index, struct squashfs_page_actor *output)
143
+		       u64 *next_index, struct squashfs_page_actor *output)
93144 {
94145 	struct squashfs_sb_info *msblk = sb->s_fs_info;
95
-	struct buffer_head **bh;
96
-	int offset = index & ((1 << msblk->devblksize_log2) - 1);
97
-	u64 cur_index = index >> msblk->devblksize_log2;
98
-	int bytes, compressed, b = 0, k = 0, avail, i;
99
-
100
-	bh = kcalloc(((output->length + msblk->devblksize - 1)
101
-		>> msblk->devblksize_log2) + 1, sizeof(*bh), GFP_KERNEL);
102
-	if (bh == NULL)
103
-		return -ENOMEM;
146
+	struct bio *bio = NULL;
147
+	int compressed;
148
+	int res;
149
+	int offset;
104150 
105151 	if (length) {
106152 		/*
107153 		 * Datablock.
108154 		 */
109
-		bytes = -offset;
110155 		compressed = SQUASHFS_COMPRESSED_BLOCK(length);
111156 		length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length);
112
-		if (next_index)
113
-			*next_index = index + length;
114
-
115157 		TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
116158 			index, compressed ? "" : "un", length, output->length);
117
-
118
-		if (length < 0 || length > output->length ||
119
-				(index + length) > msblk->bytes_used)
120
-			goto read_failure;
121
-
122
-		for (b = 0; bytes < length; b++, cur_index++) {
123
-			bh[b] = sb_getblk(sb, cur_index);
124
-			if (bh[b] == NULL)
125
-				goto block_release;
126
-			bytes += msblk->devblksize;
127
-		}
128
-		ll_rw_block(REQ_OP_READ, 0, b, bh);
129159 	} else {
130160 		/*
131161 		 * Metadata block.
132162 		 */
133
-		if ((index + 2) > msblk->bytes_used)
134
-			goto read_failure;
163
+		const u8 *data;
164
+		struct bvec_iter_all iter_all = {};
165
+		struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
135166 
136
-		bh[0] = get_block_length(sb, &cur_index, &offset, &length);
137
-		if (bh[0] == NULL)
138
-			goto read_failure;
139
-		b = 1;
167
+		if (index + 2 > msblk->bytes_used) {
168
+			res = -EIO;
169
+			goto out;
170
+		}
171
+		res = squashfs_bio_read(sb, index, 2, &bio, &offset);
172
+		if (res)
173
+			goto out;
140174 
141
-		bytes = msblk->devblksize - offset;
175
+		if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
176
+			res = -EIO;
177
+			goto out_free_bio;
178
+		}
179
+		/* Extract the length of the metadata block */
180
+		data = page_address(bvec->bv_page) + bvec->bv_offset;
181
+		length = data[offset];
182
+		if (offset < bvec->bv_len - 1) {
183
+			length |= data[offset + 1] << 8;
184
+		} else {
185
+			if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
186
+				res = -EIO;
187
+				goto out_free_bio;
188
+			}
189
+			data = page_address(bvec->bv_page) + bvec->bv_offset;
190
+			length |= data[0] << 8;
191
+		}
192
+		bio_free_pages(bio);
193
+		bio_put(bio);
194
+
142195 		compressed = SQUASHFS_COMPRESSED(length);
143196 		length = SQUASHFS_COMPRESSED_SIZE(length);
144
-		if (next_index)
145
-			*next_index = index + length + 2;
197
+		index += 2;
146198 
147
-		TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
148
-				compressed ? "" : "un", length);
149
-
150
-		if (length < 0 || length > output->length ||
151
-					(index + length) > msblk->bytes_used)
152
-			goto block_release;
153
-
154
-		for (; bytes < length; b++) {
155
-			bh[b] = sb_getblk(sb, ++cur_index);
156
-			if (bh[b] == NULL)
157
-				goto block_release;
158
-			bytes += msblk->devblksize;
159
-		}
160
-		ll_rw_block(REQ_OP_READ, 0, b - 1, bh + 1);
199
+		TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2,
200
+		      compressed ? "" : "un", length);
201
+	}
202
+	if (length < 0 || length > output->length ||
203
+			(index + length) > msblk->bytes_used) {
204
+		res = -EIO;
205
+		goto out;
161206 	}
162207 
163
-	for (i = 0; i < b; i++) {
164
-		wait_on_buffer(bh[i]);
165
-		if (!buffer_uptodate(bh[i]))
166
-			goto block_release;
167
-	}
208
+	if (next_index)
209
+		*next_index = index + length;
210
+
211
+	res = squashfs_bio_read(sb, index, length, &bio, &offset);
212
+	if (res)
213
+		goto out;
168214 
169215 	if (compressed) {
170
-		if (!msblk->stream)
171
-			goto read_failure;
172
-		length = squashfs_decompress(msblk, bh, b, offset, length,
173
-			output);
174
-		if (length < 0)
175
-			goto read_failure;
176
-	} else {
177
-		/*
178
-		 * Block is uncompressed.
179
-		 */
180
-		int in, pg_offset = 0;
181
-		void *data = squashfs_first_page(output);
182
-
183
-		for (bytes = length; k < b; k++) {
184
-			in = min(bytes, msblk->devblksize - offset);
185
-			bytes -= in;
186
-			while (in) {
187
-				if (pg_offset == PAGE_SIZE) {
188
-					data = squashfs_next_page(output);
189
-					pg_offset = 0;
190
-				}
191
-				avail = min_t(int, in, PAGE_SIZE -
192
-						pg_offset);
193
-				memcpy(data + pg_offset, bh[k]->b_data + offset,
194
-						avail);
195
-				in -= avail;
196
-				pg_offset += avail;
197
-				offset += avail;
198
-			}
199
-			offset = 0;
200
-			put_bh(bh[k]);
216
+		if (!msblk->stream) {
217
+			res = -EIO;
218
+			goto out_free_bio;
201219 		}
202
-		squashfs_finish_page(output);
220
+		res = squashfs_decompress(msblk, bio, offset, length, output);
221
+	} else {
222
+		res = copy_bio_to_actor(bio, output, offset, length);
203223 	}
204224 
205
-	kfree(bh);
206
-	return length;
225
+out_free_bio:
226
+	bio_free_pages(bio);
227
+	bio_put(bio);
228
+out:
229
+	if (res < 0)
230
+		ERROR("Failed to read block 0x%llx: %d\n", index, res);
207231 
208
-block_release:
209
-	for (; k < b; k++)
210
-		put_bh(bh[k]);
211
-
212
-read_failure:
213
-	ERROR("squashfs_read_data failed to read block 0x%llx\n",
214
-					(unsigned long long) index);
215
-	kfree(bh);
216
-	return -EIO;
232
+	return res;
217233 }