1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * Squashfs - a compressed read only filesystem for Linux
8  * block.c
12  * This file implements the low-level routines to read and decompress
35 			     int offset, int req_length)  in copy_bio_to_actor()  argument
50 		int bytes_to_copy = min_t(int, bvec->bv_len - offset,  in copy_bio_to_actor()
51 					  PAGE_SIZE - actor_offset);  in copy_bio_to_actor()
54 				      req_length - copied_bytes);  in copy_bio_to_actor()
57 					offset, bytes_to_copy);  in copy_bio_to_actor()
61 		offset += bytes_to_copy;  in copy_bio_to_actor()
69 		if (offset >= bvec->bv_len) {  in copy_bio_to_actor()
72 			offset = 0;  in copy_bio_to_actor()
84 	struct block_device *bdev = fullbio->bi_bdev;  in squashfs_bio_read_cached()
97 		struct page *page = bv->bv_page;  in squashfs_bio_read_cached()
99 		if (page->mapping == cache_mapping) {  in squashfs_bio_read_cached()
105 		 * We only use this when the device block size is the same as  in squashfs_bio_read_cached()
115 		else if (idx == page_count - 1 && index + length != read_end)  in squashfs_bio_read_cached()
129 					 (end_idx - start_idx) * PAGE_SECTORS);  in squashfs_bio_read_cached()
144 			 (end_idx - start_idx) * PAGE_SECTORS);  in squashfs_bio_read_cached()
166 						(read_end >> PAGE_SHIFT) - 1,  in squashfs_bio_read_cached()
220 	struct squashfs_sb_info *msblk = sb->s_fs_info;  in squashfs_bio_read()
221 	struct address_space *cache_mapping = msblk->cache_mapping;  in squashfs_bio_read()
222 	const u64 read_start = round_down(index, msblk->devblksize);  in squashfs_bio_read()
223 	const sector_t block = read_start >> msblk->devblksize_log2;  in squashfs_bio_read()  local
224 	const u64 read_end = round_up(index + length, msblk->devblksize);  in squashfs_bio_read()
225 	const sector_t block_end = read_end >> msblk->devblksize_log2;  in squashfs_bio_read()
226 	int offset = read_start - round_down(index, PAGE_SIZE);  in squashfs_bio_read()  local
227 	int total_len = (block_end - block) << msblk->devblksize_log2;  in squashfs_bio_read()
228 	const int page_count = DIV_ROUND_UP(total_len + offset, PAGE_SIZE);  in squashfs_bio_read()
234 		return -ENOMEM;  in squashfs_bio_read()
235 	bio_init(bio, sb->s_bdev, bio->bi_inline_vecs, page_count, REQ_OP_READ);  in squashfs_bio_read()
236 	bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT);  in squashfs_bio_read()
240 			min_t(unsigned int, PAGE_SIZE - offset, total_len);  in squashfs_bio_read()
249 			error = -ENOMEM;  in squashfs_bio_read()
257 		__bio_add_page(bio, page, len, offset);  in squashfs_bio_read()
258 		offset = 0;  in squashfs_bio_read()
259 		total_len -= len;  in squashfs_bio_read()
272 	*block_offset = index & ((1 << msblk->devblksize_log2) - 1);  in squashfs_bio_read()
283  * Read and decompress a metadata block or datablock.  Length is non-zero
286  * the metadata block.  A bit in the length field indicates if the block
288  * generated a larger block - this does occasionally happen with compression
294 	struct squashfs_sb_info *msblk = sb->s_fs_info;  in squashfs_read_data()
298 	int offset;  in squashfs_read_data()  local
306 		TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",  in squashfs_read_data()
307 			index, compressed ? "" : "un", length, output->length);  in squashfs_read_data()
310 		 * Metadata block.  in squashfs_read_data()
316 		if (index + 2 > msblk->bytes_used) {  in squashfs_read_data()
317 			res = -EIO;  in squashfs_read_data()
320 		res = squashfs_bio_read(sb, index, 2, &bio, &offset);  in squashfs_read_data()
325 			res = -EIO;  in squashfs_read_data()
328 		/* Extract the length of the metadata block */  in squashfs_read_data()
330 		length = data[offset];  in squashfs_read_data()
331 		if (offset < bvec->bv_len - 1) {  in squashfs_read_data()
332 			length |= data[offset + 1] << 8;  in squashfs_read_data()
335 				res = -EIO;  in squashfs_read_data()
349 		TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2,  in squashfs_read_data()
352 	if (length <= 0 || length > output->length ||  in squashfs_read_data()
353 			(index + length) > msblk->bytes_used) {  in squashfs_read_data()
354 		res = -EIO;  in squashfs_read_data()
361 	res = squashfs_bio_read(sb, index, length, &bio, &offset);  in squashfs_read_data()
366 		if (!msblk->stream) {  in squashfs_read_data()
367 			res = -EIO;  in squashfs_read_data()
370 		res = msblk->thread_ops->decompress(msblk, bio, offset, length, output);  in squashfs_read_data()
372 		res = copy_bio_to_actor(bio, output, offset, length);  in squashfs_read_data()
381 		ERROR("Failed to read block 0x%llx: %d\n", index, res);  in squashfs_read_data()
382 		if (msblk->panic_on_errors)  in squashfs_read_data()