168252eb5SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later 2e2780ab1SPhillip Lougher /* 3e2780ab1SPhillip Lougher * Squashfs - a compressed read only filesystem for Linux 4e2780ab1SPhillip Lougher * 5e2780ab1SPhillip Lougher * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 6d7f2ff67SPhillip Lougher * Phillip Lougher <phillip@squashfs.org.uk> 7e2780ab1SPhillip Lougher * 8e2780ab1SPhillip Lougher * block.c 9e2780ab1SPhillip Lougher */ 10e2780ab1SPhillip Lougher 11e2780ab1SPhillip Lougher /* 12e2780ab1SPhillip Lougher * This file implements the low-level routines to read and decompress 13e2780ab1SPhillip Lougher * datablocks and metadata blocks. 14e2780ab1SPhillip Lougher */ 15e2780ab1SPhillip Lougher 1693e72b3cSPhilippe Liard #include <linux/blkdev.h> 17e2780ab1SPhillip Lougher #include <linux/fs.h> 18e2780ab1SPhillip Lougher #include <linux/vfs.h> 19e2780ab1SPhillip Lougher #include <linux/slab.h> 20e2780ab1SPhillip Lougher #include <linux/string.h> 21e2780ab1SPhillip Lougher #include <linux/buffer_head.h> 222f8b5444SChristoph Hellwig #include <linux/bio.h> 23e2780ab1SPhillip Lougher 24e2780ab1SPhillip Lougher #include "squashfs_fs.h" 25e2780ab1SPhillip Lougher #include "squashfs_fs_sb.h" 26e2780ab1SPhillip Lougher #include "squashfs.h" 274c0f0bb2SPhillip Lougher #include "decompressor.h" 28846b730eSPhillip Lougher #include "page_actor.h" 29e2780ab1SPhillip Lougher 30e2780ab1SPhillip Lougher /* 3193e72b3cSPhilippe Liard * Returns the amount of bytes copied to the page actor. 32e2780ab1SPhillip Lougher */ 3393e72b3cSPhilippe Liard static int copy_bio_to_actor(struct bio *bio, 3493e72b3cSPhilippe Liard struct squashfs_page_actor *actor, 3593e72b3cSPhilippe Liard int offset, int req_length) 3693e72b3cSPhilippe Liard { 3793e72b3cSPhilippe Liard void *actor_addr = squashfs_first_page(actor); 3893e72b3cSPhilippe Liard struct bvec_iter_all iter_all = {}; 3993e72b3cSPhilippe Liard struct bio_vec *bvec = bvec_init_iter_all(&iter_all); 4093e72b3cSPhilippe Liard int copied_bytes = 0; 4193e72b3cSPhilippe Liard int actor_offset = 0; 4293e72b3cSPhilippe Liard 4393e72b3cSPhilippe Liard if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) 4493e72b3cSPhilippe Liard return 0; 4593e72b3cSPhilippe Liard 4693e72b3cSPhilippe Liard while (copied_bytes < req_length) { 4793e72b3cSPhilippe Liard int bytes_to_copy = min_t(int, bvec->bv_len - offset, 4893e72b3cSPhilippe Liard PAGE_SIZE - actor_offset); 4993e72b3cSPhilippe Liard 5093e72b3cSPhilippe Liard bytes_to_copy = min_t(int, bytes_to_copy, 5193e72b3cSPhilippe Liard req_length - copied_bytes); 5293e72b3cSPhilippe Liard memcpy(actor_addr + actor_offset, 5393e72b3cSPhilippe Liard page_address(bvec->bv_page) + bvec->bv_offset + offset, 5493e72b3cSPhilippe Liard bytes_to_copy); 5593e72b3cSPhilippe Liard 5693e72b3cSPhilippe Liard actor_offset += bytes_to_copy; 5793e72b3cSPhilippe Liard copied_bytes += bytes_to_copy; 5893e72b3cSPhilippe Liard offset += bytes_to_copy; 5993e72b3cSPhilippe Liard 6093e72b3cSPhilippe Liard if (actor_offset >= PAGE_SIZE) { 6193e72b3cSPhilippe Liard actor_addr = squashfs_next_page(actor); 6293e72b3cSPhilippe Liard if (!actor_addr) 6393e72b3cSPhilippe Liard break; 6493e72b3cSPhilippe Liard actor_offset = 0; 6593e72b3cSPhilippe Liard } 6693e72b3cSPhilippe Liard if (offset >= bvec->bv_len) { 6793e72b3cSPhilippe Liard if (!bio_next_segment(bio, &iter_all)) 6893e72b3cSPhilippe Liard break; 6993e72b3cSPhilippe Liard offset = 0; 7093e72b3cSPhilippe Liard } 7193e72b3cSPhilippe Liard } 7293e72b3cSPhilippe Liard squashfs_finish_page(actor); 7393e72b3cSPhilippe Liard return copied_bytes; 7493e72b3cSPhilippe Liard } 7593e72b3cSPhilippe Liard 7693e72b3cSPhilippe Liard static int squashfs_bio_read(struct super_block *sb, u64 index, int length, 7793e72b3cSPhilippe Liard struct bio **biop, int *block_offset) 78e2780ab1SPhillip Lougher { 79e2780ab1SPhillip Lougher struct squashfs_sb_info *msblk = sb->s_fs_info; 8093e72b3cSPhilippe Liard const u64 read_start = round_down(index, msblk->devblksize); 8193e72b3cSPhilippe Liard const sector_t block = read_start >> msblk->devblksize_log2; 8293e72b3cSPhilippe Liard const u64 read_end = round_up(index + length, msblk->devblksize); 8393e72b3cSPhilippe Liard const sector_t block_end = read_end >> msblk->devblksize_log2; 8493e72b3cSPhilippe Liard int offset = read_start - round_down(index, PAGE_SIZE); 8593e72b3cSPhilippe Liard int total_len = (block_end - block) << msblk->devblksize_log2; 8693e72b3cSPhilippe Liard const int page_count = DIV_ROUND_UP(total_len + offset, PAGE_SIZE); 8793e72b3cSPhilippe Liard int error, i; 8893e72b3cSPhilippe Liard struct bio *bio; 89e2780ab1SPhillip Lougher 9093e72b3cSPhilippe Liard bio = bio_alloc(GFP_NOIO, page_count); 9193e72b3cSPhilippe Liard if (!bio) 9293e72b3cSPhilippe Liard return -ENOMEM; 93e2780ab1SPhillip Lougher 9493e72b3cSPhilippe Liard bio_set_dev(bio, sb->s_bdev); 9593e72b3cSPhilippe Liard bio->bi_opf = READ; 9693e72b3cSPhilippe Liard bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT); 973689456bSPhillip Lougher 9893e72b3cSPhilippe Liard for (i = 0; i < page_count; ++i) { 9993e72b3cSPhilippe Liard unsigned int len = 10093e72b3cSPhilippe Liard min_t(unsigned int, PAGE_SIZE - offset, total_len); 10193e72b3cSPhilippe Liard struct page *page = alloc_page(GFP_NOIO); 10293e72b3cSPhilippe Liard 10393e72b3cSPhilippe Liard if (!page) { 10493e72b3cSPhilippe Liard error = -ENOMEM; 10593e72b3cSPhilippe Liard goto out_free_bio; 1063689456bSPhillip Lougher } 10793e72b3cSPhilippe Liard if (!bio_add_page(bio, page, len, offset)) { 10893e72b3cSPhilippe Liard error = -EIO; 10993e72b3cSPhilippe Liard goto out_free_bio; 11093e72b3cSPhilippe Liard } 11193e72b3cSPhilippe Liard offset = 0; 11293e72b3cSPhilippe Liard total_len -= len; 113e2780ab1SPhillip Lougher } 114e2780ab1SPhillip Lougher 11593e72b3cSPhilippe Liard error = submit_bio_wait(bio); 11693e72b3cSPhilippe Liard if (error) 11793e72b3cSPhilippe Liard goto out_free_bio; 118e2780ab1SPhillip Lougher 11993e72b3cSPhilippe Liard *biop = bio; 12093e72b3cSPhilippe Liard *block_offset = index & ((1 << msblk->devblksize_log2) - 1); 12193e72b3cSPhilippe Liard return 0; 12293e72b3cSPhilippe Liard 12393e72b3cSPhilippe Liard out_free_bio: 12493e72b3cSPhilippe Liard bio_free_pages(bio); 12593e72b3cSPhilippe Liard bio_put(bio); 12693e72b3cSPhilippe Liard return error; 12793e72b3cSPhilippe Liard } 128e2780ab1SPhillip Lougher 129e2780ab1SPhillip Lougher /* 130e2780ab1SPhillip Lougher * Read and decompress a metadata block or datablock. Length is non-zero 131e2780ab1SPhillip Lougher * if a datablock is being read (the size is stored elsewhere in the 132e2780ab1SPhillip Lougher * filesystem), otherwise the length is obtained from the first two bytes of 133e2780ab1SPhillip Lougher * the metadata block. A bit in the length field indicates if the block 134e2780ab1SPhillip Lougher * is stored uncompressed in the filesystem (usually because compression 135ec9267b6SPhillip Lougher * generated a larger block - this does occasionally happen with compression 136ec9267b6SPhillip Lougher * algorithms). 137e2780ab1SPhillip Lougher */ 138846b730eSPhillip Lougher int squashfs_read_data(struct super_block *sb, u64 index, int length, 139846b730eSPhillip Lougher u64 *next_index, struct squashfs_page_actor *output) 140e2780ab1SPhillip Lougher { 141e2780ab1SPhillip Lougher struct squashfs_sb_info *msblk = sb->s_fs_info; 14293e72b3cSPhilippe Liard struct bio *bio = NULL; 14393e72b3cSPhilippe Liard int compressed; 14493e72b3cSPhilippe Liard int res; 14593e72b3cSPhilippe Liard int offset; 146e2780ab1SPhillip Lougher 147e2780ab1SPhillip Lougher if (length) { 148e2780ab1SPhillip Lougher /* 149e2780ab1SPhillip Lougher * Datablock. 150e2780ab1SPhillip Lougher */ 151e2780ab1SPhillip Lougher compressed = SQUASHFS_COMPRESSED_BLOCK(length); 152e2780ab1SPhillip Lougher length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length); 153e2780ab1SPhillip Lougher TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n", 154846b730eSPhillip Lougher index, compressed ? "" : "un", length, output->length); 155e2780ab1SPhillip Lougher } else { 156e2780ab1SPhillip Lougher /* 157e2780ab1SPhillip Lougher * Metadata block. 158e2780ab1SPhillip Lougher */ 15993e72b3cSPhilippe Liard const u8 *data; 16093e72b3cSPhilippe Liard struct bvec_iter_all iter_all = {}; 16193e72b3cSPhilippe Liard struct bio_vec *bvec = bvec_init_iter_all(&iter_all); 162e2780ab1SPhillip Lougher 16393e72b3cSPhilippe Liard if (index + 2 > msblk->bytes_used) { 16493e72b3cSPhilippe Liard res = -EIO; 16593e72b3cSPhilippe Liard goto out; 16693e72b3cSPhilippe Liard } 16793e72b3cSPhilippe Liard res = squashfs_bio_read(sb, index, 2, &bio, &offset); 16893e72b3cSPhilippe Liard if (res) 16993e72b3cSPhilippe Liard goto out; 170e2780ab1SPhillip Lougher 17193e72b3cSPhilippe Liard if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { 17293e72b3cSPhilippe Liard res = -EIO; 17393e72b3cSPhilippe Liard goto out_free_bio; 17493e72b3cSPhilippe Liard } 17593e72b3cSPhilippe Liard /* Extract the length of the metadata block */ 17693e72b3cSPhilippe Liard data = page_address(bvec->bv_page) + bvec->bv_offset; 17793e72b3cSPhilippe Liard length = data[offset]; 1782910c59fSPhillip Lougher if (offset < bvec->bv_len - 1) { 17993e72b3cSPhilippe Liard length |= data[offset + 1] << 8; 18093e72b3cSPhilippe Liard } else { 18193e72b3cSPhilippe Liard if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { 18293e72b3cSPhilippe Liard res = -EIO; 18393e72b3cSPhilippe Liard goto out_free_bio; 18493e72b3cSPhilippe Liard } 18593e72b3cSPhilippe Liard data = page_address(bvec->bv_page) + bvec->bv_offset; 18693e72b3cSPhilippe Liard length |= data[0] << 8; 18793e72b3cSPhilippe Liard } 18893e72b3cSPhilippe Liard bio_free_pages(bio); 18993e72b3cSPhilippe Liard bio_put(bio); 19093e72b3cSPhilippe Liard 191e2780ab1SPhillip Lougher compressed = SQUASHFS_COMPRESSED(length); 192e2780ab1SPhillip Lougher length = SQUASHFS_COMPRESSED_SIZE(length); 19393e72b3cSPhilippe Liard index += 2; 194e2780ab1SPhillip Lougher 195e2780ab1SPhillip Lougher TRACE("Block @ 0x%llx, %scompressed size %d\n", index, 196e2780ab1SPhillip Lougher compressed ? "" : "un", length); 197e2780ab1SPhillip Lougher } 19893e72b3cSPhilippe Liard if (next_index) 19993e72b3cSPhilippe Liard *next_index = index + length; 200e2780ab1SPhillip Lougher 20193e72b3cSPhilippe Liard res = squashfs_bio_read(sb, index, length, &bio, &offset); 20293e72b3cSPhilippe Liard if (res) 20393e72b3cSPhilippe Liard goto out; 2049508c6b9SPhillip Lougher 205e2780ab1SPhillip Lougher if (compressed) { 20693e72b3cSPhilippe Liard if (!msblk->stream) { 20793e72b3cSPhilippe Liard res = -EIO; 20893e72b3cSPhilippe Liard goto out_free_bio; 20993e72b3cSPhilippe Liard } 21093e72b3cSPhilippe Liard res = squashfs_decompress(msblk, bio, offset, length, output); 211e2780ab1SPhillip Lougher } else { 21293e72b3cSPhilippe Liard res = copy_bio_to_actor(bio, output, offset, length); 213e2780ab1SPhillip Lougher } 214e2780ab1SPhillip Lougher 21593e72b3cSPhilippe Liard out_free_bio: 21693e72b3cSPhilippe Liard bio_free_pages(bio); 21793e72b3cSPhilippe Liard bio_put(bio); 21893e72b3cSPhilippe Liard out: 21993e72b3cSPhilippe Liard if (res < 0) 22093e72b3cSPhilippe Liard ERROR("Failed to read block 0x%llx: %d\n", index, res); 221e2780ab1SPhillip Lougher 22293e72b3cSPhilippe Liard return res; 223e2780ab1SPhillip Lougher } 224