1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2013 4 * Phillip Lougher <phillip@squashfs.org.uk> 5 */ 6 7 #include <linux/fs.h> 8 #include <linux/vfs.h> 9 #include <linux/kernel.h> 10 #include <linux/slab.h> 11 #include <linux/string.h> 12 #include <linux/pagemap.h> 13 #include <linux/mutex.h> 14 15 #include "squashfs_fs.h" 16 #include "squashfs_fs_sb.h" 17 #include "squashfs_fs_i.h" 18 #include "squashfs.h" 19 #include "page_actor.h" 20 21 /* Read separately compressed datablock directly into page cache */ 22 int squashfs_readpage_block(struct page *target_page, u64 block, int bsize, 23 int expected) 24 25 { 26 struct folio *folio = page_folio(target_page); 27 struct inode *inode = target_page->mapping->host; 28 struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; 29 loff_t file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT; 30 int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1; 31 loff_t start_index = folio->index & ~mask; 32 loff_t end_index = start_index | mask; 33 int i, n, pages, bytes, res = -ENOMEM; 34 struct page **page, *last_page; 35 struct squashfs_page_actor *actor; 36 void *pageaddr; 37 38 if (end_index > file_end) 39 end_index = file_end; 40 41 pages = end_index - start_index + 1; 42 43 page = kmalloc_array(pages, sizeof(void *), GFP_KERNEL); 44 if (page == NULL) 45 return res; 46 47 /* Try to grab all the pages covered by the Squashfs block */ 48 for (i = 0, n = start_index; n <= end_index; n++) { 49 page[i] = (n == folio->index) ? target_page : 50 grab_cache_page_nowait(target_page->mapping, n); 51 52 if (page[i] == NULL) 53 continue; 54 55 if (PageUptodate(page[i])) { 56 unlock_page(page[i]); 57 put_page(page[i]); 58 continue; 59 } 60 61 i++; 62 } 63 64 pages = i; 65 66 /* 67 * Create a "page actor" which will kmap and kunmap the 68 * page cache pages appropriately within the decompressor 69 */ 70 actor = squashfs_page_actor_init_special(msblk, page, pages, expected, 71 start_index << PAGE_SHIFT); 72 if (actor == NULL) 73 goto out; 74 75 /* Decompress directly into the page cache buffers */ 76 res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor); 77 78 last_page = squashfs_page_actor_free(actor); 79 80 if (res < 0) 81 goto mark_errored; 82 83 if (res != expected || IS_ERR(last_page)) { 84 res = -EIO; 85 goto mark_errored; 86 } 87 88 /* Last page (if present) may have trailing bytes not filled */ 89 bytes = res % PAGE_SIZE; 90 if (end_index == file_end && last_page && bytes) { 91 pageaddr = kmap_local_page(last_page); 92 memset(pageaddr + bytes, 0, PAGE_SIZE - bytes); 93 kunmap_local(pageaddr); 94 } 95 96 /* Mark pages as uptodate, unlock and release */ 97 for (i = 0; i < pages; i++) { 98 flush_dcache_page(page[i]); 99 SetPageUptodate(page[i]); 100 unlock_page(page[i]); 101 if (page[i] != target_page) 102 put_page(page[i]); 103 } 104 105 kfree(page); 106 107 return 0; 108 109 mark_errored: 110 /* Decompression failed. Target_page is 111 * dealt with by the caller 112 */ 113 for (i = 0; i < pages; i++) { 114 if (page[i] == NULL || page[i] == target_page) 115 continue; 116 flush_dcache_page(page[i]); 117 unlock_page(page[i]); 118 put_page(page[i]); 119 } 120 121 out: 122 kfree(page); 123 return res; 124 } 125