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 loff_t index; 34 int i, pages, bytes, res = -ENOMEM; 35 struct page **page, *last_page; 36 struct squashfs_page_actor *actor; 37 void *pageaddr; 38 39 if (end_index > file_end) 40 end_index = file_end; 41 42 pages = end_index - start_index + 1; 43 44 page = kmalloc_array(pages, sizeof(void *), GFP_KERNEL); 45 if (page == NULL) 46 return res; 47 48 /* Try to grab all the pages covered by the Squashfs block */ 49 for (i = 0, index = start_index; index <= end_index; index++) { 50 page[i] = (index == folio->index) ? target_page : 51 grab_cache_page_nowait(target_page->mapping, index); 52 53 if (page[i] == NULL) 54 continue; 55 56 if (PageUptodate(page[i])) { 57 unlock_page(page[i]); 58 put_page(page[i]); 59 continue; 60 } 61 62 i++; 63 } 64 65 pages = i; 66 67 /* 68 * Create a "page actor" which will kmap and kunmap the 69 * page cache pages appropriately within the decompressor 70 */ 71 actor = squashfs_page_actor_init_special(msblk, page, pages, expected, 72 start_index << PAGE_SHIFT); 73 if (actor == NULL) 74 goto out; 75 76 /* Decompress directly into the page cache buffers */ 77 res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor); 78 79 last_page = squashfs_page_actor_free(actor); 80 81 if (res < 0) 82 goto mark_errored; 83 84 if (res != expected || IS_ERR(last_page)) { 85 res = -EIO; 86 goto mark_errored; 87 } 88 89 /* Last page (if present) may have trailing bytes not filled */ 90 bytes = res % PAGE_SIZE; 91 if (end_index == file_end && last_page && bytes) { 92 pageaddr = kmap_local_page(last_page); 93 memset(pageaddr + bytes, 0, PAGE_SIZE - bytes); 94 kunmap_local(pageaddr); 95 } 96 97 /* Mark pages as uptodate, unlock and release */ 98 for (i = 0; i < pages; i++) { 99 flush_dcache_page(page[i]); 100 SetPageUptodate(page[i]); 101 unlock_page(page[i]); 102 if (page[i] != target_page) 103 put_page(page[i]); 104 } 105 106 kfree(page); 107 108 return 0; 109 110 mark_errored: 111 /* Decompression failed. Target_page is 112 * dealt with by the caller 113 */ 114 for (i = 0; i < pages; i++) { 115 if (page[i] == NULL || page[i] == target_page) 116 continue; 117 flush_dcache_page(page[i]); 118 unlock_page(page[i]); 119 put_page(page[i]); 120 } 121 122 out: 123 kfree(page); 124 return res; 125 } 126