--- /dev/null
+/*
+ * Copyright (c) 2013
+ * Phillip Lougher <phillip@squashfs.org.uk>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/pagemap.h>
+#include <linux/mutex.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+#include "page_actor.h"
+
+static int squashfs_read_cache(struct page *target_page, u64 block, int bsize,
+ int pages, struct page **page);
+
+/* Read separately compressed datablock directly into page cache */
+int squashfs_readpage_block(struct page *target_page, u64 block, int bsize)
+
+{
+ struct inode *inode = target_page->mapping->host;
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+
+ int file_end = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
+ int mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
+ int start_index = target_page->index & ~mask;
+ int end_index = start_index | mask;
+ int i, n, pages, missing_pages, bytes, res = -ENOMEM;
+ struct page **page;
+ struct squashfs_page_actor *actor;
+ void *pageaddr;
+
+ if (end_index > file_end)
+ end_index = file_end;
+
+ pages = end_index - start_index + 1;
+
+ page = kmalloc(sizeof(void *) * pages, GFP_KERNEL);
+ if (page == NULL)
+ return res;
+
+ /*
+ * Create a "page actor" which will kmap and kunmap the
+ * page cache pages appropriately within the decompressor
+ */
+ actor = squashfs_page_actor_init_special(page, pages, 0);
+ if (actor == NULL)
+ goto out;
+
+ /* Try to grab all the pages covered by the Squashfs block */
+ for (missing_pages = 0, i = 0, n = start_index; i < pages; i++, n++) {
+ page[i] = (n == target_page->index) ? target_page :
+ grab_cache_page_nowait(target_page->mapping, n);
+
+ if (page[i] == NULL) {
+ missing_pages++;
+ continue;
+ }
+
+ if (PageUptodate(page[i])) {
+ unlock_page(page[i]);
+ page_cache_release(page[i]);
+ page[i] = NULL;
+ missing_pages++;
+ }
+ }
+
+ if (missing_pages) {
+ /*
+ * Couldn't get one or more pages, this page has either
+ * been VM reclaimed, but others are still in the page cache
+ * and uptodate, or we're racing with another thread in
+ * squashfs_readpage also trying to grab them. Fall back to
+ * using an intermediate buffer.
+ */
+ res = squashfs_read_cache(target_page, block, bsize, pages,
+ page);
+ goto out;
+ }
+
+ /* Decompress directly into the page cache buffers */
+ res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
+ if (res < 0)
+ goto mark_errored;
+
+ /* Last page may have trailing bytes not filled */
+ bytes = res % PAGE_CACHE_SIZE;
+ if (bytes) {
+ pageaddr = kmap_atomic(page[pages - 1]);
+ memset(pageaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
+ kunmap_atomic(pageaddr);
+ }
+
+ /* Mark pages as uptodate, unlock and release */
+ for (i = 0; i < pages; i++) {
+ flush_dcache_page(page[i]);
+ SetPageUptodate(page[i]);
+ unlock_page(page[i]);
+ if (page[i] != target_page)
+ page_cache_release(page[i]);
+ }
+
+ kfree(actor);
+ kfree(page);
+
+ return 0;
+
+mark_errored:
+ /* Decompression failed, mark pages as errored. Target_page is
+ * dealt with by the caller
+ */
+ for (i = 0; i < pages; i++) {
+ if (page[i] == target_page)
+ continue;
+ flush_dcache_page(page[i]);
+ SetPageError(page[i]);
+ unlock_page(page[i]);
+ page_cache_release(page[i]);
+ }
+
+out:
+ kfree(actor);
+ kfree(page);
+ return res;
+}
+
+
+static int squashfs_read_cache(struct page *target_page, u64 block, int bsize,
+ int pages, struct page **page)
+{
+ struct inode *i = target_page->mapping->host;
+ struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb,
+ block, bsize);
+ int bytes = buffer->length, res = buffer->error, n, offset = 0;
+ void *pageaddr;
+
+ if (res) {
+ ERROR("Unable to read page, block %llx, size %x\n", block,
+ bsize);
+ goto out;
+ }
+
+ for (n = 0; n < pages && bytes > 0; n++,
+ bytes -= PAGE_CACHE_SIZE, offset += PAGE_CACHE_SIZE) {
+ int avail = min_t(int, bytes, PAGE_CACHE_SIZE);
+
+ if (page[n] == NULL)
+ continue;
+
+ pageaddr = kmap_atomic(page[n]);
+ squashfs_copy_data(pageaddr, buffer, offset, avail);
+ memset(pageaddr + avail, 0, PAGE_CACHE_SIZE - avail);
+ kunmap_atomic(pageaddr);
+ flush_dcache_page(page[n]);
+ SetPageUptodate(page[n]);
+ unlock_page(page[n]);
+ if (page[n] != target_page)
+ page_cache_release(page[n]);
+ }
+
+out:
+ squashfs_cache_put(buffer);
+ return res;
+}
--- /dev/null
+/*
+ * Copyright (c) 2013
+ * Phillip Lougher <phillip@squashfs.org.uk>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include "page_actor.h"
+
+/*
+ * This file contains implementations of page_actor for decompressing into
+ * an intermediate buffer, and for decompressing directly into the
+ * page cache.
+ *
+ * Calling code should avoid sleeping between calls to squashfs_first_page()
+ * and squashfs_finish_page().
+ */
+
+/* Implementation of page_actor for decompressing into intermediate buffer */
+static void *cache_first_page(struct squashfs_page_actor *actor)
+{
+ actor->next_page = 1;
+ return actor->buffer[0];
+}
+
+static void *cache_next_page(struct squashfs_page_actor *actor)
+{
+ if (actor->next_page == actor->pages)
+ return NULL;
+
+ return actor->buffer[actor->next_page++];
+}
+
+static void cache_finish_page(struct squashfs_page_actor *actor)
+{
+ /* empty */
+}
+
+struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
+ int pages, int length)
+{
+ struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
+
+ if (actor == NULL)
+ return NULL;
+
+ actor->length = length ? : pages * PAGE_CACHE_SIZE;
+ actor->buffer = buffer;
+ actor->pages = pages;
+ actor->next_page = 0;
+ actor->squashfs_first_page = cache_first_page;
+ actor->squashfs_next_page = cache_next_page;
+ actor->squashfs_finish_page = cache_finish_page;
+ return actor;
+}
+
+/* Implementation of page_actor for decompressing directly into page cache. */
+static void *direct_first_page(struct squashfs_page_actor *actor)
+{
+ actor->next_page = 1;
+ return actor->pageaddr = kmap_atomic(actor->page[0]);
+}
+
+static void *direct_next_page(struct squashfs_page_actor *actor)
+{
+ if (actor->pageaddr)
+ kunmap_atomic(actor->pageaddr);
+
+ return actor->pageaddr = actor->next_page == actor->pages ? NULL :
+ kmap_atomic(actor->page[actor->next_page++]);
+}
+
+static void direct_finish_page(struct squashfs_page_actor *actor)
+{
+ if (actor->pageaddr)
+ kunmap_atomic(actor->pageaddr);
+}
+
+struct squashfs_page_actor *squashfs_page_actor_init_special(struct page **page,
+ int pages, int length)
+{
+ struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
+
+ if (actor == NULL)
+ return NULL;
+
+ actor->length = length ? : pages * PAGE_CACHE_SIZE;
+ actor->page = page;
+ actor->pages = pages;
+ actor->next_page = 0;
+ actor->pageaddr = NULL;
+ actor->squashfs_first_page = direct_first_page;
+ actor->squashfs_next_page = direct_next_page;
+ actor->squashfs_finish_page = direct_finish_page;
+ return actor;
+}
projects / GitHub / LineageOS / G12 / android_kernel_amlogic_linux-4.9.git / commitdiff