1 files changed, 113 insertions, 130 deletions

diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c
index 43e7a7eddac0..23458bca945d 100644
--- a/fs/squashfs/file_direct.c
+++ b/fs/squashfs/file_direct.c
@@ -13,6 +13,7 @@
 #include <linux/string.h>
 #include <linux/pagemap.h>
 #include <linux/mutex.h>
+#include <linux/mm_inline.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
@@ -20,157 +21,139 @@
 #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)
+// Backported from 4.5
+#define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
 
+static void release_actor_pages(struct page **page, int pages, int error)
 {
-	struct inode *inode = target_page->mapping->host;
-	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	int i;
 
-	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;
+	for (i = 0; i < pages; i++) {
+		if (!page[i])
+			continue;
+		flush_dcache_page(page[i]);
+		if (!error)
+			SetPageUptodate(page[i]);
+		else {
+			SetPageError(page[i]);
+			zero_user_segment(page[i], 0, PAGE_CACHE_SIZE);
+		}
+		unlock_page(page[i]);
+		put_page(page[i]);
+	}
+	kfree(page);
+}
+
+/*
+ * Create a "page actor" which will kmap and kunmap the
+ * page cache pages appropriately within the decompressor
+ */
+static struct squashfs_page_actor *actor_from_page_cache(
+	unsigned int actor_pages, struct page *target_page,
+	struct list_head *rpages, unsigned int *nr_pages, int start_index,
+	struct address_space *mapping)
+{
 	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_array(pages, sizeof(void *), 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);
+	int i, n;
+	gfp_t gfp = GFP_KERNEL;
+
+	page = kmalloc_array(actor_pages, sizeof(void *), GFP_KERNEL);
+	if (!page)
+		return NULL;
+
+	for (i = 0, n = start_index; i < actor_pages; i++, n++) {
+		if (target_page == NULL && rpages && !list_empty(rpages)) {
+			struct page *cur_page = lru_to_page(rpages);
+
+			if (cur_page->index < start_index + actor_pages) {
+				list_del(&cur_page->lru);
+				--(*nr_pages);
+				if (add_to_page_cache_lru(cur_page, mapping,
+							  cur_page->index, gfp))
+					put_page(cur_page);
+				else
+					target_page = cur_page;
+			} else
+				rpages = NULL;
+		}
 
-		if (page[i] == NULL) {
-			missing_pages++;
-			continue;
+		if (target_page && target_page->index == n) {
+			page[i] = target_page;
+			target_page = NULL;
+		} else {
+			page[i] = grab_cache_page_nowait(mapping, n);
+			if (page[i] == NULL)
+				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);
-		if (res < 0)
-			goto mark_errored;
-
-		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]);
+	actor = squashfs_page_actor_init(page, actor_pages, 0,
+			release_actor_pages);
+	if (!actor) {
+		release_actor_pages(page, actor_pages, -ENOMEM);
+		kfree(page);
+		return NULL;
 	}
-
-	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] == NULL || 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;
+	return actor;
 }
 
+int squashfs_readpages_block(struct page *target_page,
+			     struct list_head *readahead_pages,
+			     unsigned int *nr_pages,
+			     struct address_space *mapping,
+			     int page_index, u64 block, int bsize)
 
-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;
+	struct squashfs_page_actor *actor;
+	struct inode *inode = mapping->host;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	int start_index, end_index, file_end, actor_pages, res;
+	int mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
 
-		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]);
+	/*
+	 * If readpage() is called on an uncompressed datablock, we can just
+	 * read the pages instead of fetching the whole block.
+	 * This greatly improves the performance when a process keep doing
+	 * random reads because we only fetch the necessary data.
+	 * The readahead algorithm will take care of doing speculative reads
+	 * if necessary.
+	 * We can't read more than 1 block even if readahead provides use more
+	 * pages because we don't know yet if the next block is compressed or
+	 * not.
+	 */
+	if (bsize && !SQUASHFS_COMPRESSED_BLOCK(bsize)) {
+		u64 block_end = block + msblk->block_size;
+
+		block += (page_index & mask) * PAGE_SIZE;
+		actor_pages = (block_end - block) / PAGE_SIZE;
+		if (*nr_pages < actor_pages)
+			actor_pages = *nr_pages;
+		start_index = page_index;
+		bsize = min_t(int, bsize, (PAGE_SIZE * actor_pages)
+					  | SQUASHFS_COMPRESSED_BIT_BLOCK);
+	} else {
+		file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT;
+		start_index = page_index & ~mask;
+		end_index = start_index | mask;
+		if (end_index > file_end)
+			end_index = file_end;
+		actor_pages = end_index - start_index + 1;
 	}
 
-out:
-	squashfs_cache_put(buffer);
-	return res;
+	actor = actor_from_page_cache(actor_pages, target_page,
+				      readahead_pages, nr_pages, start_index,
+				      mapping);
+	if (!actor)
+		return -ENOMEM;
+
+	res = squashfs_read_data_async(inode->i_sb, block, bsize, NULL,
+				       actor);
+	return res < 0 ? res : 0;
 }