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authorPhillip Lougher <phillip@squashfs.org.uk>2013-11-18 06:59:12 +0400
committerPhillip Lougher <phillip@squashfs.org.uk>2013-11-20 07:59:01 +0400
commit846b730e99518a1c9945afcb2afbe4d08a02ed80 (patch)
treec70eb16cbec15e5bfa1db80c5f18e062673331a9 /fs/squashfs/page_actor.h
parentd208383d640727b70cd6689bc17e67e9b5ebf4ff (diff)
downloadlinux-846b730e99518a1c9945afcb2afbe4d08a02ed80.tar.xz
Squashfs: Generalise paging handling in the decompressors
Further generalise the decompressors by adding a page handler abstraction. This adds helpers to allow the decompressors to access and process the output buffers in an implementation independant manner. This allows different types of output buffer to be passed to the decompressors, with the implementation specific aspects handled at decompression time, but without the knowledge being held in the decompressor wrapper code. This will allow the decompressors to handle Squashfs cache buffers, and page cache pages. This patch adds the abstraction and an implementation for the caches. Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
Diffstat (limited to 'fs/squashfs/page_actor.h')
-rw-r--r--fs/squashfs/page_actor.h49
1 files changed, 49 insertions, 0 deletions
diff --git a/fs/squashfs/page_actor.h b/fs/squashfs/page_actor.h
new file mode 100644
index 000000000000..5b0ba5a7133a
--- /dev/null
+++ b/fs/squashfs/page_actor.h
@@ -0,0 +1,49 @@
+#ifndef PAGE_ACTOR_H
+#define PAGE_ACTOR_H
+/*
+ * 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.
+ */
+
+struct squashfs_page_actor {
+ void **page;
+ int pages;
+ int length;
+ int next_page;
+};
+
+static inline struct squashfs_page_actor *squashfs_page_actor_init(void **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;
+ return actor;
+}
+
+static inline void *squashfs_first_page(struct squashfs_page_actor *actor)
+{
+ actor->next_page = 1;
+ return actor->page[0];
+}
+
+static inline void *squashfs_next_page(struct squashfs_page_actor *actor)
+{
+ return actor->next_page == actor->pages ? NULL :
+ actor->page[actor->next_page++];
+}
+
+static inline void squashfs_finish_page(struct squashfs_page_actor *actor)
+{
+ /* empty */
+}
+#endif