4 files changed, 457 insertions, 273 deletions

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 0cea9b9236d0..8a75d812ffdf 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -28,9 +28,12 @@
 
 #include <linux/fs.h>
 #include <linux/vfs.h>
+#include <linux/bio.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/pagemap.h>
 #include <linux/buffer_head.h>
+#include <linux/workqueue.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
@@ -38,45 +41,355 @@
 #include "decompressor.h"
 #include "page_actor.h"
 
-/*
- * Read the metadata block length, this is stored in the first two
- * bytes of the metadata block.
- */
-static struct buffer_head *get_block_length(struct super_block *sb,
-			u64 *cur_index, int *offset, int *length)
+static struct workqueue_struct *squashfs_read_wq;
+
+struct squashfs_read_request {
+	struct super_block *sb;
+	u64 index;
+	int length;
+	int compressed;
+	int offset;
+	u64 read_end;
+	struct squashfs_page_actor *output;
+	enum {
+		SQUASHFS_COPY,
+		SQUASHFS_DECOMPRESS,
+		SQUASHFS_METADATA,
+	} data_processing;
+	bool synchronous;
+
+	/*
+	 * If the read is synchronous, it is possible to retrieve information
+	 * about the request by setting these pointers.
+	 */
+	int *res;
+	int *bytes_read;
+	int *bytes_uncompressed;
+
+	int nr_buffers;
+	struct buffer_head **bh;
+	struct work_struct offload;
+};
+
+struct squashfs_bio_request {
+	struct buffer_head **bh;
+	int nr_buffers;
+};
+
+static int squashfs_bio_submit(struct squashfs_read_request *req);
+
+int squashfs_init_read_wq(void)
+{
+	squashfs_read_wq = create_workqueue("SquashFS read wq");
+	return !!squashfs_read_wq;
+}
+
+void squashfs_destroy_read_wq(void)
 {
-	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	flush_workqueue(squashfs_read_wq);
+	destroy_workqueue(squashfs_read_wq);
+}
+
+static void free_read_request(struct squashfs_read_request *req, int error)
+{
+	if (!req->synchronous)
+		squashfs_page_actor_free(req->output, error);
+	if (req->res)
+		*(req->res) = error;
+	kfree(req->bh);
+	kfree(req);
+}
+
+static void squashfs_process_blocks(struct squashfs_read_request *req)
+{
+	int error = 0;
+	int bytes, i, length;
+	struct squashfs_sb_info *msblk = req->sb->s_fs_info;
+	struct squashfs_page_actor *actor = req->output;
+	struct buffer_head **bh = req->bh;
+	int nr_buffers = req->nr_buffers;
+
+	for (i = 0; i < nr_buffers; ++i) {
+		if (!bh[i])
+			continue;
+		wait_on_buffer(bh[i]);
+		if (!buffer_uptodate(bh[i]))
+			error = -EIO;
+	}
+	if (error)
+		goto cleanup;
+
+	if (req->data_processing == SQUASHFS_METADATA) {
+		/* Extract the length of the metadata block */
+		if (req->offset != msblk->devblksize - 1)
+			length = *((u16 *)(bh[0]->b_data + req->offset));
+		else {
+			length = bh[0]->b_data[req->offset];
+			length |= bh[1]->b_data[0] << 8;
+		}
+		req->compressed = SQUASHFS_COMPRESSED(length);
+		req->data_processing = req->compressed ? SQUASHFS_DECOMPRESS
+						       : SQUASHFS_COPY;
+		length = SQUASHFS_COMPRESSED_SIZE(length);
+		if (req->index + length + 2 > req->read_end) {
+			for (i = 0; i < nr_buffers; ++i)
+				put_bh(bh[i]);
+			kfree(bh);
+			req->length = length;
+			req->index += 2;
+			squashfs_bio_submit(req);
+			return;
+		}
+		req->length = length;
+		req->offset = (req->offset + 2) % PAGE_SIZE;
+		if (req->offset < 2) {
+			put_bh(bh[0]);
+			++bh;
+			--nr_buffers;
+		}
+	}
+	if (req->bytes_read)
+		*(req->bytes_read) = req->length;
+
+	if (req->data_processing == SQUASHFS_COPY) {
+		squashfs_bh_to_actor(bh, nr_buffers, req->output, req->offset,
+			req->length, msblk->devblksize);
+	} else if (req->data_processing == SQUASHFS_DECOMPRESS) {
+		req->length = squashfs_decompress(msblk, bh, nr_buffers,
+			req->offset, req->length, actor);
+		if (req->length < 0) {
+			error = -EIO;
+			goto cleanup;
+		}
+	}
+
+	/* Last page may have trailing bytes not filled */
+	bytes = req->length % PAGE_SIZE;
+	if (bytes && actor->page[actor->pages - 1])
+		zero_user_segment(actor->page[actor->pages - 1], bytes,
+				  PAGE_SIZE);
+
+cleanup:
+	if (req->bytes_uncompressed)
+		*(req->bytes_uncompressed) = req->length;
+	if (error) {
+		for (i = 0; i < nr_buffers; ++i)
+			if (bh[i])
+				put_bh(bh[i]);
+	}
+	free_read_request(req, error);
+}
+
+static void read_wq_handler(struct work_struct *work)
+{
+	squashfs_process_blocks(container_of(work,
+		    struct squashfs_read_request, offload));
+}
+
+static void squashfs_bio_end_io(struct bio *bio)
+{
+	int i;
+	int error = bio->bi_error;
+	struct squashfs_bio_request *bio_req = bio->bi_private;
+
+	bio_put(bio);
+
+	for (i = 0; i < bio_req->nr_buffers; ++i) {
+		if (!bio_req->bh[i])
+			continue;
+		if (!error)
+			set_buffer_uptodate(bio_req->bh[i]);
+		else
+			clear_buffer_uptodate(bio_req->bh[i]);
+		unlock_buffer(bio_req->bh[i]);
+	}
+	kfree(bio_req);
+}
+
+static int actor_getblks(struct squashfs_read_request *req, u64 block)
+{
+	int i;
+
+	req->bh = kmalloc_array(req->nr_buffers, sizeof(*(req->bh)), GFP_NOIO);
+	if (!req->bh)
+		return -ENOMEM;
+
+	for (i = 0; i < req->nr_buffers; ++i) {
+		req->bh[i] = sb_getblk(req->sb, block + i);
+		if (!req->bh[i]) {
+			while (--i) {
+				if (req->bh[i])
+					put_bh(req->bh[i]);
+			}
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static int squashfs_bio_submit(struct squashfs_read_request *req)
+{
+	struct bio *bio = NULL;
 	struct buffer_head *bh;
+	struct squashfs_bio_request *bio_req = NULL;
+	int b = 0, prev_block = 0;
+	struct squashfs_sb_info *msblk = req->sb->s_fs_info;
+
+	u64 read_start = round_down(req->index, msblk->devblksize);
+	u64 read_end = round_up(req->index + req->length, msblk->devblksize);
+	sector_t block = read_start >> msblk->devblksize_log2;
+	sector_t block_end = read_end >> msblk->devblksize_log2;
+	int offset = read_start - round_down(req->index, PAGE_SIZE);
+	int nr_buffers = block_end - block;
+	int blksz = msblk->devblksize;
+	int bio_max_pages = nr_buffers > BIO_MAX_PAGES ? BIO_MAX_PAGES
+						       : nr_buffers;
+
+	/* Setup the request */
+	req->read_end = read_end;
+	req->offset = req->index - read_start;
+	req->nr_buffers = nr_buffers;
+	if (actor_getblks(req, block) < 0)
+		goto getblk_failed;
 
-	bh = sb_bread(sb, *cur_index);
-	if (bh == NULL)
-		return NULL;
-
-	if (msblk->devblksize - *offset == 1) {
-		*length = (unsigned char) bh->b_data[*offset];
-		put_bh(bh);
-		bh = sb_bread(sb, ++(*cur_index));
-		if (bh == NULL)
-			return NULL;
-		*length |= (unsigned char) bh->b_data[0] << 8;
-		*offset = 1;
-	} else {
-		*length = (unsigned char) bh->b_data[*offset] |
-			(unsigned char) bh->b_data[*offset + 1] << 8;
-		*offset += 2;
-
-		if (*offset == msblk->devblksize) {
-			put_bh(bh);
-			bh = sb_bread(sb, ++(*cur_index));
-			if (bh == NULL)
-				return NULL;
-			*offset = 0;
+	/* Create and submit the BIOs */
+	for (b = 0; b < nr_buffers; ++b, offset += blksz) {
+		bh = req->bh[b];
+		if (!bh || !trylock_buffer(bh))
+			continue;
+		if (buffer_uptodate(bh)) {
+			unlock_buffer(bh);
+			continue;
 		}
+		offset %= PAGE_SIZE;
+
+		/* Append the buffer to the current BIO if it is contiguous */
+		if (bio && bio_req && prev_block + 1 == b) {
+			if (bio_add_page(bio, bh->b_page, blksz, offset)) {
+				bio_req->nr_buffers += 1;
+				prev_block = b;
+				continue;
+			}
+		}
+
+		/* Otherwise, submit the current BIO and create a new one */
+		if (bio)
+			submit_bio(READ, bio);
+		bio_req = kcalloc(1, sizeof(struct squashfs_bio_request),
+				  GFP_NOIO);
+		if (!bio_req)
+			goto req_alloc_failed;
+		bio_req->bh = &req->bh[b];
+		bio = bio_alloc(GFP_NOIO, bio_max_pages);
+		if (!bio)
+			goto bio_alloc_failed;
+		bio->bi_bdev = req->sb->s_bdev;
+		bio->bi_iter.bi_sector = (block + b)
+				       << (msblk->devblksize_log2 - 9);
+		bio->bi_private = bio_req;
+		bio->bi_end_io = squashfs_bio_end_io;
+
+		bio_add_page(bio, bh->b_page, blksz, offset);
+		bio_req->nr_buffers += 1;
+		prev_block = b;
 	}
+	if (bio)
+		submit_bio(READ, bio);
 
-	return bh;
+	if (req->synchronous)
+		squashfs_process_blocks(req);
+	else {
+		INIT_WORK(&req->offload, read_wq_handler);
+		schedule_work(&req->offload);
+	}
+	return 0;
+
+bio_alloc_failed:
+	kfree(bio_req);
+req_alloc_failed:
+	unlock_buffer(bh);
+	while (--nr_buffers >= b)
+		if (req->bh[nr_buffers])
+			put_bh(req->bh[nr_buffers]);
+	while (--b >= 0)
+		if (req->bh[b])
+			wait_on_buffer(req->bh[b]);
+getblk_failed:
+	free_read_request(req, -ENOMEM);
+	return -ENOMEM;
+}
+
+static int read_metadata_block(struct squashfs_read_request *req,
+			       u64 *next_index)
+{
+	int ret, error, bytes_read = 0, bytes_uncompressed = 0;
+	struct squashfs_sb_info *msblk = req->sb->s_fs_info;
+
+	if (req->index + 2 > msblk->bytes_used) {
+		free_read_request(req, -EINVAL);
+		return -EINVAL;
+	}
+	req->length = 2;
+
+	/* Do not read beyond the end of the device */
+	if (req->index + req->length > msblk->bytes_used)
+		req->length = msblk->bytes_used - req->index;
+	req->data_processing = SQUASHFS_METADATA;
+
+	/*
+	 * Reading metadata is always synchronous because we don't know the
+	 * length in advance and the function is expected to update
+	 * 'next_index' and return the length.
+	 */
+	req->synchronous = true;
+	req->res = &error;
+	req->bytes_read = &bytes_read;
+	req->bytes_uncompressed = &bytes_uncompressed;
+
+	TRACE("Metadata block @ 0x%llx, %scompressed size %d, src size %d\n",
+	      req->index, req->compressed ? "" : "un", bytes_read,
+	      req->output->length);
+
+	ret = squashfs_bio_submit(req);
+	if (ret)
+		return ret;
+	if (error)
+		return error;
+	if (next_index)
+		*next_index += 2 + bytes_read;
+	return bytes_uncompressed;
 }
 
+static int read_data_block(struct squashfs_read_request *req, int length,
+			   u64 *next_index, bool synchronous)
+{
+	int ret, error = 0, bytes_uncompressed = 0, bytes_read = 0;
+
+	req->compressed = SQUASHFS_COMPRESSED_BLOCK(length);
+	req->length = length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length);
+	req->data_processing = req->compressed ? SQUASHFS_DECOMPRESS
+					       : SQUASHFS_COPY;
+
+	req->synchronous = synchronous;
+	if (synchronous) {
+		req->res = &error;
+		req->bytes_read = &bytes_read;
+		req->bytes_uncompressed = &bytes_uncompressed;
+	}
+
+	TRACE("Data block @ 0x%llx, %scompressed size %d, src size %d\n",
+	      req->index, req->compressed ? "" : "un", req->length,
+	      req->output->length);
+
+	ret = squashfs_bio_submit(req);
+	if (ret)
+		return ret;
+	if (synchronous)
+		ret = error ? error : bytes_uncompressed;
+	if (next_index)
+		*next_index += length;
+	return ret;
+}
 
 /*
  * Read and decompress a metadata block or datablock.  Length is non-zero
@@ -87,128 +400,50 @@ static struct buffer_head *get_block_length(struct super_block *sb,
  * generated a larger block - this does occasionally happen with compression
  * algorithms).
  */
-int squashfs_read_data(struct super_block *sb, u64 index, int length,
-		u64 *next_index, struct squashfs_page_actor *output)
+static int __squashfs_read_data(struct super_block *sb, u64 index, int length,
+	u64 *next_index, struct squashfs_page_actor *output, bool sync)
 {
-	struct squashfs_sb_info *msblk = sb->s_fs_info;
-	struct buffer_head **bh;
-	int offset = index & ((1 << msblk->devblksize_log2) - 1);
-	u64 cur_index = index >> msblk->devblksize_log2;
-	int bytes, compressed, b = 0, k = 0, avail, i;
+	struct squashfs_read_request *req;
 
-	bh = kcalloc(((output->length + msblk->devblksize - 1)
-		>> msblk->devblksize_log2) + 1, sizeof(*bh), GFP_KERNEL);
-	if (bh == NULL)
+	req = kcalloc(1, sizeof(struct squashfs_read_request), GFP_KERNEL);
+	if (!req) {
+		if (!sync)
+			squashfs_page_actor_free(output, -ENOMEM);
 		return -ENOMEM;
+	}
 
-	if (length) {
-		/*
-		 * Datablock.
-		 */
-		bytes = -offset;
-		compressed = SQUASHFS_COMPRESSED_BLOCK(length);
-		length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length);
-		if (next_index)
-			*next_index = index + length;
-
-		TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
-			index, compressed ? "" : "un", length, output->length);
-
-		if (length < 0 || length > output->length ||
-				(index + length) > msblk->bytes_used)
-			goto read_failure;
-
-		for (b = 0; bytes < length; b++, cur_index++) {
-			bh[b] = sb_getblk(sb, cur_index);
-			if (bh[b] == NULL)
-				goto block_release;
-			bytes += msblk->devblksize;
-		}
-		ll_rw_block(READ, b, bh);
-	} else {
-		/*
-		 * Metadata block.
-		 */
-		if ((index + 2) > msblk->bytes_used)
-			goto read_failure;
-
-		bh[0] = get_block_length(sb, &cur_index, &offset, &length);
-		if (bh[0] == NULL)
-			goto read_failure;
-		b = 1;
-
-		bytes = msblk->devblksize - offset;
-		compressed = SQUASHFS_COMPRESSED(length);
-		length = SQUASHFS_COMPRESSED_SIZE(length);
-		if (next_index)
-			*next_index = index + length + 2;
+	req->sb = sb;
+	req->index = index;
+	req->output = output;
 
-		TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
-				compressed ? "" : "un", length);
+	if (next_index)
+		*next_index = index;
 
-		if (length < 0 || length > output->length ||
-					(index + length) > msblk->bytes_used)
-			goto block_release;
+	if (length)
+		length = read_data_block(req, length, next_index, sync);
+	else
+		length = read_metadata_block(req, next_index);
 
-		for (; bytes < length; b++) {
-			bh[b] = sb_getblk(sb, ++cur_index);
-			if (bh[b] == NULL)
-				goto block_release;
-			bytes += msblk->devblksize;
-		}
-		ll_rw_block(READ, b - 1, bh + 1);
+	if (length < 0) {
+		ERROR("squashfs_read_data failed to read block 0x%llx\n",
+		      (unsigned long long)index);
+		return -EIO;
 	}
 
-	for (i = 0; i < b; i++) {
-		wait_on_buffer(bh[i]);
-		if (!buffer_uptodate(bh[i]))
-			goto block_release;
-	}
-
-	if (compressed) {
-		length = squashfs_decompress(msblk, bh, b, offset, length,
-			output);
-		if (length < 0)
-			goto read_failure;
-	} else {
-		/*
-		 * Block is uncompressed.
-		 */
-		int in, pg_offset = 0;
-		void *data = squashfs_first_page(output);
-
-		for (bytes = length; k < b; k++) {
-			in = min(bytes, msblk->devblksize - offset);
-			bytes -= in;
-			while (in) {
-				if (pg_offset == PAGE_CACHE_SIZE) {
-					data = squashfs_next_page(output);
-					pg_offset = 0;
-				}
-				avail = min_t(int, in, PAGE_CACHE_SIZE -
-						pg_offset);
-				memcpy(data + pg_offset, bh[k]->b_data + offset,
-						avail);
-				in -= avail;
-				pg_offset += avail;
-				offset += avail;
-			}
-			offset = 0;
-			put_bh(bh[k]);
-		}
-		squashfs_finish_page(output);
-	}
-
-	kfree(bh);
 	return length;
+}
+
+int squashfs_read_data(struct super_block *sb, u64 index, int length,
+	u64 *next_index, struct squashfs_page_actor *output)
+{
+	return __squashfs_read_data(sb, index, length, next_index, output,
+				    true);
+}
 
-block_release:
-	for (; k < b; k++)
-		put_bh(bh[k]);
+int squashfs_read_data_async(struct super_block *sb, u64 index, int length,
+	u64 *next_index, struct squashfs_page_actor *output)
+{
 
-read_failure:
-	ERROR("squashfs_read_data failed to read block 0x%llx\n",
-					(unsigned long long) index);
-	kfree(bh);
-	return -EIO;
+	return __squashfs_read_data(sb, index, length, next_index, output,
+				    false);
 }
diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c
index 9d033ec0f133..10fe1272535f 100644
--- a/fs/squashfs/file_direct.c
+++ b/fs/squashfs/file_direct.c
@@ -20,157 +20,93 @@
 #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);
+static void release_actor_pages(struct page **page, int pages, int error)
+{
+	int i;
 
-/* Read separately compressed datablock directly into page cache */
-int squashfs_readpage_block(struct page *target_page, u64 block, int bsize)
+	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(
+	struct page *target_page, int start_index, int nr_pages)
 {
-	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;
+	int i, n;
 	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(page, pages, 0, NULL);
-	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;
+	page = kmalloc_array(nr_pages, sizeof(void *), GFP_KERNEL);
+	if (!page)
+		return NULL;
+
+	/* Try to grab all the pages covered by the SquashFS block */
+	for (i = 0, n = start_index; i < nr_pages; i++, n++) {
+		if (target_page->index == n) {
+			page[i] = target_page;
+		} else {
+			page[i] = grab_cache_page_nowait(target_page->mapping,
+							 n);
+			if (page[i] == NULL)
+				continue;
 		}
 
 		if (PageUptodate(page[i])) {
 			unlock_page(page[i]);
-			page_cache_release(page[i]);
+			put_page(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);
+	actor = squashfs_page_actor_init(page, nr_pages, 0,
+			release_actor_pages);
+	if (!actor) {
+		release_actor_pages(page, nr_pages, -ENOMEM);
+		kfree(page);
+		return NULL;
 	}
-
-	/* 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] == NULL || page[i] == target_page)
-			continue;
-		flush_dcache_page(page[i]);
-		SetPageError(page[i]);
-		unlock_page(page[i]);
-		page_cache_release(page[i]);
-	}
-
-out:
-	squashfs_page_actor_free(actor, 0);
-	kfree(page);
-	return res;
+	return actor;
 }
 
+/* Read separately compressed datablock directly into page cache */
+int squashfs_readpage_block(struct page *target_page, 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;
-	}
+	struct inode *inode = target_page->mapping->host;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
 
-	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);
+	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 pages, res = -ENOMEM;
+	struct squashfs_page_actor *actor;
 
-		if (page[n] == NULL)
-			continue;
+	if (end_index > file_end)
+		end_index = file_end;
+	pages = end_index - start_index + 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]);
-	}
+	actor = actor_from_page_cache(target_page, start_index, pages);
+	if (!actor)
+		return -ENOMEM;
 
-out:
-	squashfs_cache_put(buffer);
-	return res;
+	get_page(target_page);
+	res = squashfs_read_data_async(inode->i_sb, block, bsize, NULL,
+				       actor);
+	return res < 0 ? res : 0;
 }
diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
index 887d6d270080..985317fbf6c2 100644
--- a/fs/squashfs/squashfs.h
+++ b/fs/squashfs/squashfs.h
@@ -28,8 +28,14 @@
 #define WARNING(s, args...)	pr_warn("SQUASHFS: "s, ## args)
 
 /* block.c */
+extern int squashfs_init_read_wq(void);
+extern void squashfs_destroy_read_wq(void);
 extern int squashfs_read_data(struct super_block *, u64, int, u64 *,
 				struct squashfs_page_actor *);
+extern int squashfs_read_data(struct super_block *, u64, int, u64 *,
+	struct squashfs_page_actor *);
+extern int squashfs_read_data_async(struct super_block *, u64, int, u64 *,
+	struct squashfs_page_actor *);
 
 /* cache.c */
 extern struct squashfs_cache *squashfs_cache_init(char *, int, int);
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 5056babe00df..61cd0b39ed0e 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -444,9 +444,15 @@ static int __init init_squashfs_fs(void)
 	if (err)
 		return err;
 
+	if (!squashfs_init_read_wq()) {
+		destroy_inodecache();
+		return -ENOMEM;
+        }
+
 	err = register_filesystem(&squashfs_fs_type);
 	if (err) {
 		destroy_inodecache();
+		squashfs_destroy_read_wq();
 		return err;
 	}
 
@@ -460,6 +466,7 @@ static void __exit exit_squashfs_fs(void)
 {
 	unregister_filesystem(&squashfs_fs_type);
 	destroy_inodecache();
+	squashfs_destroy_read_wq();
 }