From 9508c6b90b3f57ecea4e7a896cf8325400fc0c6e Mon Sep 17 00:00:00 2001
From: Phillip Lougher <phillip@squashfs.org.uk>
Date: Wed, 13 Nov 2013 02:56:26 +0000
Subject: Squashfs: Refactor decompressor interface and code

The decompressor interface and code was written from
the point of view of single-threaded operation.  In doing
so it mixed a lot of single-threaded implementation specific
aspects into the decompressor code and elsewhere which makes it
difficult to seamlessly support multiple different decompressor
implementations.

This patch does the following:

1.  It removes compressor_options parsing from the decompressor
    init() function.  This allows the decompressor init() function
    to be dynamically called to instantiate multiple decompressors,
    without the compressor options needing to be read and parsed each
    time.

2.  It moves threading and all sleeping operations out of the
    decompressors.  In doing so, it makes the decompressors
    non-blocking wrappers which only deal with interfacing with
    the decompressor implementation.

3. It splits decompressor.[ch] into decompressor generic functions
   in decompressor.[ch], and moves the single threaded
   decompressor implementation into decompressor_single.c.

The result of this patch is Squashfs should now be able to
support multiple decompressors by adding new decompressor_xxx.c
files with specialised implementations of the functions in
decompressor_single.c

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>

diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index 110b047..c223c84 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -4,7 +4,7 @@
 
 obj-$(CONFIG_SQUASHFS) += squashfs.o
 squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
-squashfs-y += namei.o super.o symlink.o decompressor.o
+squashfs-y += namei.o super.o symlink.o decompressor.o decompressor_single.o
 squashfs-$(CONFIG_SQUASHFS_XATTR) += xattr.o xattr_id.o
 squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 41d108e..4dd4025 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -93,7 +93,7 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 	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, page = 0, avail;
+	int bytes, compressed, b = 0, k = 0, page = 0, avail, i;
 
 	bh = kcalloc(((srclength + msblk->devblksize - 1)
 		>> msblk->devblksize_log2) + 1, sizeof(*bh), GFP_KERNEL);
@@ -158,6 +158,12 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 		ll_rw_block(READ, b - 1, bh + 1);
 	}
 
+	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, buffer, bh, b, offset,
 			 length, srclength, pages);
@@ -172,9 +178,6 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 		for (bytes = length; k < b; k++) {
 			in = min(bytes, msblk->devblksize - offset);
 			bytes -= in;
-			wait_on_buffer(bh[k]);
-			if (!buffer_uptodate(bh[k]))
-				goto block_release;
 			while (in) {
 				if (pg_offset == PAGE_CACHE_SIZE) {
 					page++;
diff --git a/fs/squashfs/decompressor.c b/fs/squashfs/decompressor.c
index 3f6271d..234291f 100644
--- a/fs/squashfs/decompressor.c
+++ b/fs/squashfs/decompressor.c
@@ -37,29 +37,29 @@
  */
 
 static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
-	NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
+	NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
 };
 
 #ifndef CONFIG_SQUASHFS_LZO
 static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
-	NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
+	NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
 };
 #endif
 
 #ifndef CONFIG_SQUASHFS_XZ
 static const struct squashfs_decompressor squashfs_xz_comp_ops = {
-	NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
+	NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
 };
 #endif
 
 #ifndef CONFIG_SQUASHFS_ZLIB
 static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
-	NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
+	NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
 };
 #endif
 
 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
-	NULL, NULL, NULL, 0, "unknown", 0
+	NULL, NULL, NULL, NULL, 0, "unknown", 0
 };
 
 static const struct squashfs_decompressor *decompressor[] = {
@@ -83,10 +83,10 @@ const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
 }
 
 
-void *squashfs_decompressor_init(struct super_block *sb, unsigned short flags)
+static void *get_comp_opts(struct super_block *sb, unsigned short flags)
 {
 	struct squashfs_sb_info *msblk = sb->s_fs_info;
-	void *strm, *buffer = NULL;
+	void *buffer = NULL, *comp_opts;
 	int length = 0;
 
 	/*
@@ -94,23 +94,40 @@ void *squashfs_decompressor_init(struct super_block *sb, unsigned short flags)
 	 */
 	if (SQUASHFS_COMP_OPTS(flags)) {
 		buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
-		if (buffer == NULL)
-			return ERR_PTR(-ENOMEM);
+		if (buffer == NULL) {
+			comp_opts = ERR_PTR(-ENOMEM);
+			goto out;
+		}
 
 		length = squashfs_read_data(sb, &buffer,
 			sizeof(struct squashfs_super_block), 0, NULL,
-			PAGE_CACHE_SIZE, 1);
+				PAGE_CACHE_SIZE, 1);
 
 		if (length < 0) {
-			strm = ERR_PTR(length);
-			goto finished;
+			comp_opts = ERR_PTR(length);
+			goto out;
 		}
 	}
 
-	strm = msblk->decompressor->init(msblk, buffer, length);
+	comp_opts = squashfs_comp_opts(msblk, buffer, length);
 
-finished:
+out:
 	kfree(buffer);
+	return comp_opts;
+}
+
+
+void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	void *stream, *comp_opts = get_comp_opts(sb, flags);
+
+	if (IS_ERR(comp_opts))
+		return comp_opts;
+
+	stream = squashfs_decompressor_create(msblk, comp_opts);
+	if (IS_ERR(stream))
+		kfree(comp_opts);
 
-	return strm;
+	return stream;
 }
diff --git a/fs/squashfs/decompressor.h b/fs/squashfs/decompressor.h
index 330073e..6cdb20a 100644
--- a/fs/squashfs/decompressor.h
+++ b/fs/squashfs/decompressor.h
@@ -24,28 +24,21 @@
  */
 
 struct squashfs_decompressor {
-	void	*(*init)(struct squashfs_sb_info *, void *, int);
+	void	*(*init)(struct squashfs_sb_info *, void *);
+	void	*(*comp_opts)(struct squashfs_sb_info *, void *, int);
 	void	(*free)(void *);
-	int	(*decompress)(struct squashfs_sb_info *, void **,
+	int	(*decompress)(struct squashfs_sb_info *, void *, void **,
 		struct buffer_head **, int, int, int, int, int);
 	int	id;
 	char	*name;
 	int	supported;
 };
 
-static inline void squashfs_decompressor_free(struct squashfs_sb_info *msblk,
-	void *s)
+static inline void *squashfs_comp_opts(struct squashfs_sb_info *msblk,
+							void *buff, int length)
 {
-	if (msblk->decompressor)
-		msblk->decompressor->free(s);
-}
-
-static inline int squashfs_decompress(struct squashfs_sb_info *msblk,
-	void **buffer, struct buffer_head **bh, int b, int offset, int length,
-	int srclength, int pages)
-{
-	return msblk->decompressor->decompress(msblk, buffer, bh, b, offset,
-		length, srclength, pages);
+	return msblk->decompressor->comp_opts ?
+		msblk->decompressor->comp_opts(msblk, buff, length) : NULL;
 }
 
 #ifdef CONFIG_SQUASHFS_XZ
diff --git a/fs/squashfs/decompressor_single.c b/fs/squashfs/decompressor_single.c
new file mode 100644
index 0000000..f857cf6
--- /dev/null
+++ b/fs/squashfs/decompressor_single.c
@@ -0,0 +1,86 @@
+/*
+ * 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/types.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/buffer_head.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "decompressor.h"
+#include "squashfs.h"
+
+/*
+ * This file implements single-threaded decompression in the
+ * decompressor framework
+ */
+
+struct squashfs_stream {
+	void		*stream;
+	struct mutex	mutex;
+};
+
+void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
+						void *comp_opts)
+{
+	struct squashfs_stream *stream;
+	int err = -ENOMEM;
+
+	stream = kmalloc(sizeof(*stream), GFP_KERNEL);
+	if (stream == NULL)
+		goto out;
+
+	stream->stream = msblk->decompressor->init(msblk, comp_opts);
+	if (IS_ERR(stream->stream)) {
+		err = PTR_ERR(stream->stream);
+		goto out;
+	}
+
+	kfree(comp_opts);
+	mutex_init(&stream->mutex);
+	return stream;
+
+out:
+	kfree(stream);
+	return ERR_PTR(err);
+}
+
+void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
+{
+	struct squashfs_stream *stream = msblk->stream;
+
+	if (stream) {
+		msblk->decompressor->free(stream->stream);
+		kfree(stream);
+	}
+}
+
+int squashfs_decompress(struct squashfs_sb_info *msblk,
+	void **buffer, struct buffer_head **bh, int b, int offset, int length,
+	int srclength, int pages)
+{
+	int res;
+	struct squashfs_stream *stream = msblk->stream;
+
+	mutex_lock(&stream->mutex);
+	res = msblk->decompressor->decompress(msblk, stream->stream, buffer,
+		bh, b, offset, length, srclength, pages);
+	mutex_unlock(&stream->mutex);
+
+	if (res < 0)
+		ERROR("%s decompression failed, data probably corrupt\n",
+			msblk->decompressor->name);
+
+	return res;
+}
+
+int squashfs_max_decompressors(void)
+{
+	return 1;
+}
diff --git a/fs/squashfs/lzo_wrapper.c b/fs/squashfs/lzo_wrapper.c
index 00f4dfc..75c3b57 100644
--- a/fs/squashfs/lzo_wrapper.c
+++ b/fs/squashfs/lzo_wrapper.c
@@ -37,7 +37,7 @@ struct squashfs_lzo {
 	void	*output;
 };
 
-static void *lzo_init(struct squashfs_sb_info *msblk, void *buff, int len)
+static void *lzo_init(struct squashfs_sb_info *msblk, void *buff)
 {
 	int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
 
@@ -74,22 +74,16 @@ static void lzo_free(void *strm)
 }
 
 
-static int lzo_uncompress(struct squashfs_sb_info *msblk, void **buffer,
-	struct buffer_head **bh, int b, int offset, int length, int srclength,
-	int pages)
+static int lzo_uncompress(struct squashfs_sb_info *msblk, void *strm,
+	void **buffer, struct buffer_head **bh, int b, int offset, int length,
+	int srclength, int pages)
 {
-	struct squashfs_lzo *stream = msblk->stream;
+	struct squashfs_lzo *stream = strm;
 	void *buff = stream->input;
 	int avail, i, bytes = length, res;
 	size_t out_len = srclength;
 
-	mutex_lock(&msblk->read_data_mutex);
-
 	for (i = 0; i < b; i++) {
-		wait_on_buffer(bh[i]);
-		if (!buffer_uptodate(bh[i]))
-			goto block_release;
-
 		avail = min(bytes, msblk->devblksize - offset);
 		memcpy(buff, bh[i]->b_data + offset, avail);
 		buff += avail;
@@ -111,17 +105,9 @@ static int lzo_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 		bytes -= avail;
 	}
 
-	mutex_unlock(&msblk->read_data_mutex);
 	return res;
 
-block_release:
-	for (; i < b; i++)
-		put_bh(bh[i]);
-
 failed:
-	mutex_unlock(&msblk->read_data_mutex);
-
-	ERROR("lzo decompression failed, data probably corrupt\n");
 	return -EIO;
 }
 
diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
index d126651..2e2751d 100644
--- a/fs/squashfs/squashfs.h
+++ b/fs/squashfs/squashfs.h
@@ -48,7 +48,14 @@ extern void *squashfs_read_table(struct super_block *, u64, int);
 
 /* decompressor.c */
 extern const struct squashfs_decompressor *squashfs_lookup_decompressor(int);
-extern void *squashfs_decompressor_init(struct super_block *, unsigned short);
+extern void *squashfs_decompressor_setup(struct super_block *, unsigned short);
+
+/* decompressor_xxx.c */
+extern void *squashfs_decompressor_create(struct squashfs_sb_info *, void *);
+extern void squashfs_decompressor_destroy(struct squashfs_sb_info *);
+extern int squashfs_decompress(struct squashfs_sb_info *, void **,
+	struct buffer_head **, int, int, int, int, int);
+extern int squashfs_max_decompressors(void);
 
 /* export.c */
 extern __le64 *squashfs_read_inode_lookup_table(struct super_block *, u64, u64,
diff --git a/fs/squashfs/squashfs_fs_sb.h b/fs/squashfs/squashfs_fs_sb.h
index 52934a2..9cdcf41 100644
--- a/fs/squashfs/squashfs_fs_sb.h
+++ b/fs/squashfs/squashfs_fs_sb.h
@@ -63,10 +63,9 @@ struct squashfs_sb_info {
 	__le64					*id_table;
 	__le64					*fragment_index;
 	__le64					*xattr_id_table;
-	struct mutex				read_data_mutex;
 	struct mutex				meta_index_mutex;
 	struct meta_index			*meta_index;
-	void					*stream;
+	struct squashfs_stream			*stream;
 	__le64					*inode_lookup_table;
 	u64					inode_table;
 	u64					directory_table;
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 60553a9..202df63 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -98,7 +98,6 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
 	msblk->devblksize_log2 = ffz(~msblk->devblksize);
 
-	mutex_init(&msblk->read_data_mutex);
 	mutex_init(&msblk->meta_index_mutex);
 
 	/*
@@ -206,13 +205,14 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 		goto failed_mount;
 
 	/* Allocate read_page block */
-	msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size);
+	msblk->read_page = squashfs_cache_init("data",
+		squashfs_max_decompressors(), msblk->block_size);
 	if (msblk->read_page == NULL) {
 		ERROR("Failed to allocate read_page block\n");
 		goto failed_mount;
 	}
 
-	msblk->stream = squashfs_decompressor_init(sb, flags);
+	msblk->stream = squashfs_decompressor_setup(sb, flags);
 	if (IS_ERR(msblk->stream)) {
 		err = PTR_ERR(msblk->stream);
 		msblk->stream = NULL;
@@ -336,7 +336,7 @@ failed_mount:
 	squashfs_cache_delete(msblk->block_cache);
 	squashfs_cache_delete(msblk->fragment_cache);
 	squashfs_cache_delete(msblk->read_page);
-	squashfs_decompressor_free(msblk, msblk->stream);
+	squashfs_decompressor_destroy(msblk);
 	kfree(msblk->inode_lookup_table);
 	kfree(msblk->fragment_index);
 	kfree(msblk->id_table);
@@ -383,7 +383,7 @@ static void squashfs_put_super(struct super_block *sb)
 		squashfs_cache_delete(sbi->block_cache);
 		squashfs_cache_delete(sbi->fragment_cache);
 		squashfs_cache_delete(sbi->read_page);
-		squashfs_decompressor_free(sbi, sbi->stream);
+		squashfs_decompressor_destroy(sbi);
 		kfree(sbi->id_table);
 		kfree(sbi->fragment_index);
 		kfree(sbi->meta_index);
diff --git a/fs/squashfs/xz_wrapper.c b/fs/squashfs/xz_wrapper.c
index 1760b7d1..5d1d07c 100644
--- a/fs/squashfs/xz_wrapper.c
+++ b/fs/squashfs/xz_wrapper.c
@@ -38,38 +38,63 @@ struct squashfs_xz {
 	struct xz_buf buf;
 };
 
-struct comp_opts {
+struct disk_comp_opts {
 	__le32 dictionary_size;
 	__le32 flags;
 };
 
-static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,
-	int len)
+struct comp_opts {
+	int dict_size;
+};
+
+static void *squashfs_xz_comp_opts(struct squashfs_sb_info *msblk,
+	void *buff, int len)
 {
-	struct comp_opts *comp_opts = buff;
-	struct squashfs_xz *stream;
-	int dict_size = msblk->block_size;
-	int err, n;
+	struct disk_comp_opts *comp_opts = buff;
+	struct comp_opts *opts;
+	int err = 0, n;
+
+	opts = kmalloc(sizeof(*opts), GFP_KERNEL);
+	if (opts == NULL) {
+		err = -ENOMEM;
+		goto out2;
+	}
 
 	if (comp_opts) {
 		/* check compressor options are the expected length */
 		if (len < sizeof(*comp_opts)) {
 			err = -EIO;
-			goto failed;
+			goto out;
 		}
 
-		dict_size = le32_to_cpu(comp_opts->dictionary_size);
+		opts->dict_size = le32_to_cpu(comp_opts->dictionary_size);
 
 		/* the dictionary size should be 2^n or 2^n+2^(n+1) */
-		n = ffs(dict_size) - 1;
-		if (dict_size != (1 << n) && dict_size != (1 << n) +
+		n = ffs(opts->dict_size) - 1;
+		if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) +
 						(1 << (n + 1))) {
 			err = -EIO;
-			goto failed;
+			goto out;
 		}
-	}
+	} else
+		/* use defaults */
+		opts->dict_size = max_t(int, msblk->block_size,
+							SQUASHFS_METADATA_SIZE);
 
-	dict_size = max_t(int, dict_size, SQUASHFS_METADATA_SIZE);
+	return opts;
+
+out:
+	kfree(opts);
+out2:
+	return ERR_PTR(err);
+}
+
+
+static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff)
+{
+	struct comp_opts *comp_opts = buff;
+	struct squashfs_xz *stream;
+	int err;
 
 	stream = kmalloc(sizeof(*stream), GFP_KERNEL);
 	if (stream == NULL) {
@@ -77,7 +102,7 @@ static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,
 		goto failed;
 	}
 
-	stream->state = xz_dec_init(XZ_PREALLOC, dict_size);
+	stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size);
 	if (stream->state == NULL) {
 		kfree(stream);
 		err = -ENOMEM;
@@ -103,15 +128,13 @@ static void squashfs_xz_free(void *strm)
 }
 
 
-static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
-	struct buffer_head **bh, int b, int offset, int length, int srclength,
-	int pages)
+static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
+	void **buffer, struct buffer_head **bh, int b, int offset, int length,
+	int srclength, int pages)
 {
 	enum xz_ret xz_err;
 	int avail, total = 0, k = 0, page = 0;
-	struct squashfs_xz *stream = msblk->stream;
-
-	mutex_lock(&msblk->read_data_mutex);
+	struct squashfs_xz *stream = strm;
 
 	xz_dec_reset(stream->state);
 	stream->buf.in_pos = 0;
@@ -124,10 +147,6 @@ static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 		if (stream->buf.in_pos == stream->buf.in_size && k < b) {
 			avail = min(length, msblk->devblksize - offset);
 			length -= avail;
-			wait_on_buffer(bh[k]);
-			if (!buffer_uptodate(bh[k]))
-				goto release_mutex;
-
 			stream->buf.in = bh[k]->b_data + offset;
 			stream->buf.in_size = avail;
 			stream->buf.in_pos = 0;
@@ -147,23 +166,12 @@ static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 			put_bh(bh[k++]);
 	} while (xz_err == XZ_OK);
 
-	if (xz_err != XZ_STREAM_END) {
-		ERROR("xz_dec_run error, data probably corrupt\n");
-		goto release_mutex;
-	}
-
-	if (k < b) {
-		ERROR("xz_uncompress error, input remaining\n");
-		goto release_mutex;
-	}
-
-	total += stream->buf.out_pos;
-	mutex_unlock(&msblk->read_data_mutex);
-	return total;
+	if (xz_err != XZ_STREAM_END || k < b)
+		goto out;
 
-release_mutex:
-	mutex_unlock(&msblk->read_data_mutex);
+	return total + stream->buf.out_pos;
 
+out:
 	for (; k < b; k++)
 		put_bh(bh[k]);
 
@@ -172,6 +180,7 @@ release_mutex:
 
 const struct squashfs_decompressor squashfs_xz_comp_ops = {
 	.init = squashfs_xz_init,
+	.comp_opts = squashfs_xz_comp_opts,
 	.free = squashfs_xz_free,
 	.decompress = squashfs_xz_uncompress,
 	.id = XZ_COMPRESSION,
diff --git a/fs/squashfs/zlib_wrapper.c b/fs/squashfs/zlib_wrapper.c
index 55d918f..bb04902 100644
--- a/fs/squashfs/zlib_wrapper.c
+++ b/fs/squashfs/zlib_wrapper.c
@@ -33,7 +33,7 @@
 #include "squashfs.h"
 #include "decompressor.h"
 
-static void *zlib_init(struct squashfs_sb_info *dummy, void *buff, int len)
+static void *zlib_init(struct squashfs_sb_info *dummy, void *buff)
 {
 	z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
 	if (stream == NULL)
@@ -61,15 +61,13 @@ static void zlib_free(void *strm)
 }
 
 
-static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
-	struct buffer_head **bh, int b, int offset, int length, int srclength,
-	int pages)
+static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
+	void **buffer, struct buffer_head **bh, int b, int offset, int length,
+	int srclength, int pages)
 {
 	int zlib_err, zlib_init = 0;
 	int k = 0, page = 0;
-	z_stream *stream = msblk->stream;
-
-	mutex_lock(&msblk->read_data_mutex);
+	z_stream *stream = strm;
 
 	stream->avail_out = 0;
 	stream->avail_in = 0;
@@ -78,10 +76,6 @@ static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 		if (stream->avail_in == 0 && k < b) {
 			int avail = min(length, msblk->devblksize - offset);
 			length -= avail;
-			wait_on_buffer(bh[k]);
-			if (!buffer_uptodate(bh[k]))
-				goto release_mutex;
-
 			stream->next_in = bh[k]->b_data + offset;
 			stream->avail_in = avail;
 			offset = 0;
@@ -94,12 +88,8 @@ static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 
 		if (!zlib_init) {
 			zlib_err = zlib_inflateInit(stream);
-			if (zlib_err != Z_OK) {
-				ERROR("zlib_inflateInit returned unexpected "
-					"result 0x%x, srclength %d\n",
-					zlib_err, srclength);
-				goto release_mutex;
-			}
+			if (zlib_err != Z_OK)
+				goto out;
 			zlib_init = 1;
 		}
 
@@ -109,29 +99,19 @@ static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
 			put_bh(bh[k++]);
 	} while (zlib_err == Z_OK);
 
-	if (zlib_err != Z_STREAM_END) {
-		ERROR("zlib_inflate error, data probably corrupt\n");
-		goto release_mutex;
-	}
+	if (zlib_err != Z_STREAM_END)
+		goto out;
 
 	zlib_err = zlib_inflateEnd(stream);
-	if (zlib_err != Z_OK) {
-		ERROR("zlib_inflate error, data probably corrupt\n");
-		goto release_mutex;
-	}
-
-	if (k < b) {
-		ERROR("zlib_uncompress error, data remaining\n");
-		goto release_mutex;
-	}
+	if (zlib_err != Z_OK)
+		goto out;
 
-	length = stream->total_out;
-	mutex_unlock(&msblk->read_data_mutex);
-	return length;
+	if (k < b)
+		goto out;
 
-release_mutex:
-	mutex_unlock(&msblk->read_data_mutex);
+	return stream->total_out;
 
+out:
 	for (; k < b; k++)
 		put_bh(bh[k]);
 
-- 
cgit v0.10.2


From cd59c2ec5f37a2bc1315c9324aab6c21d43ffa1a Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Mon, 28 Oct 2013 14:26:30 +0900
Subject: squashfs: Enhance parallel I/O

Now squashfs have used for only one stream buffer for decompression
so it hurts parallel read performance so this patch supports
multiple decompressor to enhance performance parallel I/O.

Four 1G file dd read on KVM machine which has 2 CPU and 4G memory.

dd if=test/test1.dat of=/dev/null &
dd if=test/test2.dat of=/dev/null &
dd if=test/test3.dat of=/dev/null &
dd if=test/test4.dat of=/dev/null &

old : 1m39s -> new : 9s

* From v1
  * Change comp_strm with decomp_strm - Phillip
  * Change/add comments - Phillip

Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>

diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index c70111e..1c6d340 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -63,6 +63,19 @@ config SQUASHFS_LZO
 
 	  If unsure, say N.
 
+config SQUASHFS_MULTI_DECOMPRESSOR
+	bool "Use multiple decompressors for handling parallel I/O"
+	depends on SQUASHFS
+	help
+	  By default Squashfs uses a single decompressor but it gives
+	  poor performance on parallel I/O workloads when using multiple CPU
+	  machines due to waiting on decompressor availability.
+
+	  If you have a parallel I/O workload and your system has enough memory,
+	  using this option may improve overall I/O performance.
+
+	  If unsure, say N.
+
 config SQUASHFS_XZ
 	bool "Include support for XZ compressed file systems"
 	depends on SQUASHFS
diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index c223c84..dfebc3b 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -4,8 +4,15 @@
 
 obj-$(CONFIG_SQUASHFS) += squashfs.o
 squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
-squashfs-y += namei.o super.o symlink.o decompressor.o decompressor_single.o
+squashfs-y += namei.o super.o symlink.o decompressor.o
+
 squashfs-$(CONFIG_SQUASHFS_XATTR) += xattr.o xattr_id.o
 squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_ZLIB) += zlib_wrapper.o
+
+ifdef CONFIG_SQUASHFS_MULTI_DECOMPRESSOR
+	squashfs-y		+= decompressor_multi.o
+else
+	squashfs-y		+= decompressor_single.o
+endif
diff --git a/fs/squashfs/decompressor_multi.c b/fs/squashfs/decompressor_multi.c
new file mode 100644
index 0000000..462731d
--- /dev/null
+++ b/fs/squashfs/decompressor_multi.c
@@ -0,0 +1,200 @@
+/*
+ *  Copyright (c) 2013
+ *  Minchan Kim <minchan@kernel.org>
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2. See
+ *  the COPYING file in the top-level directory.
+ */
+#include <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/buffer_head.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/cpumask.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "decompressor.h"
+#include "squashfs.h"
+
+/*
+ * This file implements multi-threaded decompression in the
+ * decompressor framework
+ */
+
+
+/*
+ * The reason that multiply two is that a CPU can request new I/O
+ * while it is waiting previous request.
+ */
+#define MAX_DECOMPRESSOR	(num_online_cpus() * 2)
+
+
+int squashfs_max_decompressors(void)
+{
+	return MAX_DECOMPRESSOR;
+}
+
+
+struct squashfs_stream {
+	void			*comp_opts;
+	struct list_head	strm_list;
+	struct mutex		mutex;
+	int			avail_decomp;
+	wait_queue_head_t	wait;
+};
+
+
+struct decomp_stream {
+	void *stream;
+	struct list_head list;
+};
+
+
+static void put_decomp_stream(struct decomp_stream *decomp_strm,
+				struct squashfs_stream *stream)
+{
+	mutex_lock(&stream->mutex);
+	list_add(&decomp_strm->list, &stream->strm_list);
+	mutex_unlock(&stream->mutex);
+	wake_up(&stream->wait);
+}
+
+void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
+				void *comp_opts)
+{
+	struct squashfs_stream *stream;
+	struct decomp_stream *decomp_strm = NULL;
+	int err = -ENOMEM;
+
+	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
+	if (!stream)
+		goto out;
+
+	stream->comp_opts = comp_opts;
+	mutex_init(&stream->mutex);
+	INIT_LIST_HEAD(&stream->strm_list);
+	init_waitqueue_head(&stream->wait);
+
+	/*
+	 * We should have a decompressor at least as default
+	 * so if we fail to allocate new decompressor dynamically,
+	 * we could always fall back to default decompressor and
+	 * file system works.
+	 */
+	decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
+	if (!decomp_strm)
+		goto out;
+
+	decomp_strm->stream = msblk->decompressor->init(msblk,
+						stream->comp_opts);
+	if (IS_ERR(decomp_strm->stream)) {
+		err = PTR_ERR(decomp_strm->stream);
+		goto out;
+	}
+
+	list_add(&decomp_strm->list, &stream->strm_list);
+	stream->avail_decomp = 1;
+	return stream;
+
+out:
+	kfree(decomp_strm);
+	kfree(stream);
+	return ERR_PTR(err);
+}
+
+
+void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
+{
+	struct squashfs_stream *stream = msblk->stream;
+	if (stream) {
+		struct decomp_stream *decomp_strm;
+
+		while (!list_empty(&stream->strm_list)) {
+			decomp_strm = list_entry(stream->strm_list.prev,
+						struct decomp_stream, list);
+			list_del(&decomp_strm->list);
+			msblk->decompressor->free(decomp_strm->stream);
+			kfree(decomp_strm);
+			stream->avail_decomp--;
+		}
+	}
+
+	WARN_ON(stream->avail_decomp);
+	kfree(stream->comp_opts);
+	kfree(stream);
+}
+
+
+static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
+					struct squashfs_stream *stream)
+{
+	struct decomp_stream *decomp_strm;
+
+	while (1) {
+		mutex_lock(&stream->mutex);
+
+		/* There is available decomp_stream */
+		if (!list_empty(&stream->strm_list)) {
+			decomp_strm = list_entry(stream->strm_list.prev,
+				struct decomp_stream, list);
+			list_del(&decomp_strm->list);
+			mutex_unlock(&stream->mutex);
+			break;
+		}
+
+		/*
+		 * If there is no available decomp and already full,
+		 * let's wait for releasing decomp from other users.
+		 */
+		if (stream->avail_decomp >= MAX_DECOMPRESSOR)
+			goto wait;
+
+		/* Let's allocate new decomp */
+		decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
+		if (!decomp_strm)
+			goto wait;
+
+		decomp_strm->stream = msblk->decompressor->init(msblk,
+						stream->comp_opts);
+		if (IS_ERR(decomp_strm->stream)) {
+			kfree(decomp_strm);
+			goto wait;
+		}
+
+		stream->avail_decomp++;
+		WARN_ON(stream->avail_decomp > MAX_DECOMPRESSOR);
+
+		mutex_unlock(&stream->mutex);
+		break;
+wait:
+		/*
+		 * If system memory is tough, let's for other's
+		 * releasing instead of hurting VM because it could
+		 * make page cache thrashing.
+		 */
+		mutex_unlock(&stream->mutex);
+		wait_event(stream->wait,
+			!list_empty(&stream->strm_list));
+	}
+
+	return decomp_strm;
+}
+
+
+int squashfs_decompress(struct squashfs_sb_info *msblk,
+	void **buffer, struct buffer_head **bh, int b, int offset, int length,
+	int srclength, int pages)
+{
+	int res;
+	struct squashfs_stream *stream = msblk->stream;
+	struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream);
+	res = msblk->decompressor->decompress(msblk, decomp_stream->stream,
+		buffer, bh, b, offset, length, srclength, pages);
+	put_decomp_stream(decomp_stream, stream);
+	if (res < 0)
+		ERROR("%s decompression failed, data probably corrupt\n",
+			msblk->decompressor->name);
+	return res;
+}
-- 
cgit v0.10.2


From d208383d640727b70cd6689bc17e67e9b5ebf4ff Mon Sep 17 00:00:00 2001
From: Phillip Lougher <phillip@squashfs.org.uk>
Date: Mon, 18 Nov 2013 02:31:36 +0000
Subject: Squashfs: add multi-threaded decompression using percpu variable

Add a multi-threaded decompression implementation which uses
percpu variables.

Using percpu variables has advantages and disadvantages over
implementations which do not use percpu variables.

Advantages:
  * the nature of percpu variables ensures decompression is
    load-balanced across the multiple cores.
  * simplicity.

Disadvantages: it limits decompression to one thread per core.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>

diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 1c6d340..159bd66 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -25,6 +25,50 @@ config SQUASHFS
 
 	  If unsure, say N.
 
+choice
+	prompt "Decompressor parallelisation options"
+	depends on SQUASHFS
+	help
+	  Squashfs now supports three parallelisation options for
+	  decompression.  Each one exhibits various trade-offs between
+	  decompression performance and CPU and memory usage.
+
+	  If in doubt, select "Single threaded compression"
+
+config SQUASHFS_DECOMP_SINGLE
+	bool "Single threaded compression"
+	help
+	  Traditionally Squashfs has used single-threaded decompression.
+	  Only one block (data or metadata) can be decompressed at any
+	  one time.  This limits CPU and memory usage to a minimum.
+
+config SQUASHFS_DECOMP_MULTI
+	bool "Use multiple decompressors for parallel I/O"
+	help
+	  By default Squashfs uses a single decompressor but it gives
+	  poor performance on parallel I/O workloads when using multiple CPU
+	  machines due to waiting on decompressor availability.
+
+	  If you have a parallel I/O workload and your system has enough memory,
+	  using this option may improve overall I/O performance.
+
+	  This decompressor implementation uses up to two parallel
+	  decompressors per core.  It dynamically allocates decompressors
+	  on a demand basis.
+
+config SQUASHFS_DECOMP_MULTI_PERCPU
+	bool "Use percpu multiple decompressors for parallel I/O"
+	help
+	  By default Squashfs uses a single decompressor but it gives
+	  poor performance on parallel I/O workloads when using multiple CPU
+	  machines due to waiting on decompressor availability.
+
+	  This decompressor implementation uses a maximum of one
+	  decompressor per core.  It uses percpu variables to ensure
+	  decompression is load-balanced across the cores.
+
+endchoice
+
 config SQUASHFS_XATTR
 	bool "Squashfs XATTR support"
 	depends on SQUASHFS
@@ -63,19 +107,6 @@ config SQUASHFS_LZO
 
 	  If unsure, say N.
 
-config SQUASHFS_MULTI_DECOMPRESSOR
-	bool "Use multiple decompressors for handling parallel I/O"
-	depends on SQUASHFS
-	help
-	  By default Squashfs uses a single decompressor but it gives
-	  poor performance on parallel I/O workloads when using multiple CPU
-	  machines due to waiting on decompressor availability.
-
-	  If you have a parallel I/O workload and your system has enough memory,
-	  using this option may improve overall I/O performance.
-
-	  If unsure, say N.
-
 config SQUASHFS_XZ
 	bool "Include support for XZ compressed file systems"
 	depends on SQUASHFS
diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index dfebc3b..5833b96 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -5,14 +5,10 @@
 obj-$(CONFIG_SQUASHFS) += squashfs.o
 squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
 squashfs-y += namei.o super.o symlink.o decompressor.o
-
+squashfs-$(CONFIG_SQUASHFS_DECOMP_SINGLE) += decompressor_single.o
+squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI) += decompressor_multi.o
+squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU) += decompressor_multi_percpu.o
 squashfs-$(CONFIG_SQUASHFS_XATTR) += xattr.o xattr_id.o
 squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_ZLIB) += zlib_wrapper.o
-
-ifdef CONFIG_SQUASHFS_MULTI_DECOMPRESSOR
-	squashfs-y		+= decompressor_multi.o
-else
-	squashfs-y		+= decompressor_single.o
-endif
diff --git a/fs/squashfs/decompressor_multi_percpu.c b/fs/squashfs/decompressor_multi_percpu.c
new file mode 100644
index 0000000..0e7b679
--- /dev/null
+++ b/fs/squashfs/decompressor_multi_percpu.c
@@ -0,0 +1,98 @@
+/*
+ * 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/types.h>
+#include <linux/slab.h>
+#include <linux/percpu.h>
+#include <linux/buffer_head.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "decompressor.h"
+#include "squashfs.h"
+
+/*
+ * This file implements multi-threaded decompression using percpu
+ * variables, one thread per cpu core.
+ */
+
+struct squashfs_stream {
+	void		*stream;
+};
+
+void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
+						void *comp_opts)
+{
+	struct squashfs_stream *stream;
+	struct squashfs_stream __percpu *percpu;
+	int err, cpu;
+
+	percpu = alloc_percpu(struct squashfs_stream);
+	if (percpu == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	for_each_possible_cpu(cpu) {
+		stream = per_cpu_ptr(percpu, cpu);
+		stream->stream = msblk->decompressor->init(msblk, comp_opts);
+		if (IS_ERR(stream->stream)) {
+			err = PTR_ERR(stream->stream);
+			goto out;
+		}
+	}
+
+	kfree(comp_opts);
+	return (__force void *) percpu;
+
+out:
+	for_each_possible_cpu(cpu) {
+		stream = per_cpu_ptr(percpu, cpu);
+		if (!IS_ERR_OR_NULL(stream->stream))
+			msblk->decompressor->free(stream->stream);
+	}
+	free_percpu(percpu);
+	return ERR_PTR(err);
+}
+
+void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
+{
+	struct squashfs_stream __percpu *percpu =
+			(struct squashfs_stream __percpu *) msblk->stream;
+	struct squashfs_stream *stream;
+	int cpu;
+
+	if (msblk->stream) {
+		for_each_possible_cpu(cpu) {
+			stream = per_cpu_ptr(percpu, cpu);
+			msblk->decompressor->free(stream->stream);
+		}
+		free_percpu(percpu);
+	}
+}
+
+int squashfs_decompress(struct squashfs_sb_info *msblk,
+	void **buffer, struct buffer_head **bh, int b, int offset, int length,
+	int srclength, int pages)
+{
+	struct squashfs_stream __percpu *percpu =
+			(struct squashfs_stream __percpu *) msblk->stream;
+	struct squashfs_stream *stream = get_cpu_ptr(percpu);
+	int res = msblk->decompressor->decompress(msblk, stream->stream, buffer,
+		bh, b, offset, length, srclength, pages);
+	put_cpu_ptr(stream);
+
+	if (res < 0)
+		ERROR("%s decompression failed, data probably corrupt\n",
+			msblk->decompressor->name);
+
+	return res;
+}
+
+int squashfs_max_decompressors(void)
+{
+	return num_possible_cpus();
+}
-- 
cgit v0.10.2


From 846b730e99518a1c9945afcb2afbe4d08a02ed80 Mon Sep 17 00:00:00 2001
From: Phillip Lougher <phillip@squashfs.org.uk>
Date: Mon, 18 Nov 2013 02:59:12 +0000
Subject: 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>

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 4dd4025..0cea9b9 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -36,6 +36,7 @@
 #include "squashfs_fs_sb.h"
 #include "squashfs.h"
 #include "decompressor.h"
+#include "page_actor.h"
 
 /*
  * Read the metadata block length, this is stored in the first two
@@ -86,16 +87,16 @@ 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, void **buffer, u64 index,
-			int length, u64 *next_index, int srclength, int pages)
+int squashfs_read_data(struct super_block *sb, u64 index, int length,
+		u64 *next_index, struct squashfs_page_actor *output)
 {
 	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, page = 0, avail, i;
+	int bytes, compressed, b = 0, k = 0, avail, i;
 
-	bh = kcalloc(((srclength + msblk->devblksize - 1)
+	bh = kcalloc(((output->length + msblk->devblksize - 1)
 		>> msblk->devblksize_log2) + 1, sizeof(*bh), GFP_KERNEL);
 	if (bh == NULL)
 		return -ENOMEM;
@@ -111,9 +112,9 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 			*next_index = index + length;
 
 		TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
-			index, compressed ? "" : "un", length, srclength);
+			index, compressed ? "" : "un", length, output->length);
 
-		if (length < 0 || length > srclength ||
+		if (length < 0 || length > output->length ||
 				(index + length) > msblk->bytes_used)
 			goto read_failure;
 
@@ -145,7 +146,7 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 		TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
 				compressed ? "" : "un", length);
 
-		if (length < 0 || length > srclength ||
+		if (length < 0 || length > output->length ||
 					(index + length) > msblk->bytes_used)
 			goto block_release;
 
@@ -165,8 +166,8 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 	}
 
 	if (compressed) {
-		length = squashfs_decompress(msblk, buffer, bh, b, offset,
-			 length, srclength, pages);
+		length = squashfs_decompress(msblk, bh, b, offset, length,
+			output);
 		if (length < 0)
 			goto read_failure;
 	} else {
@@ -174,19 +175,20 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 		 * 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) {
-					page++;
+					data = squashfs_next_page(output);
 					pg_offset = 0;
 				}
 				avail = min_t(int, in, PAGE_CACHE_SIZE -
 						pg_offset);
-				memcpy(buffer[page] + pg_offset,
-						bh[k]->b_data + offset, avail);
+				memcpy(data + pg_offset, bh[k]->b_data + offset,
+						avail);
 				in -= avail;
 				pg_offset += avail;
 				offset += avail;
@@ -194,6 +196,7 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
 			offset = 0;
 			put_bh(bh[k]);
 		}
+		squashfs_finish_page(output);
 	}
 
 	kfree(bh);
diff --git a/fs/squashfs/cache.c b/fs/squashfs/cache.c
index af0b738..1cb70a0 100644
--- a/fs/squashfs/cache.c
+++ b/fs/squashfs/cache.c
@@ -56,6 +56,7 @@
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
 #include "squashfs.h"
+#include "page_actor.h"
 
 /*
  * Look-up block in cache, and increment usage count.  If not in cache, read
@@ -119,9 +120,8 @@ struct squashfs_cache_entry *squashfs_cache_get(struct super_block *sb,
 			entry->error = 0;
 			spin_unlock(&cache->lock);
 
-			entry->length = squashfs_read_data(sb, entry->data,
-				block, length, &entry->next_index,
-				cache->block_size, cache->pages);
+			entry->length = squashfs_read_data(sb, block, length,
+				&entry->next_index, entry->actor);
 
 			spin_lock(&cache->lock);
 
@@ -220,6 +220,7 @@ void squashfs_cache_delete(struct squashfs_cache *cache)
 				kfree(cache->entry[i].data[j]);
 			kfree(cache->entry[i].data);
 		}
+		kfree(cache->entry[i].actor);
 	}
 
 	kfree(cache->entry);
@@ -280,6 +281,13 @@ struct squashfs_cache *squashfs_cache_init(char *name, int entries,
 				goto cleanup;
 			}
 		}
+
+		entry->actor = squashfs_page_actor_init(entry->data,
+						cache->pages, 0);
+		if (entry->actor == NULL) {
+			ERROR("Failed to allocate %s cache entry\n", name);
+			goto cleanup;
+		}
 	}
 
 	return cache;
@@ -410,6 +418,7 @@ void *squashfs_read_table(struct super_block *sb, u64 block, int length)
 	int pages = (length + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 	int i, res;
 	void *table, *buffer, **data;
+	struct squashfs_page_actor *actor;
 
 	table = buffer = kmalloc(length, GFP_KERNEL);
 	if (table == NULL)
@@ -421,19 +430,28 @@ void *squashfs_read_table(struct super_block *sb, u64 block, int length)
 		goto failed;
 	}
 
+	actor = squashfs_page_actor_init(data, pages, length);
+	if (actor == NULL) {
+		res = -ENOMEM;
+		goto failed2;
+	}
+
 	for (i = 0; i < pages; i++, buffer += PAGE_CACHE_SIZE)
 		data[i] = buffer;
 
-	res = squashfs_read_data(sb, data, block, length |
-		SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length, pages);
+	res = squashfs_read_data(sb, block, length |
+		SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, actor);
 
 	kfree(data);
+	kfree(actor);
 
 	if (res < 0)
 		goto failed;
 
 	return table;
 
+failed2:
+	kfree(data);
 failed:
 	kfree(table);
 	return ERR_PTR(res);
diff --git a/fs/squashfs/decompressor.c b/fs/squashfs/decompressor.c
index 234291f..ac22fe7 100644
--- a/fs/squashfs/decompressor.c
+++ b/fs/squashfs/decompressor.c
@@ -30,6 +30,7 @@
 #include "squashfs_fs_sb.h"
 #include "decompressor.h"
 #include "squashfs.h"
+#include "page_actor.h"
 
 /*
  * This file (and decompressor.h) implements a decompressor framework for
@@ -87,6 +88,7 @@ static void *get_comp_opts(struct super_block *sb, unsigned short flags)
 {
 	struct squashfs_sb_info *msblk = sb->s_fs_info;
 	void *buffer = NULL, *comp_opts;
+	struct squashfs_page_actor *actor = NULL;
 	int length = 0;
 
 	/*
@@ -99,9 +101,14 @@ static void *get_comp_opts(struct super_block *sb, unsigned short flags)
 			goto out;
 		}
 
-		length = squashfs_read_data(sb, &buffer,
-			sizeof(struct squashfs_super_block), 0, NULL,
-				PAGE_CACHE_SIZE, 1);
+		actor = squashfs_page_actor_init(&buffer, 1, 0);
+		if (actor == NULL) {
+			comp_opts = ERR_PTR(-ENOMEM);
+			goto out;
+		}
+
+		length = squashfs_read_data(sb,
+			sizeof(struct squashfs_super_block), 0, NULL, actor);
 
 		if (length < 0) {
 			comp_opts = ERR_PTR(length);
@@ -112,6 +119,7 @@ static void *get_comp_opts(struct super_block *sb, unsigned short flags)
 	comp_opts = squashfs_comp_opts(msblk, buffer, length);
 
 out:
+	kfree(actor);
 	kfree(buffer);
 	return comp_opts;
 }
diff --git a/fs/squashfs/decompressor.h b/fs/squashfs/decompressor.h
index 6cdb20a..af09853 100644
--- a/fs/squashfs/decompressor.h
+++ b/fs/squashfs/decompressor.h
@@ -27,8 +27,9 @@ struct squashfs_decompressor {
 	void	*(*init)(struct squashfs_sb_info *, void *);
 	void	*(*comp_opts)(struct squashfs_sb_info *, void *, int);
 	void	(*free)(void *);
-	int	(*decompress)(struct squashfs_sb_info *, void *, void **,
-		struct buffer_head **, int, int, int, int, int);
+	int	(*decompress)(struct squashfs_sb_info *, void *,
+		struct buffer_head **, int, int, int,
+		struct squashfs_page_actor *);
 	int	id;
 	char	*name;
 	int	supported;
diff --git a/fs/squashfs/decompressor_multi.c b/fs/squashfs/decompressor_multi.c
index 462731d..ae54675 100644
--- a/fs/squashfs/decompressor_multi.c
+++ b/fs/squashfs/decompressor_multi.c
@@ -183,15 +183,14 @@ wait:
 }
 
 
-int squashfs_decompress(struct squashfs_sb_info *msblk,
-	void **buffer, struct buffer_head **bh, int b, int offset, int length,
-	int srclength, int pages)
+int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
+	int b, int offset, int length, struct squashfs_page_actor *output)
 {
 	int res;
 	struct squashfs_stream *stream = msblk->stream;
 	struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream);
 	res = msblk->decompressor->decompress(msblk, decomp_stream->stream,
-		buffer, bh, b, offset, length, srclength, pages);
+		bh, b, offset, length, output);
 	put_decomp_stream(decomp_stream, stream);
 	if (res < 0)
 		ERROR("%s decompression failed, data probably corrupt\n",
diff --git a/fs/squashfs/decompressor_multi_percpu.c b/fs/squashfs/decompressor_multi_percpu.c
index 0e7b679..23a9c28 100644
--- a/fs/squashfs/decompressor_multi_percpu.c
+++ b/fs/squashfs/decompressor_multi_percpu.c
@@ -74,15 +74,14 @@ void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
 	}
 }
 
-int squashfs_decompress(struct squashfs_sb_info *msblk,
-	void **buffer, struct buffer_head **bh, int b, int offset, int length,
-	int srclength, int pages)
+int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
+	int b, int offset, int length, struct squashfs_page_actor *output)
 {
 	struct squashfs_stream __percpu *percpu =
 			(struct squashfs_stream __percpu *) msblk->stream;
 	struct squashfs_stream *stream = get_cpu_ptr(percpu);
-	int res = msblk->decompressor->decompress(msblk, stream->stream, buffer,
-		bh, b, offset, length, srclength, pages);
+	int res = msblk->decompressor->decompress(msblk, stream->stream, bh, b,
+		offset, length, output);
 	put_cpu_ptr(stream);
 
 	if (res < 0)
diff --git a/fs/squashfs/decompressor_single.c b/fs/squashfs/decompressor_single.c
index f857cf6..a6c7592 100644
--- a/fs/squashfs/decompressor_single.c
+++ b/fs/squashfs/decompressor_single.c
@@ -61,16 +61,15 @@ void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
 	}
 }
 
-int squashfs_decompress(struct squashfs_sb_info *msblk,
-	void **buffer, struct buffer_head **bh, int b, int offset, int length,
-	int srclength, int pages)
+int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
+	int b, int offset, int length, struct squashfs_page_actor *output)
 {
 	int res;
 	struct squashfs_stream *stream = msblk->stream;
 
 	mutex_lock(&stream->mutex);
-	res = msblk->decompressor->decompress(msblk, stream->stream, buffer,
-		bh, b, offset, length, srclength, pages);
+	res = msblk->decompressor->decompress(msblk, stream->stream, bh, b,
+		offset, length, output);
 	mutex_unlock(&stream->mutex);
 
 	if (res < 0)
diff --git a/fs/squashfs/lzo_wrapper.c b/fs/squashfs/lzo_wrapper.c
index 75c3b57..244b9fb 100644
--- a/fs/squashfs/lzo_wrapper.c
+++ b/fs/squashfs/lzo_wrapper.c
@@ -31,6 +31,7 @@
 #include "squashfs_fs_sb.h"
 #include "squashfs.h"
 #include "decompressor.h"
+#include "page_actor.h"
 
 struct squashfs_lzo {
 	void	*input;
@@ -75,13 +76,13 @@ static void lzo_free(void *strm)
 
 
 static int lzo_uncompress(struct squashfs_sb_info *msblk, void *strm,
-	void **buffer, struct buffer_head **bh, int b, int offset, int length,
-	int srclength, int pages)
+	struct buffer_head **bh, int b, int offset, int length,
+	struct squashfs_page_actor *output)
 {
 	struct squashfs_lzo *stream = strm;
-	void *buff = stream->input;
+	void *buff = stream->input, *data;
 	int avail, i, bytes = length, res;
-	size_t out_len = srclength;
+	size_t out_len = output->length;
 
 	for (i = 0; i < b; i++) {
 		avail = min(bytes, msblk->devblksize - offset);
@@ -98,12 +99,20 @@ static int lzo_uncompress(struct squashfs_sb_info *msblk, void *strm,
 		goto failed;
 
 	res = bytes = (int)out_len;
-	for (i = 0, buff = stream->output; bytes && i < pages; i++) {
-		avail = min_t(int, bytes, PAGE_CACHE_SIZE);
-		memcpy(buffer[i], buff, avail);
-		buff += avail;
-		bytes -= avail;
+	data = squashfs_first_page(output);
+	buff = stream->output;
+	while (data) {
+		if (bytes <= PAGE_CACHE_SIZE) {
+			memcpy(data, buff, bytes);
+			break;
+		} else {
+			memcpy(data, buff, PAGE_CACHE_SIZE);
+			buff += PAGE_CACHE_SIZE;
+			bytes -= PAGE_CACHE_SIZE;
+			data = squashfs_next_page(output);
+		}
 	}
+	squashfs_finish_page(output);
 
 	return res;
 
diff --git a/fs/squashfs/page_actor.h b/fs/squashfs/page_actor.h
new file mode 100644
index 0000000..5b0ba5a
--- /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
diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
index 2e2751d..6a97e63 100644
--- a/fs/squashfs/squashfs.h
+++ b/fs/squashfs/squashfs.h
@@ -28,8 +28,8 @@
 #define WARNING(s, args...)	pr_warning("SQUASHFS: "s, ## args)
 
 /* block.c */
-extern int squashfs_read_data(struct super_block *, void **, u64, int, u64 *,
-				int, int);
+extern int squashfs_read_data(struct super_block *, u64, int, u64 *,
+				struct squashfs_page_actor *);
 
 /* cache.c */
 extern struct squashfs_cache *squashfs_cache_init(char *, int, int);
@@ -53,8 +53,8 @@ extern void *squashfs_decompressor_setup(struct super_block *, unsigned short);
 /* decompressor_xxx.c */
 extern void *squashfs_decompressor_create(struct squashfs_sb_info *, void *);
 extern void squashfs_decompressor_destroy(struct squashfs_sb_info *);
-extern int squashfs_decompress(struct squashfs_sb_info *, void **,
-	struct buffer_head **, int, int, int, int, int);
+extern int squashfs_decompress(struct squashfs_sb_info *, struct buffer_head **,
+	int, int, int, struct squashfs_page_actor *);
 extern int squashfs_max_decompressors(void);
 
 /* export.c */
diff --git a/fs/squashfs/squashfs_fs_sb.h b/fs/squashfs/squashfs_fs_sb.h
index 9cdcf41..1da565c 100644
--- a/fs/squashfs/squashfs_fs_sb.h
+++ b/fs/squashfs/squashfs_fs_sb.h
@@ -50,6 +50,7 @@ struct squashfs_cache_entry {
 	wait_queue_head_t	wait_queue;
 	struct squashfs_cache	*cache;
 	void			**data;
+	struct squashfs_page_actor	*actor;
 };
 
 struct squashfs_sb_info {
diff --git a/fs/squashfs/xz_wrapper.c b/fs/squashfs/xz_wrapper.c
index 5d1d07c..c609624 100644
--- a/fs/squashfs/xz_wrapper.c
+++ b/fs/squashfs/xz_wrapper.c
@@ -32,6 +32,7 @@
 #include "squashfs_fs_sb.h"
 #include "squashfs.h"
 #include "decompressor.h"
+#include "page_actor.h"
 
 struct squashfs_xz {
 	struct xz_dec *state;
@@ -129,11 +130,11 @@ static void squashfs_xz_free(void *strm)
 
 
 static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
-	void **buffer, struct buffer_head **bh, int b, int offset, int length,
-	int srclength, int pages)
+	struct buffer_head **bh, int b, int offset, int length,
+	struct squashfs_page_actor *output)
 {
 	enum xz_ret xz_err;
-	int avail, total = 0, k = 0, page = 0;
+	int avail, total = 0, k = 0;
 	struct squashfs_xz *stream = strm;
 
 	xz_dec_reset(stream->state);
@@ -141,7 +142,7 @@ static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
 	stream->buf.in_size = 0;
 	stream->buf.out_pos = 0;
 	stream->buf.out_size = PAGE_CACHE_SIZE;
-	stream->buf.out = buffer[page++];
+	stream->buf.out = squashfs_first_page(output);
 
 	do {
 		if (stream->buf.in_pos == stream->buf.in_size && k < b) {
@@ -153,11 +154,12 @@ static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
 			offset = 0;
 		}
 
-		if (stream->buf.out_pos == stream->buf.out_size
-							&& page < pages) {
-			stream->buf.out = buffer[page++];
-			stream->buf.out_pos = 0;
-			total += PAGE_CACHE_SIZE;
+		if (stream->buf.out_pos == stream->buf.out_size) {
+			stream->buf.out = squashfs_next_page(output);
+			if (stream->buf.out != NULL) {
+				stream->buf.out_pos = 0;
+				total += PAGE_CACHE_SIZE;
+			}
 		}
 
 		xz_err = xz_dec_run(stream->state, &stream->buf);
@@ -166,6 +168,8 @@ static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
 			put_bh(bh[k++]);
 	} while (xz_err == XZ_OK);
 
+	squashfs_finish_page(output);
+
 	if (xz_err != XZ_STREAM_END || k < b)
 		goto out;
 
diff --git a/fs/squashfs/zlib_wrapper.c b/fs/squashfs/zlib_wrapper.c
index bb04902..8727cab 100644
--- a/fs/squashfs/zlib_wrapper.c
+++ b/fs/squashfs/zlib_wrapper.c
@@ -32,6 +32,7 @@
 #include "squashfs_fs_sb.h"
 #include "squashfs.h"
 #include "decompressor.h"
+#include "page_actor.h"
 
 static void *zlib_init(struct squashfs_sb_info *dummy, void *buff)
 {
@@ -62,14 +63,14 @@ static void zlib_free(void *strm)
 
 
 static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
-	void **buffer, struct buffer_head **bh, int b, int offset, int length,
-	int srclength, int pages)
+	struct buffer_head **bh, int b, int offset, int length,
+	struct squashfs_page_actor *output)
 {
-	int zlib_err, zlib_init = 0;
-	int k = 0, page = 0;
+	int zlib_err, zlib_init = 0, k = 0;
 	z_stream *stream = strm;
 
-	stream->avail_out = 0;
+	stream->avail_out = PAGE_CACHE_SIZE;
+	stream->next_out = squashfs_first_page(output);
 	stream->avail_in = 0;
 
 	do {
@@ -81,15 +82,18 @@ static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
 			offset = 0;
 		}
 
-		if (stream->avail_out == 0 && page < pages) {
-			stream->next_out = buffer[page++];
-			stream->avail_out = PAGE_CACHE_SIZE;
+		if (stream->avail_out == 0) {
+			stream->next_out = squashfs_next_page(output);
+			if (stream->next_out != NULL)
+				stream->avail_out = PAGE_CACHE_SIZE;
 		}
 
 		if (!zlib_init) {
 			zlib_err = zlib_inflateInit(stream);
-			if (zlib_err != Z_OK)
+			if (zlib_err != Z_OK) {
+				squashfs_finish_page(output);
 				goto out;
+			}
 			zlib_init = 1;
 		}
 
@@ -99,6 +103,8 @@ static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
 			put_bh(bh[k++]);
 	} while (zlib_err == Z_OK);
 
+	squashfs_finish_page(output);
+
 	if (zlib_err != Z_STREAM_END)
 		goto out;
 
-- 
cgit v0.10.2


From 5f55dbc0c5c466a9cdfa4da7ac1bfe351c7fc52a Mon Sep 17 00:00:00 2001
From: Phillip Lougher <phillip@squashfs.org.uk>
Date: Thu, 31 Oct 2013 19:24:27 +0000
Subject: Squashfs: Restructure squashfs_readpage()

Restructure squashfs_readpage() splitting it into separate
functions for datablocks, fragments and sparse blocks.

Move the memcpying (from squashfs cache entry) implementation of
squashfs_readpage_block into file_cache.c

This allows different implementations to be supported.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>

diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index 5833b96..e01ba11 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -4,7 +4,7 @@
 
 obj-$(CONFIG_SQUASHFS) += squashfs.o
 squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
-squashfs-y += namei.o super.o symlink.o decompressor.o
+squashfs-y += namei.o super.o symlink.o decompressor.o file_cache.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_SINGLE) += decompressor_single.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI) += decompressor_multi.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU) += decompressor_multi_percpu.o
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 8ca62c2..e5c9689 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -370,77 +370,15 @@ static int read_blocklist(struct inode *inode, int index, u64 *block)
 	return le32_to_cpu(size);
 }
 
-
-static int squashfs_readpage(struct file *file, struct page *page)
+/* Copy data into page cache  */
+void squashfs_copy_cache(struct page *page, struct squashfs_cache_entry *buffer,
+	int bytes, int offset)
 {
 	struct inode *inode = page->mapping->host;
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
-	int bytes, i, offset = 0, sparse = 0;
-	struct squashfs_cache_entry *buffer = NULL;
 	void *pageaddr;
-
-	int mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
-	int index = page->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
-	int start_index = page->index & ~mask;
-	int end_index = start_index | mask;
-	int file_end = i_size_read(inode) >> msblk->block_log;
-
-	TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
-				page->index, squashfs_i(inode)->start);
-
-	if (page->index >= ((i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
-					PAGE_CACHE_SHIFT))
-		goto out;
-
-	if (index < file_end || squashfs_i(inode)->fragment_block ==
-					SQUASHFS_INVALID_BLK) {
-		/*
-		 * Reading a datablock from disk.  Need to read block list
-		 * to get location and block size.
-		 */
-		u64 block = 0;
-		int bsize = read_blocklist(inode, index, &block);
-		if (bsize < 0)
-			goto error_out;
-
-		if (bsize == 0) { /* hole */
-			bytes = index == file_end ?
-				(i_size_read(inode) & (msblk->block_size - 1)) :
-				 msblk->block_size;
-			sparse = 1;
-		} else {
-			/*
-			 * Read and decompress datablock.
-			 */
-			buffer = squashfs_get_datablock(inode->i_sb,
-								block, bsize);
-			if (buffer->error) {
-				ERROR("Unable to read page, block %llx, size %x"
-					"\n", block, bsize);
-				squashfs_cache_put(buffer);
-				goto error_out;
-			}
-			bytes = buffer->length;
-		}
-	} else {
-		/*
-		 * Datablock is stored inside a fragment (tail-end packed
-		 * block).
-		 */
-		buffer = squashfs_get_fragment(inode->i_sb,
-				squashfs_i(inode)->fragment_block,
-				squashfs_i(inode)->fragment_size);
-
-		if (buffer->error) {
-			ERROR("Unable to read page, block %llx, size %x\n",
-				squashfs_i(inode)->fragment_block,
-				squashfs_i(inode)->fragment_size);
-			squashfs_cache_put(buffer);
-			goto error_out;
-		}
-		bytes = i_size_read(inode) & (msblk->block_size - 1);
-		offset = squashfs_i(inode)->fragment_offset;
-	}
+	int i, mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
+	int start_index = page->index & ~mask, end_index = start_index | mask;
 
 	/*
 	 * Loop copying datablock into pages.  As the datablock likely covers
@@ -451,7 +389,7 @@ static int squashfs_readpage(struct file *file, struct page *page)
 	for (i = start_index; i <= end_index && bytes > 0; i++,
 			bytes -= PAGE_CACHE_SIZE, offset += PAGE_CACHE_SIZE) {
 		struct page *push_page;
-		int avail = sparse ? 0 : min_t(int, bytes, PAGE_CACHE_SIZE);
+		int avail = buffer ? min_t(int, bytes, PAGE_CACHE_SIZE) : 0;
 
 		TRACE("bytes %d, i %d, available_bytes %d\n", bytes, i, avail);
 
@@ -475,11 +413,75 @@ skip_page:
 		if (i != page->index)
 			page_cache_release(push_page);
 	}
+}
+
+/* Read datablock stored packed inside a fragment (tail-end packed block) */
+static int squashfs_readpage_fragment(struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
+		squashfs_i(inode)->fragment_block,
+		squashfs_i(inode)->fragment_size);
+	int res = buffer->error;
+
+	if (res)
+		ERROR("Unable to read page, block %llx, size %x\n",
+			squashfs_i(inode)->fragment_block,
+			squashfs_i(inode)->fragment_size);
+	else
+		squashfs_copy_cache(page, buffer, i_size_read(inode) &
+			(msblk->block_size - 1),
+			squashfs_i(inode)->fragment_offset);
+
+	squashfs_cache_put(buffer);
+	return res;
+}
 
-	if (!sparse)
-		squashfs_cache_put(buffer);
+static int squashfs_readpage_sparse(struct page *page, int index, int file_end)
+{
+	struct inode *inode = page->mapping->host;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	int bytes = index == file_end ?
+			(i_size_read(inode) & (msblk->block_size - 1)) :
+			 msblk->block_size;
 
+	squashfs_copy_cache(page, NULL, bytes, 0);
 	return 0;
+}
+
+static int squashfs_readpage(struct file *file, struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+	int index = page->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
+	int file_end = i_size_read(inode) >> msblk->block_log;
+	int res;
+	void *pageaddr;
+
+	TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
+				page->index, squashfs_i(inode)->start);
+
+	if (page->index >= ((i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+					PAGE_CACHE_SHIFT))
+		goto out;
+
+	if (index < file_end || squashfs_i(inode)->fragment_block ==
+					SQUASHFS_INVALID_BLK) {
+		u64 block = 0;
+		int bsize = read_blocklist(inode, index, &block);
+		if (bsize < 0)
+			goto error_out;
+
+		if (bsize == 0)
+			res = squashfs_readpage_sparse(page, index, file_end);
+		else
+			res = squashfs_readpage_block(page, block, bsize);
+	} else
+		res = squashfs_readpage_fragment(page);
+
+	if (!res)
+		return 0;
 
 error_out:
 	SetPageError(page);
diff --git a/fs/squashfs/file_cache.c b/fs/squashfs/file_cache.c
new file mode 100644
index 0000000..f2310d2
--- /dev/null
+++ b/fs/squashfs/file_cache.c
@@ -0,0 +1,38 @@
+/*
+ * 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"
+
+/* Read separately compressed datablock and memcopy into page cache */
+int squashfs_readpage_block(struct page *page, u64 block, int bsize)
+{
+	struct inode *i = page->mapping->host;
+	struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb,
+		block, bsize);
+	int res = buffer->error;
+
+	if (res)
+		ERROR("Unable to read page, block %llx, size %x\n", block,
+			bsize);
+	else
+		squashfs_copy_cache(page, buffer, buffer->length, 0);
+
+	squashfs_cache_put(buffer);
+	return res;
+}
diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
index 6a97e63..9e1bb79 100644
--- a/fs/squashfs/squashfs.h
+++ b/fs/squashfs/squashfs.h
@@ -66,6 +66,13 @@ extern int squashfs_frag_lookup(struct super_block *, unsigned int, u64 *);
 extern __le64 *squashfs_read_fragment_index_table(struct super_block *,
 				u64, u64, unsigned int);
 
+/* file.c */
+void squashfs_copy_cache(struct page *, struct squashfs_cache_entry *, int,
+				int);
+
+/* file_xxx.c */
+extern int squashfs_readpage_block(struct page *, u64, int);
+
 /* id.c */
 extern int squashfs_get_id(struct super_block *, unsigned int, unsigned int *);
 extern __le64 *squashfs_read_id_index_table(struct super_block *, u64, u64,
-- 
cgit v0.10.2


From 0d455c12c6428647547bacccaaced3cae0f35570 Mon Sep 17 00:00:00 2001
From: Phillip Lougher <phillip@squashfs.org.uk>
Date: Wed, 13 Nov 2013 02:04:19 +0000
Subject: Squashfs: Directly decompress into the page cache for file data

This introduces an implementation of squashfs_readpage_block()
that directly decompresses into the page cache.

This uses the previously added page handler abstraction to push
down the necessary kmap_atomic/kunmap_atomic operations on the
page cache buffers into the decompressors.  This enables
direct copying into the page cache without using the slow
kmap/kunmap calls.

The code detects when multiple threads are racing in
squashfs_readpage() to decompress the same block, and avoids
this regression by falling back to using an intermediate
buffer.

This patch enhances the performance of Squashfs significantly
when multiple processes are accessing the filesystem simultaneously
because it not only reduces memcopying, but it more importantly
eliminates the lock contention on the intermediate buffer.

Using single-thread decompression.

        dd if=file1 of=/dev/null bs=4096 &
        dd if=file2 of=/dev/null bs=4096 &
        dd if=file3 of=/dev/null bs=4096 &
        dd if=file4 of=/dev/null bs=4096

Before:

629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s

After:

629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>

diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 159bd66..b6fa865 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -26,6 +26,34 @@ config SQUASHFS
 	  If unsure, say N.
 
 choice
+	prompt "File decompression options"
+	depends on SQUASHFS
+	help
+	  Squashfs now supports two options for decompressing file
+	  data.  Traditionally Squashfs has decompressed into an
+	  intermediate buffer and then memcopied it into the page cache.
+	  Squashfs now supports the ability to decompress directly into
+	  the page cache.
+
+	  If unsure, select "Decompress file data into an intermediate buffer"
+
+config SQUASHFS_FILE_CACHE
+	bool "Decompress file data into an intermediate buffer"
+	help
+	  Decompress file data into an intermediate buffer and then
+	  memcopy it into the page cache.
+
+config SQUASHFS_FILE_DIRECT
+	bool "Decompress files directly into the page cache"
+	help
+	  Directly decompress file data into the page cache.
+	  Doing so can significantly improve performance because
+	  it eliminates a memcpy and it also removes the lock contention
+	  on the single buffer.
+
+endchoice
+
+choice
 	prompt "Decompressor parallelisation options"
 	depends on SQUASHFS
 	help
diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index e01ba11..4132520 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -4,7 +4,9 @@
 
 obj-$(CONFIG_SQUASHFS) += squashfs.o
 squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
-squashfs-y += namei.o super.o symlink.o decompressor.o file_cache.o
+squashfs-y += namei.o super.o symlink.o decompressor.o
+squashfs-$(CONFIG_SQUASHFS_FILE_CACHE) += file_cache.o
+squashfs-$(CONFIG_SQUASHFS_FILE_DIRECT) += file_direct.o page_actor.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_SINGLE) += decompressor_single.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI) += decompressor_multi.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU) += decompressor_multi_percpu.o
diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c
new file mode 100644
index 0000000..2943b2b
--- /dev/null
+++ b/fs/squashfs/file_direct.c
@@ -0,0 +1,173 @@
+/*
+ * 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;
+}
diff --git a/fs/squashfs/page_actor.c b/fs/squashfs/page_actor.c
new file mode 100644
index 0000000..5a1c11f
--- /dev/null
+++ b/fs/squashfs/page_actor.c
@@ -0,0 +1,100 @@
+/*
+ * 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;
+}
diff --git a/fs/squashfs/page_actor.h b/fs/squashfs/page_actor.h
index 5b0ba5a..26dd820 100644
--- a/fs/squashfs/page_actor.h
+++ b/fs/squashfs/page_actor.h
@@ -8,6 +8,7 @@
  * the COPYING file in the top-level directory.
  */
 
+#ifndef CONFIG_SQUASHFS_FILE_DIRECT
 struct squashfs_page_actor {
 	void	**page;
 	int	pages;
@@ -46,4 +47,35 @@ static inline void squashfs_finish_page(struct squashfs_page_actor *actor)
 {
 	/* empty */
 }
+#else
+struct squashfs_page_actor {
+	union {
+		void		**buffer;
+		struct page	**page;
+	};
+	void	*pageaddr;
+	void    *(*squashfs_first_page)(struct squashfs_page_actor *);
+	void    *(*squashfs_next_page)(struct squashfs_page_actor *);
+	void    (*squashfs_finish_page)(struct squashfs_page_actor *);
+	int	pages;
+	int	length;
+	int	next_page;
+};
+
+extern struct squashfs_page_actor *squashfs_page_actor_init(void **, int, int);
+extern struct squashfs_page_actor *squashfs_page_actor_init_special(struct page
+							 **, int, int);
+static inline void *squashfs_first_page(struct squashfs_page_actor *actor)
+{
+	return actor->squashfs_first_page(actor);
+}
+static inline void *squashfs_next_page(struct squashfs_page_actor *actor)
+{
+	return actor->squashfs_next_page(actor);
+}
+static inline void squashfs_finish_page(struct squashfs_page_actor *actor)
+{
+	actor->squashfs_finish_page(actor);
+}
+#endif
 #endif
-- 
cgit v0.10.2


From ed4f381ec15e5f11724cdbc68cffd2c22d1eaebd Mon Sep 17 00:00:00 2001
From: Phillip Lougher <phillip@squashfs.org.uk>
Date: Sun, 10 Nov 2013 00:02:29 +0000
Subject: Squashfs: Check stream is not NULL in decompressor_multi.c

Fix static checker complaint that stream is not checked in
squashfs_decompressor_destroy().

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>

diff --git a/fs/squashfs/decompressor_multi.c b/fs/squashfs/decompressor_multi.c
index ae54675..d6008a6 100644
--- a/fs/squashfs/decompressor_multi.c
+++ b/fs/squashfs/decompressor_multi.c
@@ -119,11 +119,10 @@ void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
 			kfree(decomp_strm);
 			stream->avail_decomp--;
 		}
+		WARN_ON(stream->avail_decomp);
+		kfree(stream->comp_opts);
+		kfree(stream);
 	}
-
-	WARN_ON(stream->avail_decomp);
-	kfree(stream->comp_opts);
-	kfree(stream);
 }
 
 
-- 
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