[RFC 1/4] squashfs: use percpu for zlib decompression

[Stephen Hemminger <shemminger@vyatta.com>]

[-- Attachment #1: squashfs-gzip-percpu.patch --]
[-- Type: text/plain, Size: 3520 bytes --]

Make zlib decompression multi-threaded.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>


--- a/fs/squashfs/zlib_wrapper.c	2011-04-22 10:57:09.450024619 -0700
+++ b/fs/squashfs/zlib_wrapper.c	2011-04-22 13:15:52.509266395 -0700
@@ -26,6 +26,7 @@
 #include <linux/buffer_head.h>
 #include <linux/slab.h>
 #include <linux/zlib.h>
+#include <linux/percpu.h>
 #include <linux/vmalloc.h>
 
 #include "squashfs_fs.h"
@@ -33,31 +34,53 @@
 #include "squashfs.h"
 #include "decompressor.h"
 
+/* don't use per superblock stream anymore. */
 static void *zlib_init(struct squashfs_sb_info *dummy, void *buff, int len)
 {
-	z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
-	if (stream == NULL)
-		goto failed;
-	stream->workspace = vmalloc(zlib_inflate_workspacesize());
-	if (stream->workspace == NULL)
-		goto failed;
+	z_stream __percpu *percpu;
+	z_stream *stream;
+	int cpu, cpu0;
+
+	percpu = alloc_percpu(z_stream);
+	if (!percpu) {
+		ERROR("Failed to allocate per cpu stream\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	for_each_possible_cpu(cpu) {
+		stream = per_cpu_ptr(percpu, cpu);
+
+		stream->workspace = vmalloc(zlib_inflate_workspacesize());
+		if (stream->workspace == NULL)
+			goto failed;
+	}
 
-	return stream;
+	return (__force void *) percpu;
 
 failed:
-	ERROR("Failed to allocate zlib workspace\n");
-	kfree(stream);
+	for_each_possible_cpu(cpu0) {
+		if (cpu0 == cpu)
+			break;
+		stream = per_cpu_ptr(percpu, cpu);
+		vfree(stream->workspace);
+	}
+	free_percpu(percpu);
+
+	ERROR("Failed to allocate zlib workspaces\n");
 	return ERR_PTR(-ENOMEM);
 }
 
-
 static void zlib_free(void *strm)
 {
-	z_stream *stream = strm;
+	z_stream __percpu *percpu = (z_stream __percpu *) strm;
+	int cpu;
 
-	if (stream)
+	for_each_possible_cpu(cpu) {
+		z_stream *stream = per_cpu_ptr(percpu, cpu);
 		vfree(stream->workspace);
-	kfree(stream);
+
+	}
+	free_percpu(percpu);
 }
 
 
@@ -67,9 +90,8 @@ static int zlib_uncompress(struct squash
 {
 	int zlib_err, zlib_init = 0;
 	int k = 0, page = 0;
-	z_stream *stream = msblk->stream;
-
-	mutex_lock(&msblk->read_data_mutex);
+	z_stream __percpu *percpu = (z_stream __percpu *)msblk->stream;
+	z_stream *stream = get_cpu_ptr(percpu);
 
 	stream->avail_out = 0;
 	stream->avail_in = 0;
@@ -80,7 +102,7 @@ static int zlib_uncompress(struct squash
 			length -= avail;
 			wait_on_buffer(bh[k]);
 			if (!buffer_uptodate(bh[k]))
-				goto release_mutex;
+				goto put_per_cpu;
 
 			stream->next_in = bh[k]->b_data + offset;
 			stream->avail_in = avail;
@@ -98,7 +120,7 @@ static int zlib_uncompress(struct squash
 				ERROR("zlib_inflateInit returned unexpected "
 					"result 0x%x, srclength %d\n",
 					zlib_err, srclength);
-				goto release_mutex;
+				goto put_per_cpu;
 			}
 			zlib_init = 1;
 		}
@@ -111,26 +133,26 @@ static int zlib_uncompress(struct squash
 
 	if (zlib_err != Z_STREAM_END) {
 		ERROR("zlib_inflate error, data probably corrupt\n");
-		goto release_mutex;
+		goto put_per_cpu;
 	}
 
 	zlib_err = zlib_inflateEnd(stream);
 	if (zlib_err != Z_OK) {
 		ERROR("zlib_inflate error, data probably corrupt\n");
-		goto release_mutex;
+		goto put_per_cpu;
 	}
 
 	if (k < b) {
 		ERROR("zlib_uncompress error, data remaining\n");
-		goto release_mutex;
+		goto put_per_cpu;
 	}
 
 	length = stream->total_out;
-	mutex_unlock(&msblk->read_data_mutex);
+	put_cpu_ptr(stream);
 	return length;
 
-release_mutex:
-	mutex_unlock(&msblk->read_data_mutex);
+put_per_cpu:
+	put_cpu_ptr(stream);
 
 	for (; k < b; k++)
 		put_bh(bh[k]);