[PATCH 2/17] [LogFS] compr.c

Joern Engel
2009-11-20T20:22:29Z

---
fs/logfs/compr.c | 95 ++

diff --git a/fs/logfs/compr.c b/fs/logfs/compr.c
new file mode 100644
index 0000000..44bbfd2
--- /dev/null
+++ b/fs/logfs/compr.c
@@ -0,0 +1,95 @@
+/*
+ * fs/logfs/compr.c - compression routines
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
+ */
+#include "logfs.h"
+#include <linux/vmalloc.h>
+#include <linux/zlib.h>
+
+#define COMPR_LEVEL 3
+
+static DEFINE_MUTEX(compr_mutex);
+static struct z_stream_s stream;
+
+int logfs_compress(void *in, void *out, size_t inlen, size_t outlen)
+{
+ int err, ret;
+
+ ret = -EIO;
+ mutex_lock(&compr_mutex);
+ err = zlib_deflateInit(&stream, COMPR_LEVEL);
+ if (err != Z_OK)
+ goto error;
+
+ stream.next_in = in;
+ stream.avail_in = inlen;
+ stream.total_in = 0;
+ stream.next_out = out;
+ stream.avail_out = outlen;
+ stream.total_out = 0;
+
+ err = zlib_deflate(&stream, Z_FINISH);
+ if (err != Z_STREAM_END)
+ goto error;
+
+ err = zlib_deflateEnd(&stream);
+ if (err != Z_OK)
+ goto error;
+
+ if (stream.total_out >= stream.total_in)
+ goto error;
+
+ ret = stream.total_out;
+error:
+ mutex_unlock(&compr_mutex);
+ return ret;
+}
+
+int logfs_uncompress(void *in, void *out, size_t inlen, size_t outlen)
+{
+ int err, ret;
+
+ ret = -EIO;
+ mutex_lock(&compr_mutex);
+ err = zlib_inflateInit(&stream);
+ if (err != Z_OK)
+ goto error;
+
+ stream.next_in = in;
+ stream.avail_in = inlen;
+ stream.total_in = 0;
+ stream.next_out = out;
+ stream.avail_out = outlen;
+ stream.total_out = 0;
+
+ err = zlib_inflate(&stream, Z_FINISH);
+ if (err != Z_STREAM_END)
+ goto error;
+
+ err = zlib_inflateEnd(&stream);
+ if (err != Z_OK)
+ goto error;
+
+ ret = 0;
+error:
+ mutex_unlock(&compr_mutex);
+ return ret;
+}
+
+int __init logfs_compr_init(void)
+{
+ size_t size = max(zlib_deflate_workspacesize(),
+ zlib_inflate_workspacesize());
+ stream.workspace = vmalloc(size);
+ if (!stream.workspace)
+ return -ENOMEM;
+ return 0;
+}
+
+void logfs_compr_exit(void)
+{
+ vfree(stream.workspace);
+}