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Message-ID: <20130816131805.3338.68767.stgit@aruna-ThinkPad-T420>
Date: Fri, 16 Aug 2013 18:48:05 +0530
From: Aruna Balakrishnaiah <aruna@...ux.vnet.ibm.com>
To: linuxppc-dev@...abs.org, tony.luck@...el.com,
linux-kernel@...r.kernel.org, keescook@...omium.org
Cc: jkenisto@...ux.vnet.ibm.com, ananth@...ibm.com,
benh@...nel.crashing.org, cbouatmailru@...il.com,
mahesh@...ux.vnet.ibm.com, ccross@...roid.com
Subject: [RFC PATCH v2 04/11] pstore: Add compression support to pstore
Add compression support to pstore which will help in capturing more data.
Initially, pstore will make a call to kmsg_dump with a bigger buffer
and will pass the size of bigger buffer to kmsg_dump and then compress
the data to registered buffer of registered size.
In case compression fails, pstore will capture the uncompressed
data by making a call again to kmsg_dump with registered_buffer
of registered size.
Pstore will indicate the data is compressed or not with a flag
in the write callback.
Signed-off-by: Aruna Balakrishnaiah <aruna@...ux.vnet.ibm.com>
---
fs/pstore/platform.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 139 insertions(+), 9 deletions(-)
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 20fa686..56218cb 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -26,6 +26,7 @@
#include <linux/console.h>
#include <linux/module.h>
#include <linux/pstore.h>
+#include <linux/zlib.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/slab.h>
@@ -65,6 +66,15 @@ struct pstore_info *psinfo;
static char *backend;
+/* Compression parameters */
+#define COMPR_LEVEL 6
+#define WINDOW_BITS 12
+#define MEM_LEVEL 4
+static struct z_stream_s stream;
+
+static char *big_oops_buf;
+static size_t big_oops_buf_sz;
+
/* How much of the console log to snapshot */
static unsigned long kmsg_bytes = 10240;
@@ -117,6 +127,91 @@ bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
}
EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
+/* Derived from logfs_compress() */
+static int pstore_compress(const void *in, void *out, size_t inlen,
+ size_t outlen)
+{
+ int err, ret;
+
+ ret = -EIO;
+ err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
+ MEM_LEVEL, Z_DEFAULT_STRATEGY);
+ 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:
+ return ret;
+}
+
+static void allocate_buf_for_compression(void)
+{
+ size_t size;
+
+ big_oops_buf_sz = (psinfo->bufsize * 100) / 45;
+ big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
+ if (big_oops_buf) {
+ size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
+ zlib_inflate_workspacesize());
+ stream.workspace = kmalloc(size, GFP_KERNEL);
+ if (!stream.workspace) {
+ pr_err("pstore: No memory for compression workspace; "
+ "skipping compression\n");
+ kfree(big_oops_buf);
+ big_oops_buf = NULL;
+ }
+ } else {
+ pr_err("No memory for uncompressed data; "
+ "skipping compression\n");
+ stream.workspace = NULL;
+ }
+
+}
+
+/*
+ * Called when compression fails, since the printk buffer
+ * would be fetched for compression calling it again when
+ * compression fails would have moved the iterator of
+ * printk buffer which results in fetching old contents.
+ * Copy the recent messages from big_oops_buf to psinfo->buf
+ */
+static size_t copy_kmsg_to_buffer(int hsize, size_t len)
+{
+ size_t total_len;
+ size_t diff;
+
+ total_len = hsize + len;
+
+ if (total_len > psinfo->bufsize) {
+ diff = total_len - psinfo->bufsize + hsize;
+ memcpy(psinfo->buf, big_oops_buf, hsize);
+ memcpy(psinfo->buf + hsize, big_oops_buf + diff,
+ psinfo->bufsize - hsize);
+ total_len = psinfo->bufsize;
+ } else
+ memcpy(psinfo->buf, big_oops_buf, total_len);
+
+ return total_len;
+}
+
/*
* callback from kmsg_dump. (s2,l2) has the most recently
* written bytes, older bytes are in (s1,l1). Save as much
@@ -148,23 +243,56 @@ static void pstore_dump(struct kmsg_dumper *dumper,
char *dst;
unsigned long size;
int hsize;
+ int zipped_len = -1;
size_t len;
- bool compressed = false;
+ bool compressed;
+ size_t total_len;
- dst = psinfo->buf;
- hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
- size = psinfo->bufsize - hsize;
- dst += hsize;
+ if (big_oops_buf) {
+ dst = big_oops_buf;
+ hsize = sprintf(dst, "%s#%d Part%d\n", why,
+ oopscount, part);
+ size = big_oops_buf_sz - hsize;
- if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
- break;
+ if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
+ size, &len))
+ break;
+
+ zipped_len = pstore_compress(dst, psinfo->buf,
+ hsize + len, psinfo->bufsize);
+
+ if (zipped_len > 0) {
+ compressed = true;
+ total_len = zipped_len;
+ } else {
+ pr_err("pstore: compression failed for Part %d"
+ " returned %d\n", part, zipped_len);
+ pr_err("pstore: Capture uncompressed"
+ " oops/panic report of Part %d\n", part);
+ compressed = false;
+ total_len = copy_kmsg_to_buffer(hsize, len);
+ }
+ } else {
+ dst = psinfo->buf;
+ hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount,
+ part);
+ size = psinfo->bufsize - hsize;
+ dst += hsize;
+
+ if (!kmsg_dump_get_buffer(dumper, true, dst,
+ size, &len))
+ break;
+
+ compressed = false;
+ total_len = hsize + len;
+ }
ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
- oopscount, compressed, hsize + len, psinfo);
+ oopscount, compressed, total_len, psinfo);
if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
pstore_new_entry = 1;
- total += hsize + len;
+ total += total_len;
part++;
}
if (pstore_cannot_block_path(reason)) {
@@ -262,6 +390,8 @@ int pstore_register(struct pstore_info *psi)
return -EINVAL;
}
+ allocate_buf_for_compression();
+
if (pstore_is_mounted())
pstore_get_records(0);
--
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