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 <ar...@linux.vnet.ibm.com>
---
fs/pstore/platform.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 115 insertions(+), 9 deletions(-)
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 20fa686..5b95524 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 +66,12 @@ 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;
+
/* How much of the console log to snapshot */
static unsigned long kmsg_bytes = 10240;
@@ -117,6 +124,80 @@ 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;
+}
+
+/* Compress the text from dst into psinfo->buf. */
+static int zip_data(char *dst, size_t text_len)
+{
+ int zipped_len = pstore_compress(dst, psinfo->buf, text_len,
+ psinfo->bufsize);
+
+ kfree(dst);
+ kfree(stream.workspace);
+ if (zipped_len < 0) {
+ pr_err("pstore: compression failed; returned %d\n", zipped_len);
+ pr_err("pstore: logging uncompressed oops/panic report\n");
+ return -1;
+ }
+
+ return zipped_len;
+}
+
+static char *allocate_buf_for_compression(unsigned long big_buf_sz)
+{
+ char *big_buf;
+
+ big_buf = kmalloc(big_buf_sz, GFP_KERNEL);
+ if (big_buf) {
+ stream.workspace = kmalloc(zlib_deflate_workspacesize(
+ WINDOW_BITS, MEM_LEVEL), GFP_KERNEL);
+ if (!stream.workspace) {
+ pr_err("pstore: No memory for compression workspace; "
+ "skipping compression\n");
+ kfree(big_buf);
+ big_buf = NULL;
+ }
+ } else {
+ pr_err("No memory for uncompressed data; "
+ "skipping compression\n");
+ stream.workspace = NULL;
+ }
+
+ return big_buf;
+}
/*
* callback from kmsg_dump. (s2,l2) has the most recently
* written bytes, older bytes are in (s1,l1). Save as much
@@ -146,18 +227,43 @@ static void pstore_dump(struct kmsg_dumper *dumper,
oopscount++;
while (total < kmsg_bytes) {
char *dst;
- unsigned long size;
- int hsize;
+ unsigned long size, big_buf_sz;
+ int hsize = 0;
+ int zipped_len = -1;
size_t len;
- bool compressed = false;
+ bool compressed;
+
+ big_buf_sz = (psinfo->bufsize * 100) / 45;
+ dst = allocate_buf_for_compression(big_buf_sz);
- dst = psinfo->buf;
- hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
- size = psinfo->bufsize - hsize;
- dst += hsize;
+ if (dst) {
+ hsize = sprintf(dst, "%s#%d Part%d\n", why,
+ oopscount, part);
+ size = big_buf_sz - hsize;
+ dst += hsize;
- if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
- break;
+ if (!kmsg_dump_get_buffer(dumper, true, dst,
+ size, &len))
+ break;
+
+ zipped_len = zip_data(dst, hsize + len);
+ }
+
+ if (zipped_len < 0) {
+ dst = psinfo->buf;
+ hsize = sprintf(dst, "%s#%d Part%d\n",
+ why, oopscount, part);
+ size = psinfo->bufsize - hsize;
+ dst += hsize;
+ compressed = false;
+
+ if (!kmsg_dump_get_buffer(dumper, true, dst,
+ size, &len))
+ break;
+ } else {
+ compressed = true;
+ len = zipped_len;
+ }
ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
oopscount, compressed, hsize + len, psinfo);
--
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