UBUNTU: SAUCE: (noup) Update spl to 0.6.5.9-1, zfs to 0.6.5.9-2

[mirror_ubuntu-artful-kernel.git] / zfs / module / zfs / lzjb.c

diff --git a/zfs/module/zfs/lzjb.c b/zfs/module/zfs/lzjb.c
new file mode 100644 (file)
index 0000000..ae18467
--- /dev/null
+++ b/zfs/module/zfs/lzjb.c
@@ -0,0 +1,131 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ */
+
+/*
+ * We keep our own copy of this algorithm for 3 main reasons:
+ *     1. If we didn't, anyone modifying common/os/compress.c would
+ *         directly break our on disk format
+ *     2. Our version of lzjb does not have a number of checks that the
+ *         common/os version needs and uses
+ *     3. We initialize the lempel to ensure deterministic results,
+ *        so that identical blocks can always be deduplicated.
+ * In particular, we are adding the "feature" that compress() can
+ * take a destination buffer size and returns the compressed length, or the
+ * source length if compression would overflow the destination buffer.
+ */
+
+#include <sys/zfs_context.h>
+
+#define        MATCH_BITS      6
+#define        MATCH_MIN       3
+#define        MATCH_MAX       ((1 << MATCH_BITS) + (MATCH_MIN - 1))
+#define        OFFSET_MASK     ((1 << (16 - MATCH_BITS)) - 1)
+#define        LEMPEL_SIZE     1024
+
+/*ARGSUSED*/
+size_t
+lzjb_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
+{
+       uchar_t *src = s_start;
+       uchar_t *dst = d_start;
+       uchar_t *cpy;
+       uchar_t *copymap = NULL;
+       int copymask = 1 << (NBBY - 1);
+       int mlen, offset, hash;
+       uint16_t *hp;
+       uint16_t *lempel;
+
+       lempel = kmem_zalloc(LEMPEL_SIZE * sizeof (uint16_t), KM_SLEEP);
+       while (src < (uchar_t *)s_start + s_len) {
+               if ((copymask <<= 1) == (1 << NBBY)) {
+                       if (dst >= (uchar_t *)d_start + d_len - 1 - 2 * NBBY) {
+                               kmem_free(lempel,
+                                   LEMPEL_SIZE*sizeof (uint16_t));
+                               return (s_len);
+                       }
+                       copymask = 1;
+                       copymap = dst;
+                       *dst++ = 0;
+               }
+               if (src > (uchar_t *)s_start + s_len - MATCH_MAX) {
+                       *dst++ = *src++;
+                       continue;
+               }
+               hash = (src[0] << 16) + (src[1] << 8) + src[2];
+               hash += hash >> 9;
+               hash += hash >> 5;
+               hp = &lempel[hash & (LEMPEL_SIZE - 1)];
+               offset = (intptr_t)(src - *hp) & OFFSET_MASK;
+               *hp = (uint16_t)(uintptr_t)src;
+               cpy = src - offset;
+               if (cpy >= (uchar_t *)s_start && cpy != src &&
+                   src[0] == cpy[0] && src[1] == cpy[1] && src[2] == cpy[2]) {
+                       *copymap |= copymask;
+                       for (mlen = MATCH_MIN; mlen < MATCH_MAX; mlen++)
+                               if (src[mlen] != cpy[mlen])
+                                       break;
+                       *dst++ = ((mlen - MATCH_MIN) << (NBBY - MATCH_BITS)) |
+                           (offset >> NBBY);
+                       *dst++ = (uchar_t)offset;
+                       src += mlen;
+               } else {
+                       *dst++ = *src++;
+               }
+       }
+
+       kmem_free(lempel, LEMPEL_SIZE * sizeof (uint16_t));
+       return (dst - (uchar_t *)d_start);
+}
+
+/*ARGSUSED*/
+int
+lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
+{
+       uchar_t *src = s_start;
+       uchar_t *dst = d_start;
+       uchar_t *d_end = (uchar_t *)d_start + d_len;
+       uchar_t *cpy;
+       uchar_t copymap = 0;
+       int copymask = 1 << (NBBY - 1);
+
+       while (dst < d_end) {
+               if ((copymask <<= 1) == (1 << NBBY)) {
+                       copymask = 1;
+                       copymap = *src++;
+               }
+               if (copymap & copymask) {
+                       int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
+                       int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
+                       src += 2;
+                       if ((cpy = dst - offset) < (uchar_t *)d_start)
+                               return (-1);
+                       while (--mlen >= 0 && dst < d_end)
+                               *dst++ = *cpy++;
+               } else {
+                       *dst++ = *src++;
+               }
+       }
+       return (0);
+}