#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/uio.h>
+#include <linux/sort.h>
#include "cifsglob.h"
#include "../common/smb2pdu.h"
#include "compress/lz77.h"
#include "compress.h"
-int smb_compress(void *buf, const void *data, size_t *len)
+/*
+ * The heuristic_*() functions below try to determine data compressibility.
+ *
+ * Derived from fs/btrfs/compression.c, changing coding style, some parameters, and removing
+ * unused parts.
+ *
+ * Read that file for better and more detailed explanation of the calculations.
+ *
+ * The algorithms are ran in a collected sample of the input (uncompressed) data.
+ * The sample is formed of 2K reads in PAGE_SIZE intervals, with a maximum size of 4M.
+ *
+ * Parsing the sample goes from "low-hanging fruits" (fastest algorithms, likely compressible)
+ * to "need more analysis" (likely uncompressible).
+ */
+
+struct bucket {
+ unsigned int count;
+};
+
+/**
+ * calc_shannon_entropy() - Compute Shannon entropy of the sampled data.
+ * @bkt: Bytes counts of the sample.
+ * @slen: Size of the sample.
+ *
+ * Return: true if the level (percentage of number of bits that would be required to
+ * compress the data) is below the minimum threshold.
+ *
+ * Note:
+ * There _is_ an entropy level here that's > 65 (minimum threshold) that would indicate a
+ * possibility of compression, but compressing, or even further analysing, it would waste so much
+ * resources that it's simply not worth it.
+ *
+ * Also Shannon entropy is the last computed heuristic; if we got this far and ended up
+ * with uncertainty, just stay on the safe side and call it uncompressible.
+ */
+static bool calc_shannon_entropy(struct bucket *bkt, size_t slen)
+{
+ const size_t threshold = 65, max_entropy = 8 * ilog2(16);
+ size_t i, p, p2, len, sum = 0;
+
+#define pow4(n) (n * n * n * n)
+ len = ilog2(pow4(slen));
+
+ for (i = 0; i < 256 && bkt[i].count > 0; i++) {
+ p = bkt[i].count;
+ p2 = ilog2(pow4(p));
+ sum += p * (len - p2);
+ }
+
+ sum /= slen;
+
+ return ((sum * 100 / max_entropy) <= threshold);
+}
+
+/**
+ * calc_byte_distribution() - Compute byte distribution on the sampled data.
+ * @bkt: Byte counts of the sample.
+ * @slen: Size of the sample.
+ *
+ * Return:
+ * 1: High probability (normal (Gaussian) distribution) of the data being compressible.
+ * 0: A "hard no" for compression -- either a computed uniform distribution of the bytes (e.g.
+ * random or encrypted data), or calc_shannon_entropy() returned false (see above).
+ * 2: When computed byte distribution resulted in "low > n < high" grounds.
+ * calc_shannon_entropy() should be used for a final decision.
+ */
+static int calc_byte_distribution(struct bucket *bkt, size_t slen)
{
- struct smb2_compression_hdr *hdr;
- size_t buf_len, data_len;
+ const size_t low = 64, high = 200, threshold = slen * 90 / 100;
+ size_t sum = 0;
+ int i;
+
+ for (i = 0; i < low; i++)
+ sum += bkt[i].count;
+
+ if (sum > threshold)
+ return i;
+
+ for (; i < high && bkt[i].count > 0; i++) {
+ sum += bkt[i].count;
+ if (sum > threshold)
+ break;
+ }
+
+ if (i <= low)
+ return 1;
+
+ if (i >= high)
+ return 0;
+
+ return 2;
+}
+
+static bool check_ascii_bytes(const struct bucket *bkt)
+{
+ const size_t threshold = 64;
+ size_t count = 0;
+ int i;
+
+ for (i = 0; i < threshold; i++)
+ if (bkt[i].count > 0)
+ count++;
+
+ for (; i < 256; i++) {
+ if (bkt[i].count > 0) {
+ count++;
+ if (count > threshold)
+ break;
+ }
+ }
+
+ return (count < threshold);
+}
+
+static bool check_repeated_data(const u8 *sample, size_t len)
+{
+ size_t s = len / 2;
+
+ return (!memcmp(&sample[0], &sample[s], s));
+}
+
+static int cmp_bkt(const void *_a, const void *_b)
+{
+ const struct bucket *a = _a, *b = _b;
+
+ /* Reverse sort. */
+ if (a->count > b->count)
+ return -1;
+
+ return 1;
+}
+
+/*
+ * TODO:
+ * Support other iter types, if required.
+ * Only ITER_XARRAY is supported for now.
+ */
+static int collect_sample(const struct iov_iter *iter, ssize_t max, u8 *sample)
+{
+ struct folio *folios[16], *folio;
+ unsigned int nr, i, j, npages;
+ loff_t start = iter->xarray_start + iter->iov_offset;
+ pgoff_t last, index = start / PAGE_SIZE;
+ size_t len, off, foff;
+ ssize_t ret = 0;
+ void *p;
+ int s = 0;
+
+ last = (start + max - 1) / PAGE_SIZE;
+ do {
+ nr = xa_extract(iter->xarray, (void **)folios, index, last, ARRAY_SIZE(folios),
+ XA_PRESENT);
+ if (nr == 0)
+ return -EIO;
+
+ for (i = 0; i < nr; i++) {
+ folio = folios[i];
+ npages = folio_nr_pages(folio);
+ foff = start - folio_pos(folio);
+ off = foff % PAGE_SIZE;
+
+ for (j = foff / PAGE_SIZE; j < npages; j++) {
+ size_t len2;
+
+ len = min_t(size_t, max, PAGE_SIZE - off);
+ len2 = min_t(size_t, len, SZ_2K);
+
+ p = kmap_local_page(folio_page(folio, j));
+ memcpy(&sample[s], p, len2);
+ kunmap_local(p);
+
+ if (ret < 0)
+ return ret;
+
+ s += len2;
+
+ if (len2 < SZ_2K || s >= max - SZ_2K)
+ return s;
+
+ max -= len;
+ if (max <= 0)
+ return s;
+
+ start += len;
+ off = 0;
+ index++;
+ }
+ }
+ } while (nr == ARRAY_SIZE(folios));
+
+ return s;
+}
+
+/**
+ * is_compressible() - Determines if a chunk of data is compressible.
+ * @data: Iterator containing uncompressed data.
+ *
+ * Return:
+ * 0: @data is not compressible
+ * 1: @data is compressible
+ * -ENOMEM: failed to allocate memory for sample buffer
+ *
+ * Tests shows that this function is quite reliable in predicting data compressibility,
+ * matching close to 1:1 with the behaviour of LZ77 compression success and failures.
+ */
+static int is_compressible(const struct iov_iter *data)
+{
+ const size_t read_size = SZ_2K, bkt_size = 256, max = SZ_4M;
+ struct bucket *bkt;
+ int i = 0, ret = 0;
+ size_t len;
+ u8 *sample;
+
+ len = iov_iter_count(data);
+ if (len < read_size)
+ return 0;
+
+ if (len - read_size > max)
+ len = max;
+
+ sample = kvzalloc(len, GFP_KERNEL);
+ if (!sample)
+ return -ENOMEM;
+
+ /* Sample 2K bytes per page of the uncompressed data. */
+ ret = collect_sample(data, len, sample);
+ if (ret < 0)
+ goto out;
+
+ len = ret;
+ ret = 1;
+
+ if (check_repeated_data(sample, len))
+ goto out;
+
+ bkt = kcalloc(bkt_size, sizeof(*bkt), GFP_KERNEL);
+ if (!bkt) {
+ kvfree(sample);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < len; i++)
+ bkt[sample[i]].count++;
+
+ if (check_ascii_bytes(bkt))
+ goto out;
+
+ /* Sort in descending order */
+ sort(bkt, bkt_size, sizeof(*bkt), cmp_bkt, NULL);
+
+ ret = calc_byte_distribution(bkt, len);
+ if (ret != 2)
+ goto out;
+
+ ret = calc_shannon_entropy(bkt, len);
+out:
+ kvfree(sample);
+ kfree(bkt);
+
+ WARN(ret < 0, "%s: ret=%d\n", __func__, ret);
+
+ return !!ret;
+}
+
+bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq)
+{
+ const struct smb2_hdr *shdr = rq->rq_iov->iov_base;
+
+ if (unlikely(!tcon || !tcon->ses || !tcon->ses->server))
+ return false;
+
+ if (!tcon->ses->server->compression.enabled)
+ return false;
+
+ if (!(tcon->share_flags & SMB2_SHAREFLAG_COMPRESS_DATA))
+ return false;
+
+ if (shdr->Command == SMB2_WRITE) {
+ const struct smb2_write_req *wreq = rq->rq_iov->iov_base;
+
+ if (wreq->Length < SMB_COMPRESS_MIN_LEN)
+ return false;
+
+ return is_compressible(&rq->rq_iter);
+ }
+
+ return (shdr->Command == SMB2_READ);
+}
+
+int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq, compress_send_fn send_fn)
+{
+ struct iov_iter iter;
+ u32 slen, dlen;
+ void *src, *dst;
int ret;
- buf_len = sizeof(struct smb2_write_req);
- data_len = *len;
- *len = 0;
-
- hdr = buf;
- hdr->ProtocolId = SMB2_COMPRESSION_TRANSFORM_ID;
- hdr->OriginalCompressedSegmentSize = cpu_to_le32(data_len);
- hdr->Offset = cpu_to_le32(buf_len);
- hdr->Flags = SMB2_COMPRESSION_FLAG_NONE;
- hdr->CompressionAlgorithm = SMB3_COMPRESS_LZ77;
-
- /* XXX: add other algs here as they're implemented */
- ret = lz77_compress(data, data_len, buf + SMB_COMPRESS_HDR_LEN + buf_len, &data_len);
- if (!ret)
- *len = SMB_COMPRESS_HDR_LEN + buf_len + data_len;
+ if (!server || !rq || !rq->rq_iov || !rq->rq_iov->iov_base)
+ return -EINVAL;
+
+ if (rq->rq_iov->iov_len != sizeof(struct smb2_write_req))
+ return -EINVAL;
+
+ slen = iov_iter_count(&rq->rq_iter);
+ src = kvzalloc(slen, GFP_KERNEL);
+ if (!src) {
+ ret = -ENOMEM;
+ goto err_free;
+ }
+
+ /* Keep the original iter intact. */
+ iter = rq->rq_iter;
+
+ if (!copy_from_iter_full(src, slen, &iter)) {
+ ret = -EIO;
+ goto err_free;
+ }
+
+ /*
+ * This is just overprovisioning, as the algorithm will error out if @dst reaches 7/8
+ * of @slen.
+ */
+ dlen = slen;
+ dst = kvzalloc(dlen, GFP_KERNEL);
+ if (!dst) {
+ ret = -ENOMEM;
+ goto err_free;
+ }
+
+ ret = lz77_compress(src, slen, dst, &dlen);
+ if (!ret) {
+ struct smb2_compression_hdr hdr = { 0 };
+ struct smb_rqst comp_rq = { .rq_nvec = 3, };
+ struct kvec iov[3];
+
+ hdr.ProtocolId = SMB2_COMPRESSION_TRANSFORM_ID;
+ hdr.OriginalCompressedSegmentSize = cpu_to_le32(slen);
+ hdr.CompressionAlgorithm = SMB3_COMPRESS_LZ77;
+ hdr.Flags = SMB2_COMPRESSION_FLAG_NONE;
+ hdr.Offset = cpu_to_le32(rq->rq_iov[0].iov_len);
+
+ iov[0].iov_base = &hdr;
+ iov[0].iov_len = sizeof(hdr);
+ iov[1] = rq->rq_iov[0];
+ iov[2].iov_base = dst;
+ iov[2].iov_len = dlen;
+
+ comp_rq.rq_iov = iov;
+
+ ret = send_fn(server, 1, &comp_rq);
+ } else if (ret == -EMSGSIZE || dlen >= slen) {
+ ret = send_fn(server, 1, rq);
+ }
+err_free:
+ kvfree(dst);
+ kvfree(src);
return ret;
}
#define SMB_COMPRESS_PAYLOAD_HDR_LEN 8
#define SMB_COMPRESS_MIN_LEN PAGE_SIZE
-struct smb_compress_ctx {
- struct TCP_Server_Info *server;
- struct work_struct work;
- struct mid_q_entry *mid;
+#ifdef CONFIG_CIFS_COMPRESSION
+typedef int (*compress_send_fn)(struct TCP_Server_Info *, int, struct smb_rqst *);
- void *buf; /* compressed data */
- void *data; /* uncompressed data */
- size_t len;
-};
+int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq, compress_send_fn send_fn);
-#ifdef CONFIG_CIFS_COMPRESSION
-int smb_compress(void *buf, const void *data, size_t *len);
+/**
+ * should_compress() - Determines if a request (write) or the response to a
+ * request (read) should be compressed.
+ * @tcon: tcon of the request is being sent to
+ * @rqst: request to evaluate
+ *
+ * Return: true iff:
+ * - compression was successfully negotiated with server
+ * - server has enabled compression for the share
+ * - it's a read or write request
+ * - (write only) request length is >= SMB_COMPRESS_MIN_LEN
+ * - (write only) is_compressible() returns 1
+ *
+ * Return false otherwise.
+ */
+bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq);
/**
* smb_compress_alg_valid() - Validate a compression algorithm.
return false;
}
-
-/**
- * should_compress() - Determines if a request (write) or the response to a
- * request (read) should be compressed.
- * @tcon: tcon of the request is being sent to
- * @buf: buffer with an SMB2 READ/WRITE request
- *
- * Return: true iff:
- * - compression was successfully negotiated with server
- * - server has enabled compression for the share
- * - it's a read or write request
- * - if write, request length is >= SMB_COMPRESS_MIN_LEN
- *
- * Return false otherwise.
- */
-static __always_inline bool should_compress(const struct cifs_tcon *tcon, const void *buf)
+#else /* !CONFIG_CIFS_COMPRESSION */
+static inline int smb_compress(void *unused1, void *unused2, void *unused3)
{
- const struct smb2_hdr *shdr = buf;
-
- if (!tcon || !tcon->ses || !tcon->ses->server)
- return false;
-
- if (!tcon->ses->server->compression.enabled)
- return false;
-
- if (!(tcon->share_flags & SMB2_SHAREFLAG_COMPRESS_DATA))
- return false;
-
- if (shdr->Command == SMB2_WRITE) {
- const struct smb2_write_req *req = buf;
+ return -EOPNOTSUPP;
+}
- return (req->Length >= SMB_COMPRESS_MIN_LEN);
- }
+static inline bool should_compress(void *unused1, void *unused2)
+{
+ return false;
+}
- return (shdr->Command == SMB2_READ);
+static inline int smb_compress_alg_valid(__le16 unused1, bool unused2)
+{
+ return -EOPNOTSUPP;
}
-/*
- * #else !CONFIG_CIFS_COMPRESSION ...
- * These routines should not be called when CONFIG_CIFS_COMPRESSION disabled
- * #define smb_compress(arg1, arg2, arg3) (-EOPNOTSUPP)
- * #define smb_compress_alg_valid(arg1, arg2) (-EOPNOTSUPP)
- * #define should_compress(arg1, arg2) (false)
- */
#endif /* !CONFIG_CIFS_COMPRESSION */
#endif /* _SMB_COMPRESS_H */
* Implementation of the LZ77 "plain" compression algorithm, as per MS-XCA spec.
*/
#include <linux/slab.h>
+#include <linux/sizes.h>
+#include <linux/count_zeros.h>
+#include <asm/unaligned.h>
+
#include "lz77.h"
-static __always_inline u32 hash3(const u8 *ptr)
+/*
+ * Compression parameters.
+ */
+#define LZ77_MATCH_MIN_LEN 4
+#define LZ77_MATCH_MIN_DIST 1
+#define LZ77_MATCH_MAX_DIST SZ_1K
+#define LZ77_HASH_LOG 15
+#define LZ77_HASH_SIZE (1 << LZ77_HASH_LOG)
+#define LZ77_STEP_SIZE sizeof(u64)
+
+static __always_inline u8 lz77_read8(const u8 *ptr)
+{
+ return get_unaligned(ptr);
+}
+
+static __always_inline u64 lz77_read64(const u64 *ptr)
+{
+ return get_unaligned(ptr);
+}
+
+static __always_inline void lz77_write8(u8 *ptr, u8 v)
+{
+ put_unaligned(v, ptr);
+}
+
+static __always_inline void lz77_write16(u16 *ptr, u16 v)
+{
+ put_unaligned_le16(v, ptr);
+}
+
+static __always_inline void lz77_write32(u32 *ptr, u32 v)
+{
+ put_unaligned_le32(v, ptr);
+}
+
+static __always_inline u32 lz77_match_len(const void *wnd, const void *cur, const void *end)
{
- return lz77_hash32(lz77_read32(ptr) & 0xffffff, LZ77_HASH_LOG);
+ const void *start = cur;
+ u64 diff;
+
+ /* Safe for a do/while because otherwise we wouldn't reach here from the main loop. */
+ do {
+ diff = lz77_read64(cur) ^ lz77_read64(wnd);
+ if (!diff) {
+ cur += LZ77_STEP_SIZE;
+ wnd += LZ77_STEP_SIZE;
+
+ continue;
+ }
+
+ /* This computes the number of common bytes in @diff. */
+ cur += count_trailing_zeros(diff) >> 3;
+
+ return (cur - start);
+ } while (likely(cur + LZ77_STEP_SIZE < end));
+
+ while (cur < end && lz77_read8(cur++) == lz77_read8(wnd++))
+ ;
+
+ return (cur - start);
}
-static u8 *write_match(u8 *dst, u8 **nib, u32 dist, u32 len)
+static __always_inline void *lz77_write_match(void *dst, void **nib, u32 dist, u32 len)
{
len -= 3;
dist--;
if (len < 7) {
lz77_write16(dst, dist + len);
+
return dst + 2;
}
len -= 7;
if (!*nib) {
+ lz77_write8(dst, umin(len, 15));
*nib = dst;
- lz77_write8(dst, min_t(unsigned int, len, 15));
dst++;
} else {
- **nib |= min_t(unsigned int, len, 15) << 4;
+ u8 *b = *nib;
+
+ lz77_write8(b, *b | umin(len, 15) << 4);
*nib = NULL;
}
len -= 15;
if (len < 255) {
lz77_write8(dst, len);
+
return dst + 1;
}
lz77_write8(dst, 0xff);
dst++;
-
len += 7 + 15;
if (len <= 0xffff) {
lz77_write16(dst, len);
+
return dst + 2;
}
return dst + 4;
}
-static u8 *write_literals(u8 *dst, const u8 *dst_end, const u8 *src, size_t count,
- struct lz77_flags *flags)
+noinline int lz77_compress(const void *src, u32 slen, void *dst, u32 *dlen)
{
- const u8 *end = src + count;
-
- while (src < end) {
- size_t c = lz77_min(count, 32 - flags->count);
-
- if (dst + c >= dst_end)
- return ERR_PTR(-EFAULT);
-
- if (lz77_copy(dst, src, c))
- return ERR_PTR(-EFAULT);
-
- dst += c;
- src += c;
- count -= c;
-
- flags->val <<= c;
- flags->count += c;
- if (flags->count == 32) {
- lz77_write32(flags->pos, flags->val);
- flags->count = 0;
- flags->pos = dst;
- dst += 4;
- }
- }
-
- return dst;
-}
-
-static __always_inline bool is_valid_match(const u32 dist, const u32 len)
-{
- return (dist >= LZ77_MATCH_MIN_DIST && dist < LZ77_MATCH_MAX_DIST) &&
- (len >= LZ77_MATCH_MIN_LEN && len < LZ77_MATCH_MAX_LEN);
-}
-
-static __always_inline const u8 *find_match(u32 *htable, const u8 *base, const u8 *cur,
- const u8 *end, u32 *best_len)
-{
- const u8 *match;
- u32 hash;
- size_t offset;
-
- hash = hash3(cur);
- offset = cur - base;
-
- if (htable[hash] >= offset)
- return cur;
-
- match = base + htable[hash];
- *best_len = lz77_match(match, cur, end);
- if (is_valid_match(cur - match, *best_len))
- return match;
-
- return cur;
-}
-
-int lz77_compress(const u8 *src, size_t src_len, u8 *dst, size_t *dst_len)
-{
- const u8 *srcp, *src_end, *anchor;
- struct lz77_flags flags = { 0 };
- u8 *dstp, *dst_end, *nib;
- u32 *htable;
- int ret;
+ const void *srcp, *end;
+ void *dstp, *nib, *flag_pos;
+ u32 flag_count = 0;
+ long flag = 0;
+ u64 *htable;
srcp = src;
- anchor = srcp;
- src_end = src + src_len;
-
+ end = src + slen;
dstp = dst;
- dst_end = dst + *dst_len;
- flags.pos = dstp;
nib = NULL;
-
- memset(dstp, 0, *dst_len);
+ flag_pos = dstp;
dstp += 4;
- htable = kvcalloc(LZ77_HASH_SIZE, sizeof(u32), GFP_KERNEL);
+ htable = kvcalloc(LZ77_HASH_SIZE, sizeof(*htable), GFP_KERNEL);
if (!htable)
return -ENOMEM;
- /* fill hashtable with invalid offsets */
- memset(htable, 0xff, LZ77_HASH_SIZE * sizeof(u32));
+ /* Main loop. */
+ do {
+ u32 dist, len = 0;
+ const void *wnd;
+ u64 hash;
- /* from here on, any error is because @dst_len reached >= @src_len */
- ret = -EMSGSIZE;
+ hash = ((lz77_read64(srcp) << 24) * 889523592379ULL) >> (64 - LZ77_HASH_LOG);
+ wnd = src + htable[hash];
+ htable[hash] = srcp - src;
+ dist = srcp - wnd;
- /* main loop */
- while (srcp < src_end) {
- u32 hash, dist, len;
- const u8 *match;
+ if (dist && dist < LZ77_MATCH_MAX_DIST)
+ len = lz77_match_len(wnd, srcp, end);
- while (srcp + 3 < src_end) {
- len = LZ77_MATCH_MIN_LEN - 1;
- match = find_match(htable, src, srcp, src_end, &len);
- hash = hash3(srcp);
- htable[hash] = srcp - src;
+ if (len < LZ77_MATCH_MIN_LEN) {
+ lz77_write8(dstp, lz77_read8(srcp));
+
+ dstp++;
+ srcp++;
- if (likely(match < srcp)) {
- dist = srcp - match;
- break;
+ flag <<= 1;
+ flag_count++;
+ if (flag_count == 32) {
+ lz77_write32(flag_pos, flag);
+ flag_count = 0;
+ flag_pos = dstp;
+ dstp += 4;
}
- srcp++;
+ continue;
}
- dstp = write_literals(dstp, dst_end, anchor, srcp - anchor, &flags);
- if (IS_ERR(dstp))
- goto err_free;
-
- if (srcp + 3 >= src_end)
- goto leftovers;
+ /*
+ * Bail out if @dstp reached >= 7/8 of @slen -- already compressed badly, not worth
+ * going further.
+ */
+ if (unlikely(dstp - dst >= slen - (slen >> 3))) {
+ *dlen = slen;
+ goto out;
+ }
- dstp = write_match(dstp, &nib, dist, len);
+ dstp = lz77_write_match(dstp, &nib, dist, len);
srcp += len;
- anchor = srcp;
-
- flags.val = (flags.val << 1) | 1;
- flags.count++;
- if (flags.count == 32) {
- lz77_write32(flags.pos, flags.val);
- flags.count = 0;
- flags.pos = dstp;
+
+ flag = (flag << 1) | 1;
+ flag_count++;
+ if (flag_count == 32) {
+ lz77_write32(flag_pos, flag);
+ flag_count = 0;
+ flag_pos = dstp;
+ dstp += 4;
+ }
+ } while (likely(srcp + LZ77_STEP_SIZE < end));
+
+ while (srcp < end) {
+ u32 c = umin(end - srcp, 32 - flag_count);
+
+ memcpy(dstp, srcp, c);
+
+ dstp += c;
+ srcp += c;
+
+ flag <<= c;
+ flag_count += c;
+ if (flag_count == 32) {
+ lz77_write32(flag_pos, flag);
+ flag_count = 0;
+ flag_pos = dstp;
dstp += 4;
}
- }
-leftovers:
- if (srcp < src_end) {
- dstp = write_literals(dstp, dst_end, srcp, src_end - srcp, &flags);
- if (IS_ERR(dstp))
- goto err_free;
}
- flags.val <<= (32 - flags.count);
- flags.val |= (1 << (32 - flags.count)) - 1;
- lz77_write32(flags.pos, flags.val);
+ flag <<= (32 - flag_count);
+ flag |= (1 << (32 - flag_count)) - 1;
+ lz77_write32(flag_pos, flag);
- *dst_len = dstp - dst;
- ret = 0;
-err_free:
+ *dlen = dstp - dst;
+out:
kvfree(htable);
- return ret;
+ if (*dlen < slen)
+ return 0;
+
+ return -EMSGSIZE;
}
*
* Authors: Enzo Matsumiya <ematsumiya@suse.de>
*
- * Definitions and optmized helpers for LZ77 compression.
+ * Implementation of the LZ77 "plain" compression algorithm, as per MS-XCA spec.
*/
#ifndef _SMB_COMPRESS_LZ77_H
#define _SMB_COMPRESS_LZ77_H
-#include <linux/uaccess.h>
-#ifdef CONFIG_CIFS_COMPRESSION
-#include <asm/ptrace.h>
#include <linux/kernel.h>
-#include <linux/string.h>
-#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
-#include <asm-generic/unaligned.h>
-#endif
-#define LZ77_HASH_LOG 13
-#define LZ77_HASH_SIZE (1 << LZ77_HASH_LOG)
-#define LZ77_HASH_MASK lz77_hash_mask(LZ77_HASH_LOG)
-
-/* We can increase this for better compression (but worse performance). */
-#define LZ77_MATCH_MIN_LEN 3
-/* From MS-XCA, but it's arbitrarily chosen. */
-#define LZ77_MATCH_MAX_LEN S32_MAX
-/*
- * Check this to ensure we don't match the current position, which would
- * end up doing a verbatim copy of the input, and actually overflowing
- * the output buffer because of the encoded metadata.
- */
-#define LZ77_MATCH_MIN_DIST 1
-/* How far back in the buffer can we try to find a match (i.e. window size) */
-#define LZ77_MATCH_MAX_DIST 8192
-
-#define LZ77_STEPSIZE_16 sizeof(u16)
-#define LZ77_STEPSIZE_32 sizeof(u32)
-#define LZ77_STEPSIZE_64 sizeof(u64)
-
-struct lz77_flags {
- u8 *pos;
- size_t count;
- long val;
-};
-
-static __always_inline u32 lz77_hash_mask(const unsigned int log2)
-{
- return ((1 << log2) - 1);
-}
-
-static __always_inline u32 lz77_hash64(const u64 v, const unsigned int log2)
-{
- const u64 prime5bytes = 889523592379ULL;
-
- return (u32)(((v << 24) * prime5bytes) >> (64 - log2));
-}
-
-static __always_inline u32 lz77_hash32(const u32 v, const unsigned int log2)
-{
- return ((v * 2654435769LL) >> (32 - log2)) & lz77_hash_mask(log2);
-}
-
-static __always_inline u32 lz77_log2(unsigned int x)
-{
- return x ? ((u32)(31 - __builtin_clz(x))) : 0;
-}
-
-#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
-static __always_inline u8 lz77_read8(const void *ptr)
-{
- return *(u8 *)ptr;
-}
-
-static __always_inline u16 lz77_read16(const void *ptr)
-{
- return *(u16 *)ptr;
-}
-
-static __always_inline u32 lz77_read32(const void *ptr)
-{
- return *(u32 *)ptr;
-}
-
-static __always_inline u64 lz77_read64(const void *ptr)
-{
- return *(u64 *)ptr;
-}
-
-static __always_inline void lz77_write8(void *ptr, const u8 v)
-{
- *(u8 *)ptr = v;
-}
-
-static __always_inline void lz77_write16(void *ptr, const u16 v)
-{
- *(u16 *)ptr = v;
-}
-
-static __always_inline void lz77_write32(void *ptr, const u32 v)
-{
- *(u32 *)ptr = v;
-}
-
-static __always_inline void lz77_write64(void *ptr, const u64 v)
-{
- *(u64 *)ptr = v;
-}
-
-static __always_inline void lz77_write_ptr16(void *ptr, const void *vp)
-{
- *(u16 *)ptr = *(const u16 *)vp;
-}
-
-static __always_inline void lz77_write_ptr32(void *ptr, const void *vp)
-{
- *(u32 *)ptr = *(const u32 *)vp;
-}
-
-static __always_inline void lz77_write_ptr64(void *ptr, const void *vp)
-{
- *(u64 *)ptr = *(const u64 *)vp;
-}
-
-static __always_inline long lz77_copy(u8 *dst, const u8 *src, size_t count)
-{
- return copy_from_kernel_nofault(dst, src, count);
-}
-#else /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
-static __always_inline u8 lz77_read8(const void *ptr)
-{
- return get_unaligned((u8 *)ptr);
-}
-
-static __always_inline u16 lz77_read16(const void *ptr)
-{
- return lz77_read8(ptr) | (lz77_read8(ptr + 1) << 8);
-}
-
-static __always_inline u32 lz77_read32(const void *ptr)
-{
- return lz77_read16(ptr) | (lz77_read16(ptr + 2) << 16);
-}
-
-static __always_inline u64 lz77_read64(const void *ptr)
-{
- return lz77_read32(ptr) | ((u64)lz77_read32(ptr + 4) << 32);
-}
-
-static __always_inline void lz77_write8(void *ptr, const u8 v)
-{
- put_unaligned(v, (u8 *)ptr);
-}
-
-static __always_inline void lz77_write16(void *ptr, const u16 v)
-{
- lz77_write8(ptr, v & 0xff);
- lz77_write8(ptr + 1, (v >> 8) & 0xff);
-}
-
-static __always_inline void lz77_write32(void *ptr, const u32 v)
-{
- lz77_write16(ptr, v & 0xffff);
- lz77_write16(ptr + 2, (v >> 16) & 0xffff);
-}
-
-static __always_inline void lz77_write64(void *ptr, const u64 v)
-{
- lz77_write32(ptr, v & 0xffffffff);
- lz77_write32(ptr + 4, (v >> 32) & 0xffffffff);
-}
-
-static __always_inline void lz77_write_ptr16(void *ptr, const void *vp)
-{
- const u16 v = lz77_read16(vp);
-
- lz77_write16(ptr, v);
-}
-
-static __always_inline void lz77_write_ptr32(void *ptr, const void *vp)
-{
- const u32 v = lz77_read32(vp);
-
- lz77_write32(ptr, v);
-}
-
-static __always_inline void lz77_write_ptr64(void *ptr, const void *vp)
-{
- const u64 v = lz77_read64(vp);
-
- lz77_write64(ptr, v);
-}
-static __always_inline long lz77_copy(u8 *dst, const u8 *src, size_t count)
-{
- memcpy(dst, src, count);
- return 0;
-}
-#endif /* !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
-
-static __always_inline unsigned int __count_common_bytes(const unsigned long diff)
-{
-#ifdef __has_builtin
-# if __has_builtin(__builtin_ctzll)
- return (unsigned int)__builtin_ctzll(diff) >> 3;
-# endif
-#else
- /* count trailing zeroes */
- unsigned long bits = 0, i, z = 0;
-
- bits |= diff;
- for (i = 0; i < 64; i++) {
- if (bits[i])
- break;
- z++;
- }
-
- return (unsigned int)z >> 3;
-#endif
-}
-
-static __always_inline size_t lz77_match(const u8 *match, const u8 *cur, const u8 *end)
-{
- const u8 *start = cur;
-
- if (cur == match)
- return 0;
-
- if (likely(cur < end - (LZ77_STEPSIZE_64 - 1))) {
- u64 const diff = lz77_read64(cur) ^ lz77_read64(match);
-
- if (!diff) {
- cur += LZ77_STEPSIZE_64;
- match += LZ77_STEPSIZE_64;
- } else {
- return __count_common_bytes(diff);
- }
- }
-
- while (likely(cur < end - (LZ77_STEPSIZE_64 - 1))) {
- u64 const diff = lz77_read64(cur) ^ lz77_read64(match);
-
- if (!diff) {
- cur += LZ77_STEPSIZE_64;
- match += LZ77_STEPSIZE_64;
- continue;
- }
-
- cur += __count_common_bytes(diff);
- return (size_t)(cur - start);
- }
-
- if (cur < end - 3 && !(lz77_read32(cur) ^ lz77_read32(match))) {
- cur += LZ77_STEPSIZE_32;
- match += LZ77_STEPSIZE_32;
- }
-
- if (cur < end - 1 && lz77_read16(cur) == lz77_read16(match)) {
- cur += LZ77_STEPSIZE_16;
- match += LZ77_STEPSIZE_16;
- }
-
- if (cur < end && *cur == *match)
- cur++;
-
- return (size_t)(cur - start);
-}
-
-static __always_inline unsigned long lz77_max(unsigned long a, unsigned long b)
-{
- int m = (a < b) - 1;
-
- return (a & m) | (b & ~m);
-}
-
-static __always_inline unsigned long lz77_min(unsigned long a, unsigned long b)
-{
- int m = (a > b) - 1;
-
- return (a & m) | (b & ~m);
-}
-
-int lz77_compress(const u8 *src, size_t src_len, u8 *dst, size_t *dst_len);
-/* when CONFIG_CIFS_COMPRESSION not set lz77_compress() is not called */
-#endif /* !CONFIG_CIFS_COMPRESSION */
+int lz77_compress(const void *src, u32 slen, void *dst, u32 *dlen);
#endif /* _SMB_COMPRESS_LZ77_H */
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