smb: client: compress: use iterate_and_advance_kernel

Move sample collection to use the generic iov_iter API.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>

1 files changed, 38 insertions, 33 deletions

diff --git a/fs/smb/client/compress.c b/fs/smb/client/compress.c
index db18c93f8ee8..7349f1dc6b1f 100644
--- a/fs/smb/client/compress.c
+++ b/fs/smb/client/compress.c
@@ -16,6 +16,7 @@
 #include <linux/kernel.h>
 #include <linux/uio.h>
 #include <linux/sort.h>
+#include <linux/iov_iter.h>
 
 #include "cifsglob.h"
 #include "../common/smb2pdu.h"
@@ -154,32 +155,44 @@ static int cmp_bkt(const void *_a, const void *_b)
 	return 1;
 }
 
-/*
- * Collect some 2K samples with 2K gaps between.
- */
-static int collect_sample(const struct iov_iter *source, ssize_t max, u8 *sample)
+static size_t collect_step(void *base, size_t progress, size_t len, void *priv_iov, void *priv_len)
 {
-	struct iov_iter iter = *source;
-	size_t s = 0;
+	size_t plen, *slen = priv_len;
+	struct kvec *iov = priv_iov;
 
-	while (iov_iter_count(&iter) >= SZ_2K) {
-		size_t part = umin(umin(iov_iter_count(&iter), SZ_2K), max);
-		size_t n;
+	if (progress >= iov->iov_len)
+		return len;
 
-		n = copy_from_iter(sample + s, part, &iter);
-		if (n != part)
-			return -EFAULT;
+	plen = min_t(size_t, len, SZ_2K);
 
-		s += n;
-		max -= n;
+	memcpy(iov->iov_base + *slen, base, plen);
 
-		if (iov_iter_count(&iter) < PAGE_SIZE - SZ_2K)
-			break;
+	*slen += plen;
 
-		iov_iter_advance(&iter, SZ_2K);
-	}
+	if (len < SZ_2K)
+		return len;
+
+	return 0;
+}
+
+/*
+ * Collect sample buffers from @iter.
+ * Return sample size, or 0 if too big (> @max_sample_len).
+ */
+static size_t collect_sample(const struct iov_iter *iter, u8 *sample, ssize_t max_sample_len)
+{
+	struct iov_iter it = *iter;
+	size_t ret, len = 0, max = iov_iter_count(iter);
+	struct kvec iov = {
+		.iov_base = sample,
+		.iov_len = max_sample_len,
+	};
 
-	return s;
+	ret = iterate_and_advance_kernel(&it, max, &iov, &len, collect_step);
+	if (ret > max || ret > max_sample_len)
+		return 0;
+
+	return ret;
 }
 
 /**
@@ -193,12 +206,11 @@ static int collect_sample(const struct iov_iter *source, ssize_t max, u8 *sample
  */
 static bool is_compressible(const struct iov_iter *data)
 {
-	const size_t read_size = SZ_2K, bkt_size = 256, max = SZ_4M;
+	const size_t read_size = SZ_2K, bkt_size = 256, max = SZ_2M;
 	struct bucket *bkt = NULL;
-	size_t len;
+	size_t i, len;
 	u8 *sample;
 	bool ret = false;
-	int i;
 
 	/* Preventive double check -- already checked in should_compress(). */
 	len = iov_iter_count(data);
@@ -208,24 +220,17 @@ static bool is_compressible(const struct iov_iter *data)
 	if (len - read_size > max)
 		len = max;
 
+	len = round_down(len / 2, read_size);
 	sample = kvzalloc(len, GFP_KERNEL);
-	if (!sample) {
-		WARN_ON_ONCE(1);
-
+	if (WARN_ON_ONCE(!sample))
 		return ret;
-	}
 
 	/* Sample 2K bytes per page of the uncompressed data. */
-	i = collect_sample(data, len, sample);
-	if (i <= 0) {
-		WARN_ON_ONCE(1);
-
+	len = collect_sample(data, sample, len);
+	if (len == 0)
 		goto out;
-	}
 
-	len = i;
 	ret = true;
-
 	if (has_repeated_data(sample, len))
 		goto out;