diff --git a/include/common/buf.h b/include/common/buf.h
index fccad45b2..0ee9c5474 100644
--- a/include/common/buf.h
+++ b/include/common/buf.h
@@ -278,6 +278,21 @@ static inline int b_space_wraps(const struct buffer *b)
 	return 1;
 }
 
+/* b_contig_data() : returns the amount of data that can contiguously be read
+ * at once starting from a relative offset <start> (which allows to easily
+ * pre-compute blocks for memcpy). The start point will typically contain the
+ * amount of past data already returned by a previous call to this function.
+ */
+static inline size_t b_contig_data(const struct buffer *b, size_t start)
+{
+	size_t data = b_wrap(b) - b_peek(b, start);
+	size_t limit = b_data(b) - start;
+
+	if (data > limit)
+		data = limit;
+	return data;
+}
+
 
 /*********************************************/
 /* Functions used to modify the buffer state */
diff --git a/include/common/buffer.h b/include/common/buffer.h
index b34c38922..da65e89c5 100644
--- a/include/common/buffer.h
+++ b/include/common/buffer.h
@@ -123,16 +123,6 @@ static inline char *bi_end(const struct buffer *b)
 	return ret;
 }
 
-/* Returns the amount of input data that can contiguously be read at once */
-static inline int bi_contig_data(const struct buffer *b)
-{
-	int data = b->data + b->size - b->p;
-
-	if (data > b->i)
-		data = b->i;
-	return data;
-}
-
 /* Returns the start of the output data in a buffer */
 static inline char *bo_ptr(const struct buffer *b)
 {
diff --git a/include/proto/channel.h b/include/proto/channel.h
index 9429689ab..956805057 100644
--- a/include/proto/channel.h
+++ b/include/proto/channel.h
@@ -309,6 +309,12 @@ static inline const char *ci_stop(const struct channel *c)
 }
 
 
+/* Returns the amount of input data that can contiguously be read at once */
+static inline size_t ci_contig_data(const struct channel *c)
+{
+	return b_contig_data(c->buf, co_data(c));
+}
+
 /* Initialize all fields in the channel. */
 static inline void channel_init(struct channel *chn)
 {
diff --git a/src/cache.c b/src/cache.c
index aec9ba670..c1e6bcc85 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -225,7 +225,7 @@ cache_store_http_forward_data(struct stream *s, struct filter *filter,
 				ret = shctx_row_data_append(shctx,
 							    st->first_block,
 							    (unsigned char *)bi_ptr(msg->chn->buf),
-							    MIN(bi_contig_data(msg->chn->buf), len - st->hdrs_len));
+							    MIN(ci_contig_data(msg->chn), len - st->hdrs_len));
 				/* Rewind the buffer to forward all data */
 				c_rew(msg->chn, st->hdrs_len);
 				st->hdrs_len = 0;
diff --git a/src/flt_http_comp.c b/src/flt_http_comp.c
index df59d7d55..f26b28b67 100644
--- a/src/flt_http_comp.c
+++ b/src/flt_http_comp.c
@@ -206,7 +206,7 @@ comp_http_data(struct stream *s, struct filter *filter, struct http_msg *msg)
 		len = MIN(tmpbuf->size - buffer_len(tmpbuf), len);
 
 		c_adv(chn, *nxt);
-		block = bi_contig_data(buf);
+		block = ci_contig_data(chn);
 		memcpy(bi_end(tmpbuf), bi_ptr(buf), block);
 		if (len > block)
 			memcpy(bi_end(tmpbuf)+block, buf->data, len-block);
@@ -644,8 +644,8 @@ http_compression_buffer_add_data(struct comp_state *st, struct buffer *in,
 	data_process_len = MIN(out->size - buffer_len(out), sz);
 
 	block1 = data_process_len;
-	if (block1 > bi_contig_data(in))
-		block1 = bi_contig_data(in);
+	if (block1 > b_contig_data(in, in->o))
+		block1 = b_contig_data(in, in->o);
 	block2 = data_process_len - block1;
 
 	/* compressors return < 0 upon error or the amount of bytes read */
@@ -765,7 +765,7 @@ http_compression_buffer_end(struct comp_state *st, struct stream *s,
 	/* copy the remaining data in the tmp buffer. */
 	c_adv(chn, st->consumed);
 	if (ib->i > 0) {
-		left = bi_contig_data(ib);
+		left = ci_contig_data(chn);
 		memcpy(ob->p + ob->i, bi_ptr(ib), left);
 		ob->i += left;
 		if (ib->i - left) {
diff --git a/src/flt_trace.c b/src/flt_trace.c
index f088340b7..b1d208fdb 100644
--- a/src/flt_trace.c
+++ b/src/flt_trace.c
@@ -84,9 +84,9 @@ trace_hexdump(struct buffer *buf, int len)
 	int block1, block2, i, j, padding;
 
 	block1 = len;
-        if (block1 > bi_contig_data(buf))
-                block1 = bi_contig_data(buf);
-        block2 = len - block1;
+	if (block1 > b_contig_data(buf, buf->o))
+		block1 = b_contig_data(buf, buf->o);
+	block2 = len - block1;
 
 	memcpy(p, buf->p, block1);
 	memcpy(p+block1, buf->data, block2);
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 8aab234e5..2f41c6fe8 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -2838,7 +2838,7 @@ static int h2_frt_transfer_data(struct h2s *h2s, struct buffer *buf, int count)
 	/* Block1 is the length of the first block before the buffer wraps,
 	 * block2 is the optional second block to reach the end of the frame.
 	 */
-	block1 = bi_contig_data(h2c->dbuf);
+	block1 = b_contig_data(h2c->dbuf, 0);
 	if (block1 > flen)
 		block1 = flen;
 	block2 = flen - block1;