From b39ce6cd6811cc2095fd2dabe82150da7168f800 Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Mon, 20 May 2013 03:18:55 +0400
Subject: [PATCH] Stupidly switch buffer

---
 sftl.c | 48 ++++++++++++++++++++++++++++++++++++------------
 1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/sftl.c b/sftl.c
index cc94a73..11d5d94 100644
--- a/sftl.c
+++ b/sftl.c
@@ -91,6 +91,21 @@ static void sftl_complete_seg(struct bio *bio, int err)
 	bio_put(bio);
 }
 
+struct sftl_buf_info
+{
+	struct bio *complete_bio;
+	void *free_buf;
+};
+
+static void sftl_complete_buf(struct bio *bio, int err)
+{
+	struct sftl_buf_info *i = bio->bi_private;
+	bio_endio(i->complete_bio, err);
+	bio_put(bio);
+	kfree(i->free_buf);
+	kfree(i);
+}
+
 static void sftl_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct sftl_dev *sftl = (struct sftl_dev*)q->queuedata;
@@ -151,20 +166,28 @@ static void sftl_make_request(struct request_queue *q, struct bio *bio)
 			(unsigned long)bio->bi_sector, (unsigned long)bio_sectors(bio));
 		if (sftl->buf_size >= sftl->buf_max)
 		{
-			// Need to flush the buffer before completing this bio
-			int err = bio_submit_kern_seq(sftl->blkdev, sftl->buf, seg_clust*clust_sz+phy_sz, GFP_KERNEL,
-				sftl->nextfreeseg*(seg_clust*clust_blocks+1), bio, sftl_complete_seg, WRITE);
-			if (err)
-				bio_endio(bio, -EIO);
-			// FIXME Is it correct?.. I think no...
+			// Need to flush current buffer before completing this bio
+			void *buf = sftl->buf;
+			struct sftl_buf_info *info = kmalloc(sizeof(struct sftl_buf_info), GFP_KERNEL);
+			int err;
+			info->free_buf = buf;
+			info->complete_bio = bio;
+			// We stupidly switch buffer (there always will be a finite number of those)
+			sftl->buf = kmalloc(seg_clust*clust_sz + phy_sz, GFP_KERNEL);
 			sftl->buf_size = 0;
+			err = bio_submit_kern_seq(sftl->blkdev, buf, seg_clust*clust_sz+phy_sz, GFP_KERNEL,
+				sftl->nextfreeseg*(seg_clust*clust_blocks+1), info, sftl_complete_buf, WRITE);
+			if (err)
+			{
+				bio_endio(bio, -EIO);
+				kfree(buf);
+				kfree(info);
+			}
 			// FIXME Correctly adjust free segment address
 			sftl->nextfreeseg++;
 		}
 		else
-		{
 			bio_endio(bio, 0);
-		}
 	}
 }
 
@@ -318,7 +341,7 @@ static void bio_map_kern_seq_endio(struct bio *bio, int err)
 	struct bio_seq *seq = bio->bi_private;
 	if (err)
 	{
-		INFO("I/O err %d", err);
+		INFO("I/O error %d", err);
 		seq->err = err;
 	}
 	if (atomic_dec_and_test(&seq->count))
@@ -362,6 +385,7 @@ static long bio_submit_kern_seq(
 		int n = 1;
 		bio->bi_private = NULL;
 		bio->bi_end_io = bio_map_kern_seq_endio;
+		seq->err = 0;
 		seq->endio = endio;
 		seq->private = private;
 		data += bio->bi_size;
@@ -382,13 +406,13 @@ static long bio_submit_kern_seq(
 				}
 				return PTR_ERR(bio2);
 			}
-			data += bio2->bi_size;
-			len -= bio2->bi_size;
-			sector += bio2->bi_size >> 9;
 			bio2->bi_bdev = bdev;
 			bio2->bi_sector = sector;
 			bio2->bi_private = bio;
 			bio2->bi_end_io = bio_map_kern_seq_endio;
+			data += bio2->bi_size;
+			len -= bio2->bi_size;
+			sector += bio2->bi_size >> 9;
 			bio = bio2;
 			n++;
 		}