[PATCH 4.16 72/81] block/swim: Fix IO error at end of medium

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>

commit 5a13388d7aa1177b98d7168330ecbeeac52f844d upstream.

Reading to the end of a 720K disk results in an IO error instead of EOF
because the block layer thinks the disk has 2880 sectors. (Partly this
is a result of inverted logic of the ONEMEG_MEDIA bit that's now fixed.)

Initialize the density and head count in swim_add_floppy() to agree
with the device size passed to set_capacity() during drive probe.

Call set_capacity() again upon device open, after refreshing the density
and head count values.

Cc: Laurent Vivier <lvivier@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.14+
Tested-by: Stan Johnson <userm57@xxxxxxxxx>
Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
Acked-by: Laurent Vivier <lvivier@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/block/swim.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/block/swim.c
+++ b/drivers/block/swim.c
@@ -612,7 +612,6 @@ static void setup_medium(struct floppy_s
 		struct floppy_struct *g;
 		fs->disk_in = 1;
 		fs->write_protected = swim_readbit(base, WRITE_PROT);
-		fs->type = swim_readbit(base, TWOMEG_MEDIA);
 
 		if (swim_track00(base))
 			printk(KERN_ERR
@@ -620,6 +619,9 @@ static void setup_medium(struct floppy_s
 
 		swim_track00(base);
 
+		fs->type = swim_readbit(base, TWOMEG_MEDIA) ?
+			HD_MEDIA : DD_MEDIA;
+		fs->head_number = swim_readbit(base, SINGLE_SIDED) ? 1 : 2;
 		get_floppy_geometry(fs, 0, &g);
 		fs->total_secs = g->size;
 		fs->secpercyl = g->head * g->sect;
@@ -656,6 +658,8 @@ static int floppy_open(struct block_devi
 		goto out;
 	}
 
+	set_capacity(fs->disk, fs->total_secs);
+
 	if (mode & FMODE_NDELAY)
 		return 0;
 
@@ -808,10 +812,9 @@ static int swim_add_floppy(struct swim_p
 
 	swim_motor(base, OFF);
 
-	if (swim_readbit(base, SINGLE_SIDED))
-		fs->head_number = 1;
-	else
-		fs->head_number = 2;
+	fs->type = HD_MEDIA;
+	fs->head_number = 2;
+
 	fs->ref_count = 0;
 	fs->ejected = 1;