s390/dasd: fix data corruption for thin provisioned devices

Devices are formatted in multiple of tracks.
For an Extent Space Efficient (ESE) volume we get errors when accessing
unformatted tracks. In this case the driver either formats the track on
the flight for write requests or returns zero data for read requests.

In case a request spans multiple tracks, the indication of an unformatted
track presented for the first track is incorrectly applied to all tracks
covered by the request. As a result, tracks containing data will be handled
as empty, resulting in zero data being returned on read, or overwriting
existing data with zero on write.

Fix by determining the track that gets the NRF error.
For write requests only format the track that is surely not formatted.
For Read requests all tracks before have returned valid data and should not
be touched.
All tracks after the unformatted track might be formatted or not. Those are
returned to the blocklayer to build a new request.

When using alias devices there is a chance that multiple write requests
trigger a format of the same track which might lead to data loss. Ensure
that a track is formatted only once by maintaining a list of currently
processed tracks.

Fixes: 5e2b17e712cf ("s390/dasd: Add dynamic formatting support for ESE volumes")
Cc: stable@vger.kernel.org # 5.3+
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index 91c9f9586e0f..fa552f9f1666 100644
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -187,6 +187,7 @@ struct dasd_ccw_req {
 
 	void (*callback)(struct dasd_ccw_req *, void *data);
 	void *callback_data;
+	unsigned int proc_bytes;	/* bytes for partial completion */
 };
 
 /*
@@ -387,8 +388,9 @@ struct dasd_discipline {
 	int (*ext_pool_warn_thrshld)(struct dasd_device *);
 	int (*ext_pool_oos)(struct dasd_device *);
 	int (*ext_pool_exhaust)(struct dasd_device *, struct dasd_ccw_req *);
-	struct dasd_ccw_req *(*ese_format)(struct dasd_device *, struct dasd_ccw_req *);
-	void (*ese_read)(struct dasd_ccw_req *);
+	struct dasd_ccw_req *(*ese_format)(struct dasd_device *,
+					   struct dasd_ccw_req *, struct irb *);
+	int (*ese_read)(struct dasd_ccw_req *, struct irb *);
 };
 
 extern struct dasd_discipline *dasd_diag_discipline_pointer;
@@ -474,6 +476,11 @@ struct dasd_profile {
 	spinlock_t lock;
 };
 
+struct dasd_format_entry {
+	struct list_head list;
+	sector_t track;
+};
+
 struct dasd_device {
 	/* Block device stuff. */
 	struct dasd_block *block;
@@ -539,6 +546,7 @@ struct dasd_device {
 	struct dentry *debugfs_dentry;
 	struct dentry *hosts_dentry;
 	struct dasd_profile profile;
+	struct dasd_format_entry format_entry;
 };
 
 struct dasd_block {
@@ -564,6 +572,9 @@ struct dasd_block {
 
 	struct dentry *debugfs_dentry;
 	struct dasd_profile profile;
+
+	struct list_head format_list;
+	spinlock_t format_lock;
 };
 
 struct dasd_attention_data {