From: Jan Höppner hoeppner@linux.ibm.com
[ Upstream commit ce6915f5343f5f2a2a937b683d8ffbf12dab3ad4 ]
The disk layout and volume information of a DASD reside in the first two tracks of cylinder 0. When a DASD is set online, currently the first three tracks are read and analysed to confirm an expected layout.
For CDL (Compatible Disk Layout) only count area data of the first track is evaluated and checked against expected key and data lengths. For LDL (Linux Disk Layout) the first and third track is evaluated. However, an LDL formatted volume is expected to be in the same format across all tracks. Checking the third track therefore doesn't have any more value than checking any other track at random.
Now, an Extent Space Efficient (ESE) DASD is initialised by only formatting the first two tracks, as those tracks always contain all information necessarry.
Checking the third track on an ESE volume will therefore most likely fail with a record not found error, as the third track will be empty. This in turn leads to the device being recognised with a volume size of 0. Attempts to write volume information on the first two tracks then fail with "no space left on device" errors.
Initialising the first three tracks for an ESE volume is not a viable solution, because the third track is already a regular track and could contain user data. With that there is potential for data corruption.
Instead, always only analyse the first two tracks, as it is sufficiant for both CDL and LDL, and allow ESE volumes to be recognised as well.
Signed-off-by: Jan Höppner hoeppner@linux.ibm.com Reviewed-by: Stefan Haberland sth@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/block/dasd_eckd.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c index c09039eea707..c7aec1b44b7c 100644 --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -157,7 +157,7 @@ static const int sizes_trk0[] = { 28, 148, 84 }; #define LABEL_SIZE 140
/* head and record addresses of count_area read in analysis ccw */ -static const int count_area_head[] = { 0, 0, 0, 0, 2 }; +static const int count_area_head[] = { 0, 0, 0, 0, 1 }; static const int count_area_rec[] = { 1, 2, 3, 4, 1 };
static inline unsigned int @@ -1823,8 +1823,8 @@ dasd_eckd_analysis_ccw(struct dasd_device *device) if (IS_ERR(cqr)) return cqr; ccw = cqr->cpaddr; - /* Define extent for the first 3 tracks. */ - define_extent(ccw++, cqr->data, 0, 2, + /* Define extent for the first 2 tracks. */ + define_extent(ccw++, cqr->data, 0, 1, DASD_ECKD_CCW_READ_COUNT, device, 0); LO_data = cqr->data + sizeof(struct DE_eckd_data); /* Locate record for the first 4 records on track 0. */ @@ -1843,9 +1843,9 @@ dasd_eckd_analysis_ccw(struct dasd_device *device) count_data++; }
- /* Locate record for the first record on track 2. */ + /* Locate record for the first record on track 1. */ ccw[-1].flags |= CCW_FLAG_CC; - locate_record(ccw++, LO_data++, 2, 0, 1, + locate_record(ccw++, LO_data++, 1, 0, 1, DASD_ECKD_CCW_READ_COUNT, device, 0); /* Read count ccw. */ ccw[-1].flags |= CCW_FLAG_CC; @@ -1967,7 +1967,7 @@ static int dasd_eckd_end_analysis(struct dasd_block *block) } } if (i == 3) - count_area = &private->count_area[4]; + count_area = &private->count_area[3];
if (private->uses_cdl == 0) { for (i = 0; i < 5; i++) {