[SRU][Zesty][PATCH 1/1] scsi: cxlflash: Fix vlun resize failure in the shrink path

[Joseph Salisbury]

From: Uma Krishnan <ukrishn at linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1713575

The ioctl DK_CAPI_VLUN_RESIZE can fail if the allocated vlun size is
reduced from almost maximum capacity and then increased again.

The shrink_lxt() routine is currently using the SISL_ASTATUS_MASK to
mask the higher 48 bits of the lxt entry. This is unnecessary and
incorrect as it uses a mask designed for the asynchronous interrupt
status register.  When the 4 port support was added to cxlflash, the
SISL_ASTATUS_MASK was updated to reflect the status bits for all 4
ports. This change indirectly affected the shrink_lxt() code path.

To extract the base, simply shift the bits without masking.

Fixes: 565180723294 ("scsi: cxlflash: SISlite updates to support 4 ports")
Signed-off-by: Uma Krishnan <ukrishn at linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
(cherry picked from commit 07a191f762a7b8d0db13c38036380927116e29bb)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 drivers/scsi/cxlflash/vlun.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/scsi/cxlflash/vlun.c b/drivers/scsi/cxlflash/vlun.c
index 6c4cd3f..8de6a80 100644
--- a/drivers/scsi/cxlflash/vlun.c
+++ b/drivers/scsi/cxlflash/vlun.c
@@ -694,11 +694,7 @@ static int shrink_lxt(struct afu *afu,
 	/* Free LBAs allocated to freed chunks */
 	mutex_lock(&blka->mutex);
 	for (i = delta - 1; i >= 0; i--) {
-		/* Mask the higher 48 bits before shifting, even though
-		 * it is a noop
-		 */
-		aun = (lxt_old[my_new_size + i].rlba_base & SISL_ASTATUS_MASK);
-		aun = (aun >> MC_CHUNK_SHIFT);
+		aun = lxt_old[my_new_size + i].rlba_base >> MC_CHUNK_SHIFT;
 		if (needs_ws)
 			write_same16(sdev, aun, MC_CHUNK_SIZE);
 		ba_free(&blka->ba_lun, aun);
-- 
2.7.4