[SCSI] megaraid_sas: Add fpRead/WriteCapable, fpRead/WriteAcrossStripe checks

The following patch for megaraid_sas fixes the fastpath code decision
logic to use fpRead/WriteCapable, fpRead/WriteAcrossStripe flags
instead of the old logic.  This fixes a bug where fastpath writes
could be sent to a read only LD.

Signed-off-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 13 insertions, 8 deletions

diff --git a/drivers/scsi/megaraid/megaraid_sas_fp.c b/drivers/scsi/megaraid/megaraid_sas_fp.c
index 294abb0defa6..e3d251a2e26a 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fp.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fp.c
@@ -362,15 +362,20 @@ MR_BuildRaidContext(struct megasas_instance *instance,
         /* assume this IO needs the full row - we'll adjust if not true */
         regSize             = stripSize;
 
-        /* If IO spans more than 1 strip, fp is not possible
-           FP is not possible for writes on non-0 raid levels
-           FP is not possible if LD is not capable */
-        if (num_strips > 1 || (!isRead && raid->level != 0) ||
-            !raid->capability.fpCapable) {
+        /* Check if we can send this I/O via FastPath */
+        if (raid->capability.fpCapable) {
+                if (isRead)
+                        io_info->fpOkForIo = (raid->capability.fpReadCapable &&
+                                              ((num_strips == 1) ||
+                                               raid->capability.
+                                               fpReadAcrossStripe));
+                else
+                        io_info->fpOkForIo = (raid->capability.fpWriteCapable &&
+                                              ((num_strips == 1) ||
+                                               raid->capability.
+                                               fpWriteAcrossStripe));
+        } else
                 io_info->fpOkForIo = FALSE;
-        } else {
-                io_info->fpOkForIo = TRUE;
-        }
 
         if (numRows == 1) {
                 /* single-strip IOs can always lock only the data needed */