[SCSI] tgt: fix scsi command leak

The failure to map user-space pages leads to scsi command leak. It can
happens mostly because of user-space daemon bugs (or OOM). This patch
makes tgt just notify a LLD of the failure with sense when
blk_rq_map_user() fails.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 20 insertions, 3 deletions

diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c
index dc8781a68d7c..c05dff95bd95 100644
--- a/drivers/scsi/scsi_tgt_lib.c
+++ b/drivers/scsi/scsi_tgt_lib.c
@@ -459,6 +459,16 @@ static struct request *tgt_cmd_hash_lookup(struct request_queue *q, u64 tag)
         return rq;
 }
 
+static void scsi_tgt_build_sense(unsigned char *sense_buffer, unsigned char key,
+                                 unsigned char asc, unsigned char asq)
+{
+        sense_buffer[0] = 0x70;
+        sense_buffer[2] = key;
+        sense_buffer[7] = 0xa;
+        sense_buffer[12] = asc;
+        sense_buffer[13] = asq;
+}
+
 int scsi_tgt_kspace_exec(int host_no, int result, u64 tag,
                          unsigned long uaddr, u32 len, unsigned long sense_uaddr,
                          u32 sense_len, u8 rw)
@@ -514,9 +524,16 @@ int scsi_tgt_kspace_exec(int host_no, int result, u64 tag,
         if (len) {
                 err = scsi_map_user_pages(rq->end_io_data, cmd, uaddr, len, rw);
                 if (err) {
-                        eprintk("%p %d\n", cmd, err);
-                        err = -EAGAIN;
-                        goto done;
+                        /*
+                         * user-space daemon bugs or OOM
+                         * TODO: we can do better for OOM.
+                         */
+                        eprintk("cmd %p ret %d uaddr %lx len %d rw %d\n",
+                                cmd, err, uaddr, len, rw);
+                        cmd->result = SAM_STAT_CHECK_CONDITION;
+                        memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
+                        scsi_tgt_build_sense(cmd->sense_buffer,
+                                             HARDWARE_ERROR, 0, 0);
                 }
         }
         err = scsi_tgt_transfer_response(cmd);