[Xen-devel] [PATCH] linux-2.6.18/blkfront: properly fail packet requests

["Jan Beulich" <JBeulich@xxxxxxxx>]

c/s 1036:f5635e334aa5 ("blkfront: forward unknown IOCTLs to
scsi_cmd_ioctl() for /dev/sdX") uncovered a problem in blkfront's
request handling: blk_pc_request()-s, among other sources resulting
from the handling of the SG_IO ioctl in scsi_cmd_ioctl(), must not be
passed to end_request() without prior adjustment: Neither is their
->hard_cur_sectors necessarily correct (potentially resulting in an
infinite loop), nor is ->errors ever getting set properly to reflect
the failure (sg_io() intentionally ignores the return value from
blk_execute_rq()).

As blktap2's internally created devices have the same deficiency, fix
this there too.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/drivers/xen/blkfront/blkfront.c
+++ b/drivers/xen/blkfront/blkfront.c
@@ -709,6 +709,12 @@ void do_blkif_request(request_queue_t *r
        while ((req = elv_next_request(rq)) != NULL) {
                info = req->rq_disk->private_data;
                if (!blk_fs_request(req)) {
+                       if (blk_pc_request(req)) {
+                               req->errors = (DID_ERROR << 16)
+                                             | (DRIVER_INVALID << 24);
+                               req->hard_cur_sectors = (req->data_len
+                                                        + 511) >> 9;
+                       }
                        end_request(req, 0);
                        continue;
                }
--- a/drivers/xen/blktap2/device.c
+++ b/drivers/xen/blktap2/device.c
@@ -3,6 +3,7 @@
 #include <linux/cdrom.h>
 #include <linux/hdreg.h>
 #include <linux/module.h>
+#include <scsi/scsi.h>
 #include <asm/tlbflush.h>
 
 #include <scsi/scsi.h>
@@ -825,6 +826,12 @@ blktap_device_run_queue(struct blktap *t
 
        while ((req = elv_next_request(rq)) != NULL) {
                if (!blk_fs_request(req)) {
+                       if (blk_pc_request(req)) {
+                               req->errors = (DID_ERROR << 16)
+                                             | (DRIVER_INVALID << 24);
+                               req->hard_cur_sectors = (req->data_len
+                                                        + 511) >> 9;
+                       }
                        end_request(req, 0);
                        continue;
                }
@@ -912,9 +919,16 @@ blktap_device_do_request(request_queue_t
 
 fail:
        while ((req = elv_next_request(rq))) {
-               BTERR("device closed: failing secs %llu - %llu\n",
-                     (unsigned long long)req->sector,
-                     (unsigned long long)req->sector + req->nr_sectors);
+               if (blk_fs_request(req)) {
+                       unsigned long long sec = req->sector;
+
+                       BTERR("device closed: failing secs %#Lx-%#Lx\n",
+                             sec, sec + req->nr_sectors - 1);
+               } else if (blk_pc_request(req)) {
+                       req->errors = (DID_ERROR << 16)
+                                     | (DRIVER_INVALID << 24);
+                       req->hard_cur_sectors = (req->data_len + 511) >> 9;
+               }
                end_request(req, 0);
        }
 }

Attachment: xen-blkfront-sg_io.patch
Description: Text document

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