ide: Fix IDE taskfile with cfq scheduler

commit 720fc22a7af79d91ec460c80efa92c65c12d105e upstream.

When ide taskfile access is being used (for example with hdparm --security
commands) and cfq scheduler is selected, the scheduler crashes on BUG in
cfq_put_request.

The reason is that the cfq scheduler is tracking counts of read and write
requests separately; the ide-taskfile subsystem allocates a read request and
then flips the flag to make it a write request. The counters in cfq will
mismatch.

This patch changes ide-taskfile to allocate the READ or WRITE request as
required and don't change the flag later.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index cc8633cbe133db4d9b7f81330ef66a547a6176ac..67fb73559fd582e0bbd477500636c315834b7764 100644 (file)
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -428,13 +428,11 @@ int ide_raw_taskfile(ide_drive_t *drive, struct ide_cmd *cmd, u8 *buf,
 {
        struct request *rq;
        int error;
+       int rw = !(cmd->tf_flags & IDE_TFLAG_WRITE) ? READ : WRITE;
 
-       rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
+       rq = blk_get_request(drive->queue, rw, __GFP_WAIT);
        rq->cmd_type = REQ_TYPE_ATA_TASKFILE;
 
-       if (cmd->tf_flags & IDE_TFLAG_WRITE)
-               rq->cmd_flags |= REQ_RW;
-
        /*
         * (ks) We transfer currently only whole sectors.
         * This is suffient for now.  But, it would be great,