Re: [PATCH 12/30] blk_end_request: changing ub (take 4)

2007-12-13 Thread Pete Zaitcev 
On Wed, 12 Dec 2007 15:38:15 -0500 (EST), Kiyoshi Ueda [EMAIL PROTECTED] 
wrote:
 On Tue, 11 Dec 2007 15:48:03 -0800, Pete Zaitcev [EMAIL PROTECTED] wrote:

   - end_that_request_first(rq, uptodate, rq-hard_nr_sectors);
   - end_that_request_last(rq, uptodate);
   + if (__blk_end_request(rq, error, blk_rq_bytes(rq)))
   + BUG();

  My understanding was, blk_end_request() is the same thing, only
  takes the queue lock. But then, should I refactor ub so that it
  calls __blk_end_request if request function ends with an error
  and blk_end_request if the end-of-IO even is processed?

 I'm using __blk_end_request() here and I think it's sufficient, because:
   o end_that_request_last() must be called with the queue lock held
   o ub_end_rq() calls end_that_request_last() without taking
 the queue lock in itself.
 So the queue lock must have been taken outside ub_end_rq().

 But, if ub is calling end_that_request_last() without the queue lock,
 it is a bug in the original code and we should use blk_end_request()
 to fix that.

So, I have to rewrite ub to split the paths after all, right?
Let's do this then: I'll wait until your patch gets to Linus and
then update it with the split. The reason is, I need the whole
enchilada applied and I don't want to bother tracking iterations
and all the little segments (of which you already have 30).
Until then, ub will have a race by using your original small patch.

Best wishes,
-- Pete
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Re: [PATCH 12/30] blk_end_request: changing ub (take 4)

2007-12-12 Thread Kiyoshi Ueda 
Hi Pete,

On Tue, 11 Dec 2007 15:48:03 -0800, Pete Zaitcev [EMAIL PROTECTED] wrote:
  if (scsi_status == 0) {
  -   uptodate = 1;
  +   error = 0;
  } else {
  -   uptodate = 0;
  +   error = -EIO;
  rq-errors = scsi_status;
  }
  -   end_that_request_first(rq, uptodate, rq-hard_nr_sectors);
  -   end_that_request_last(rq, uptodate);
  +   if (__blk_end_request(rq, error, blk_rq_bytes(rq)))
  +   BUG();
 
 Acked-by: Pete Zaitcev [EMAIL PROTECTED]
 
 I follow the discussion, actually, and wanted to ask someone to look
 closer if it's appropriate to use __blk_end_request() here.
 My understanding was, blk_end_request() is the same thing, only
 takes the queue lock. But then, should I refactor ub so that it
 calls __blk_end_request if request function ends with an error
 and blk_end_request if the end-of-IO even is processed? If not,
 and the above is sufficient, why have blk_end_request at all?

The difference between blk_end_request() and __blk_end_request() is
whether the queue lock is held or not when end_that_request_last()
is called.
It's not relevant to the status of the request (error or not).

I'm using __blk_end_request() here and I think it's sufficient, because:
  o end_that_request_last() must be called with the queue lock held
  o ub_end_rq() calls end_that_request_last() without taking
the queue lock in itself.
So the queue lock must have been taken outside ub_end_rq().

But, if ub is calling end_that_request_last() without the queue lock,
it is a bug in the original code and we should use blk_end_request()
to fix that.

Does that answer satisfy you?

Thanks,
Kiyoshi Ueda
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[PATCH 12/30] blk_end_request: changing ub (take 4)

2007-12-11 Thread Kiyoshi Ueda 
This patch converts ub to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.

Cc: Pete Zaitcev [EMAIL PROTECTED]
Signed-off-by: Kiyoshi Ueda [EMAIL PROTECTED]
Signed-off-by: Jun'ichi Nomura [EMAIL PROTECTED]
---
 drivers/block/ub.c |   10 +-
 1 files changed, 5 insertions(+), 5 deletions(-)

Index: 2.6.24-rc4/drivers/block/ub.c
===
--- 2.6.24-rc4.orig/drivers/block/ub.c
+++ 2.6.24-rc4/drivers/block/ub.c
@@ -808,16 +808,16 @@ static void ub_rw_cmd_done(struct ub_dev
 
 static void ub_end_rq(struct request *rq, unsigned int scsi_status)
 {
-   int uptodate;
+   int error;
 
if (scsi_status == 0) {
-   uptodate = 1;
+   error = 0;
} else {
-   uptodate = 0;
+   error = -EIO;
rq-errors = scsi_status;
}
-   end_that_request_first(rq, uptodate, rq-hard_nr_sectors);
-   end_that_request_last(rq, uptodate);
+   if (__blk_end_request(rq, error, blk_rq_bytes(rq)))
+   BUG();
 }
 
 static int ub_rw_cmd_retry(struct ub_dev *sc, struct ub_lun *lun,
-
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Re: [PATCH 12/30] blk_end_request: changing ub (take 4)

2007-12-11 Thread Pete Zaitcev 
On Tue, 11 Dec 2007 17:46:47 -0500 (EST), Kiyoshi Ueda [EMAIL PROTECTED] 
wrote:

   if (scsi_status == 0) {
 - uptodate = 1;
 + error = 0;
   } else {
 - uptodate = 0;
 + error = -EIO;
   rq-errors = scsi_status;
   }
 - end_that_request_first(rq, uptodate, rq-hard_nr_sectors);
 - end_that_request_last(rq, uptodate);
 + if (__blk_end_request(rq, error, blk_rq_bytes(rq)))
 + BUG();

Acked-by: Pete Zaitcev [EMAIL PROTECTED]

I follow the discussion, actually, and wanted to ask someone to look
closer if it's appropriate to use __blk_end_request() here.
My understanding was, blk_end_request() is the same thing, only
takes the queue lock. But then, should I refactor ub so that it
calls __blk_end_request if request function ends with an error
and blk_end_request if the end-of-IO even is processed? If not,
and the above is sufficient, why have blk_end_request at all?

-- Pete
-
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