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block: ataflop: more blk-mq refactoring fixes

PATCH In review Michael Schmitz 2 participants 2 messages Feb 27, 2024

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Michael Schmitz

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PATCH 1/1 block: ataflop: more blk-mq refactoring fixes

[ commit d28e4dff085c5a87025c9a0a85fb798bd8e9ca17 upstream ]

As it turns out, my earlier patch in commit 86d46fdaa12a (block:
ataflop: fix breakage introduced at blk-mq refactoring) was incomplete. This patch fixes any remaining issues found during more testing and code review.

Requests exceeding 4 k are handled in 4k segments but __blk_mq_end_request() is never called on these (still sectors outstanding on the request). With redo_fd_request() removed, there is no provision to kick off processing of the next segment, causing requests exceeding 4k to hang. (By setting /sys/block/fd0/queue/max_sectors_k <= 4 as workaround, this behaviour can be avoided).

Instead of reintroducing redo_fd_request(), requeue the remainder of the request by calling blk_mq_requeue_request() on incomplete requests (i.e. when blk_update_request() still returns true), and rely on the block layer to queue the residual as new request.

Both error handling and formatting needs to release the ST-DMA lock, so call finish_fdc() on these (this was previously handled by redo_fd_request()). finish_fdc() may be called legitimately without the ST-DMA lock held - make sure we only release the lock if we actually held it. In a similar way, early exit due to errors in ataflop_queue_rq() must release the lock.

After minor errors, fd_error sets up to recalibrate the drive but never re-runs the current operation (another task handled by redo_fd_request() before). Call do_fd_action() to get the next steps (seek, retry read/write) underway.

Signed-off-by Michael Schmitz <[email protected]>
Fixes 6ec3938cff95f (ataflop: convert to blk-mq)
Fixes 86d46fdaa12a (block: ataflop: fix breakage introduced at blk-mq refactoring)
CC [email protected] # 5.10.x
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Jens Axboe <[email protected]>
[MSch: v5.10 backport merge conflict fix]
---
 drivers/block/ataflop.c | 42 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 37 insertions(+), 5 deletions(-)
drivers/block/ataflop.c +37 -5
index cd612cd04767..224450c90e45 100644
@@ -456,10 +456,20 @@ static DEFINE_TIMER(fd_timer, check_change);
 	
 static void fd_end_request_cur(blk_status_t err)
 {
+	DPRINT(("fd_end_request_cur(), bytes %d of %d\n",
+		blk_rq_cur_bytes(fd_request),
+		blk_rq_bytes(fd_request)));
+
 	if (!blk_update_request(fd_request, err,
 				blk_rq_cur_bytes(fd_request))) {
+		DPRINT(("calling __blk_mq_end_request()\n"));
 		__blk_mq_end_request(fd_request, err);
 		fd_request = NULL;
+	} else {
+		/* requeue rest of request */
+		DPRINT(("calling blk_mq_requeue_request()\n"));
+		blk_mq_requeue_request(fd_request, true);
+		fd_request = NULL;
 	}
 }
 

@@ -697,12 +707,21 @@ static void fd_error( void )
 	if (fd_request->error_count >= MAX_ERRORS) {
 		printk(KERN_ERR "fd%d: too many errors.\n", SelectedDrive );
 		fd_end_request_cur(BLK_STS_IOERR);
+		finish_fdc();
+		return;
 	}
 	else if (fd_request->error_count == RECALIBRATE_ERRORS) {
 		printk(KERN_WARNING "fd%d: recalibrating\n", SelectedDrive );
 		if (SelectedDrive != -1)
 			SUD.track = -1;
 	}
+	/* need to re-run request to recalibrate */
+	atari_disable_irq( IRQ_MFP_FDC );
+
+	setup_req_params( SelectedDrive );
+	do_fd_action( SelectedDrive );
+
+	atari_enable_irq( IRQ_MFP_FDC );
 }
 
 

@@ -737,6 +756,7 @@ static int do_format(int drive, int type, struct atari_format_descr *desc)
 	if (type) {
 		if (--type >= NUM_DISK_MINORS ||
 		    minor2disktype[type].drive_types > DriveType) {
+			finish_fdc();
 			ret = -EINVAL;
 			goto out;
 		}

@@ -745,6 +765,7 @@ static int do_format(int drive, int type, struct atari_format_descr *desc)
 	}
 
 	if (!UDT || desc->track >= UDT->blocks/UDT->spt/2 || desc->head >= 2) {
+		finish_fdc();
 		ret = -EINVAL;
 		goto out;
 	}

@@ -785,6 +806,7 @@ static int do_format(int drive, int type, struct atari_format_descr *desc)
 
 	wait_for_completion(&format_wait);
 
+	finish_fdc();
 	ret = FormatError ? -EIO : 0;
 out:
 	blk_mq_unquiesce_queue(q);

@@ -819,6 +841,7 @@ static void do_fd_action( int drive )
 		    else {
 			/* all sectors finished */
 			fd_end_request_cur(BLK_STS_OK);
+			finish_fdc();
 			return;
 		    }
 		}

@@ -1222,8 +1245,8 @@ static void fd_rwsec_done1(int status)
 	}
 	else {
 		/* all sectors finished */
-		finish_fdc();
 		fd_end_request_cur(BLK_STS_OK);
+		finish_fdc();
 	}
 	return;
   

@@ -1345,7 +1368,7 @@ static void fd_times_out(struct timer_list *unused)
 
 static void finish_fdc( void )
 {
-	if (!NeedSeek) {
+	if (!NeedSeek || !stdma_is_locked_by(floppy_irq)) {
 		finish_fdc_done( 0 );
 	}
 	else {

@@ -1380,7 +1403,8 @@ static void finish_fdc_done( int dummy )
 	start_motor_off_timer();
 
 	local_irq_save(flags);
-	stdma_release();
+	if (stdma_is_locked_by(floppy_irq))
+		stdma_release();
 	local_irq_restore(flags);
 
 	DPRINT(("finish_fdc() finished\n"));

@@ -1477,7 +1501,9 @@ static blk_status_t ataflop_queue_rq(struct blk_mq_hw_ctx *hctx,
 	int drive = floppy - unit;
 	int type = floppy->type;
 
-	DPRINT(("Queue request: drive %d type %d last %d\n", drive, type, bd->last));
+	DPRINT(("Queue request: drive %d type %d sectors %d of %d last %d\n",
+		drive, type, blk_rq_cur_sectors(bd->rq),
+		blk_rq_sectors(bd->rq), bd->last));
 
 	spin_lock_irq(&ataflop_lock);
 	if (fd_request) {

@@ -1499,6 +1525,7 @@ static blk_status_t ataflop_queue_rq(struct blk_mq_hw_ctx *hctx,
 		/* drive not connected */
 		printk(KERN_ERR "Unknown Device: fd%d\n", drive );
 		fd_end_request_cur(BLK_STS_IOERR);
+		stdma_release();
 		goto out;
 	}
 		

@@ -1515,11 +1542,13 @@ static blk_status_t ataflop_queue_rq(struct blk_mq_hw_ctx *hctx,
 		if (--type >= NUM_DISK_MINORS) {
 			printk(KERN_WARNING "fd%d: invalid disk format", drive );
 			fd_end_request_cur(BLK_STS_IOERR);
+			stdma_release();
 			goto out;
 		}
 		if (minor2disktype[type].drive_types > DriveType)  {
 			printk(KERN_WARNING "fd%d: unsupported disk format", drive );
 			fd_end_request_cur(BLK_STS_IOERR);
+			stdma_release();
 			goto out;
 		}
 		type = minor2disktype[type].index;

@@ -1620,6 +1649,7 @@ static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode,
 		/* what if type > 0 here? Overwrite specified entry ? */
 		if (type) {
 		        /* refuse to re-set a predefined type for now */
+			finish_fdc();
 			return -EINVAL;
 		}
 

@@ -1687,8 +1717,10 @@ static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode,
 
 		/* sanity check */
 		if (setprm.track != dtp->blocks/dtp->spt/2 ||
-		    setprm.head != 2)
+		    setprm.head != 2) {
+			finish_fdc();
 			return -EINVAL;
+		}
 
 		UDT = dtp;
 		set_capacity(floppy->disk, UDT->blocks);
Signature · 1 line
2.17.1
maintainer
#1 lore raw
Quoted 33 lines · Michael Schmitz

[ commit d28e4dff085c5a87025c9a0a85fb798bd8e9ca17 upstream ]

As it turns out, my earlier patch in commit 86d46fdaa12a (block:
ataflop: fix breakage introduced at blk-mq refactoring) was incomplete. This patch fixes any remaining issues found during more testing and code review.

Requests exceeding 4 k are handled in 4k segments but __blk_mq_end_request() is never called on these (still sectors outstanding on the request). With redo_fd_request() removed, there is no provision to kick off processing of the next segment, causing requests exceeding 4k to hang. (By setting /sys/block/fd0/queue/max_sectors_k <= 4 as workaround, this behaviour can be avoided).

Instead of reintroducing redo_fd_request(), requeue the remainder of the request by calling blk_mq_requeue_request() on incomplete requests (i.e. when blk_update_request() still returns true), and rely on the block layer to queue the residual as new request.

Both error handling and formatting needs to release the ST-DMA lock, so call finish_fdc() on these (this was previously handled by redo_fd_request()). finish_fdc() may be called legitimately without the ST-DMA lock held - make sure we only release the lock if we actually held it. In a similar way, early exit due to errors in ataflop_queue_rq() must release the lock.

After minor errors, fd_error sets up to recalibrate the drive but never re-runs the current operation (another task handled by redo_fd_request() before). Call do_fd_action() to get the next steps (seek, retry read/write) underway.

Quoted 7 lines
Signed-off-by Michael Schmitz <[email protected]>
Fixes 6ec3938cff95f (ataflop: convert to blk-mq)
Fixes 86d46fdaa12a (block: ataflop: fix breakage introduced at blk-mq refactoring)
CC [email protected] # 5.10.x
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Jens Axboe <[email protected]>
[MSch: v5.10 backport merge conflict fix]

Now queued up, thanks.

greg k-h