linux-kernel - [162/165] block: dont block events on excl write for non-optical

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Message-Id: <20110601081229.084861472@blue.kroah.org>
Date:	Wed, 01 Jun 2011 17:12:12 +0900
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Tejun Heo <tj@...nel.org>, Jens Axboe <jaxboe@...ionio.com>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [162/165] block: dont block events on excl write for non-optical

2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------
 devices
Content-Length: 4265
Lines: 120

From: Tejun Heo <tj@...nel.org>

commit d4dc210f69bcb0b4bef5a83b1c323817be89bad1 upstream.

Disk event code automatically blocks events on excl write.  This is
primarily to avoid issuing polling commands while burning is in
progress.  This behavior doesn't fit other types of devices with
removeable media where polling commands don't have adverse side
effects and door locking usually doesn't exist.

This patch introduces new genhd flag which controls the auto-blocking
behavior and uses it to enable auto-blocking only on optical devices.

Note for stable: 2.6.38 and later only

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: Kay Sievers <kay.sievers@...y.org>
Signed-off-by: Jens Axboe <jaxboe@...ionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/block/paride/pcd.c |    1 +
 drivers/cdrom/viocd.c      |    3 ++-
 drivers/ide/ide-cd.c       |    3 ++-
 drivers/scsi/sr.c          |    2 +-
 fs/block_dev.c             |   17 ++++++++++-------
 include/linux/genhd.h      |    1 +
 6 files changed, 17 insertions(+), 10 deletions(-)

--- a/drivers/block/paride/pcd.c
+++ b/drivers/block/paride/pcd.c
@@ -320,6 +320,7 @@ static void pcd_init_units(void)
 		disk->first_minor = unit;
 		strcpy(disk->disk_name, cd->name);	/* umm... */
 		disk->fops = &pcd_bdops;
+		disk->flags = GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
 	}
 }
 
--- a/drivers/cdrom/viocd.c
+++ b/drivers/cdrom/viocd.c
@@ -625,7 +625,8 @@ static int viocd_probe(struct vio_dev *v
 	blk_queue_max_hw_sectors(q, 4096 / 512);
 	gendisk->queue = q;
 	gendisk->fops = &viocd_fops;
-	gendisk->flags = GENHD_FL_CD|GENHD_FL_REMOVABLE;
+	gendisk->flags = GENHD_FL_CD | GENHD_FL_REMOVABLE |
+			 GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
 	set_capacity(gendisk, 0);
 	gendisk->private_data = d;
 	d->viocd_disk = gendisk;
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -1773,7 +1773,8 @@ static int ide_cd_probe(ide_drive_t *dri
 
 	g->minors = 1;
 	g->driverfs_dev = &drive->gendev;
-	g->flags = GENHD_FL_CD | GENHD_FL_REMOVABLE;
+	g->flags = GENHD_FL_CD | GENHD_FL_REMOVABLE |
+		   GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
 	if (ide_cdrom_setup(drive)) {
 		put_device(&info->dev);
 		goto failed;
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -636,7 +636,7 @@ static int sr_probe(struct device *dev)
 	disk->first_minor = minor;
 	sprintf(disk->disk_name, "sr%d", minor);
 	disk->fops = &sr_bdops;
-	disk->flags = GENHD_FL_CD;
+	disk->flags = GENHD_FL_CD | GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
 	disk->events = DISK_EVENT_MEDIA_CHANGE | DISK_EVENT_EJECT_REQUEST;
 
 	blk_queue_rq_timeout(sdev->request_queue, SR_TIMEOUT);
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1238,6 +1238,8 @@ int blkdev_get(struct block_device *bdev
 	res = __blkdev_get(bdev, mode, 0);
 
 	if (whole) {
+		struct gendisk *disk = whole->bd_disk;
+
 		/* finish claiming */
 		mutex_lock(&bdev->bd_mutex);
 		spin_lock(&bdev_lock);
@@ -1264,15 +1266,16 @@ int blkdev_get(struct block_device *bdev
 		spin_unlock(&bdev_lock);
 
 		/*
-		 * Block event polling for write claims.  Any write
-		 * holder makes the write_holder state stick until all
-		 * are released.  This is good enough and tracking
-		 * individual writeable reference is too fragile given
-		 * the way @mode is used in blkdev_get/put().
+		 * Block event polling for write claims if requested.  Any
+		 * write holder makes the write_holder state stick until
+		 * all are released.  This is good enough and tracking
+		 * individual writeable reference is too fragile given the
+		 * way @mode is used in blkdev_get/put().
 		 */
-		if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) {
+		if ((disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE) &&
+		    !res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) {
 			bdev->bd_write_holder = true;
-			disk_block_events(bdev->bd_disk);
+			disk_block_events(disk);
 		}
 
 		mutex_unlock(&bdev->bd_mutex);
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -127,6 +127,7 @@ struct hd_struct {
 #define GENHD_FL_SUPPRESS_PARTITION_INFO	32
 #define GENHD_FL_EXT_DEVT			64 /* allow extended devt */
 #define GENHD_FL_NATIVE_CAPACITY		128
+#define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE	256
 
 enum {
 	DISK_EVENT_MEDIA_CHANGE			= 1 << 0, /* media changed */


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