linux-kernel - [PATCH v3 7/7] scsi: sr: wait for the medium to become ready

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Message-Id: <f374f9c072563c8aafed4a5aefe583ecb4b3c362.1572002144.git.msuchanek@suse.de>
Date:   Fri, 25 Oct 2019 13:21:44 +0200
From:   Michal Suchanek <msuchanek@...e.de>
To:     linux-scsi@...r.kernel.org
Cc:     Michal Suchanek <msuchanek@...e.de>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        "Ewan D. Milne" <emilne@...hat.com>,
        Jonathan Corbet <corbet@....net>, Jens Axboe <axboe@...nel.dk>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "J. Bruce Fields" <bfields@...hat.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Eric Biggers <ebiggers@...gle.com>,
        Benjamin Coddington <bcodding@...hat.com>,
        Hannes Reinecke <hare@...e.com>,
        Omar Sandoval <osandov@...com>, Ming Lei <ming.lei@...hat.com>,
        Damien Le Moal <damien.lemoal@....com>,
        Bart Van Assche <bvanassche@....org>,
        Tejun Heo <tj@...nel.org>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH v3 7/7] scsi: sr: wait for the medium to become ready

Use the autoclose function provided by cdrom driver to wait for drive to
close in open_finish, and attempt to open once more after the door
closes.

Signed-off-by: Michal Suchanek <msuchanek@...e.de>
---
v3: use function call rather than IOCTL
---
 drivers/scsi/sr.c | 54 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 07c319494bf4..d144ad085b35 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -522,29 +522,58 @@ static blk_status_t sr_init_command(struct scsi_cmnd *SCpnt)
 	return ret;
 }
 
-static int sr_block_open(struct block_device *bdev, fmode_t mode)
+static int __sr_block_open(struct block_device *bdev, fmode_t mode)
 {
-	struct scsi_cd *cd;
-	struct scsi_device *sdev;
-	int ret = -ENXIO;
-
-	cd = scsi_cd_get(bdev->bd_disk);
-	if (!cd)
-		goto out;
+	struct scsi_cd *cd = scsi_cd(bdev->bd_disk);
+	int ret;
 
-	sdev = cd->device;
-	scsi_autopm_get_device(sdev);
 	check_disk_change(bdev);
 
 	mutex_lock(&sr_mutex);
 	ret = cdrom_open(&cd->cdi, bdev, mode);
 	mutex_unlock(&sr_mutex);
 
+	return ret;
+}
+
+static int sr_block_open(struct block_device *bdev, fmode_t mode)
+{
+	struct scsi_cd *cd = scsi_cd_get(bdev->bd_disk);
+	struct scsi_device *sdev;
+	int ret;
+
+	if (!cd)
+		return -ENXIO;
+
+	sdev = cd->device;
+	scsi_autopm_get_device(sdev);
+	ret = __sr_block_open(bdev, mode);
 	scsi_autopm_put_device(sdev);
-	if (ret)
+
+	if (ret == -ERESTARTSYS)
 		scsi_cd_put(cd);
 
-out:
+	return ret;
+}
+
+static int sr_block_open_finish(struct block_device *bdev, fmode_t mode,
+				int ret)
+{
+	struct scsi_cd *cd = scsi_cd(bdev->bd_disk);
+
+	/* wait for drive to get ready */
+	if ((ret == -ENOMEDIUM) && !(mode & FMODE_NDELAY)) {
+		struct scsi_device *sdev = cd->device;
+		/*
+		 * Cannot use sr_block_ioctl because it locks sr_mutex blocking
+		 * out any processes trying to access the drive
+		 */
+		scsi_autopm_get_device(sdev);
+		cdrom_autoclose(&cd->cdi);
+		ret = __sr_block_open(bdev, mode);
+		scsi_autopm_put_device(sdev);
+	}
+
 	return ret;
 }
 
@@ -640,6 +669,7 @@ static const struct block_device_operations sr_bdops =
 {
 	.owner		= THIS_MODULE,
 	.open		= sr_block_open,
+	.open_finish	= sr_block_open_finish,
 	.release	= sr_block_release,
 	.ioctl		= sr_block_ioctl,
 	.check_events	= sr_block_check_events,
-- 
2.23.0