[PATCH 3/9] sg: do not allocate a gendisk

Christoph Hellwig
2021-08-16T13:24:22Z

sg is a character driver and thus does not need to allocate a gendisk,
which is only used for file system-like block layer I/O on block
devices.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/scsi/sg.c | 32 +++++++++-----------------------
1 file changed, 9 insertions(+), 23 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 91e2221bbb0d..477267add49d 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -166,7 +166,7 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
bool exclude; /* 1->open(O_EXCL) succeeded and is active */
int open_cnt; /* count of opens (perhaps < num(sfds) ) */
char sgdebug; /* 0->off, 1->sense, 9->dump dev, 10-> all devs */
- struct gendisk *disk;
+ char name[DISK_NAME_LEN];
struct cdev * cdev; /* char_dev [sysfs: /sys/cdev/major/sg<n>] */
struct kref d_ref;
} Sg_device;
@@ -202,8 +202,7 @@ static void sg_device_destroy(struct kref *kref);
#define SZ_SG_REQ_INFO sizeof(sg_req_info_t)

#define sg_printk(prefix, sdp, fmt, a...) \
- sdev_prefix_printk(prefix, (sdp)->device, \
- (sdp)->disk->disk_name, fmt, ##a)
+ sdev_prefix_printk(prefix, (sdp)->device, (sdp)->name, fmt, ##a)

/*
* The SCSI interfaces that use read() and write() as an asynchronous variant of
@@ -832,7 +831,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,

srp->rq->timeout = timeout;
kref_get(&sfp->f_ref); /* sg_rq_end_io() does kref_put(). */
- blk_execute_rq_nowait(sdp->disk, srp->rq, at_head, sg_rq_end_io);
+ blk_execute_rq_nowait(NULL, srp->rq, at_head, sg_rq_end_io);
return 0;
}

@@ -1119,8 +1118,7 @@ sg_ioctl_common(struct file *filp, Sg_device *sdp, Sg_fd *sfp,
return put_user(max_sectors_bytes(sdp->device->request_queue),
ip);
case BLKTRACESETUP:
- return blk_trace_setup(sdp->device->request_queue,
- sdp->disk->disk_name,
+ return blk_trace_setup(sdp->device->request_queue, NULL,
MKDEV(SCSI_GENERIC_MAJOR, sdp->index),
NULL, p);
case BLKTRACESTART:
@@ -1456,7 +1454,7 @@ static struct class *sg_sysfs_class;
static int sg_sysfs_valid = 0;

static Sg_device *
-sg_alloc(struct gendisk *disk, struct scsi_device *scsidp)
+sg_alloc(struct scsi_device *scsidp)
{
struct request_queue *q = scsidp->request_queue;
Sg_device *sdp;
@@ -1492,9 +1490,7 @@ sg_alloc(struct gendisk *disk, struct scsi_device *scsidp)

SCSI_LOG_TIMEOUT(3, sdev_printk(KERN_INFO, scsidp,
"sg_alloc: dev=%d \n", k));
- sprintf(disk->disk_name, "sg%d", k);
- disk->first_minor = k;
- sdp->disk = disk;
+ sprintf(sdp->name, "sg%d", k);
sdp->device = scsidp;
mutex_init(&sdp->open_rel_lock);
INIT_LIST_HEAD(&sdp->sfds);
@@ -1521,19 +1517,11 @@ static int
sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
{
struct scsi_device *scsidp = to_scsi_device(cl_dev->parent);
- struct gendisk *disk;
Sg_device *sdp = NULL;
struct cdev * cdev = NULL;
int error;
unsigned long iflags;

- disk = alloc_disk(1);
- if (!disk) {
- pr_warn("%s: alloc_disk failed\n", __func__);
- return -ENOMEM;
- }
- disk->major = SCSI_GENERIC_MAJOR;
-
error = -ENOMEM;
cdev = cdev_alloc();
if (!cdev) {
@@ -1543,7 +1531,7 @@ sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
cdev->owner = THIS_MODULE;
cdev->ops = &sg_fops;

- sdp = sg_alloc(disk, scsidp);
+ sdp = sg_alloc(scsidp);
if (IS_ERR(sdp)) {
pr_warn("%s: sg_alloc failed\n", __func__);
error = PTR_ERR(sdp);
@@ -1561,7 +1549,7 @@ sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
sg_class_member = device_create(sg_sysfs_class, cl_dev->parent,
MKDEV(SCSI_GENERIC_MAJOR,
sdp->index),
- sdp, "%s", disk->disk_name);
+ sdp, "%s", sdp->name);
if (IS_ERR(sg_class_member)) {
pr_err("%s: device_create failed\n", __func__);
error = PTR_ERR(sg_class_member);
@@ -1589,7 +1577,6 @@ sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
kfree(sdp);

out:
- put_disk(disk);
if (cdev)
cdev_del(cdev);
return error;
@@ -1613,7 +1600,6 @@ sg_device_destroy(struct kref *kref)
SCSI_LOG_TIMEOUT(3,
sg_printk(KERN_INFO, sdp, "sg_device_destroy\n"));

- put_disk(sdp->disk);
kfree(sdp);
}

@@ -2606,7 +2592,7 @@ static int sg_proc_seq_show_debug(struct seq_file *s, void *v)
goto skip;
read_lock(&sdp->sfd_lock);
if (!list_empty(&sdp->sfds)) {
- seq_printf(s, " >>> device=%s ", sdp->disk->disk_name);
+ seq_printf(s, " >>> device=%s ", sdp->name);
if (atomic_read(&sdp->detaching))
seq_puts(s, "detaching pending close ");
else if (sdp->device) {
--
2.30.2