Some devices come online in write protected state and switch to
read-write once they are ready to process I/O requests. These devices
broke with commit 20bd1d026aac ("scsi: sd: Keep disk read-only when
re-reading partition") because we had no way to distinguish between a
user decision to set a block_device read-only and the actual hardware
device being write-protected.
Because partitions are dropped and recreated on revalidate we are
unable to persist any user-provided policy in hd_struct. Introduce a
bitmap in struct gendisk to track the user configuration. This bitmap
is updated when BLKROSET is called on a given disk or partition.
A helper function, get_user_ro(), is provided to determine whether the
ioctl has forced read-only state for a given block device. This helper
is used by set_disk_ro() and add_partition() to ensure that both
existing and newly created partitions will get the correct state.
- If BLKROSET sets a whole disk device read-only, all partitions will
now end up in a read-only state.
- If BLKROSET sets a given partition read-only, that partition will
remain read-only post revalidate.
- Otherwise both the whole disk device and any partitions will
reflect the write protect state of the underlying device.
Since nobody knows what "policy" means, rename the field to
"read_only" for clarity.
Cc: Jeremy Cline <jeremy@xxxxxxxxxx>
Cc: Oleksii Kurochko <olkuroch@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.16+
Reported-by: Oleksii Kurochko <olkuroch@xxxxxxxxx>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201221
Fixes: 20bd1d026aac ("scsi: sd: Keep disk read-only when re-reading partition")
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
---
v3:
- Drop ?: since gcc complains about mixing int and bool (zeroday)
- Drop EXPORT_SYMBOL (hch)
- s/policy/read_only/ and make it a boolean
v2:
- Track user read-only state in a bitmap
- Work around the regression that caused us to drop user
preferences on revalidate
---
block/blk-core.c | 2 +-
block/genhd.c | 34 ++++++++++++++++++++++++----------
block/ioctl.c | 4 ++++
block/partition-generic.c | 7 +++++--
drivers/scsi/sd.c | 4 +---
include/linux/genhd.h | 11 +++++++----
6 files changed, 42 insertions(+), 20 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index c78042975737..c28d7ee3a05e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -790,7 +790,7 @@ static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
{
const int op = bio_op(bio);
- if (part->policy && op_is_write(op)) {
+ if (part->read_only && op_is_write(op)) {
char b[BDEVNAME_SIZE];
if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
diff --git a/block/genhd.c b/block/genhd.c
index 1dd8fd6613b8..c07037c0b03f 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1537,26 +1537,40 @@ static void set_disk_ro_uevent(struct gendisk *gd, int ro)
kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
}
-void set_device_ro(struct block_device *bdev, int flag)
+void set_device_ro(struct block_device *bdev, bool state)
{
- bdev->bd_part->policy = flag;
+ bdev->bd_part->read_only = state;
}
EXPORT_SYMBOL(set_device_ro);
-void set_disk_ro(struct gendisk *disk, int flag)
+bool get_user_ro(struct gendisk *disk, unsigned int partno)
+{
+ /* Is the user read-only bit set for the whole disk device? */
+ if (test_bit(0, disk->user_ro_bitmap))
+ return true;
+
+ /* Is the user read-only bit set for this particular partition? */
+ if (test_bit(partno, disk->user_ro_bitmap))
+ return true;
+
+ return false;
+}
+
+void set_disk_ro(struct gendisk *disk, bool state)
{
struct disk_part_iter piter;
struct hd_struct *part;
- if (disk->part0.policy != flag) {
- set_disk_ro_uevent(disk, flag);
- disk->part0.policy = flag;
- }
+ if (disk->part0.read_only != state)
+ set_disk_ro_uevent(disk, state);
- disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
+ disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY_PART0);
while ((part = disk_part_iter_next(&piter)))
- part->policy = flag;
+ if (get_user_ro(disk, part->partno))
+ part->read_only = true;
+ else
+ part->read_only = state;
disk_part_iter_exit(&piter);
}
@@ -1566,7 +1580,7 @@ int bdev_read_only(struct block_device *bdev)
{
if (!bdev)
return 0;
- return bdev->bd_part->policy;
+ return bdev->bd_part->read_only;
}
EXPORT_SYMBOL(bdev_read_only);
diff --git a/block/ioctl.c b/block/ioctl.c
index 4825c78a6baa..41206df89485 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -451,6 +451,10 @@ static int blkdev_roset(struct block_device *bdev, fmode_t mode,
return ret;
if (get_user(n, (int __user *)arg))
return -EFAULT;
+ if (n)
+ set_bit(bdev->bd_partno, bdev->bd_disk->user_ro_bitmap);
+ else
+ clear_bit(bdev->bd_partno, bdev->bd_disk->user_ro_bitmap);
set_device_ro(bdev, n);
return 0;
}
diff --git a/block/partition-generic.c b/block/partition-generic.c
index 8e596a8dff32..2bade849cc5c 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -98,7 +98,7 @@ static ssize_t part_ro_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct hd_struct *p = dev_to_part(dev);
- return sprintf(buf, "%d\n", p->policy ? 1 : 0);
+ return sprintf(buf, "%u\n", p->read_only ? 1 : 0);
}
static ssize_t part_alignment_offset_show(struct device *dev,
@@ -338,7 +338,10 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
queue_limit_discard_alignment(&disk->queue->limits, start);
p->nr_sects = len;
p->partno = partno;
- p->policy = get_disk_ro(disk);
+ if (get_user_ro(disk, partno))
+ p->read_only = true;
+ else
+ p->read_only = get_disk_ro(disk);
if (info) {
struct partition_meta_info *pinfo = alloc_part_info(disk);
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 67cc439b86e4..5dfe37b08d3b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2591,10 +2591,8 @@ sd_read_write_protect_flag(struct scsi_disk *sdkp, unsigned char *buffer)
int res;
struct scsi_device *sdp = sdkp->device;
struct scsi_mode_data data;
- int disk_ro = get_disk_ro(sdkp->disk);
int old_wp = sdkp->write_prot;
- set_disk_ro(sdkp->disk, 0);
if (sdp->skip_ms_page_3f) {
sd_first_printk(KERN_NOTICE, sdkp, "Assuming Write Enabled\n");
return;
@@ -2632,7 +2630,7 @@ sd_read_write_protect_flag(struct scsi_disk *sdkp, unsigned char *buffer)
"Test WP failed, assume Write Enabled\n");
} else {
sdkp->write_prot = ((data.device_specific & 0x80) != 0);
- set_disk_ro(sdkp->disk, sdkp->write_prot || disk_ro);
+ set_disk_ro(sdkp->disk, sdkp->write_prot);
if (sdkp->first_scan || old_wp != sdkp->write_prot) {
sd_printk(KERN_NOTICE, sdkp, "Write Protect is %s\n",
sdkp->write_prot ? "on" : "off");
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 06c0fd594097..1abde0e88ccb 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -118,7 +118,8 @@ struct hd_struct {
unsigned int discard_alignment;
struct device __dev;
struct kobject *holder_dir;
- int policy, partno;
+ bool read_only;
+ int partno;
struct partition_meta_info *info;
#ifdef CONFIG_FAIL_MAKE_REQUEST
int make_it_fail;
@@ -194,6 +195,7 @@ struct gendisk {
*/
struct disk_part_tbl __rcu *part_tbl;
struct hd_struct part0;
+ DECLARE_BITMAP(user_ro_bitmap, DISK_MAX_PARTS);
const struct block_device_operations *fops;
struct request_queue *queue;
@@ -431,12 +433,13 @@ extern void del_gendisk(struct gendisk *gp);
extern struct gendisk *get_gendisk(dev_t dev, int *partno);
extern struct block_device *bdget_disk(struct gendisk *disk, int partno);
-extern void set_device_ro(struct block_device *bdev, int flag);
-extern void set_disk_ro(struct gendisk *disk, int flag);
+extern void set_device_ro(struct block_device *bdev, bool state);
+extern void set_disk_ro(struct gendisk *disk, bool state);
+extern bool get_user_ro(struct gendisk *disk, unsigned int partno);
static inline int get_disk_ro(struct gendisk *disk)
{
- return disk->part0.policy;
+ return disk->part0.read_only;
}
extern void disk_block_events(struct gendisk *disk);
--
2.19.2
