| Message ID | 20190327162141.23882-1-martin.petersen@oracle.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [REPOST] scsi: sd: block: Fix regressions in read-only block device handling | expand |
On Wed, 2019-03-27 at 12:21 -0400, Martin K. Petersen wrote: > 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@jcline.org> > Cc: Oleksii Kurochko <olkuroch@cisco.com> > Cc: stable@vger.kernel.org # v4.16+ > Reported-by: Oleksii Kurochko <olkuroch@cisco.com> > 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@oracle.com> > > --- > > 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 4673ebe42255..932f179a9095 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -792,7 +792,7 @@ 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 703267865f14..9f3a93ca1851 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -1539,26 +1539,40 @@ 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); > } > > @@ -1568,7 +1582,7 @@ 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 251db30d0882..9d8e15d03d2b 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -2608,10 +2608,8 @@ 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; > @@ -2649,7 +2647,7 @@ 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); Looks good. Reviewed-by: Ewan D. Milne <emilne@redhat.com>
diff --git a/block/blk-core.c b/block/blk-core.c index 4673ebe42255..932f179a9095 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -792,7 +792,7 @@ 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 703267865f14..9f3a93ca1851 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1539,26 +1539,40 @@ 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); } @@ -1568,7 +1582,7 @@ 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 251db30d0882..9d8e15d03d2b 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -2608,10 +2608,8 @@ 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; @@ -2649,7 +2647,7 @@ 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);
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@jcline.org> Cc: Oleksii Kurochko <olkuroch@cisco.com> Cc: stable@vger.kernel.org # v4.16+ Reported-by: Oleksii Kurochko <olkuroch@cisco.com> 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@oracle.com> --- 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(-)