| Message ID | 20201207131918.2252553-4-hch@lst.de |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/6] dm: use bdev_read_only to check if a device is read-only | expand |
Christoph, > Commit 20bd1d026aac ("scsi: sd: Keep disk read-only when re-reading > partition") addressed a long-standing problem with user read-only > policy being overridden as a result of a device-initiated revalidate. > The commit has since been reverted due to a regression that left some > USB devices read-only indefinitely. Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> -- Martin K. Petersen Oracle Linux Engineering
Christoph, > diff --git a/block/blk-core.c b/block/blk-core.c > index ad041e903b0a8f..ecd68415c6acad 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -693,7 +693,7 @@ static inline bool should_fail_request(struct block_device *part, > > static inline bool bio_check_ro(struct bio *bio) > { > - if (op_is_write(bio_op(bio)) && bio->bi_bdev->bd_read_only) { > + if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) Build failure, opening brace is missing ^^^^^ > char b[BDEVNAME_SIZE]; > > if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) -- Martin K. Petersen Oracle Linux Engineering
On Mon, Dec 07, 2020 at 02:19:15PM +0100, Christoph Hellwig wrote: > Commit 20bd1d026aac ("scsi: sd: Keep disk read-only when re-reading > partition") addressed a long-standing problem with user read-only > policy being overridden as a result of a device-initiated revalidate. > The commit has since been reverted due to a regression that left some > USB devices read-only indefinitely. > > To fix the underlying problems with revalidate we need to keep track > of hardware state and user policy separately. > > The gendisk has been updated to reflect the current hardware state set > by the device driver. This is done to allow returning the device to > the hardware state once the user clears the BLKROSET flag. > > The resulting semantics are as follows: > > - If BLKROSET sets a given partition read-only, that partition will > remain read-only even if the underlying storage stack initiates a > revalidate. However, the BLKRRPART ioctl will cause the partition > table to be dropped and any user policy on partitions will be lost. > > - If BLKROSET has not been set, both the whole disk device and any > partitions will reflect the current write-protect state of the > underlying device. > > Based on a patch from Martin K. Petersen <martin.petersen@oracle.com>. > > Reported-by: Oleksii Kurochko <olkuroch@cisco.com> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201221 > Signed-off-by: Christoph Hellwig <hch@lst.de> > Reviewed-by: Hannes Reinecke <hare@suse.de> > --- > block/blk-core.c | 2 +- > block/genhd.c | 33 +++++++++++++++++++-------------- > block/partitions/core.c | 3 +-- > include/linux/genhd.h | 6 ++++-- > 4 files changed, 25 insertions(+), 19 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index ad041e903b0a8f..ecd68415c6acad 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -693,7 +693,7 @@ static inline bool should_fail_request(struct block_device *part, > > static inline bool bio_check_ro(struct bio *bio) > { > - if (op_is_write(bio_op(bio)) && bio->bi_bdev->bd_read_only) { > + if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) > 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 c87013879b8650..878f94727aaa96 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -1425,27 +1425,32 @@ static void set_disk_ro_uevent(struct gendisk *gd, int ro) > kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp); > } > > -void set_disk_ro(struct gendisk *disk, int flag) > +/** > + * set_disk_ro - set a gendisk read-only > + * @disk: gendisk to operate on > + * @ready_only: %true to set the disk read-only, %false set the disk read/write > + * > + * This function is used to indicate whether a given disk device should have its > + * read-only flag set. set_disk_ro() is typically used by device drivers to > + * indicate whether the underlying physical device is write-protected. > + */ > +void set_disk_ro(struct gendisk *disk, bool read_only) > { > - struct disk_part_iter piter; > - struct block_device *part; > - > - if (disk->part0->bd_read_only != flag) { > - set_disk_ro_uevent(disk, flag); > - disk->part0->bd_read_only = flag; > + if (read_only) { > + if (test_and_set_bit(GD_READ_ONLY, &disk->state)) > + return; > + } else { > + if (!test_and_clear_bit(GD_READ_ONLY, &disk->state)) > + return; > } > - > - disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY); > - while ((part = disk_part_iter_next(&piter))) > - part->bd_read_only = flag; > - disk_part_iter_exit(&piter); > + set_disk_ro_uevent(disk, read_only); > } > - > EXPORT_SYMBOL(set_disk_ro); > > int bdev_read_only(struct block_device *bdev) > { > - return bdev->bd_read_only; > + return bdev->bd_read_only || > + test_bit(GD_READ_ONLY, &bdev->bd_disk->state); > } > EXPORT_SYMBOL(bdev_read_only); Maybe one inline version can be added for fast path(bio_check_ro()), and the approach is good: Reviewed-by: Ming Lei <ming.lei@redhat.com> -- Ming
On Tue, Dec 08, 2020 at 06:22:11PM +0800, Ming Lei wrote: > > int bdev_read_only(struct block_device *bdev) > > { > > - return bdev->bd_read_only; > > + return bdev->bd_read_only || > > + test_bit(GD_READ_ONLY, &bdev->bd_disk->state); > > } > > EXPORT_SYMBOL(bdev_read_only); > > Maybe one inline version can be added for fast path(bio_check_ro()), and the approach > is good: I thought of that, but our header mess means it would have to be a macro. I have a plan to reorganize the headers in the not too far future, at which point this should become an inline.
diff --git a/block/blk-core.c b/block/blk-core.c index ad041e903b0a8f..ecd68415c6acad 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -693,7 +693,7 @@ static inline bool should_fail_request(struct block_device *part, static inline bool bio_check_ro(struct bio *bio) { - if (op_is_write(bio_op(bio)) && bio->bi_bdev->bd_read_only) { + if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) 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 c87013879b8650..878f94727aaa96 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1425,27 +1425,32 @@ static void set_disk_ro_uevent(struct gendisk *gd, int ro) kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp); } -void set_disk_ro(struct gendisk *disk, int flag) +/** + * set_disk_ro - set a gendisk read-only + * @disk: gendisk to operate on + * @ready_only: %true to set the disk read-only, %false set the disk read/write + * + * This function is used to indicate whether a given disk device should have its + * read-only flag set. set_disk_ro() is typically used by device drivers to + * indicate whether the underlying physical device is write-protected. + */ +void set_disk_ro(struct gendisk *disk, bool read_only) { - struct disk_part_iter piter; - struct block_device *part; - - if (disk->part0->bd_read_only != flag) { - set_disk_ro_uevent(disk, flag); - disk->part0->bd_read_only = flag; + if (read_only) { + if (test_and_set_bit(GD_READ_ONLY, &disk->state)) + return; + } else { + if (!test_and_clear_bit(GD_READ_ONLY, &disk->state)) + return; } - - disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY); - while ((part = disk_part_iter_next(&piter))) - part->bd_read_only = flag; - disk_part_iter_exit(&piter); + set_disk_ro_uevent(disk, read_only); } - EXPORT_SYMBOL(set_disk_ro); int bdev_read_only(struct block_device *bdev) { - return bdev->bd_read_only; + return bdev->bd_read_only || + test_bit(GD_READ_ONLY, &bdev->bd_disk->state); } EXPORT_SYMBOL(bdev_read_only); diff --git a/block/partitions/core.c b/block/partitions/core.c index c88f03ddaefe29..278e2419b163bb 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -194,7 +194,7 @@ static ssize_t part_start_show(struct device *dev, static ssize_t part_ro_show(struct device *dev, struct device_attribute *attr, char *buf) { - return sprintf(buf, "%d\n", dev_to_bdev(dev)->bd_read_only); + return sprintf(buf, "%d\n", bdev_read_only(dev_to_bdev(dev))); } static ssize_t part_alignment_offset_show(struct device *dev, @@ -348,7 +348,6 @@ static struct block_device *add_partition(struct gendisk *disk, int partno, bdev->bd_start_sect = start; bdev_set_nr_sectors(bdev, len); - bdev->bd_read_only = get_disk_ro(disk); if (info) { err = -ENOMEM; diff --git a/include/linux/genhd.h b/include/linux/genhd.h index e8821bfe07b955..f364619092cca0 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -152,6 +152,7 @@ struct gendisk { int flags; unsigned long state; #define GD_NEED_PART_SCAN 0 +#define GD_READ_ONLY 1 struct kobject *slave_dir; struct timer_rand_state *random; @@ -238,11 +239,12 @@ static inline void add_disk_no_queue_reg(struct gendisk *disk) extern void del_gendisk(struct gendisk *gp); extern struct block_device *bdget_disk(struct gendisk *disk, int partno); -extern void set_disk_ro(struct gendisk *disk, int flag); +void set_disk_ro(struct gendisk *disk, bool read_only); static inline int get_disk_ro(struct gendisk *disk) { - return disk->part0->bd_read_only; + return disk->part0->bd_read_only || + test_bit(GD_READ_ONLY, &disk->state); } extern void disk_block_events(struct gendisk *disk);
Commit 20bd1d026aac ("scsi: sd: Keep disk read-only when re-reading partition") addressed a long-standing problem with user read-only policy being overridden as a result of a device-initiated revalidate. The commit has since been reverted due to a regression that left some USB devices read-only indefinitely. To fix the underlying problems with revalidate we need to keep track of hardware state and user policy separately. The gendisk has been updated to reflect the current hardware state set by the device driver. This is done to allow returning the device to the hardware state once the user clears the BLKROSET flag. The resulting semantics are as follows: - If BLKROSET sets a given partition read-only, that partition will remain read-only even if the underlying storage stack initiates a revalidate. However, the BLKRRPART ioctl will cause the partition table to be dropped and any user policy on partitions will be lost. - If BLKROSET has not been set, both the whole disk device and any partitions will reflect the current write-protect state of the underlying device. Based on a patch from Martin K. Petersen <martin.petersen@oracle.com>. Reported-by: Oleksii Kurochko <olkuroch@cisco.com> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201221 Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> --- block/blk-core.c | 2 +- block/genhd.c | 33 +++++++++++++++++++-------------- block/partitions/core.c | 3 +-- include/linux/genhd.h | 6 ++++-- 4 files changed, 25 insertions(+), 19 deletions(-)