| Message ID | 20231017184823.1383356-3-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] block: simplify bdev_del_partition() | expand |
On Tue, Oct 17, 2023 at 08:48:20PM +0200, Christoph Hellwig wrote: > From: Christian Brauner <brauner@kernel.org> > > The logic for disk->open_partitions is: > > blkdev_get_by_*() > -> bdev_is_partition() > -> blkdev_get_part() > -> blkdev_get_whole() // bdev_whole->bd_openers++ > -> if (part->bd_openers == 0) > disk->open_partitions++ > part->bd_openers > > In other words, when we first claim/open a partition we increment > disk->open_partitions and only when all part->bd_openers are closed will > disk->open_partitions be zero. That should mean that > disk->open_partitions is always > 0 as long as there's anyone that > has an open partition. > > So the check for disk->open_partitions should meand that we can never > remove an active partition that has a holder and holder ops set. Assert > that in the code. The main disk isn't removed so that check doesn't work > for disk->part0 which is what we want. After all we only care about > partition not about the main disk. > > Signed-off-by: Christian Brauner <brauner@kernel.org> inc/dec(part->bd_openers) is always done with ->open_mutex held, so this change is correct. Reviewed-by: Ming Lei <ming.lei@redhat.com> Thanks, Ming
On Tue 17-10-23 20:48:20, Christoph Hellwig wrote: > From: Christian Brauner <brauner@kernel.org> > > The logic for disk->open_partitions is: > > blkdev_get_by_*() > -> bdev_is_partition() > -> blkdev_get_part() > -> blkdev_get_whole() // bdev_whole->bd_openers++ > -> if (part->bd_openers == 0) > disk->open_partitions++ > part->bd_openers > > In other words, when we first claim/open a partition we increment > disk->open_partitions and only when all part->bd_openers are closed will > disk->open_partitions be zero. That should mean that > disk->open_partitions is always > 0 as long as there's anyone that > has an open partition. > > So the check for disk->open_partitions should meand that we can never > remove an active partition that has a holder and holder ops set. Assert > that in the code. The main disk isn't removed so that check doesn't work > for disk->part0 which is what we want. After all we only care about > partition not about the main disk. > > Signed-off-by: Christian Brauner <brauner@kernel.org> Looks good to me. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > block/partitions/core.c | 30 +++++++++++++++++------------- > 1 file changed, 17 insertions(+), 13 deletions(-) > > diff --git a/block/partitions/core.c b/block/partitions/core.c > index b0585536b407a5..f47ffcfdfcec22 100644 > --- a/block/partitions/core.c > +++ b/block/partitions/core.c > @@ -274,17 +274,6 @@ void drop_partition(struct block_device *part) > put_device(&part->bd_device); > } > > -static void delete_partition(struct block_device *part) > -{ > - /* > - * Remove the block device from the inode hash, so that it cannot be > - * looked up any more even when openers still hold references. > - */ > - remove_inode_hash(part->bd_inode); > - bdev_mark_dead(part, false); > - drop_partition(part); > -} > - > static ssize_t whole_disk_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > @@ -674,8 +663,23 @@ int bdev_disk_changed(struct gendisk *disk, bool invalidate) > sync_blockdev(disk->part0); > invalidate_bdev(disk->part0); > > - xa_for_each_start(&disk->part_tbl, idx, part, 1) > - delete_partition(part); > + xa_for_each_start(&disk->part_tbl, idx, part, 1) { > + /* > + * Remove the block device from the inode hash, so that > + * it cannot be looked up any more even when openers > + * still hold references. > + */ > + remove_inode_hash(part->bd_inode); > + > + /* > + * If @disk->open_partitions isn't elevated but there's > + * still an active holder of that block device things > + * are broken. > + */ > + WARN_ON_ONCE(atomic_read(&part->bd_openers)); > + invalidate_bdev(part); > + drop_partition(part); > + } > clear_bit(GD_NEED_PART_SCAN, &disk->state); > > /* > -- > 2.39.2 >
diff --git a/block/partitions/core.c b/block/partitions/core.c index b0585536b407a5..f47ffcfdfcec22 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -274,17 +274,6 @@ void drop_partition(struct block_device *part) put_device(&part->bd_device); } -static void delete_partition(struct block_device *part) -{ - /* - * Remove the block device from the inode hash, so that it cannot be - * looked up any more even when openers still hold references. - */ - remove_inode_hash(part->bd_inode); - bdev_mark_dead(part, false); - drop_partition(part); -} - static ssize_t whole_disk_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -674,8 +663,23 @@ int bdev_disk_changed(struct gendisk *disk, bool invalidate) sync_blockdev(disk->part0); invalidate_bdev(disk->part0); - xa_for_each_start(&disk->part_tbl, idx, part, 1) - delete_partition(part); + xa_for_each_start(&disk->part_tbl, idx, part, 1) { + /* + * Remove the block device from the inode hash, so that + * it cannot be looked up any more even when openers + * still hold references. + */ + remove_inode_hash(part->bd_inode); + + /* + * If @disk->open_partitions isn't elevated but there's + * still an active holder of that block device things + * are broken. + */ + WARN_ON_ONCE(atomic_read(&part->bd_openers)); + invalidate_bdev(part); + drop_partition(part); + } clear_bit(GD_NEED_PART_SCAN, &disk->state); /*