| Message ID | 20231017184823.1383356-5-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 08:48:22PM +0200, Christoph Hellwig wrote: > From: Christian Brauner <brauner@kernel.org> > > blk_report_disk_dead() has the following major callers: > > (1) del_gendisk() > (2) blk_mark_disk_dead() > > Since del_gendisk() acquires disk->open_mutex it's clear that all > callers are assumed to be called without disk->open_mutex held. > In turn, blk_report_disk_dead() is called without disk->open_mutex held > in del_gendisk(). > > All callers of blk_mark_disk_dead() call it without disk->open_mutex as > well. > > Ensure that it is clear that blk_report_disk_dead() is called without > disk->open_mutex on purpose by asserting it and a comment in the code. > > Signed-off-by: Christian Brauner <brauner@kernel.org> > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > block/genhd.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/block/genhd.c b/block/genhd.c > index 4a16a424f57d4f..c9d06f72c587e8 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -559,6 +559,13 @@ static void blk_report_disk_dead(struct gendisk *disk, bool surprise) > struct block_device *bdev; > unsigned long idx; > > + /* > + * On surprise disk removal, bdev_mark_dead() may call into file > + * systems below. Make it clear that we're expecting to not hold > + * disk->open_mutex. > + */ > + lockdep_assert_not_held(&disk->open_mutex); > + > rcu_read_lock(); > xa_for_each(&disk->part_tbl, idx, bdev) { > if (!kobject_get_unless_zero(&bdev->bd_device.kobj)) Reviewed-by: Ming Lei <ming.lei@redhat.com> thanks, Ming
On Tue 17-10-23 20:48:22, Christoph Hellwig wrote: > From: Christian Brauner <brauner@kernel.org> > > blk_report_disk_dead() has the following major callers: > > (1) del_gendisk() > (2) blk_mark_disk_dead() > > Since del_gendisk() acquires disk->open_mutex it's clear that all > callers are assumed to be called without disk->open_mutex held. > In turn, blk_report_disk_dead() is called without disk->open_mutex held > in del_gendisk(). > > All callers of blk_mark_disk_dead() call it without disk->open_mutex as > well. > > Ensure that it is clear that blk_report_disk_dead() is called without > disk->open_mutex on purpose by asserting it and a comment in the code. > > Signed-off-by: Christian Brauner <brauner@kernel.org> > Signed-off-by: Christoph Hellwig <hch@lst.de> Sure. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> BTW, checking the callers I suspect that we might eventually hit some locking issues with NVME and its ctrl->namespace_sem which is held while calling blk_mark_disk_dead(). But I guess we'll deal with that once we see the problem is real. Honza > --- > block/genhd.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/block/genhd.c b/block/genhd.c > index 4a16a424f57d4f..c9d06f72c587e8 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -559,6 +559,13 @@ static void blk_report_disk_dead(struct gendisk *disk, bool surprise) > struct block_device *bdev; > unsigned long idx; > > + /* > + * On surprise disk removal, bdev_mark_dead() may call into file > + * systems below. Make it clear that we're expecting to not hold > + * disk->open_mutex. > + */ > + lockdep_assert_not_held(&disk->open_mutex); > + > rcu_read_lock(); > xa_for_each(&disk->part_tbl, idx, bdev) { > if (!kobject_get_unless_zero(&bdev->bd_device.kobj)) > -- > 2.39.2 >
diff --git a/block/genhd.c b/block/genhd.c index 4a16a424f57d4f..c9d06f72c587e8 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -559,6 +559,13 @@ static void blk_report_disk_dead(struct gendisk *disk, bool surprise) struct block_device *bdev; unsigned long idx; + /* + * On surprise disk removal, bdev_mark_dead() may call into file + * systems below. Make it clear that we're expecting to not hold + * disk->open_mutex. + */ + lockdep_assert_not_held(&disk->open_mutex); + rcu_read_lock(); xa_for_each(&disk->part_tbl, idx, bdev) { if (!kobject_get_unless_zero(&bdev->bd_device.kobj))