On Tue, May 14, 2024 at 05:04:42PM +0800, Yang Yang wrote: > Add a list to the struct dm_dev structure to store the associated > targets, while also allowing differentiation between different target > types.
I still think this is more complex than it needs to be. If devices that support flush_pass_around can guarantee that: 1. They will send a flush bio to all of their table devices 2. They are fine with another target sending the flush bio to their table devices Then I don't see why we need the table devices to keep track of all the different target types that are using them. Am I missing something here? If we don't need to worry about sending a flush bio to a target of each type that is using a table device, then all we need to do is call __send_empty_flush_bios() for enough targets to cover all the table devices. This seems a lot easier to track. We just need another flag in dm_target, something like sends_pass_around_flush. When a target calls dm_get_device(), if it adds a new table device to t->devices, then it's the first target in this table to use that device. If flush_pass_around is set for this target, then it also sets sends_pass_around_flush. In __send_empty_flush() if the table has flush_pass_around set, when you iterate through the devices, you only call __send_empty_flush_bios() for the ones with sends_pass_around_flush set. Or am I overlooking something? -Ben > > Signed-off-by: Yang Yang <[email protected]> > --- > drivers/md/dm-table.c | 36 +++++++++++++++++++++++++++++++++++ > include/linux/device-mapper.h | 3 +++ > 2 files changed, 39 insertions(+) > > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index bd68af10afed..f6554590b7af 100644 > --- a/drivers/md/dm-table.c > +++ b/drivers/md/dm-table.c > @@ -741,6 +741,8 @@ int dm_table_add_target(struct dm_table *t, const char > *type, > if (ti->flush_pass_around == 0) > t->flush_pass_around = 0; > > + INIT_LIST_HEAD(&ti->list); > + > return 0; > > bad: > @@ -2134,6 +2136,25 @@ void dm_table_postsuspend_targets(struct dm_table *t) > suspend_targets(t, POSTSUSPEND); > } > > +static int dm_link_dev_to_target(struct dm_target *ti, struct dm_dev *dev, > + sector_t start, sector_t len, void *data) > +{ > + struct list_head *targets = &dev->targets; > + struct dm_target *pti; > + > + if (!list_empty(targets)) { > + list_for_each_entry(pti, targets, list) { > + if (pti->type == ti->type) > + return 0; > + } > + } > + > + if (list_empty(&ti->list)) > + list_add_tail(&ti->list, targets); > + > + return 0; > +} > + > int dm_table_resume_targets(struct dm_table *t) > { > unsigned int i; > @@ -2162,6 +2183,21 @@ int dm_table_resume_targets(struct dm_table *t) > ti->type->resume(ti); > } > > + if (t->flush_pass_around) { > + struct list_head *devices = &t->devices; > + struct dm_dev_internal *dd; > + > + list_for_each_entry(dd, devices, list) > + INIT_LIST_HEAD(&dd->dm_dev->targets); > + > + for (i = 0; i < t->num_targets; i++) { > + struct dm_target *ti = dm_table_get_target(t, i); > + > + if (ti->type->iterate_devices) > + ti->type->iterate_devices(ti, > dm_link_dev_to_target, NULL); > + } > + } > + > return 0; > } > > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h > index 0893ff8c01b6..19e03f9b2589 100644 > --- a/include/linux/device-mapper.h > +++ b/include/linux/device-mapper.h > @@ -169,6 +169,7 @@ struct dm_dev { > struct dax_device *dax_dev; > blk_mode_t mode; > char name[16]; > + struct list_head targets; > }; > > /* > @@ -298,6 +299,8 @@ struct dm_target { > struct dm_table *table; > struct target_type *type; > > + struct list_head list; > + > /* target limits */ > sector_t begin; > sector_t len; > -- > 2.34.1 >
