>From mm/page-writeback.c:
/*
* bdi_min_ratio keeps the sum of the minimum dirty shares of all
* registered backing devices, which, for obvious reasons, can not
* exceed 100%.
*/
static unsigned int bdi_min_ratio;
But when a backing device is unregistered, the BDI's min_ratio is not
subtracted from bdi_min_ratio. So the second attempt to set min_ratio
in the following commands will fail.
# modprobe null_blk
# echo 50 > /sys/block/nullb0/bdi/min_ratio
# modprobe -r null_blk
# modprobe null_blk
# echo 50 > /sys/block/nullb0/bdi/min_ratio
Signed-off-by: Akinobu Mita <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Jens Axboe <[email protected]>
---
Resending with Tejun's ACK
mm/backing-dev.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 885361b..ccf72be 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -849,6 +849,7 @@ void bdi_destroy(struct backing_dev_info *bdi)
}
wb_exit(&bdi->wb);
+ bdi_set_min_ratio(bdi, 0);
}
EXPORT_SYMBOL(bdi_destroy);
--
1.9.1
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