evie/android_kernel_oneplus_msm8998
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rbd: protect against concurrent unmaps

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Make sure two concurrent unmap operations on the same rbd device
won't collide, by only proceeding with the removal and cleanup of a
device if is not already underway.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2013-05-31 17:40:44 -05:00 • committed by Sage Weil
parent 751cc0e3cf
commit 82a442d239
1 changed files with 4 additions and 2 deletions
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6
drivers/block/rbd.c
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@ -5137,6 +5137,7 @@ static ssize_t rbd_remove(struct bus_type *bus,
struct list_head *tmp; struct list_head *tmp;
int dev_id; int dev_id;
unsigned long ul; unsigned long ul;
bool already = false;
int ret; int ret;
ret = strict_strtoul(buf, 10, &ul); ret = strict_strtoul(buf, 10, &ul);
@ -5164,11 +5165,12 @@ static ssize_t rbd_remove(struct bus_type *bus,
if (rbd_dev->open_count) if (rbd_dev->open_count)
ret = -EBUSY; ret = -EBUSY;
else else
set_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags); already = test_and_set_bit(RBD_DEV_FLAG_REMOVING,
&rbd_dev->flags);
spin_unlock_irq(&rbd_dev->lock); spin_unlock_irq(&rbd_dev->lock);
} }
spin_unlock(&rbd_dev_list_lock); spin_unlock(&rbd_dev_list_lock);
if (ret < 0) if (ret < 0 || already)
goto done; goto done;
rbd_bus_del_dev(rbd_dev); rbd_bus_del_dev(rbd_dev);