(This patch should go in 2.6.21 as it fixes a recent regression - NB)
A device can be removed from an md array via e.g.
echo remove > /sys/block/md3/md/dev-sde/state
This will try to remove the 'dev-sde' subtree which will deadlock
since
commit e7b0d26a86943370c04d6833c6edba2a72a6e240
With this patch we run the kobject_del via schedule_work so as to
avoid the deadlock.
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>
### Diffstat output
./drivers/md/md.c | 13 ++++++++++++-
./include/linux/raid/md_k.h | 1 +
2 files changed, 13 insertions(+), 1 deletion(-)
diff .prev/drivers/md/md.c ./drivers/md/md.c
--- .prev/drivers/md/md.c 2007-04-02 17:43:03.000000000 +1000
+++ ./drivers/md/md.c 2007-04-02 17:38:46.000000000 +1000
@@ -1389,6 +1389,12 @@ static int bind_rdev_to_array(mdk_rdev_t
return err;
}
+static void delayed_delete(struct work_struct *ws)
+{
+ mdk_rdev_t *rdev = container_of(ws, mdk_rdev_t, del_work);
+ kobject_del(&rdev->kobj);
+}
+
static void unbind_rdev_from_array(mdk_rdev_t * rdev)
{
char b[BDEVNAME_SIZE];
@@ -1401,7 +1407,12 @@ static void unbind_rdev_from_array(mdk_r
printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
rdev->mddev = NULL;
sysfs_remove_link(&rdev->kobj, "block");
- kobject_del(&rdev->kobj);
+
+ /* We need to delay this, otherwise we can deadlock when
+ * writing to 'remove' to "dev/state"
+ */
+ INIT_WORK(&rdev->del_work, delayed_delete);
+ schedule_work(&rdev->del_work);
}
/*
diff .prev/include/linux/raid/md_k.h ./include/linux/raid/md_k.h
--- .prev/include/linux/raid/md_k.h 2007-04-02 17:43:03.000000000 +1000
+++ ./include/linux/raid/md_k.h 2007-04-02 17:36:32.000000000 +1000
@@ -104,6 +104,7 @@ struct mdk_rdev_s
* for reporting to userspace and storing
* in superblock.
*/
+ struct work_struct del_work; /* used for delayed sysfs removal */
};
struct mddev_s
-
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