The patch titled
md: avoid a deadlock when removing a device from an md array via sysfs
has been removed from the -mm tree. Its filename was
md-avoid-a-deadlock-when-removing-a-device-from-an-md-array-via-sysfs.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: md: avoid a deadlock when removing a device from an md array via sysfs
From: NeilBrown <neilb@xxxxxxx>
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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/md/md.c | 16 +++++++++++++++-
include/linux/raid/md_k.h | 1 +
2 files changed, 16 insertions(+), 1 deletion(-)
diff -puN drivers/md/md.c~md-avoid-a-deadlock-when-removing-a-device-from-an-md-array-via-sysfs drivers/md/md.c
--- a/drivers/md/md.c~md-avoid-a-deadlock-when-removing-a-device-from-an-md-array-via-sysfs
+++ a/drivers/md/md.c
@@ -1378,6 +1378,12 @@ 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];
@@ -1390,7 +1396,12 @@ 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);
}
/*
@@ -3389,6 +3400,9 @@ static int do_md_stop(mddev_t * mddev, i
sysfs_remove_link(&mddev->kobj, nm);
}
+ /* make sure all delayed_delete calls have finished */
+ flush_scheduled_work();
+
export_array(mddev);
mddev->array_size = 0;
diff -puN include/linux/raid/md_k.h~md-avoid-a-deadlock-when-removing-a-device-from-an-md-array-via-sysfs include/linux/raid/md_k.h
--- a/include/linux/raid/md_k.h~md-avoid-a-deadlock-when-removing-a-device-from-an-md-array-via-sysfs
+++ a/include/linux/raid/md_k.h
@@ -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
_
Patches currently in -mm which might be from neilb@xxxxxxx are
fix-quadratic-behavior-of-shrink_dcache_parent.patch
fix-__d_path-for-lazy-unmounts-and-make-it-unambiguous.patch
the-nfsv2-nfsv3-server-does-not-handle-zero-length-write.patch
readahead-nfsd-case.patch
drivers-mdc-use-array_size-macro-when-appropriate.patch
md-dm-reduce-stack-usage-with-stacked-block-devices.patch
-
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