Re: [PATCH 2/3] sysfs representation of stacked devices (dm) (rev.2)

From: Jun'ichi Nomura
Date: Wed Feb 22 2006 - 14:29:21 EST


Hi,

Alasdair G Kergon wrote:
The global _hash_lock should not be held (thereby locking out most dm ioctl operations on any device) while the slow populate_table() runs.

I'm trying out a variant of the patch that drops and reacquires that lock.

OK, thanks for the confirmation.

I guess the variant itself will need dm_get() to avoid md
being stolen. Depending on that, I might change my patch.

Attached is a revised patch based on Mike Anderson's patch.

--
Jun'ichi Nomura, NEC Solutions (America), Inc.
--- linux-2.6.15/drivers/md/dm-table.c 2006-02-22 11:25:10.000000000 -0500
+++ linux-2.6.15/drivers/md/dm-table.c 2006-02-22 11:32:54.000000000 -0500
@@ -348,7 +348,7 @@ static struct dm_dev *find_device(struct
/*
* Open a device so we can use it as a map destination.
*/
-static int open_dev(struct dm_dev *d, dev_t dev)
+static int open_dev(struct dm_dev *d, dev_t dev, struct mapped_device *md)
{
static char *_claim_ptr = "I belong to device-mapper";
struct block_device *bdev;
@@ -361,7 +361,7 @@ static int open_dev(struct dm_dev *d, de
bdev = open_by_devnum(dev, d->mode);
if (IS_ERR(bdev))
return PTR_ERR(bdev);
- r = bd_claim(bdev, _claim_ptr);
+ r = bd_claim_by_kobject(bdev, _claim_ptr, &dm_disk(md)->slave_dir);
if (r)
blkdev_put(bdev);
else
@@ -372,12 +372,12 @@ static int open_dev(struct dm_dev *d, de
/*
* Close a device that we've been using.
*/
-static void close_dev(struct dm_dev *d)
+static void close_dev(struct dm_dev *d, struct mapped_device *md)
{
if (!d->bdev)
return;

- bd_release(d->bdev);
+ bd_release_from_kobject(d->bdev, &dm_disk(md)->slave_dir);
blkdev_put(d->bdev);
d->bdev = NULL;
}
@@ -398,7 +398,7 @@ static int check_device_area(struct dm_d
* careful to leave things as they were if we fail to reopen the
* device.
*/
-static int upgrade_mode(struct dm_dev *dd, int new_mode)
+static int upgrade_mode(struct dm_dev *dd, int new_mode, struct mapped_device *md)
{
int r;
struct dm_dev dd_copy;
@@ -408,9 +408,9 @@ static int upgrade_mode(struct dm_dev *d

dd->mode |= new_mode;
dd->bdev = NULL;
- r = open_dev(dd, dev);
+ r = open_dev(dd, dev, md);
if (!r)
- close_dev(&dd_copy);
+ close_dev(&dd_copy, md);
else
*dd = dd_copy;

@@ -453,7 +453,7 @@ static int __table_get_device(struct dm_
dd->mode = mode;
dd->bdev = NULL;

- if ((r = open_dev(dd, dev))) {
+ if ((r = open_dev(dd, dev, t->md))) {
kfree(dd);
return r;
}
@@ -464,7 +464,7 @@ static int __table_get_device(struct dm_
list_add(&dd->list, &t->devices);

} else if (dd->mode != (mode | dd->mode)) {
- r = upgrade_mode(dd, mode);
+ r = upgrade_mode(dd, mode, t->md);
if (r)
return r;
}
@@ -539,7 +539,7 @@ int dm_get_device(struct dm_target *ti,
void dm_put_device(struct dm_target *ti, struct dm_dev *dd)
{
if (atomic_dec_and_test(&dd->count)) {
- close_dev(dd);
+ close_dev(dd, ti->table->md);
list_del(&dd->list);
kfree(dd);
}