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Message-ID: <52157C6E.6080406@oracle.com>
Date: Thu, 22 Aug 2013 10:50:22 +0800
From: Joe Jin <joe.jin@...cle.com>
To: Mikulas Patocka <mpatocka@...hat.com>
CC: device-mapper development <dm-devel@...hat.com>,
Mike Snitzer <snitzer@...hat.com>,
Alasdair Kergon <agk@...hat.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [dm-devel] [PATCH v2] dm ioctl: allow change device target type
to error
Mikulas, thanks for you suggestions, I create new patch, can you please help
review?
Subject: dm: add map_rq define for error
commit a5664da "dm ioctl: make bio or request based device type immutable"
prevented "dmsetup wape_table" change the target type to "error" for there
is not map_rq for error target type.
Signed-off-by: Joe Jin <joe.jin@...cle.com>
---
drivers/md/dm-target.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 37ba5db..b690910 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -131,12 +131,19 @@ static int io_err_map(struct dm_target *tt, struct bio *bio)
return -EIO;
}
+static int io_err_map_rq(struct dm_target *ti, struct request *clone,
+ union map_info *map_context)
+{
+ return -EIO;
+}
+
static struct target_type error_target = {
.name = "error",
.version = {1, 1, 0},
.ctr = io_err_ctr,
.dtr = io_err_dtr,
.map = io_err_map,
+ .map_rq = io_err_map_rq,
};
int __init dm_target_init(void)
--
1.8.3.1
On 08/21/13 22:48, Mikulas Patocka wrote:
>
>
> On Wed, 21 Aug 2013, Joe Jin wrote:
>
>> commit a5664da "dm ioctl: make bio or request based device type immutable"
>> prevented "dmsetup wape_table" change the target type to "error".
>
> That commit a5664da is there for a reason (it is not possible to change
> bio-based device to request-based and vice versa) and I don't really see
> how this patch is supposed to work.
>
> If there are bios that are in flight and that already passed through
> blk_queue_bio, and you change the device from request-based to bio-based,
> what are you going to do with them? - The patch doesn't do anything about
> it.
>
> A better approach would be to create a new request-based target "error-rq"
> and change the multipath target to "error-rq" target. That way, you don't
> have to change device type from request based to bio based.
>
> Mikulas
>
>> -v2: setup md->queue even target type is "error".
>>
>> Signed-off-by: Joe Jin <joe.jin@...cle.com>
>> ---
>> drivers/md/dm-ioctl.c | 4 ++++
>> drivers/md/dm-table.c | 12 ++++++++++++
>> drivers/md/dm.h | 1 +
>> 3 files changed, 17 insertions(+)
>>
>> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
>> index f1b7586..2a9b63d 100644
>> --- a/drivers/md/dm-ioctl.c
>> +++ b/drivers/md/dm-ioctl.c
>> @@ -1280,6 +1280,9 @@ static int table_load(struct dm_ioctl *param, size_t param_size)
>> goto out;
>> }
>>
>> + if (dm_is_error_target(t))
>> + goto error_target;
>> +
>> /* Protect md->type and md->queue against concurrent table loads. */
>> dm_lock_md_type(md);
>> if (dm_get_md_type(md) == DM_TYPE_NONE)
>> @@ -1293,6 +1296,7 @@ static int table_load(struct dm_ioctl *param, size_t param_size)
>> goto out;
>> }
>>
>> +error_target:
>> /* setup md->queue to reflect md's type (may block) */
>> r = dm_setup_md_queue(md);
>> if (r) {
>> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
>> index f221812..27be46a 100644
>> --- a/drivers/md/dm-table.c
>> +++ b/drivers/md/dm-table.c
>> @@ -184,6 +184,18 @@ static int alloc_targets(struct dm_table *t, unsigned int num)
>> return 0;
>> }
>>
>> +bool dm_is_error_target(struct dm_table *t)
>> +{
>> + unsigned i;
>> +
>> + for (i = 0; i < t->num_targets; i++) {
>> + struct dm_target *tgt = t->targets + i;
>> + if (strcmp(tgt->type->name, "error") == 0)
>> + return true;
>> + }
>> + return false;
>> +}
>> +
>> int dm_table_create(struct dm_table **result, fmode_t mode,
>> unsigned num_targets, struct mapped_device *md)
>> {
>> diff --git a/drivers/md/dm.h b/drivers/md/dm.h
>> index 45b97da..c7bceeb 100644
>> --- a/drivers/md/dm.h
>> +++ b/drivers/md/dm.h
>> @@ -69,6 +69,7 @@ unsigned dm_table_get_type(struct dm_table *t);
>> struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
>> bool dm_table_request_based(struct dm_table *t);
>> bool dm_table_supports_discards(struct dm_table *t);
>> +bool dm_is_error_target(struct dm_table *t);
>> int dm_table_alloc_md_mempools(struct dm_table *t);
>> void dm_table_free_md_mempools(struct dm_table *t);
>> struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
>> --
>> 1.8.3.1
>>
>> --
>> dm-devel mailing list
>> dm-devel@...hat.com
>> https://www.redhat.com/mailman/listinfo/dm-devel
>>
--
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