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Date: Wed, 26 Jun 2013 13:20:54 -0400 (EDT)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Geremy Condra <gcondra@...gle.com>,
device-mapper development <dm-devel@...hat.com>
cc: wad@...omium.org, linux-kernel@...r.kernel.org, agk@...hat.com
Subject: Re: [dm-devel] [PATCH v2] dm: verity: Add support for emitting
uevents on dm-verity errors.
Hi
I think the idea is fine.
There is architecture problem - that target specific routines are being
pushed into generic dm core.
I suggest that instead of dm_send_verity_uevent and dm_path_uevent you
create just one generic function (for example dm_send_uevent) that takes
variable argument list of target-specific uevent variables and that can be
used for both multipath and verity. Something like: dm_send_uevent(ti,
"DM_VERITY_BLOCK_NR=123", "DM_ACTION=VERITY_DATA_ERROR", NULL);
There is GFP_ATOMIC allocation and this type of allocation can fail
anytime. Could it be a problem if uevent is lost? It's probably not a
problem for dm-verity, because uevents are generated only in errorneous
state ... but what about multipath? Can it misbehave if we lose uevent?
Mikulas
On Thu, 20 Jun 2013, Geremy Condra wrote:
> With this change dm-verity errors will cause uevents to be
> sent to userspace, notifying it that an error has occurred
> and potentially triggering recovery actions.
>
> Signed-off-by: Geremy Condra <gcondra@...gle.com>
> ---
> Changelog since v1:
> - Removed the DM_VERITY_ERROR_NOTIFY config option
>
> drivers/md/dm-uevent.c | 40 ++++++++++++++++++++++++++++++++++++++++
> drivers/md/dm-uevent.h | 12 ++++++++++--
> drivers/md/dm-verity.c | 28 ++++++++++++++++++++++++++++
> 3 files changed, 78 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/dm-uevent.c b/drivers/md/dm-uevent.c
> index 8efe033..17a6662 100644
> --- a/drivers/md/dm-uevent.c
> +++ b/drivers/md/dm-uevent.c
> @@ -36,6 +36,8 @@ static const struct {
> } _dm_uevent_type_names[] = {
> {DM_UEVENT_PATH_FAILED, KOBJ_CHANGE, "PATH_FAILED"},
> {DM_UEVENT_PATH_REINSTATED, KOBJ_CHANGE, "PATH_REINSTATED"},
> + {DM_UEVENT_VERITY_DATA_ERROR, KOBJ_CHANGE, "VERITY_DATA_ERROR"},
> + {DM_UEVENT_VERITY_HASH_ERROR, KOBJ_CHANGE, "VERITY_HASH_ERROR"},
> };
>
> static struct kmem_cache *_dm_event_cache;
> @@ -202,6 +204,44 @@ void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
> }
> EXPORT_SYMBOL_GPL(dm_path_uevent);
>
> +void dm_send_verity_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
> + unsigned long long block_nr)
> +{
> + struct mapped_device *md = dm_table_get_md(ti->table);
> + struct dm_uevent *event = dm_uevent_alloc(md);
> + struct gendisk *disk = dm_disk(md);
> +
> + if (!event) {
> + DMERR("%s: dm_uevent_alloc() failed", __func__);
> + return;
> + }
> +
> + if (event_type >= ARRAY_SIZE(_dm_uevent_type_names)) {
> + DMERR("%s: Invalid event_type %d", __func__, event_type);
> + goto out;
> + }
> +
> + if (add_uevent_var(&event->ku_env, "DM_VERITY_BLOCK_NR=%llu", block_nr)) {
> + DMERR("%s: add_uevent_var() for DM_VERITY_BLOCK failed", __func__);
> + goto out;
> + }
> +
> + if (add_uevent_var(&event->ku_env, "DM_ACTION=%s",
> + _dm_uevent_type_names[event_type].name)) {
> + DMERR("%s: add_uevent_var() for DM_ACTION failed", __func__);
> + goto out;
> + }
> +
> + if (kobject_uevent_env(&disk_to_dev(disk)->kobj, event_type,
> + event->ku_env.envp)) {
> + DMERR("%s: kobject_uevent_env failed", __func__);
> + }
> +
> +out:
> + dm_uevent_free(event);
> +}
> +EXPORT_SYMBOL_GPL(dm_send_verity_uevent);
> +
> int dm_uevent_init(void)
> {
> _dm_event_cache = KMEM_CACHE(dm_uevent, 0);
> diff --git a/drivers/md/dm-uevent.h b/drivers/md/dm-uevent.h
> index 2eccc8b..1c59dba 100644
> --- a/drivers/md/dm-uevent.h
> +++ b/drivers/md/dm-uevent.h
> @@ -24,6 +24,8 @@
> enum dm_uevent_type {
> DM_UEVENT_PATH_FAILED,
> DM_UEVENT_PATH_REINSTATED,
> + DM_UEVENT_VERITY_DATA_ERROR,
> + DM_UEVENT_VERITY_HASH_ERROR,
> };
>
> #ifdef CONFIG_DM_UEVENT
> @@ -34,7 +36,9 @@ extern void dm_send_uevents(struct list_head *events, struct kobject *kobj);
> extern void dm_path_uevent(enum dm_uevent_type event_type,
> struct dm_target *ti, const char *path,
> unsigned nr_valid_paths);
> -
> +extern void dm_send_verity_uevent(enum dm_uevent_type event_type,
> + struct dm_target *ti,
> + unsigned long long block_nr);
> #else
>
> static inline int dm_uevent_init(void)
> @@ -53,7 +57,11 @@ static inline void dm_path_uevent(enum dm_uevent_type event_type,
> unsigned nr_valid_paths)
> {
> }
> -
> +static inline void dm_send_verity_uevent(enum dm_uevent_type event_type,
> + struct dm_target *ti,
> + unsigned long long block_nr)
> +{
> +}
> #endif /* CONFIG_DM_UEVENT */
>
> #endif /* DM_UEVENT_H */
> diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
> index 68bf5c3..2e3695b 100644
> --- a/drivers/md/dm-verity.c
> +++ b/drivers/md/dm-verity.c
> @@ -20,6 +20,8 @@
> #include <linux/device-mapper.h>
> #include <crypto/hash.h>
>
> +#include "dm-uevent.h"
> +
> #define DM_MSG_PREFIX "verity"
>
> #define DM_VERITY_IO_VEC_INLINE 16
> @@ -137,6 +139,30 @@ static void dm_bufio_alloc_callback(struct dm_buffer *buf)
> }
>
> /*
> + * Trigger userspace data corruption handler.
> + */
> +#ifdef CONFIG_DM_UEVENT
> +static void verity_data_error(struct dm_verity *v, unsigned long long block_nr)
> +{
> + dm_send_verity_uevent(DM_UEVENT_VERITY_DATA_ERROR, v->ti, block_nr);
> +}
> +
> +static void verity_hash_error(struct dm_verity *v, unsigned long long block_nr)
> +{
> + dm_send_verity_uevent(DM_UEVENT_VERITY_HASH_ERROR, v->ti, block_nr);
> +}
> +#else
> +static inline void verity_data_error(struct dm_verity *v,
> + unsigned long long block_nr)
> +{
> +}
> +static inline void verity_hash_error(struct dm_verity *v,
> + unsigned long long block_nr)
> +{
> +}
> +#endif
> +
> +/*
> * Translate input sector number to the sector number on the target device.
> */
> static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
> @@ -255,6 +281,7 @@ static int verity_verify_level(struct dm_verity_io *io, sector_t block,
> (unsigned long long)hash_block);
> v->hash_failed = 1;
> r = -EIO;
> + verity_hash_error(v, (unsigned long long)hash_block);
> goto release_ret_r;
> } else
> aux->hash_verified = 1;
> @@ -375,6 +402,7 @@ test_block_hash:
> DMERR_LIMIT("data block %llu is corrupted",
> (unsigned long long)(io->block + b));
> v->hash_failed = 1;
> + verity_data_error(v, (unsigned long long)(io->block + b));
> return -EIO;
> }
> }
> --
> 1.8.3
>
> --
> dm-devel mailing list
> dm-devel@...hat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>
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