Re: [PATCH 04/10] dm: reduce stack footprint dealing with block device names

[Mike Snitzer <snitzer@redhat.com>]

On Wed, Jun 02 2021 at 11:28P -0400,
Anton Suvorov <warwish@yandex-team.ru> wrote:

> Stack usage reduced (measured with allyesconfig):
> 
> ./drivers/md/dm-cache-target.c	cache_ctr	392	328	-64
> ./drivers/md/dm-cache-target.c	cache_io_hints	208	72	-136
> ./drivers/md/dm-clone-target.c	clone_ctr	416	352	-64
> ./drivers/md/dm-clone-target.c	clone_io_hints	216	80	-136
> ./drivers/md/dm-crypt.c	crypt_convert_block_aead	408	272	-136
> ./drivers/md/dm-crypt.c	kcryptd_async_done	192	56	-136
> ./drivers/md/dm-integrity.c	integrity_metadata	872	808	-64
> ./drivers/md/dm-mpath.c	parse_priority_group	368	304	-64
> ./drivers/md/dm-table.c	device_area_is_invalid	216	80	-136
> ./drivers/md/dm-table.c	dm_set_device_limits	200	72	-128
> ./drivers/md/dm-thin.c	pool_io_hints	216	80	-136
> 
> Signed-off-by: Anton Suvorov <warwish@yandex-team.ru>
> ---
>  drivers/md/dm-cache-target.c | 10 ++++------
>  drivers/md/dm-clone-target.c | 10 ++++------
>  drivers/md/dm-crypt.c        |  6 ++----
>  drivers/md/dm-integrity.c    |  4 ++--
>  drivers/md/dm-mpath.c        |  6 ++----
>  drivers/md/dm-table.c        | 34 ++++++++++++++++------------------
>  drivers/md/dm-thin.c         |  8 +++-----
>  7 files changed, 33 insertions(+), 45 deletions(-)
> 

<snip>

> diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
> index 20f2510db1f6..d2fec41635ff 100644
> --- a/drivers/md/dm-integrity.c
> +++ b/drivers/md/dm-integrity.c
> @@ -1781,8 +1781,8 @@ static void integrity_metadata(struct work_struct *w)
>  						checksums_ptr - checksums, dio->op == REQ_OP_READ ? TAG_CMP : TAG_WRITE);
>  			if (unlikely(r)) {
>  				if (r > 0) {
> -					char b[BDEVNAME_SIZE];
> -					DMERR_LIMIT("%s: Checksum failed at sector 0x%llx", bio_devname(bio, b),
> +					DMERR_LIMIT("%pg: Checksum failed at sector 0x%llx",
> +						    bio->bi_bdev,
>  						    (sector - ((r + ic->tag_size - 1) / ic->tag_size)));
>  					r = -EILSEQ;
>  					atomic64_inc(&ic->number_of_mismatches);
> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> index bced42f082b0..678e5bb0fa5a 100644
> --- a/drivers/md/dm-mpath.c
> +++ b/drivers/md/dm-mpath.c
> @@ -900,10 +900,8 @@ static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
>  	if (m->hw_handler_name) {
>  		r = scsi_dh_attach(q, m->hw_handler_name);
>  		if (r == -EBUSY) {
> -			char b[BDEVNAME_SIZE];
> -
> -			printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
> -			       bdevname(bdev, b));
> +			pr_info("dm-mpath: retaining handler on device %pg\n",
> +				bdev);
>  			goto retain;
>  		}
>  		if (r < 0) {

Would appreciate it if you just left the arguments on the same line,
for this dm-mpath.c change and the dm-integrity.c change, don't worry
about 80 column.

Also, would prefer you use DMINFO() instead of pr_info().  DMINFO()
achieves the same but will add "device-mapper: multipath: " prefix for
you, also you then don't need to add the newline. So use:

     DMINFO("retaining handler on device %pg", bdev);


> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 7e88e5e06922..175b9c7b1c48 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -282,20 +281,20 @@ static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
>  		return 0;
>  
>  	if (start & (logical_block_size_sectors - 1)) {
> -		DMWARN("%s: start=%llu not aligned to h/w "
> -		       "logical block size %u of %s",
> +		DMWARN("%s: start=%llu not aligned to h/w logical block size %u of %pg",
>  		       dm_device_name(ti->table->md),
>  		       (unsigned long long)start,
> -		       limits->logical_block_size, bdevname(bdev, b));
> +		       limits->logical_block_size,
> +		       bdev);
>  		return 1;
>  	}
>  
>  	if (len & (logical_block_size_sectors - 1)) {
> -		DMWARN("%s: len=%llu not aligned to h/w "
> -		       "logical block size %u of %s",
> +		DMWARN("%s: len=%llu not aligned to h/w logical block size %u of %pg",
>  		       dm_device_name(ti->table->md),
>  		       (unsigned long long)len,
> -		       limits->logical_block_size, bdevname(bdev, b));
> +		       limits->logical_block_size,
> +		       bdev);
>  		return 1;
>  	}
>  

Again, please just leave 'bdev' on the previous lines.

If you make those few tweaks, please add:

Acked-by: Mike Snitzer <snitzer@redhat.com>