Re: [PATCH 2/6] common/rc: Add _sysfs_queue_path helper with partition support

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Apr 10, 2026 at 12:06:02PM +0530, Ojaswin Mujoo wrote:
> Add a generic helper function to get the sysfs queue path for block
> devices, properly handling partitions. Partitions don't have their own
> queue directory in sysfs - they inherit from their parent device.
> 
> This helper checks if a device is a partition and returns the parent
> device's queue path accordingly, making it easier to access queue
> attributes for both whole disks and partitions.
> 
> Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>

Excellent!
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  common/rc | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/common/rc b/common/rc
> index 5fe44e21..d7db5db1 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -5172,6 +5172,30 @@ _sysfs_dev()
>  	echo /sys/dev/block/$maj:$min
>  }
>  
> +# Get the sysfs queue path for a block device, handling partitions correctly.
> +_sysfs_queue_path()
> +{
> +	local dev parent
> +	dev=$(_short_dev "$1")
> +
> +	# For partitions, queue details are in the parent device's sysfs dir
> +	if [ -e "/sys/class/block/$dev/partition" ]; then
> +		parent=$(basename "$(readlink -f /sys/class/block/$dev/..)")
> +	else
> +		parent="$dev"
> +	fi
> +
> +	local queue_path="/sys/block/$parent/queue"
> +
> +	# Verify the path exists before returning
> +	if [ -e "$queue_path" ]; then
> +		echo "$queue_path"
> +		return 0
> +	else
> +		return 1
> +	fi
> +}
> +
>  # Get the minimum block size of a file.  Usually this is the
>  # minimum fs block size, but some filesystems (ocfs2) do block
>  # mappings in larger units.
> -- 
> 2.53.0
> 
>