zram-swap: compression algorithm configuration option

Compression algorithms for zram are provided by kernel crypto API, could
be any of [lzo|zl4|deflate|<some_more>] depending on kernel modules.
Compress algo for zram-swap could be defined via 'zram_comp_algo' option
in 'system' section of '/etc/config/system' file, or via cli (for e.x.
with 'uci set system.@System[0].zram_comp_algo=lz4 && uci commit
system'). check available algo's via 'cat /sys/block/zram0
/comp_algorithm'

Signed-off-by: Emil Muratov <gpm@hotplug.ru>

diff --git a/package/system/zram-swap/files/zram.init b/package/system/zram-swap/files/zram.init
index 63a20479d1011b2665b1a76cfe54dbf1ccdab58e..419221b1a3ac173672333e5c6bba0ad83588f45e 100644 (file)
--- a/package/system/zram-swap/files/zram.init
+++ b/package/system/zram-swap/files/zram.init
@@ -69,6 +69,23 @@ zram_reset()
        echo "1" >"$proc_entry"
 }
 
+zram_comp_algo()
+{
+       local dev="$1"
+       local zram_comp_algo="$( uci -q get system.@system[0].zram_comp_algo )"
+
+       if [ -z "$zram_comp_algo" ] || [ ! -e /sys/block/$( basename $dev )/comp_algorithm ]; then
+               return 0
+       fi
+
+       if [ `grep -c "$zram_comp_algo" /sys/block/$( basename $dev )/comp_algorithm` -ne 0 ]; then
+               logger -s -t zram_comp_algo -p daemon.debug "Set compression algorithm '$zram_comp_algo' for zram '$dev'"
+               echo $zram_comp_algo > "/sys/block/$( basename $dev )/comp_algorithm"
+       else
+               logger -s -t zram_comp_algo -p daemon.debug "Compression algorithm '$zram_comp_algo' is not supported for '$dev'"
+       fi
+}
+
 list_cpu_idx()
 {
        # Offset by 1 if /dev/zram0 is in use by /tmp
@@ -108,6 +125,7 @@ start()
 
                zram_reset "$zram_dev" "enforcing defaults"
                echo $(( zram_size * 1024 * 1024 )) >"/sys/block/$( basename "$zram_dev" )/disksize"
+               zram_comp_algo "$zram_dev"
                mkswap "$zram_dev"
                swapon "$zram_dev"
        } done