zram: support priority parameter in recompression

recompress device attribute supports alg=NAME parameter so that we can
specify only one particular algorithm we want to perform recompression
with.  However, with algo params we now can have several exactly same
secondary algorithms but each with its own params tuning (e.g.  priority 1
configured to use more aggressive level, and priority 2 configured to use
a pre-trained dictionary).  Support priority=NUM parameter so that we can
correctly determine which secondary algorithm we want to use.

Link: https://lkml.kernel.org/r/20240902105656.1383858-25-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst
index d3b676273528045a34f8ee9ce52775b042ed0a30..678d70d6e1c3ac6b3f442d0f7f03ac781532342b 100644 (file)
--- a/Documentation/admin-guide/blockdev/zram.rst
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -512,11 +512,14 @@ registered compression algorithms, increases our chances of finding the
 algorithm that successfully compresses a particular page. Sometimes, however,
 it is convenient (and sometimes even necessary) to limit recompression to
 only one particular algorithm so that it will not try any other algorithms.
-This can be achieved by providing a algo=NAME parameter:::
+This can be achieved by providing a `algo` or `priority` parameter:::
 
        #use zstd algorithm only (if registered)
        echo "type=huge algo=zstd" > /sys/block/zramX/recompress
 
+       #use zstd algorithm only (if zstd was registered under priority 1)
+       echo "type=huge priority=1" > /sys/block/zramX/recompress
+
 memory tracking
 ===============
 

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9b29f9e6cb503ed391774f0610d47b367ed40d38..1f1bf175a6c347b6a659ed1ac678dab64e50b917 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1855,6 +1855,18 @@ static ssize_t recompress_store(struct device *dev,
                        algo = val;
                        continue;
                }
+
+               if (!strcmp(param, "priority")) {
+                       ret = kstrtouint(val, 10, &prio);
+                       if (ret)
+                               return ret;
+
+                       if (prio == ZRAM_PRIMARY_COMP)
+                               prio = ZRAM_SECONDARY_COMP;
+
+                       prio_max = min(prio + 1, ZRAM_MAX_COMPS);
+                       continue;
+               }
        }
 
        if (threshold >= huge_class_size)