From: Sergey Senozhatsky <senozhatsky@chromium.org>
Date: Wed, 11 Mar 2026 08:42:46 +0000 (+0900)
Subject: zram: drop ->num_active_comps
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5004a27edba5987bd75fe84c40b1b486ffae8f99;p=thirdparty%2Fkernel%2Flinux.git

zram: drop ->num_active_comps

It's not entirely correct to use ->num_active_comps for max-prio limit, as
->num_active_comps just tells the number of configured algorithms, not the
max configured priority.  For instance, in the following theoretical
example:

    [lz4] [nil] [nil] [deflate]

->num_active_comps is 2, while the actual max-prio is 3.

Drop ->num_active_comps and use ZRAM_MAX_COMPS instead.

Link: https://lkml.kernel.org/r/20260311084312.1766036-4-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Suggested-by: Minchan Kim <minchan@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: gao xu <gaoxu2@honor.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 71c4e2d350ced..74c522c14c787 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -2324,6 +2324,18 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 #define RECOMPRESS_IDLE		(1 << 0)
 #define RECOMPRESS_HUGE		(1 << 1)
 
+static bool highest_priority_algorithm(struct zram *zram, u32 prio)
+{
+	u32 p;
+
+	for (p = prio + 1; p < ZRAM_MAX_COMPS; p++) {
+		if (zram->comp_algs[p])
+			return false;
+	}
+
+	return true;
+}
+
 static int scan_slots_for_recompress(struct zram *zram, u32 mode, u32 prio_max,
 				     struct zram_pp_ctl *ctl)
 {
@@ -2471,12 +2483,11 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page,
 		 * Secondary algorithms failed to re-compress the page
 		 * in a way that would save memory.
 		 *
-		 * Mark the object incompressible if the max-priority
-		 * algorithm couldn't re-compress it.
+		 * Mark the object incompressible if the max-priority (the
+		 * last configured one) algorithm couldn't re-compress it.
 		 */
-		if (prio < zram->num_active_comps)
-			return 0;
-		set_slot_flag(zram, index, ZRAM_INCOMPRESSIBLE);
+		if (highest_priority_algorithm(zram, prio))
+			set_slot_flag(zram, index, ZRAM_INCOMPRESSIBLE);
 		return 0;
 	}
 
@@ -2608,12 +2619,6 @@ static ssize_t recompress_store(struct device *dev,
 		}
 	}
 
-	prio_max = min(prio_max, (u32)zram->num_active_comps);
-	if (prio >= prio_max) {
-		ret = -EINVAL;
-		goto out;
-	}
-
 	if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS) {
 		ret = -EINVAL;
 		goto out;
@@ -2826,7 +2831,6 @@ static void zram_destroy_comps(struct zram *zram)
 		if (!comp)
 			continue;
 		zcomp_destroy(comp);
-		zram->num_active_comps--;
 	}
 
 	for (prio = ZRAM_PRIMARY_COMP; prio < ZRAM_MAX_COMPS; prio++)
@@ -2891,7 +2895,6 @@ static ssize_t disksize_store(struct device *dev, struct device_attribute *attr,
 		}
 
 		zram->comps[prio] = comp;
-		zram->num_active_comps++;
 	}
 	zram->disksize = disksize;
 	set_capacity_and_notify(zram->disk, zram->disksize >> SECTOR_SHIFT);
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index f0de8f8218f5c..08d1774c15db6 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -125,7 +125,6 @@ struct zram {
 	 */
 	u64 disksize;	/* bytes */
 	const char *comp_algs[ZRAM_MAX_COMPS];
-	s8 num_active_comps;
 	/*
 	 * zram is claimed so open request will be failed
 	 */