zram: add set_max_streams knob

This patch allows to change max_comp_streams on initialised zcomp.

Introduce zcomp set_max_streams() knob, zcomp_strm_multi_set_max_streams()
and zcomp_strm_single_set_max_streams() callbacks to change streams limit
for zcomp_strm_multi and zcomp_strm_single, accordingly.  set_max_streams
for single steam zcomp does nothing.

If user has lowered the limit, then zcomp_strm_multi_set_max_streams()
attempts to immediately free extra streams (as much as it can, depending
on idle streams availability).

Note, this patch does not allow to change stream 'policy' from single to
multi stream (or vice versa) on already initialised compression backend.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index c06f75f547186a36346a1b89052c67aac0bbc81f..ac276f79f21ce3ff44b7b619b91dd7423479f4eb 100644 (file)
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -136,6 +136,29 @@ static void zcomp_strm_multi_release(struct zcomp *comp, struct zcomp_strm *zstr
        zcomp_strm_free(comp, zstrm);
 }
 
+/* change max_strm limit */
+static int zcomp_strm_multi_set_max_streams(struct zcomp *comp, int num_strm)
+{
+       struct zcomp_strm_multi *zs = comp->stream;
+       struct zcomp_strm *zstrm;
+
+       spin_lock(&zs->strm_lock);
+       zs->max_strm = num_strm;
+       /*
+        * if user has lowered the limit and there are idle streams,
+        * immediately free as much streams (and memory) as we can.
+        */
+       while (zs->avail_strm > num_strm && !list_empty(&zs->idle_strm)) {
+               zstrm = list_entry(zs->idle_strm.next,
+                               struct zcomp_strm, list);
+               list_del(&zstrm->list);
+               zcomp_strm_free(comp, zstrm);
+               zs->avail_strm--;
+       }
+       spin_unlock(&zs->strm_lock);
+       return 0;
+}
+
 static void zcomp_strm_multi_destroy(struct zcomp *comp)
 {
        struct zcomp_strm_multi *zs = comp->stream;
@@ -158,6 +181,7 @@ static int zcomp_strm_multi_create(struct zcomp *comp, int max_strm)
        comp->destroy = zcomp_strm_multi_destroy;
        comp->strm_find = zcomp_strm_multi_find;
        comp->strm_release = zcomp_strm_multi_release;
+       comp->set_max_streams = zcomp_strm_multi_set_max_streams;
        zs = kmalloc(sizeof(struct zcomp_strm_multi), GFP_KERNEL);
        if (!zs)
                return -ENOMEM;
@@ -192,6 +216,12 @@ static void zcomp_strm_single_release(struct zcomp *comp,
        mutex_unlock(&zs->strm_lock);
 }
 
+static int zcomp_strm_single_set_max_streams(struct zcomp *comp, int num_strm)
+{
+       /* zcomp_strm_single support only max_comp_streams == 1 */
+       return -ENOTSUPP;
+}
+
 static void zcomp_strm_single_destroy(struct zcomp *comp)
 {
        struct zcomp_strm_single *zs = comp->stream;
@@ -206,6 +236,7 @@ static int zcomp_strm_single_create(struct zcomp *comp)
        comp->destroy = zcomp_strm_single_destroy;
        comp->strm_find = zcomp_strm_single_find;
        comp->strm_release = zcomp_strm_single_release;
+       comp->set_max_streams = zcomp_strm_single_set_max_streams;
        zs = kmalloc(sizeof(struct zcomp_strm_single), GFP_KERNEL);
        if (!zs)
                return -ENOMEM;
@@ -220,6 +251,11 @@ static int zcomp_strm_single_create(struct zcomp *comp)
        return 0;
 }
 
+int zcomp_set_max_streams(struct zcomp *comp, int num_strm)
+{
+       return comp->set_max_streams(comp, num_strm);
+}
+
 struct zcomp_strm *zcomp_strm_find(struct zcomp *comp)
 {
        return comp->strm_find(comp);

diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 2a36844461606a4f6616a37d81ada10f7d89d905..bd11d59c5dd161dfdd4bc69fb23b5dcd806836c8 100644 (file)
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -46,6 +46,7 @@ struct zcomp {
 
        struct zcomp_strm *(*strm_find)(struct zcomp *comp);
        void (*strm_release)(struct zcomp *comp, struct zcomp_strm *zstrm);
+       int (*set_max_streams)(struct zcomp *comp, int num_strm);
        void (*destroy)(struct zcomp *comp);
 };
 
@@ -60,4 +61,6 @@ int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
 
 int zcomp_decompress(struct zcomp *comp, const unsigned char *src,
                size_t src_len, unsigned char *dst);
+
+int zcomp_set_max_streams(struct zcomp *comp, int num_strm);
 #endif /* _ZCOMP_H_ */

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index bdc7eb8c6df7474d61ac7f3ba930588733dbb9d0..3a5f24c341dc8f552f6da5233d291a9bf65d2a2a 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -133,9 +133,8 @@ static ssize_t max_comp_streams_store(struct device *dev,
                return -EINVAL;
        down_write(&zram->init_lock);
        if (init_done(zram)) {
-               up_write(&zram->init_lock);
-               pr_info("Can't set max_comp_streams for initialized device\n");
-               return -EBUSY;
+               if (zcomp_set_max_streams(zram->comp, num))
+                       pr_info("Cannot change max compression streams\n");
        }
        zram->max_comp_streams = num;
        up_write(&zram->init_lock);