4 files changed, 70 insertions, 2 deletions

diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index ea67fa3f3cff..b13dc993291f 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -120,6 +120,16 @@ Description:
                 statistic.
                 Unit: bytes
 
+What:           /sys/block/zram<id>/mem_used_max
+Date:           August 2014
+Contact:        Minchan Kim <minchan@kernel.org>
+Description:
+                The mem_used_max file is read/write and specifies the amount
+                of maximum memory zram have consumed to store compressed data.
+                For resetting the value, you should write "0". Otherwise,
+                you could see -EINVAL.
+                Unit: bytes
+
 What:           /sys/block/zram<id>/mem_limit
 Date:           August 2014
 Contact:        Minchan Kim <minchan@kernel.org>
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 82c6a41116db..7fcf9c6592ec 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -111,6 +111,7 @@ size of the disk when not in use so a huge zram is wasteful.
                 orig_data_size
                 compr_data_size
                 mem_used_total
+                mem_used_max
 
 8) Deactivate:
         swapoff /dev/zram0
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 64b27cf9a583..d78b245bae06 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -153,6 +153,41 @@ static ssize_t mem_limit_store(struct device *dev,
         return len;
 }
 
+static ssize_t mem_used_max_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        u64 val = 0;
+        struct zram *zram = dev_to_zram(dev);
+
+        down_read(&zram->init_lock);
+        if (init_done(zram))
+                val = atomic_long_read(&zram->stats.max_used_pages);
+        up_read(&zram->init_lock);
+
+        return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
+}
+
+static ssize_t mem_used_max_store(struct device *dev,
+                struct device_attribute *attr, const char *buf, size_t len)
+{
+        int err;
+        unsigned long val;
+        struct zram *zram = dev_to_zram(dev);
+        struct zram_meta *meta = zram->meta;
+
+        err = kstrtoul(buf, 10, &val);
+        if (err || val != 0)
+                return -EINVAL;
+
+        down_read(&zram->init_lock);
+        if (init_done(zram))
+                atomic_long_set(&zram->stats.max_used_pages,
+                                zs_get_total_pages(meta->mem_pool));
+        up_read(&zram->init_lock);
+
+        return len;
+}
+
 static ssize_t max_comp_streams_store(struct device *dev,
                 struct device_attribute *attr, const char *buf, size_t len)
 {
@@ -465,6 +500,21 @@ out_cleanup:
         return ret;
 }
 
+static inline void update_used_max(struct zram *zram,
+                                        const unsigned long pages)
+{
+        int old_max, cur_max;
+
+        old_max = atomic_long_read(&zram->stats.max_used_pages);
+
+        do {
+                cur_max = old_max;
+                if (pages > cur_max)
+                        old_max = atomic_long_cmpxchg(
+                                &zram->stats.max_used_pages, cur_max, pages);
+        } while (old_max != cur_max);
+}
+
 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
                            int offset)
 {
@@ -476,6 +526,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
         struct zram_meta *meta = zram->meta;
         struct zcomp_strm *zstrm;
         bool locked = false;
+        unsigned long alloced_pages;
 
         page = bvec->bv_page;
         if (is_partial_io(bvec)) {
@@ -545,13 +596,15 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
                 goto out;
         }
 
-        if (zram->limit_pages &&
-                zs_get_total_pages(meta->mem_pool) > zram->limit_pages) {
+        alloced_pages = zs_get_total_pages(meta->mem_pool);
+        if (zram->limit_pages && alloced_pages > zram->limit_pages) {
                 zs_free(meta->mem_pool, handle);
                 ret = -ENOMEM;
                 goto out;
         }
 
+        update_used_max(zram, alloced_pages);
+
         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
 
         if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
@@ -901,6 +954,8 @@ static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
 static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
 static DEVICE_ATTR(mem_limit, S_IRUGO | S_IWUSR, mem_limit_show,
                 mem_limit_store);
+static DEVICE_ATTR(mem_used_max, S_IRUGO | S_IWUSR, mem_used_max_show,
+                mem_used_max_store);
 static DEVICE_ATTR(max_comp_streams, S_IRUGO | S_IWUSR,
                 max_comp_streams_show, max_comp_streams_store);
 static DEVICE_ATTR(comp_algorithm, S_IRUGO | S_IWUSR,
@@ -930,6 +985,7 @@ static struct attribute *zram_disk_attrs[] = {
         &dev_attr_compr_data_size.attr,
         &dev_attr_mem_used_total.attr,
         &dev_attr_mem_limit.attr,
+        &dev_attr_mem_used_max.attr,
         &dev_attr_max_comp_streams.attr,
         &dev_attr_comp_algorithm.attr,
         NULL,
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index b7aa9c21553f..c6ee271317f5 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -90,6 +90,7 @@ struct zram_stats {
         atomic64_t notify_free; /* no. of swap slot free notifications */
         atomic64_t zero_pages;          /* no. of zero filled pages */
         atomic64_t pages_stored;        /* no. of pages currently stored */
+        atomic_long_t max_used_pages;   /* no. of maximum pages stored */
 };
 
 struct zram_meta {