staging: zsmalloc: add mapping modes

This patch improves mapping performance in zsmalloc by getting
usage information from the user in the form of a "mapping mode"
and using it to avoid unnecessary copying for objects that span
pages.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 706cb625aae..653b074035f 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -220,7 +220,8 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
                 uncmem = user_mem;
         clen = PAGE_SIZE;
 
-        cmem = zs_map_object(zram->mem_pool, zram->table[index].handle);
+        cmem = zs_map_object(zram->mem_pool, zram->table[index].handle,
+                                ZS_MM_RO);
 
         ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
                                     uncmem, &clen);
@@ -258,7 +259,7 @@ static int zram_read_before_write(struct zram *zram, char *mem, u32 index)
                 return 0;
         }
 
-        cmem = zs_map_object(zram->mem_pool, handle);
+        cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
         ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
                                     mem, &clen);
         zs_unmap_object(zram->mem_pool, handle);
@@ -351,7 +352,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
                 ret = -ENOMEM;
                 goto out;
         }
-        cmem = zs_map_object(zram->mem_pool, handle);
+        cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
 
         memcpy(cmem, src, clen);