zram: introduce zram->tb_lock
Currently, the zram table is protected by zram->lock but it's rather
coarse-grained lock and it makes hard for scalibility.
Let's use own rwlock instead of depending on zram->lock. This patch
adds new locking so obviously, it would make slow but this patch is just
prepartion for removing coarse-grained rw_semaphore(ie, zram->lock)
which is hurdle about zram scalability.
Final patch in this patchset series will remove the lock from read-path
and change rw_semaphore with mutex in write path. With bonus, we could
drop pending slot free mess in next patch.
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 81b0170..c3f453f 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -83,6 +83,7 @@
};
struct zram_meta {
+ rwlock_t tb_lock; /* protect table */
void *compress_workmem;
void *compress_buffer;
struct table *table;
@@ -96,7 +97,7 @@
struct zram {
struct zram_meta *meta;
- struct rw_semaphore lock; /* protect compression buffers, table,
+ struct rw_semaphore lock; /* protect compression buffers,
* reads and writes
*/