zswap: only save zswap header when necessary

We waste sizeof(swp_entry_t) for zswap header when using zsmalloc as
zpool driver because zsmalloc doesn't support eviction.

Add zpool_evictable() to detect if zpool is potentially evictable, and
use it in zswap to avoid waste memory for zswap header.

[[email protected]: The zpool->" prefix is a result of copy & paste]
  Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Yu Zhao <[email protected]>
Acked-by: Dan Streetman <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Cc: Seth Jennings <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions