swap: don't do discard if no discard option added
When swapon() was not passed the SWAP_FLAG_DISCARD option, sys_swapon()
will still perform a discard operation. This can cause problems if
discard is slow or buggy.
Reverse the order of the check so that a discard operation is performed
only if the sys_swapon() caller is attempting to enable discard.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Reported-by: Holger Kiehl <Holger.Kiehl@dwd.de>
Tested-by: Holger Kiehl <Holger.Kiehl@dwd.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index b82c028..21b5694 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2103,7 +2103,7 @@
p->flags |= SWP_SOLIDSTATE;
p->cluster_next = 1 + (random32() % p->highest_bit);
}
- if (discard_swap(p) == 0 && (swap_flags & SWAP_FLAG_DISCARD))
+ if ((swap_flags & SWAP_FLAG_DISCARD) && discard_swap(p) == 0)
p->flags |= SWP_DISCARDABLE;
}