Commit 052b1987 authored Mar 21, 2012 by Shaohua Li Committed by Linus Torvalds Mar 21, 2012

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>

parent 1480de03

mm/swapfile.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2103,7 +2103,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
		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;
		}

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