| Date | Mon, 28 May 2012 04:13:12 +0100 | From | Ben Hutchings <> | Subject | [ 070/117] swap: dont do discard if no discard option added |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: Shaohua Li <shli@kernel.org>
commit 052b1987faca3606109d88d96bce124851f7c4c2 upstream.
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> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- mm/swapfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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 @@ 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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