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sys_swapon: do not depend on "type" after allocation 

Within sys_swapon, after the swap_info entry has been allocated, we
always have type == p->type and swap_info[type] == p. Use this fact to
reduce the dependency on the "type" local variable within the function,
as a preparation to move the allocation of the swap_info entry to a
separate function.

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujisu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Cesar Eduardo Barros 2011-03-22 16:33:16 -07:00 committed by Linus Torvalds
parent 80b0df12b8
commit e8e6c2ec40
1 changed files with 5 additions and 5 deletions
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10
mm/swapfile.c
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@ -1927,7 +1927,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
for (i = 0; i < nr_swapfiles; i++) {
struct swap_info_struct *q = swap_info[i];
if (i == type || !q->swap_file)
if (q == p || !q->swap_file)
continue;
if (mapping == q->swap_file->f_mapping)
goto bad_swap;
@ -2062,7 +2062,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
}
}
error = swap_cgroup_swapon(type, maxpages);
error = swap_cgroup_swapon(p->type, maxpages);
if (error)
goto bad_swap;
@ -2120,9 +2120,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
}
p->next = i;
if (prev < 0)
swap_list.head = swap_list.next = type;
swap_list.head = swap_list.next = p->type;
else
swap_info[prev]->next = type;
swap_info[prev]->next = p->type;
spin_unlock(&swap_lock);
mutex_unlock(&swapon_mutex);
atomic_inc(&proc_poll_event);
@ -2136,7 +2136,7 @@ bad_swap:
blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
}
destroy_swap_extents(p);
swap_cgroup_swapoff(type);
swap_cgroup_swapoff(p->type);
bad_swap_2:
spin_lock(&swap_lock);
p->swap_file = NULL;