[PATCH] swap: move destroy_swap_extents calls

sys_swapon's call to destroy_swap_extents on failure is made after the final
swap_list_unlock, which is faintly unsafe: another sys_swapon might already be
setting up that swap_info_struct.  Calling it earlier, before taking
swap_list_lock, is safe.  sys_swapoff's call to destroy_swap_extents was safe,
but likewise move it earlier, before taking the locks (once try_to_unuse has
completed, nothing can be needing the swap extents).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 5ac5333f37a0..4b39e9501d44 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1129,6 +1129,7 @@ asmlinkage long sys_swapoff(const char __user * specialfile)
                 swap_list_unlock();
                 goto out_dput;
         }
+        destroy_swap_extents(p);
         down(&swapon_sem);
         swap_list_lock();
         drain_mmlist();
@@ -1139,7 +1140,6 @@ asmlinkage long sys_swapoff(const char __user * specialfile)
         swap_map = p->swap_map;
         p->swap_map = NULL;
         p->flags = 0;
-        destroy_swap_extents(p);
         swap_device_unlock(p);
         swap_list_unlock();
         up(&swapon_sem);
@@ -1531,6 +1531,7 @@ bad_swap:
                 set_blocksize(bdev, p->old_block_size);
                 bd_release(bdev);
         }
+        destroy_swap_extents(p);
 bad_swap_2:
         swap_list_lock();
         swap_map = p->swap_map;
@@ -1540,7 +1541,6 @@ bad_swap_2:
         if (!(swap_flags & SWAP_FLAG_PREFER))
                 ++least_priority;
         swap_list_unlock();
-        destroy_swap_extents(p);
         vfree(swap_map);
         if (swap_file)
                 filp_close(swap_file, NULL);