sys_swapon: move setting of error nearer use

Move the setting of the error variable nearer the goto in a few places.

Avoids calling PTR_ERR() if not IS_ERR() in two places, and makes the
error condition more explicit in two other places.
Signed-off-by: NCesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: NEric B Munson <emunson@mgebm.net>
Acked-by: NEric B Munson <emunson@mgebm.net>
Reviewed-by: NJesper Juhl <jj@chaosbits.net>
Reviewed-by: NPekka Enberg <penberg@kernel.org>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

@@ -1916,14 +1916,14 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		return PTR_ERR(p);
 
 	name = getname(specialfile);
-	error = PTR_ERR(name);
 	if (IS_ERR(name)) {
+		error = PTR_ERR(name);
 		name = NULL;
 		goto bad_swap_2;
 	}
 	swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
-	error = PTR_ERR(swap_file);
 	if (IS_ERR(swap_file)) {
+		error = PTR_ERR(swap_file);
 		swap_file = NULL;
 		goto bad_swap_2;
 	}
@@ -1932,17 +1932,17 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	mapping = swap_file->f_mapping;
 	inode = mapping->host;
 
-	error = -EBUSY;
 	for (i = 0; i < nr_swapfiles; i++) {
 		struct swap_info_struct *q = swap_info[i];
 
 		if (q == p || !q->swap_file)
 			continue;
-		if (mapping == q->swap_file->f_mapping)
+		if (mapping == q->swap_file->f_mapping) {
+			error = -EBUSY;
 			goto bad_swap;
+		}
 	}
 
-	error = -EINVAL;
 	if (S_ISBLK(inode->i_mode)) {
 		bdev = bdgrab(I_BDEV(inode));
 		error = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL,
@@ -1966,6 +1966,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 			goto bad_swap;
 		}
 	} else {
+		error = -EINVAL;
 		goto bad_swap;
 	}