[RFC PATCH v3 02/18] mm/swap: slightly cleanup the code for hibernation error handling

[Lian Wang <lianux.mm@gmail.com>]

From: Kairui Song <kasong@tencent.com>

Restructure the error paths in pin_hibernation_swap_type() using a
goto out pattern to avoid repeated spin_unlock() calls and simplify
the return flow.  Also simplify unpin_hibernation_swap_type() by
making the si NULL check inline, and clean up find_first_swap() to
avoid an early return inside the loop.

Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Lian Wang <lianux.mm@gmail.com>
---
 mm/swapfile.c | 39 +++++++++++++++++----------------------
 1 file changed, 17 insertions(+), 22 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 7acb33cd8b71..cf8c0999655c 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2279,21 +2279,18 @@ static int __find_hibernation_swap_type(dev_t device, sector_t offset)
  */
 int pin_hibernation_swap_type(dev_t device, sector_t offset)
 {
-	int type;
+	int ret;
 	struct swap_info_struct *si;
 
 	spin_lock(&swap_lock);
+	ret = __find_hibernation_swap_type(device, offset);
+	if (ret < 0)
+		goto out;
 
-	type = __find_hibernation_swap_type(device, offset);
-	if (type < 0) {
-		spin_unlock(&swap_lock);
-		return type;
-	}
-
-	si = swap_type_to_info(type);
+	si = swap_type_to_info(ret);
 	if (WARN_ON_ONCE(!si)) {
-		spin_unlock(&swap_lock);
-		return -ENODEV;
+		ret = -ENODEV;
+		goto out;
 	}
 
 	/*
@@ -2302,14 +2299,15 @@ int pin_hibernation_swap_type(dev_t device, sector_t offset)
 	 * the same session.
 	 */
 	if (WARN_ON_ONCE(si->flags & SWP_HIBERNATION)) {
-		spin_unlock(&swap_lock);
-		return -EBUSY;
+		ret = -EBUSY;
+		goto out;
 	}
 
 	si->flags |= SWP_HIBERNATION;
 
+out:
 	spin_unlock(&swap_lock);
-	return type;
+	return ret;
 }
 
 /**
@@ -2389,11 +2387,8 @@ void unpin_hibernation_swap_type(int type)
 
 	spin_lock(&swap_lock);
 	si = swap_type_to_info(type);
-	if (!si) {
-		spin_unlock(&swap_lock);
-		return;
-	}
-	si->flags &= ~SWP_HIBERNATION;
+	if (si)
+		si->flags &= ~SWP_HIBERNATION;
 	spin_unlock(&swap_lock);
 }
 
@@ -2428,7 +2423,7 @@ int find_hibernation_swap_type(dev_t device, sector_t offset)
 
 int find_first_swap(dev_t *device)
 {
-	int type;
+	int type, ret = -ENODEV;
 
 	spin_lock(&swap_lock);
 	for (type = 0; type < nr_swapfiles; type++) {
@@ -2437,11 +2432,11 @@ int find_first_swap(dev_t *device)
 		if (!(sis->flags & SWP_WRITEOK))
 			continue;
 		*device = sis->bdev->bd_dev;
-		spin_unlock(&swap_lock);
-		return type;
+		ret = type;
+		break;
 	}
 	spin_unlock(&swap_lock);
-	return -ENODEV;
+	return ret;
 }
 
 /*