[PATCH v2] btrfs: add helper to exit_btrfs_fs

[PATCH v2] btrfs: add helper to exit_btrfs_fs

[Anand Jain]

The module exit function exit_btrfs_fs() is duplicating a section of code
in init_btrfs_fs(). So add a helper function to remove the duplicate code.
Also, remove the comment about the function's .text section, which
doesn't make sense.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v2:
Use __always_inline in the helper function, inline regardless, helps ensure
same sections as the parent function.

David,
 This patch is on top of Qu's patch on the mailing list.
   btrfs: make btrfs module init/exit match their sequence

 This patch passed, make mrproper, compile with defconfig and Oracle Linux config.
 and, Module load/unload.
 I suggested this change in the review comment, but it wasn't going anywhere.
 Instead, I found sending a patch is more productive. Please, keep my SOB.

 fs/btrfs/super.c | 28 ++++++++++------------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 42e0d2fcc407..96456ad51eab 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2809,7 +2809,7 @@ static const struct init_sequence mod_init_seq[] = {
 
 static bool mod_init_result[ARRAY_SIZE(mod_init_seq)];
 
-static void __exit exit_btrfs_fs(void)
+static __always_inline void btrfs_exit_btrfs_fs(void)
 {
 	int i;
 
@@ -2822,6 +2822,11 @@ static void __exit exit_btrfs_fs(void)
 	}
 }
 
+static void __exit exit_btrfs_fs(void)
+{
+	btrfs_exit_btrfs_fs();
+}
+
 static int __init init_btrfs_fs(void)
 {
 	int ret;
@@ -2830,26 +2835,13 @@ static int __init init_btrfs_fs(void)
 	for (i = 0; i < ARRAY_SIZE(mod_init_seq); i++) {
 		ASSERT(!mod_init_result[i]);
 		ret = mod_init_seq[i].init_func();
-		if (ret < 0)
-			goto error;
+		if (ret < 0) {
+			btrfs_exit_btrfs_fs();
+			return ret;
+		}
 		mod_init_result[i] = true;
 	}
 	return 0;
-
-error:
-	/*
-	 * If we call exit_btrfs_fs() it would cause section mismatch.
-	 * As init_btrfs_fs() belongs to .init.text, while exit_btrfs_fs()
-	 * belongs to .exit.text.
-	 */
-	for (i = ARRAY_SIZE(mod_init_seq) - 1; i >= 0; i--) {
-		if (!mod_init_result[i])
-			continue;
-		if (mod_init_seq[i].exit_func)
-			mod_init_seq[i].exit_func();
-		mod_init_result[i] = false;
-	}
-	return ret;
 }
 
 late_initcall(init_btrfs_fs);
-- 
2.31.1

Re: [PATCH v2] btrfs: add helper to exit_btrfs_fs

[David Sterba]

On Wed, Oct 19, 2022 at 09:51:42PM +0530, Anand Jain wrote:
> The module exit function exit_btrfs_fs() is duplicating a section of code
> in init_btrfs_fs(). So add a helper function to remove the duplicate code.
> Also, remove the comment about the function's .text section, which
> doesn't make sense.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
> v2:
> Use __always_inline in the helper function, inline regardless, helps ensure
> same sections as the parent function.

This should have been mentioned in the changelog as it's explaining why
the __always_inline is there to avoid the section mismatches. Updated
and added to misc-next, thanks.