Re: [PATCH -next] xfs: Fix unused variable 'mp' warning

[Christoph Hellwig <hch@lst.de>]

I don't think declaring a variable inside a switch statement is a good
idea.  This is what I had lying around but never got around finishing
up and submitting:

---
From 5e79886f08ca4dd96c9a508a380dfeb73cd4b529 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Wed, 3 Feb 2021 13:38:27 +0100
Subject: xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl

The mp variable in xfs_file_compat_ioctl is only used when
BROKEN_X86_ALIGNMENT is define.  Remove it and just open code the
dereference in a few places.

Fixes: f736d93d76d3 ("xfs: support idmapped mounts")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_ioctl32.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
index e11139e18021c1..daf73cb53a05bb 100644
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/xfs_ioctl32.c
@@ -420,7 +420,6 @@ xfs_file_compat_ioctl(
 {
 	struct inode		*inode = file_inode(filp);
 	struct xfs_inode	*ip = XFS_I(inode);
-	struct xfs_mount	*mp = ip->i_mount;
 	void			__user *arg = compat_ptr(p);
 	int			error;
 
@@ -429,7 +428,7 @@ xfs_file_compat_ioctl(
 	switch (cmd) {
 #if defined(BROKEN_X86_ALIGNMENT)
 	case XFS_IOC_FSGEOMETRY_V1_32:
-		return xfs_compat_ioc_fsgeometry_v1(mp, arg);
+		return xfs_compat_ioc_fsgeometry_v1(ip->i_mount, arg);
 	case XFS_IOC_FSGROWFSDATA_32: {
 		struct xfs_growfs_data	in;
 
@@ -438,7 +437,7 @@ xfs_file_compat_ioctl(
 		error = mnt_want_write_file(filp);
 		if (error)
 			return error;
-		error = xfs_growfs_data(mp, &in);
+		error = xfs_growfs_data(ip->i_mount, &in);
 		mnt_drop_write_file(filp);
 		return error;
 	}
@@ -450,7 +449,7 @@ xfs_file_compat_ioctl(
 		error = mnt_want_write_file(filp);
 		if (error)
 			return error;
-		error = xfs_growfs_rt(mp, &in);
+		error = xfs_growfs_rt(ip->i_mount, &in);
 		mnt_drop_write_file(filp);
 		return error;
 	}
@@ -480,7 +479,7 @@ xfs_file_compat_ioctl(
 	case XFS_IOC_FSBULKSTAT_32:
 	case XFS_IOC_FSBULKSTAT_SINGLE_32:
 	case XFS_IOC_FSINUMBERS_32:
-		return xfs_compat_ioc_fsbulkstat(mp, cmd, arg);
+		return xfs_compat_ioc_fsbulkstat(ip->i_mount, cmd, arg);
 	case XFS_IOC_FD_TO_HANDLE_32:
 	case XFS_IOC_PATH_TO_HANDLE_32:
 	case XFS_IOC_PATH_TO_FSHANDLE_32: {
-- 
2.29.2