[PATCH] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

The newly added 'flags' variable is unused and causes a warning if
CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
into does nothing:

mm/shmem.c: In function '__shmem_file_setup':
mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
 5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
      |                       ^~~~~

Replace the macro with an equivalent inline function to get the
argument checking.

Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 mm/shmem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 3f194c9842a8..93746270c459 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5794,7 +5794,7 @@ EXPORT_SYMBOL_GPL(shmem_truncate_range);
 #define shmem_vm_ops				generic_file_vm_ops
 #define shmem_anon_vm_ops			generic_file_vm_ops
 #define shmem_file_operations			ramfs_file_operations
-#define shmem_acct_size(flags, size)		0
+static inline int shmem_acct_size(unsigned long flags, loff_t size) { return 0; }
 #define shmem_unacct_size(flags, size)		do {} while (0)
 
 static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
-- 
2.39.5