mm: shmem: add missing shmem_unacct_size() in __shmem_file_setup()

We will miss shmem_unacct_size() when is_idmapped_mnt() returns a failure.
Move is_idmapped_mnt() before shmem_acct_size() to fix the issue.

Link: https://lkml.kernel.org/r/20250516170939.965736-3-shikemeng@huaweicloud.com
Fixes: 7a80e5b8c6fa ("shmem: support idmapped mounts for tmpfs")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 980fa15..495e661 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5812,12 +5812,12 @@ static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
        if (size < 0 || size > MAX_LFS_FILESIZE)
                return ERR_PTR(-EINVAL);
 
-       if (shmem_acct_size(flags, size))
-               return ERR_PTR(-ENOMEM);
-
        if (is_idmapped_mnt(mnt))
                return ERR_PTR(-EINVAL);
 
+       if (shmem_acct_size(flags, size))
+               return ERR_PTR(-ENOMEM);
+
        inode = shmem_get_inode(&nop_mnt_idmap, mnt->mnt_sb, NULL,
                                S_IFREG | S_IRWXUGO, 0, flags);
        if (IS_ERR(inode)) {