fs: make two stat prep helpers available

to #26323588

commit 3934e36f6099e6277db33f433fe135c6644e8ac2 upstream.

To implement an async stat, we need to provide the flags mapping and
the statx user copy. Make them available internally, through
fs/internal.h.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>

fs/internal.h

@@ -190,3 +190,9 @@ loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length,
 
 /* direct-io.c: */
 int sb_init_dio_done_wq(struct super_block *sb);
+
+/*
+ * fs/stat.c:
+ */
+unsigned vfs_stat_set_lookup_flags(unsigned *lookup_flags, int flags);
+int cp_statx(const struct kstat *stat, struct statx __user *buffer);

fs/stat.c

@@ -21,6 +21,8 @@
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
 
+#include "internal.h"
+
 /**
  * generic_fillattr - Fill in the basic attributes from the inode struct
  * @inode: Inode to use as the source
@@ -148,6 +150,23 @@ int vfs_statx_fd(unsigned int fd, struct kstat *stat,
 }
 EXPORT_SYMBOL(vfs_statx_fd);
 
+inline unsigned vfs_stat_set_lookup_flags(unsigned *lookup_flags, int flags)
+{
+	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
+		       AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
+		return -EINVAL;
+
+	*lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
+	if (flags & AT_SYMLINK_NOFOLLOW)
+		*lookup_flags &= ~LOOKUP_FOLLOW;
+	if (flags & AT_NO_AUTOMOUNT)
+		*lookup_flags &= ~LOOKUP_AUTOMOUNT;
+	if (flags & AT_EMPTY_PATH)
+		*lookup_flags |= LOOKUP_EMPTY;
+
+	return 0;
+}
+
 /**
  * vfs_statx - Get basic and extra attributes by filename
  * @dfd: A file descriptor representing the base dir for a relative filename
@@ -168,19 +187,10 @@ int vfs_statx(int dfd, const char __user *filename, int flags,
 {
 	struct path path;
 	int error = -EINVAL;
-	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
+	unsigned lookup_flags;
 
-	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
-		       AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
+	if (vfs_stat_set_lookup_flags(&lookup_flags, flags))
 		return -EINVAL;
-
-	if (flags & AT_SYMLINK_NOFOLLOW)
-		lookup_flags &= ~LOOKUP_FOLLOW;
-	if (flags & AT_NO_AUTOMOUNT)
-		lookup_flags &= ~LOOKUP_AUTOMOUNT;
-	if (flags & AT_EMPTY_PATH)
-		lookup_flags |= LOOKUP_EMPTY;
-
 retry:
 	error = user_path_at(dfd, filename, lookup_flags, &path);
 	if (error)
@@ -518,7 +528,7 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
 }
 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
 
-static noinline_for_stack int
+noinline_for_stack int
 cp_statx(const struct kstat *stat, struct statx __user *buffer)
 {
 	struct statx tmp;