[RFC PATCH v1 08/18] fs: split off need_file_update_time and do_file_update_time

[Stefan Roesch <shr@fb.com>]

This splits off the functions need_file_update_time() and
do_file_update_time() from the function file_update_time().

This is required to support async buffered writes.
No intended functional changes in this patch.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/inode.c         | 72 ++++++++++++++++++++++++++++++----------------
 include/linux/fs.h |  5 ++++
 2 files changed, 52 insertions(+), 25 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 79c5702ef7c3..64047bb0b9f8 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2054,35 +2054,22 @@ int file_remove_privs(struct file *file)
 }
 EXPORT_SYMBOL(file_remove_privs);
 
-/**
- *	file_update_time	-	update mtime and ctime time
- *	@file: file accessed
- *
- *	Update the mtime and ctime members of an inode and mark the inode
- *	for writeback.  Note that this function is meant exclusively for
- *	usage in the file write path of filesystems, and filesystems may
- *	choose to explicitly ignore update via this function with the
- *	S_NOCMTIME inode flag, e.g. for network filesystem where these
- *	timestamps are handled by the server.  This can return an error for
- *	file systems who need to allocate space in order to update an inode.
- */
-
-int file_update_time(struct file *file)
+int need_file_update_time(struct inode *inode, struct file *file,
+			struct timespec64 *now)
 {
-	struct inode *inode = file_inode(file);
-	struct timespec64 now;
 	int sync_it = 0;
-	int ret;
+
+	if (unlikely(file->f_mode & FMODE_NOCMTIME))
+		return 0;
 
 	/* First try to exhaust all avenues to not sync */
 	if (IS_NOCMTIME(inode))
 		return 0;
 
-	now = current_time(inode);
-	if (!timespec64_equal(&inode->i_mtime, &now))
+	if (!timespec64_equal(&inode->i_mtime, now))
 		sync_it = S_MTIME;
 
-	if (!timespec64_equal(&inode->i_ctime, &now))
+	if (!timespec64_equal(&inode->i_ctime, now))
 		sync_it |= S_CTIME;
 
 	if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
@@ -2091,24 +2078,58 @@ int file_update_time(struct file *file)
 	if (!sync_it)
 		return 0;
 
+	return sync_it;
+}
+
+int do_file_update_time(struct inode *inode, struct file *file,
+			struct timespec64 *now, int sync_mode)
+{
+	int ret;
+
 	/* Finally allowed to write? Takes lock. */
 	if (__mnt_want_write_file(file))
 		return 0;
 
-	ret = inode_update_time(inode, &now, sync_it);
+	ret = inode_update_time(inode, now, sync_mode);
 	__mnt_drop_write_file(file);
 
 	return ret;
 }
+
+/**
+ *	file_update_time	-	update mtime and ctime time
+ *	@file: file accessed
+ *
+ *	Update the mtime and ctime members of an inode and mark the inode
+ *	for writeback.  Note that this function is meant exclusively for
+ *	usage in the file write path of filesystems, and filesystems may
+ *	choose to explicitly ignore update via this function with the
+ *	S_NOCMTIME inode flag, e.g. for network filesystem where these
+ *	timestamps are handled by the server.  This can return an error for
+ *	file systems who need to allocate space in order to update an inode.
+ */
+
+int file_update_time(struct file *file)
+{
+	int err;
+	struct inode *inode = file_inode(file);
+	struct timespec64 now = current_time(inode);
+
+	err = need_file_update_time(inode, file, &now);
+	if (err < 0)
+		return err;
+
+	return do_file_update_time(inode, file, &now, err);
+}
 EXPORT_SYMBOL(file_update_time);
 
 /* Caller must hold the file's inode lock */
 int file_modified(struct file *file)
 {
-	int err;
 	int ret;
 	struct dentry *dentry = file_dentry(file);
 	struct inode *inode = file_inode(file);
+	struct timespec64 now = current_time(inode);
 
 	/*
 	 * Clear the security bits if the process is not being run by root.
@@ -2123,10 +2144,11 @@ int file_modified(struct file *file)
 			return ret;
 	}
 
-	if (unlikely(file->f_mode & FMODE_NOCMTIME))
-		return 0;
+	ret = need_file_update_time(inode, file, &now);
+	if (ret <= 0)
+		return ret;
 
-	return file_update_time(file);
+	return do_file_update_time(inode, file, &now, ret);
 }
 EXPORT_SYMBOL(file_modified);
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c2992d12601f..e268a1a50357 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2384,6 +2384,11 @@ static inline void file_accessed(struct file *file)
 extern int need_file_remove_privs(struct inode *inode, struct dentry *dentry);
 extern int do_file_remove_privs(struct file *file, struct inode *inode,
 				struct dentry *dentry, int kill);
+extern int need_file_update_time(struct inode *inode, struct file *file,
+				struct timespec64 *now);
+extern int do_file_update_time(struct inode *inode, struct file *file,
+			struct timespec64 *now, int sync_mode);
+
 extern int file_modified(struct file *file);
 
 int sync_inode_metadata(struct inode *inode, int wait);
-- 
2.30.2