fs: new accessor methods for atime and mtime

Recently, we converted the ctime accesses in the kernel to use new
accessor functions. Linus recently pointed out though that if we add
accessors for the atime and mtime, then that would allow us to
seamlessly change how these timestamps are stored in the inode.

Add new accessor functions for the atime and mtime that mirror the
accessors for the ctime.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20231004185239.80830-1-jlayton@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 30 insertions, 11 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index 37f2d34ee090..abe2b5a40ba1 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -541,7 +541,8 @@ void simple_recursive_removal(struct dentry *dentry,
 				dput(victim);		// unpin it
 			}
 			if (victim == dentry) {
-				inode->i_mtime = inode_set_ctime_current(inode);
+				inode_set_mtime_to_ts(inode,
+						      inode_set_ctime_current(inode));
 				if (d_is_dir(dentry))
 					drop_nlink(inode);
 				inode_unlock(inode);
@@ -582,7 +583,7 @@ static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
 	 */
 	root->i_ino = 1;
 	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
-	root->i_atime = root->i_mtime = inode_set_ctime_current(root);
+	simple_inode_init_ts(root);
 	s->s_root = d_make_root(root);
 	if (!s->s_root)
 		return -ENOMEM;
@@ -638,8 +639,8 @@ int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *den
 {
 	struct inode *inode = d_inode(old_dentry);
 
-	dir->i_mtime = inode_set_ctime_to_ts(dir,
-					     inode_set_ctime_current(inode));
+	inode_set_mtime_to_ts(dir,
+			      inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
 	inc_nlink(inode);
 	ihold(inode);
 	dget(dentry);
@@ -673,8 +674,8 @@ int simple_unlink(struct inode *dir, struct dentry *dentry)
 {
 	struct inode *inode = d_inode(dentry);
 
-	dir->i_mtime = inode_set_ctime_to_ts(dir,
-					     inode_set_ctime_current(inode));
+	inode_set_mtime_to_ts(dir,
+			      inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
 	drop_nlink(inode);
 	dput(dentry);
 	return 0;
@@ -709,9 +710,10 @@ void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry,
 {
 	struct inode *newino = d_inode(new_dentry);
 
-	old_dir->i_mtime = inode_set_ctime_current(old_dir);
+	inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir));
 	if (new_dir != old_dir)
-		new_dir->i_mtime = inode_set_ctime_current(new_dir);
+		inode_set_mtime_to_ts(new_dir,
+				      inode_set_ctime_current(new_dir));
 	inode_set_ctime_current(d_inode(old_dentry));
 	if (newino)
 		inode_set_ctime_current(newino);
@@ -926,7 +928,7 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
 	 */
 	inode->i_ino = 1;
 	inode->i_mode = S_IFDIR | 0755;
-	inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
+	simple_inode_init_ts(inode);
 	inode->i_op = &simple_dir_inode_operations;
 	inode->i_fop = &simple_dir_operations;
 	set_nlink(inode, 2);
@@ -952,7 +954,7 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
 			goto out;
 		}
 		inode->i_mode = S_IFREG | files->mode;
-		inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
+		simple_inode_init_ts(inode);
 		inode->i_fop = files->ops;
 		inode->i_ino = i;
 		d_add(dentry, inode);
@@ -1520,7 +1522,7 @@ struct inode *alloc_anon_inode(struct super_block *s)
 	inode->i_uid = current_fsuid();
 	inode->i_gid = current_fsgid();
 	inode->i_flags |= S_PRIVATE;
-	inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
+	simple_inode_init_ts(inode);
 	return inode;
 }
 EXPORT_SYMBOL(alloc_anon_inode);
@@ -1912,3 +1914,20 @@ ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter,
 	return direct_written + buffered_written;
 }
 EXPORT_SYMBOL_GPL(direct_write_fallback);
+
+/**
+ * simple_inode_init_ts - initialize the timestamps for a new inode
+ * @inode: inode to be initialized
+ *
+ * When a new inode is created, most filesystems set the timestamps to the
+ * current time. Add a helper to do this.
+ */
+struct timespec64 simple_inode_init_ts(struct inode *inode)
+{
+	struct timespec64 ts = inode_set_ctime_current(inode);
+
+	inode_set_atime_to_ts(inode, ts);
+	inode_set_mtime_to_ts(inode, ts);
+	return ts;
+}
+EXPORT_SYMBOL(simple_inode_init_ts);