Btrfs: Add code to support file creation time

This patch adds a new member to the 'struct btrfs_inode' structure to hold
the file creation time.
Signed-off-by: Nchandan <chandanrmail@gmail.com>
[refreshed, removed btrfs_inode_otime]
Signed-off-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NChris Mason <clm@fb.com>

fs/btrfs/btrfs_inode.h

@@ -185,6 +185,9 @@ struct btrfs_inode {
 
 	struct btrfs_delayed_node *delayed_node;
 
+	/* File creation time. */
+	struct timespec i_otime;
+
 	struct inode vfs_inode;
 };
 

fs/btrfs/delayed-inode.c

@@ -1769,6 +1769,11 @@ static void fill_stack_inode_item(struct btrfs_trans_handle *trans,
 				     inode->i_ctime.tv_sec);
 	btrfs_set_stack_timespec_nsec(&inode_item->ctime,
 				      inode->i_ctime.tv_nsec);
+
+	btrfs_set_stack_timespec_sec(&inode_item->otime,
+				     BTRFS_I(inode)->i_otime.tv_sec);
+	btrfs_set_stack_timespec_nsec(&inode_item->otime,
+				     BTRFS_I(inode)->i_otime.tv_nsec);
 }
 
 int btrfs_fill_inode(struct inode *inode, u32 *rdev)
@@ -1810,6 +1815,11 @@ int btrfs_fill_inode(struct inode *inode, u32 *rdev)
 	inode->i_ctime.tv_sec = btrfs_stack_timespec_sec(&inode_item->ctime);
 	inode->i_ctime.tv_nsec = btrfs_stack_timespec_nsec(&inode_item->ctime);
 
+	BTRFS_I(inode)->i_otime.tv_sec =
+		btrfs_stack_timespec_sec(&inode_item->otime);
+	BTRFS_I(inode)->i_otime.tv_nsec =
+		btrfs_stack_timespec_nsec(&inode_item->otime);
+
 	inode->i_generation = BTRFS_I(inode)->generation;
 	BTRFS_I(inode)->index_cnt = (u64)-1;
 

fs/btrfs/inode.c

@@ -3535,6 +3535,11 @@ static void btrfs_read_locked_inode(struct inode *inode)
 	inode->i_ctime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->ctime);
 	inode->i_ctime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->ctime);
 
+	BTRFS_I(inode)->i_otime.tv_sec =
+		btrfs_timespec_sec(leaf, &inode_item->otime);
+	BTRFS_I(inode)->i_otime.tv_nsec =
+		btrfs_timespec_nsec(leaf, &inode_item->otime);
+
 	inode_set_bytes(inode, btrfs_inode_nbytes(leaf, inode_item));
 	BTRFS_I(inode)->generation = btrfs_inode_generation(leaf, inode_item);
 	BTRFS_I(inode)->last_trans = btrfs_inode_transid(leaf, inode_item);
@@ -3669,6 +3674,11 @@ static void fill_inode_item(struct btrfs_trans_handle *trans,
 	btrfs_set_token_timespec_nsec(leaf, &item->ctime,
 				      inode->i_ctime.tv_nsec, &token);
 
+	btrfs_set_token_timespec_sec(leaf, &item->otime,
+				     BTRFS_I(inode)->i_otime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->otime,
+				      BTRFS_I(inode)->i_otime.tv_nsec, &token);
+
 	btrfs_set_token_inode_nbytes(leaf, item, inode_get_bytes(inode),
 				     &token);
 	btrfs_set_token_inode_generation(leaf, item, BTRFS_I(inode)->generation,
@@ -5260,7 +5270,10 @@ static struct inode *new_simple_dir(struct super_block *s,
 	inode->i_op = &btrfs_dir_ro_inode_operations;
 	inode->i_fop = &simple_dir_operations;
 	inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;
-	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+	inode->i_mtime = CURRENT_TIME;
+	inode->i_atime = inode->i_mtime;
+	inode->i_ctime = inode->i_mtime;
+	BTRFS_I(inode)->i_otime = inode->i_mtime;
 
 	return inode;
 }
@@ -5828,7 +5841,12 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 
 	inode_init_owner(inode, dir, mode);
 	inode_set_bytes(inode, 0);
-	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+
+	inode->i_mtime = CURRENT_TIME;
+	inode->i_atime = inode->i_mtime;
+	inode->i_ctime = inode->i_mtime;
+	BTRFS_I(inode)->i_otime = inode->i_mtime;
+
 	inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 				  struct btrfs_inode_item);
 	memset_extent_buffer(path->nodes[0], 0, (unsigned long)inode_item,
@@ -8577,6 +8595,9 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
 
 	ei->delayed_node = NULL;
 
+	ei->i_otime.tv_sec = 0;
+	ei->i_otime.tv_nsec = 0;
+
 	inode = &ei->vfs_inode;
 	extent_map_tree_init(&ei->extent_tree);
 	extent_io_tree_init(&ei->io_tree, &inode->i_data);