From 695a0d0da09e75c4475bbb303def159023ef72ca Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Fri, 4 Mar 2011 15:46:53 -0500
Subject: [PATCH] Btrfs: add a comment explaining what btrfs_cont_expand does
Everytime I have to deal with btrfs_cont_expand I stare at it for 20 minutes
trying to remember what exactly it does and why the hell we need it. So add a
comment to save future-Josef some time. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
---
fs/btrfs/inode.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 64d57e032b4e5..888dbdb3b128b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3557,6 +3557,12 @@ out:
return ret;
}
+/*
+ * This function puts in dummy file extents for the area we're creating a hole
+ * for. So if we are truncating this file to a larger size we need to insert
+ * these file extents so that btrfs_get_extent will return a EXTENT_MAP_HOLE for
+ * the range between oldsize and size
+ */
int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
{
struct btrfs_trans_handle *trans;
--
2.30.2