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[PATCH 1/2] ext4: Fix block zeroing when punching holes in indirect bloc

To: linux-fsdevel@xxxxxxxxxxxxxxx
Subject: [PATCH 1/2] ext4: Fix block zeroing when punching holes in indirect block files
From: Jan Kara <jack@xxxxxxx>
Date: Fri, 10 Oct 2014 16:23:15 +0200
Cc: linux-ext4@xxxxxxxxxxxxxxx, Dave Chinner <david@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, cluster-devel@xxxxxxxxxx, Steven Whitehouse <swhiteho@xxxxxxxxxx>, Mark Fasheh <mfasheh@xxxxxxxx>, Joel Becker <jlbec@xxxxxxxxxxxx>, ocfs2-devel@xxxxxxxxxxxxxx, reiserfs-devel@xxxxxxxxxxxxxxx, Jeff Mahoney <jeffm@xxxxxxx>, Dave Kleikamp <shaggy@xxxxxxxxxx>, jfs-discussion@xxxxxxxxxxxxxxxxxxxxx, tytso@xxxxxxx, viro@xxxxxxxxxxxxxxxxxx, Jan Kara <jack@xxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1412951028-4085-1-git-send-email-jack@xxxxxxx>
References: <1412951028-4085-1-git-send-email-jack@xxxxxxx>
free_holes_block() passed local variable as a block pointer
to ext4_clear_blocks(). Thus ext4_clear_blocks() zeroed out this local
variable instead of proper place in inode / indirect block. We later
zero out proper place in inode / indirect block but don't dirty the
inode / buffer again which can lead to subtle issues (some changes e.g.
to inode can be lost).

Signed-off-by: Jan Kara <jack@xxxxxxx>
 fs/ext4/indirect.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 8a57e9fcd1b9..9d381707a6fc 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -1329,8 +1329,8 @@ static int free_hole_blocks(handle_t *handle, struct 
inode *inode,
                if (level == 0 ||
                    (bh && all_zeroes((__le32 *)bh->b_data,
                                      (__le32 *)bh->b_data + addr_per_block))) {
-                       ext4_free_data(handle, inode, parent_bh, &blk, &blk+1);
-                       *i_data = 0;
+                       ext4_free_data(handle, inode, parent_bh,
+                                      i_data, i_data + 1);
                bh = NULL;

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