[ 3.5.y.z extended stable ] Patch "ext4: fix extent tree corruption caused by hole punch" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    ext4: fix extent tree corruption caused by hole punch

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From fe26eb329d10a90413c585b3007af5a748c2cffe Mon Sep 17 00:00:00 2001
From: Forrest Liu <forrestl at synology.com>
Date: Mon, 17 Dec 2012 09:55:39 -0500
Subject: [PATCH] ext4: fix extent tree corruption caused by hole punch

commit c36575e663e302dbaa4d16b9c72d2c9a913a9aef upstream.

When depth of extent tree is greater than 1, logical start value of
interior node is not correctly updated in ext4_ext_rm_idx.

Signed-off-by: Forrest Liu <forrestl at synology.com>
Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
Reviewed-by: Ashish Sangwan <ashishsangwan2 at gmail.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 fs/ext4/extents.c |   22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 844e11e..8e5dd3b 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2177,13 +2177,14 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
  * removes index from the index block.
  */
 static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
-			struct ext4_ext_path *path)
+			struct ext4_ext_path *path, int depth)
 {
 	int err;
 	ext4_fsblk_t leaf;

 	/* free index block */
-	path--;
+	depth--;
+	path = path + depth;
 	leaf = ext4_idx_pblock(path->p_idx);
 	if (unlikely(path->p_hdr->eh_entries == 0)) {
 		EXT4_ERROR_INODE(inode, "path->p_hdr->eh_entries == 0");
@@ -2208,6 +2209,19 @@ static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,

 	ext4_free_blocks(handle, inode, NULL, leaf, 1,
 			 EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
+
+	while (--depth >= 0) {
+		if (path->p_idx != EXT_FIRST_INDEX(path->p_hdr))
+			break;
+		path--;
+		err = ext4_ext_get_access(handle, inode, path);
+		if (err)
+			break;
+		path->p_idx->ei_block = (path+1)->p_idx->ei_block;
+		err = ext4_ext_dirty(handle, inode, path);
+		if (err)
+			break;
+	}
 	return err;
 }

@@ -2541,7 +2555,7 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
 	/* if this leaf is free, then we should
 	 * remove it from index block above */
 	if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
-		err = ext4_ext_rm_idx(handle, inode, path + depth);
+		err = ext4_ext_rm_idx(handle, inode, path, depth);

 out:
 	return err;
@@ -2742,7 +2756,7 @@ cont:
 				/* index is empty, remove it;
 				 * handle must be already prepared by the
 				 * truncatei_leaf() */
-				err = ext4_ext_rm_idx(handle, inode, path + i);
+				err = ext4_ext_rm_idx(handle, inode, path, i);
 			}
 			/* root level has p_bh == NULL, brelse() eats this */
 			brelse(path[i].p_bh);
--
1.7.9.5