On 12/6/12 9:45 AM, Eric Sandeen wrote:
> On 12/4/12 6:11 AM, Forrest Liu wrote:
>> Extent indexes didn't update correctly in ext4_ext_rm_idx, when depth
>> of extent tree is greater than 1.
>
> This is interesting; we had 2 reports of similar corruption on the
> list, I wonder if the application in question was doing hole punching.
> I didn't expect that they were, so TBH I was pretty much ignoring
> the hole-punch cases for parent index updates. Hm. I'll have
> to look into that.
>
> Could you turn your testcase into an xfstest regression test?
Also, please note that I sent an e2fsck patch to try to fix this
problem after the fact; it'd be great if in your testing, you could
also confirm that e2fsck w/ my patch fixes it correctly.
Thanks,
-Eric
> -Eric
>
>> Signed-off-by: Forrest Liu <forrestl@xxxxxxxxxxxx>
>> ---
>> fs/ext4/extents.c | 24 ++++++++++++++++++++----
>> 1 files changed, 20 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>> index d3dd618..b10b8c0 100644
>> --- a/fs/ext4/extents.c
>> +++ b/fs/ext4/extents.c
>> @@ -2190,13 +2190,15 @@ errout:
>> * 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;
>> + __le32 border;
>>
>> /* 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");
>> @@ -2221,6 +2223,20 @@ 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);
>> +
>> + border = path->p_idx->ei_block;
>> + 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 = border;
>> + err = ext4_ext_dirty(handle, inode, path);
>> + if (err)
>> + break;
>> + }
>> return err;
>> }
>>
>> @@ -2557,7 +2573,7 @@ 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;
>> @@ -2760,7 +2776,7 @@ again:
>> /* 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);
>>
>
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