2012/12/4 forrest <forrestl@xxxxxxxxxxxx>:
> This problem is easily to reproduce
>
> Create a file with size larger than 1GB.
>
> dd if=/dev/zero of=/test_file bs=1M count=1024
>
> Punch every even block in test_file, and then use debugfs to dump
> extents, followings is dumped result
>
> 2/ 2 339/340 231197 - 231197 3917597 - 3917597 1
> 2/ 2 340/340 231199 - 231199 3917599 - 3917599 1
> 0/ 2 2/ 2 231201 - 262143 3901486 30943
> 1/ 2 1/ 46 231201 - 231880 3901488 680
> 2/ 2 1/340 231201 - 231201 3917601 - 3917601 1
> 2/ 2 2/340 231203 - 231203 3917603 - 3917603 1
>
> Punch blocks #231779 ~#231201 , to remove extent index, and then use
> debugfs to dump extents, followings is dumped result
>
> 2/ 2 340/340 231199 - 231199 3917599 - 3917599 1
> 0/ 2 2/ 2 231201 - 262143 3901486 30943
> -------> logical block index didn't update when remove extent index
> 1/ 2 1/ 45 231881 - 232560 3901490 680
> 2/ 2 1/340 231881 - 231881 3918281 - 3918281 1
> 2/ 2 2/340 231883 - 231883 3918283 - 3918283 1
After blocks #231202~#231880 had been punch out, theses blocks can't map again.
If we do map a block in #231202~#231880, we will get error messages
like followings.
EXT4-fs error (device md2): ext4_ext_search_left:1239: inode #13: comm
flush-9:2: ix (231201) != EXT_FIRST_INDEX (1) (depth 0)!
EXT4-fs (md2): delayed block allocation failed for inode 13 at logical
offset 231203 with max blocks 1 with error -5
EXT4-fs (md2): This should not happen!! Data will be lost
Regards,
Forrest
>
> 2012/12/4 Forrest Liu <forrestl@xxxxxxxxxxxx>:
>> Extent indexes didn't update correctly in ext4_ext_rm_idx, when depth
>> of extent tree is greater than 1.
>>
>> 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);
>> --
>> 1.7.5.4
>>
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