On Fri, Dec 18, 2009 at 3:49 AM, Aneesh Kumar K.V
<aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote:
> On Thu, Dec 10, 2009 at 09:28:28AM -0800, Curt Wohlgemuth wrote:
>> This fixes a bug in which new blocks returned from an extent created with
>> ext4_ext_zeroout() can have dirty metadata still associated with them.
>>
>> Signed-off-by: Curt Wohlgemuth <curtw@xxxxxxxxxx>
>> ---
>>
>> This is for the problem I reported on 23 Nov ("Bug in extent zeroout: blocks
>> not marked as new"). I'm not seeing the corruption with this fix that I was
>> seeing without it.
>>
>> diff -uprN orig/fs/ext4/extents.c new/fs/ext4/extents.c
>> --- orig/fs/ext4/extents.c 2009-12-09 15:09:25.000000000 -0800
>> +++ new/fs/ext4/extents.c 2009-12-09 15:09:37.000000000 -0800
>> @@ -2474,9 +2474,21 @@ static int ext4_ext_zeroout(struct inode
>> submit_bio(WRITE, bio);
>> wait_for_completion(&event);
>>
>> - if (test_bit(BIO_UPTODATE, &bio->bi_flags))
>> + /* On success, we need to insure all metadata associated
>> + * with each of these blocks is unmapped. */
>> + if (test_bit(BIO_UPTODATE, &bio->bi_flags)) {
>> + sector_t block = ee_pblock;
>> +
>> ret = 0;
>> - else {
>> + done = 0;
>> + while (done < len) {
>> + unmap_underlying_metadata(inode->i_sb->s_bdev,
>> + block);
>> +
>> + done++;
>> + block++;
>> + }
>> + } else {
>> ret = -EIO;
>> break;
>> }
>
> a) We are zeroing out 'done' blocks but you are unmapping 'len' blocks ?
> b) We are already doing a unmap in mpage_da_map_blocks so i guess
> what you want is to unmap the extra block allocated
> c) ee_pblock is in 512 byte units so the block number is wrong.
>
> how about the patch below ?
Thanks for pointing out the arithmetic problems in my patch. Yours
below looks good to me.
Curt
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 3a7928f..f9a735f 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -3023,6 +3023,14 @@ out:
> return err;
> }
>
> +static void unmap_underlying_metadata_blocks(struct block_device *bdev,
> + sector_t block, int count)
> +{
> + int i;
> + for (i = 0; i < count; i++)
> + unmap_underlying_metadata(bdev, block + i);
> +}
> +
> static int
> ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
> ext4_lblk_t iblock, unsigned int max_blocks,
> @@ -3098,6 +3106,18 @@ out:
> } else
> allocated = ret;
> set_buffer_new(bh_result);
> + /*
> + * if we allocated more blocks than requested
> + * we need to make sure we unmap the extra block
> + * allocated. The actual needed block will get
> + * unmapped later when we find the buffer_head marked
> + * new.
> + */
> + if (allocated > max_blocks) {
> + unmap_underlying_metadata_blocks(inode->i_sb->s_bdev,
> + newblock + max_blocks,
> + allocated - max_blocks);
> + }
> map_out:
> set_buffer_mapped(bh_result);
> out1:
>
>
>
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