Re: [PATCH] ntfs: handle a failed size rollback in the write error path

[Hongling Zeng <zhongling0719@126.com>]

在 2026年10月06日 13:53, Hyunchul Lee 写道:
> On Sun, Oct 04, 2026 at 10:48:22AM +0800, Hongling Zeng wrote:
>> ntfs_file_write_iter() extends the data and initialized sizes before
>> it copies the user data and restores them when the write then fails.
>> The restoration is best-effort: both results are discarded, even
>> though the extension is already recorded in the dirty MFT record.
>> When the restoration fails too, the extended sizes reach the disk
>> while the VFS inode keeps reporting the old ones: after a remount the
>> file appears grown again, with an uninitialized tail where the failed
>> write never put any data, and nothing records the failure.
>>
>> Keep both undo results: on failure, set NVolSetErrors(), which the next
>> persistence point persists as VOLUME_IS_DIRTY, and log a message for
>> the errors= policy.
>>
>> Fixes: 9c87959601e8 ("ntfs: update file operations")
>> Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>
>> ---
>>   fs/ntfs/file.c | 29 +++++++++++++++++++++++++++--
>>   1 file changed, 27 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
>> index 3ec82715a588..b5b30e44ac51 100644
>> --- a/fs/ntfs/file.c
>> +++ b/fs/ntfs/file.c
>> @@ -678,14 +678,39 @@ static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>   				&ntfs_iomap_folio_ops, NULL);
>>   out:
>>   	if (ret < 0 && ret != -EIOCBQUEUED) {
>> +		int undo_err = 0;
>> +
>>   		if (ni->initialized_size != old_init_size) {
>> +			int init_err;
>> +
>>   			mutex_lock(&ni->mrec_lock);
>> -			ntfs_attr_set_initialized_size(ni, old_init_size);
>> +			init_err = ntfs_attr_set_initialized_size(ni,
>> +					old_init_size);
> I think the rollback needs to distinguish resident and compressed
> attributes.
> If the data attribute is still resident,
> ntfs_attr_set_initialized_size() always return -EINVAL.
>
Hi  Hyunchul：
you are right, thanks.  The initialized size rollback now skips a
   resident attribute, where the data size rollback restores both coupled
   sizes, and ntfs_attr_truncate() is skipped on a compressed attribute
   with a warning.
>>   			mutex_unlock(&ni->mrec_lock);
>> +			if (init_err && !undo_err)
>> +				undo_err = init_err;
>>   		}
>>   		if (ni->data_size != old_data_size) {
>> +			int data_err;
>> +
>>   			truncate_setsize(vi, old_data_size);
>> -			ntfs_attr_truncate(ni, old_data_size);
>> +			data_err = ntfs_attr_truncate(ni, old_data_size);
> And ntfs_attr_truncate() always return -EOPNOTSUPP for a compressed
> attribute.
>
>> +			if (data_err && !undo_err)
>> +				undo_err = data_err;
>> +		}
>> +		if (undo_err) {
>> +			/*
>> +			 * The extension is recorded in the dirty MFT
>> +			 * record already, so a failed rollback leaves the
>> +			 * new sizes on disk while the VFS inode keeps
>> +			 * reporting the old ones.  Record the error: the
>> +			 * next persistence point persists it as
>> +			 * VOLUME_IS_DIRTY.  Run chkdsk.
>> +			 */
>> +			NVolSetErrors(vol);
>> +			ntfs_error(vi->i_sb,
>> +				   "Failed to roll back the size update: %d",
>> +				   undo_err);
>>   		}
>>   	}
>>   out_lock:
>> -- 
>> 2.25.1
>>