Re: [PATCH v8 06/19] block, fs: Propagate write hints to the block device inode

Kanchan Joshi
2024-01-23T12:17:06Z

On 1/23/2024 1:39 AM, Bart Van Assche wrote:
> On 1/22/24 01:31, Kanchan Joshi wrote:
>> On 1/19/2024 7:26 PM, Kanchan Joshi wrote:
>>> On 1/19/2024 12:24 AM, Bart Van Assche wrote:
>>>> I think the above proposal would introduce a bug: it would break the
>>>> F_GET_RW_HINT implementation.
>>>
>>> Right. I expected to keep the exact change in GET, too, but that will
>>> not be free from the side-effect.
>>> The buffered-write path (block_write_full_page) picks the hint from one
>>> inode, and the direct-write path (__blkdev_direct_IO_simple) picks the
>>> hint from a different inode.
>>> So, updating both seems needed here.
>>
>> I stand corrected. It's possible to do away with two updates.
>> The direct-io code (patch 8) should rather be changed to pick the hint
>> from bdev inode (and not from file inode).
>> With that change, this patch only need to set the hint into only one
>> inode (bdev one). What do you think?
>
> I think that would break direct I/O submitted by a filesystem.
>

By breakage do you mean not being able to set/get the hint correctly?
I tested with XFS and Ext4 direct I/O. No breakage.