Re: [PATCH] iomap: submit read bio after each extent

[Gao Xiang <hsiangkao@linux.alibaba.com>]

On 2026/6/19 13:00, Christoph Hellwig wrote:
> Currently the iomap buffered read path tries to build up read context
> (i.e. bios for the typical block based case) over multiple iomaps as
> long as the sector matches.  This does not take into account files
> that can map to multiple different devices.  While this could be fixed
> by a bdev check in iomap_bio_read_folio_range, the building up of I/O
> over iomaps actually was a problem for the not yet merged ext2 iomap
> port, as that does want to send out I/O at the end of an indirect
> block mapped range.
> 
> So instead of adding more checks move over to a model where a bio
> only spans a single iomap.  File systems can still create iomap
> that span more than an extent if they want to build larger I/O.
> 
> Reported-by: Kelu Ye <yekelu1@huawei.com>
> Reported-by: Yifan Zhao <zhaoyifan28@huawei.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Thanks,
Gao Xiang