Re: [PATCH RFC] block: enable RWF_DONTCACHE for block devices

[Jens Axboe]

On 2/18/26 2:13 PM, Tal Zussman wrote:
> Block device buffered reads and writes already pass through
> filemap_read() and iomap_file_buffered_write() respectively, both of
> which handle IOCB_DONTCACHE. Enable RWF_DONTCACHE for block device files
> by setting FOP_DONTCACHE in def_blk_fops.
> 
> For CONFIG_BUFFER_HEAD paths, thread the kiocb through
> block_write_begin() so that buffer_head-based I/O can use DONTCACHE
> behavior as well. Callers without a kiocb context (e.g. nilfs2 recovery)
> pass NULL, which preserves the existing behavior.
> 
> This support is useful for databases that operate on raw block devices,
> among other userspace applications.

OOO right now so I'll take a real look when I'm back, but when I
originally did this work, it's not the issue side that's the issue. It's
the pruning done from completion context, and you need to ensure that's
sane context for that (non-irq).

-- 
Jens Axboe