On 2024/10/17 16:09, Barry Song wrote:
On Thu, Oct 17, 2024 at 9:00 PM Gao Xiang <[email protected]> wrote:
On 2024/10/17 15:58, Gao Xiang wrote:
Hi Barry,
On 2024/10/17 15:43, Barry Song wrote:
From: Barry Song <[email protected]>
When a folio has never been zero-filled, mark it as mappedtodisk
to allow other software components to recognize and utilize the
flag.
Signed-off-by: Barry Song <[email protected]>
Thanks for this!
It looks good to me as an improvement as long as PG_mappedtodisk
is long-term lived and useful to users.
Reviewed-by: Gao Xiang <[email protected]>
thanks!
BTW, I wonder if iomap supports this since uncompressed EROFS
relies on iomap paths...
In the core layer, I only see fs/buffer.c's block_read_full_folio()
and fs/mpage.c's mpage_readahead() and mpage_readahead()
supporting this. I haven't found any code in iomap that sets the
flag.
I guess erofs doesn't call the above functions for non-compressed
files?
mpage are obsoleted interfaces (of course EROFS could use
them instead, see my backport to centos 7 [1]), and iomap
is used for recent unencoded I/O use cases.
It would be better to add support for iomap too, but I guess
PG_mappedtodisk has very few users in the upstream kernel,
so they might ask for further use cases tho ;-)
Thanks,
Gao Xiang
[1] https://github.com/erofs/kmod-erofs/blob/main/src/data.c#L249
Thanks,
Gao Xiang
Barry
