[PATCH 10/26] netfs: Bulk load the readahead-provided folios up front

[Paulo Alcantara]

David Howells <dhowells at redhat.com> writes:

> Load all the folios by the VM for readahead up front into the folio queue.
> With the number of folios provided by the VM, the folio queue can be fully
> allocated first and then the loading happen in one go inside the RCU read
> lock.  The folio refs acquired from readahead are dropped in bulk once the
> first subrequest is dispatched as it's quite a slow operation.
>
> This simplifies the buffer handling later and isn't noticeably slower as
> the xarray doesn't need to be modified and the folios are all already
> pre-locked.
>
> Signed-off-by: David Howells <dhowells at redhat.com>
> cc: Paulo Alcantara <pc at manguebit.org>
> cc: Matthew Wilcox <willy at infradead.org>
> cc: netfs at lists.linux.dev
> cc: linux-mm at kvack.org
> cc: linux-fsdevel at vger.kernel.org
> ---
>  fs/netfs/buffered_read.c       | 95 +++++++++++++++++++++-------------
>  fs/netfs/rolling_buffer.c      | 75 +++++++++++++++++++++++++++
>  include/linux/netfs.h          |  1 +
>  include/linux/rolling_buffer.h |  3 ++
>  include/trace/events/netfs.h   |  1 +
>  5 files changed, 138 insertions(+), 37 deletions(-)

Reviewed-by: Paulo Alcantara (Red Hat) <pc at manguebit.org>