From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C8C8F37DAA6 for ; Wed, 22 Jul 2026 16:32:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784737948; cv=none; b=PuZ3ckKUeQ+8qhcXZEygGZJduQIT5cn28x8Mkoi+c04ycs4KeNF0mToTL9VYYH+bDFDgNWoq7CgpuOGrhvIdkPy8dssRsnplp6qc+ABHirepcHNlXvwVwI9/s+hLTNcf6w5KgM14+9x1DJzBc++lar2gCChVFaqWLka7cWW4lRM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784737948; c=relaxed/simple; bh=+Xs4Rj1CmAXrmze4cIJbNyszF+UOlvCrEcOhbbh12ag=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=i1zjzKKMSFWZal9RlSCRf/3+ytpfShYYHdTf6fFXjfM273xsUQikjZDqQ7RoR7EP5tDIO+QRn3ZzHnzSN02SyjmkT0MjWfBFQvuiRKYd2rOQ1tS38rWm3V7io9SgQMfHIR+AnEGzBGE2N71L7XABRnLes3YveYwtuYZF9tLLi8Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=b0Rt1yNk; arc=none smtp.client-ip=91.218.175.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="b0Rt1yNk" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784737944; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bBnIrrxiyHbn5CbW2/3RvfkB4lrliRmpnHXHN4bKIgA=; b=b0Rt1yNkrfg4I8fIySJ7tAmqfRb/Rv7DlSybC9R/Cxce9tKHq48cy7/r/AoabRFRXbmLoS GTnqjiTkp4wrI86UX+LsR+yLWAl3mRARIY31Dz4xpRbhC9PecgUBRKwJScz9DmdsKW4gq/ l8Jv5MWPPRaQw8rpGnXT4vA8GhYeRgE= From: Usama Arif To: Christoph Hellwig Cc: Usama Arif , baoquan.he@linux.dev, akpm@linux-foundation.org, chrisl@kernel.org, kasong@tencent.com, nphamcs@gmail.com, shikemeng@huaweicloud.com, youngjun.park@lge.com, ryncsn@gmail.com, trondmy@kernel.org, anna@kernel.org, sfrench@samba.org, linux-mm@kvack.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org Subject: Re: [PATCH 2/3] mm/swap: add a new swap_ops.h header to allow for pluggable swap ops Date: Wed, 22 Jul 2026 09:32:17 -0700 Message-ID: <20260722163218.1240273-1-usama.arif@linux.dev> In-Reply-To: <20260722130615.3163560-3-hch@lst.de> References: Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On Wed, 22 Jul 2026 15:06:08 +0200 Christoph Hellwig wrote: > Add a new header to declare the swap_iocb, swap_ops and swap_ctx to > allow for swap_ops implementations outside of mm/page_io.c. This > will be used to remove the double indirection for file system-based > swap. > > Note that there already is a swapops.h header, which is totally > unrelated to struct swap_ops. The close naming is a bit unfortunate, > but I could not think of a better name for this header. > > Signed-off-by: Christoph Hellwig > --- > MAINTAINERS | 1 + > include/linux/swap_ops.h | 39 +++++++++++++++++++++++++++++++++++++++ > mm/madvise.c | 1 + > mm/page_io.c | 10 +--------- > mm/shmem.c | 1 + > mm/swap.h | 23 +---------------------- > mm/swap_state.c | 1 + > mm/vmscan.c | 1 + > 8 files changed, 46 insertions(+), 31 deletions(-) > create mode 100644 include/linux/swap_ops.h > > diff --git a/MAINTAINERS b/MAINTAINERS > index 5da77924c6f0..cda42b7ed945 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -17240,6 +17240,7 @@ S: Maintained > F: Documentation/ABI/testing/sysfs-kernel-mm-swap > F: Documentation/mm/swap-table.rst > F: include/linux/swap.h > +F: include/linux/swap_ops.h > F: include/linux/swapfile.h > F: include/linux/swapops.h > F: mm/page_io.c > diff --git a/include/linux/swap_ops.h b/include/linux/swap_ops.h > new file mode 100644 > index 000000000000..e92b4f532604 > --- /dev/null > +++ b/include/linux/swap_ops.h > @@ -0,0 +1,39 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef _MM_SWAP_OPS_H > +#define _MM_SWAP_OPS_H > + > +#include /* for SWAP_CLUSTER_MAX */ > + > +struct swap_iocb { > + union { > + struct kiocb iocb; > + struct bio bio; > + }; > + struct bio_vec bvecs[SWAP_CLUSTER_MAX]; > + int nr_bvecs; > + int len; > +}; > + > +struct swap_io_ctx { > + struct swap_iocb *sio; > + struct swap_info_struct *sis; > +}; zswap uses this struct, I think you need to include the header in zswap.c as well, good to check if the build is passing with CONFIG_ZSWAP=y > + > +/* > + * SWAP_OPS_F_REQUIRE_NOFS: > + * When set, all reclaim operations must operated as GFS_NOFS and not > + * just GFP_NOIO, as GFP_NOIO allocations could recourse into the > + * file system backing this swap file. > + */ > +#define SWAP_OPS_F_REQUIRE_NOFS (1U << 0) > + > +struct swap_ops { > + unsigned int flags; > + > + bool (*can_merge)(struct folio *folio, struct folio *prev_folio, > + size_t prev_folio_size, int rw); > + void (*submit_write)(struct swap_io_ctx *ctx); > + void (*submit_read)(struct swap_io_ctx *ctx); > +}; > + > +#endif /* _MM_SWAP_OPS_H */ > diff --git a/mm/madvise.c b/mm/madvise.c > index 07a21ca31bad..c179938097bf 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > > #include > > diff --git a/mm/page_io.c b/mm/page_io.c > index c984a4023a65..e741e67d6592 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -25,6 +25,7 @@ > #include > #include > #include > +#include > #include "swap.h" > #include "swap_table.h" > > @@ -300,15 +301,6 @@ static bool folio_blkg_can_merge(struct folio *folio, struct folio *prev_folio) > #define bio_associate_blkg_from_page(bio, folio) do { } while (0) > #endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */ > > -struct swap_iocb { > - union { > - struct kiocb iocb; > - struct bio bio; > - }; > - struct bio_vec bvecs[SWAP_CLUSTER_MAX]; > - int nr_bvecs; > - int len; > -}; > static mempool_t *sio_pool; > > int sio_pool_init(void) > diff --git a/mm/shmem.c b/mm/shmem.c > index 5071177059a9..797c42f024a0 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -41,6 +41,7 @@ > #include > #include > #include > +#include > #include "swap.h" > > static struct vfsmount *shm_mnt __ro_after_init; > diff --git a/mm/swap.h b/mm/swap.h > index abd26588abd2..19ea61c97df2 100644 > --- a/mm/swap.h > +++ b/mm/swap.h > @@ -8,6 +8,7 @@ > struct mempolicy; > struct swap_iocb; > struct swap_memcg_table; > +struct swap_io_ctx; > > #if defined(MAX_POSSIBLE_PHYSMEM_BITS) > #define SWAP_CACHE_PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) > @@ -77,28 +78,6 @@ enum swap_cluster_flags { > CLUSTER_FLAG_MAX, > }; > > -struct swap_io_ctx { > - struct swap_iocb *sio; > - struct swap_info_struct *sis; > -}; > - > -/* > - * SWAP_OPS_F_REQUIRE_NOFS: > - * When set, all reclaim operations must operated as GFS_NOFS and not > - * just GFP_NOIO, as GFP_NOIO allocations could recourse into the > - * file system backing this swap file. > - */ > -#define SWAP_OPS_F_REQUIRE_NOFS (1U << 0) > - > -struct swap_ops { > - unsigned int flags; > - > - bool (*can_merge)(struct folio *folio, struct folio *prev_folio, > - size_t prev_folio_size, int rw); > - void (*submit_write)(struct swap_io_ctx *ctx); > - void (*submit_read)(struct swap_io_ctx *ctx); > -}; > - > #ifdef CONFIG_SWAP > #include /* for swp_offset */ > #include /* for bio_end_io_t */ > diff --git a/mm/swap_state.c b/mm/swap_state.c > index 5be825911e64..b76eb3d876fd 100644 > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > #include "internal.h" > #include "swap_table.h" > #include "swap.h" > diff --git a/mm/vmscan.c b/mm/vmscan.c > index e26c6931f5fd..a12eb79c89c5 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -58,6 +58,7 @@ > #include > #include > #include > +#include > > #include > #include > -- > 2.53.0 > >