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mm/swap: use swap_ops to register swap device's methods

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This simplifies codes and makes logic clearer.  And also makes later any
new swap device type being added easier to handle.

Currently there are two types of swap devices: fs and bdev.

[hch@lst.de: updated for the new submit and can_merge abstraction]
Link: https://lore.kernel.org/20260713093350.2154226-6-hch@lst.de
Signed-off-by: Baoquan He <baoquan.he@linux.dev>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Youngjun Park <youngjun.park@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Christoph Hellwig 2026-07-13 11:33:42 +02:00 committed by Andrew Morton
parent 4e915b16de
commit 563597895e
4 changed files with 58 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/swap.h
View File

@ -276,6 +276,7 @@ struct swap_info_struct {
struct work_struct reclaim_work; /* reclaim worker */
struct list_head discard_clusters; /* discard clusters list */
struct plist_node avail_list; /* entry in swap_avail_head */
const struct swap_ops *ops;
};
static inline swp_entry_t page_swap_entry(struct page *page)

68
mm/page_io.c
View File

@ -334,21 +334,7 @@ static bool swap_can_merge(struct swap_io_ctx *ctx, struct folio *folio,
if (ctx->sis != sis)
return false;
if (sis->flags & SWP_FS_OPS) {
if (swap_dev_pos(folio->swap) !=
swap_dev_pos(prev_folio->swap) + prev_folio_size)
return false;
} else {
if (swap_folio_sector(folio) !=
swap_folio_sector(prev_folio) +
(prev_folio_size >> SECTOR_SHIFT))
return false;
if (rw == WRITE && !folio_blkg_can_merge(folio, prev_folio))
return false;
}
return true;
return sis->ops->can_merge(folio, prev_folio, prev_folio_size, rw);
}
static void swap_add_folio(struct swap_io_ctx *ctx, struct folio *folio, int rw)
@ -646,6 +632,23 @@ static void swap_bdev_submit_read(struct swap_io_ctx *ctx)
}
}
static bool swap_bdev_can_merge(struct folio *folio, struct folio *prev_folio,
size_t prev_folio_size, int rw)
{
if (swap_folio_sector(folio) !=
swap_folio_sector(prev_folio) + (prev_folio_size >> SECTOR_SHIFT))
return false;
if (rw == WRITE && !folio_blkg_can_merge(folio, prev_folio))
return false;
return true;
}
const struct swap_ops swap_bdev_ops = {
.submit_write = swap_bdev_submit_write,
.submit_read = swap_bdev_submit_read,
.can_merge = swap_bdev_can_merge,
};
static void swap_fs_submit(struct swap_io_ctx *ctx, int rw)
{
struct swap_iocb *sio = ctx->sio;
@ -666,15 +669,34 @@ static void swap_fs_submit(struct swap_io_ctx *ctx, int rw)
sio->iocb.ki_complete(&sio->iocb, ret);
}
static void swap_fs_submit_write(struct swap_io_ctx *ctx)
{
swap_fs_submit(ctx, WRITE);
}
static void swap_fs_submit_read(struct swap_io_ctx *ctx)
{
swap_fs_submit(ctx, READ);
}
static bool swap_fs_can_merge(struct folio *folio, struct folio *prev_folio,
size_t prev_folio_size, int rw)
{
return swap_dev_pos(folio->swap) ==
swap_dev_pos(prev_folio->swap) + prev_folio_size;
}
const struct swap_ops swap_fs_ops = {
.submit_write = swap_fs_submit_write,
.submit_read = swap_fs_submit_read,
.can_merge = swap_fs_can_merge,
};
void swap_write_submit(struct swap_io_ctx *ctx)
{
if (!ctx->sio)
return;
if (ctx->sis->flags & SWP_FS_OPS)
swap_fs_submit(ctx, WRITE);
else
swap_bdev_submit_write(ctx);
ctx->sis->ops->submit_write(ctx);
ctx->sio = NULL;
ctx->sis = NULL;
}
@ -683,11 +705,7 @@ void swap_read_submit(struct swap_io_ctx *ctx)
{
if (!ctx->sio)
return;
if (ctx->sis->flags & SWP_FS_OPS)
swap_fs_submit(ctx, READ);
else
swap_bdev_submit_read(ctx);
ctx->sis->ops->submit_read(ctx);
ctx->sio = NULL;
ctx->sis = NULL;
}

10
mm/swap.h
View File

@ -96,6 +96,13 @@ struct swap_io_ctx {
struct swap_info_struct *sis;
};
struct swap_ops {
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 <linux/swapops.h> /* for swp_offset */
#include <linux/blk_types.h> /* for bio_end_io_t */
@ -483,6 +490,9 @@ static inline unsigned int folio_swap_flags(struct folio *folio)
#endif /* CONFIG_SWAP */
extern const struct swap_ops swap_bdev_ops;
extern const struct swap_ops swap_fs_ops;
int shmem_writeout(struct swap_io_ctx *ctx, struct folio *folio,
struct list_head *folio_list);

4
mm/swapfile.c
View File

@ -2963,6 +2963,8 @@ static int setup_swap_extents(struct swap_info_struct *sis,
if (ret)
return ret;
sis->ops = &swap_bdev_ops;
if (S_ISBLK(inode->i_mode)) {
ret = add_swap_extent(sis, 0, sis->max, 0);
*span = sis->pages;
@ -2973,6 +2975,8 @@ static int setup_swap_extents(struct swap_info_struct *sis,
ret = mapping->a_ops->swap_activate(sis, swap_file, span);
if (ret < 0)
return ret;
if (sis->flags & SWP_FS_OPS)
sis->ops = &swap_fs_ops;
sis->flags |= SWP_ACTIVATED;
return ret;
}