commit caf6912f3f4af7232340d500a4a2008f81b93f14 upstream.
Fix block device sector offset calculation for swap page io on top of
blockdevs that provide a rw_page operation and do page-sized io directly
(without the block layer).
Currently swap_page_sector() maps a swap page into a blockdev sector by
obtaining the swap page offset (swap map slot), but ignores the swapfile
starting offset into the blockdev.
In setups where swapfiles are sitting on top of a filesystem, this
results into swapping out activity potentially overwriting filesystem
blocks that fall outside the swapfile region.
[This issue only affects swapfiles on filesystems on top of blockdevs
that implement rw_page ops (brd, zram, btt, pmem), and not on top of any
other block devices, in contrast to the upstream commit fix.]
Fixes: dd6bd0d9c7db ("swap: use bdev_read_page() / bdev_write_page()")
Cc: stable@xxxxxxxxxxxxxxx # 5.10+
Signed-off-by: Anthony Iliopoulos <ailiop@xxxxxxxx>
---
mm/page_io.c | 12 ++++--------
mm/swapfile.c | 2 +-
2 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/mm/page_io.c b/mm/page_io.c
index 433df1263349..1541c0d6ad6e 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -37,7 +37,6 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,
bio->bi_iter.bi_sector = map_swap_page(page, &bdev);
bio_set_dev(bio, bdev);
- bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
bio->bi_end_io = end_io;
bio_add_page(bio, page, thp_size(page), 0);
@@ -273,11 +272,6 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
return ret;
}
-static sector_t swap_page_sector(struct page *page)
-{
- return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
-}
-
static inline void count_swpout_vm_event(struct page *page)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -353,7 +347,8 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
return ret;
}
- ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
+ ret = bdev_write_page(sis->bdev, map_swap_page(page, &sis->bdev),
+ page, wbc);
if (!ret) {
count_swpout_vm_event(page);
return 0;
@@ -412,7 +407,8 @@ int swap_readpage(struct page *page, bool synchronous)
}
if (sis->flags & SWP_SYNCHRONOUS_IO) {
- ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
+ ret = bdev_read_page(sis->bdev, map_swap_page(page, &sis->bdev),
+ page);
if (!ret) {
if (trylock_page(page)) {
swap_slot_free_notify(page);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 16db9d1ebcbf..4adbb2a4a2ad 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2311,7 +2311,7 @@ sector_t map_swap_page(struct page *page, struct block_device **bdev)
{
swp_entry_t entry;
entry.val = page_private(page);
- return map_swap_entry(entry, bdev);
+ return map_swap_entry(entry, bdev) << (PAGE_SHIFT - 9);
}
/*
--
2.30.1
