From: Filipe Manana fdmanana@suse.com
commit c2f822635df873c510bda6fb7fd1b10b7c31be2d upstream.
If we extended the size of a swapfile after its header was created (by the mkswap utility) and then try to activate it, we will map the entire file when activating the swap file, instead of limiting to the max size defined in the swap file's header.
Currently test case generic/643 from fstests fails because we do not respect that size limit defined in the swap file's header.
So fix this by not mapping file ranges beyond the max size defined in the swap header.
This is the same type of bug that iomap used to have, and was fixed in commit 36ca7943ac18ae ("mm/swap: consider max pages in iomap_swapfile_add_extent").
Fixes: ed46ff3d423780 ("Btrfs: support swap files") CC: stable@vger.kernel.org # 5.4+ Reviewed-and-tested-by: Josef Bacik <josef@toxicpanda.com Signed-off-by: Filipe Manana fdmanana@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/inode.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
--- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -10595,9 +10595,19 @@ static int btrfs_add_swap_extent(struct struct btrfs_swap_info *bsi) { unsigned long nr_pages; + unsigned long max_pages; u64 first_ppage, first_ppage_reported, next_ppage; int ret;
+ /* + * Our swapfile may have had its size extended after the swap header was + * written. In that case activating the swapfile should not go beyond + * the max size set in the swap header. + */ + if (bsi->nr_pages >= sis->max) + return 0; + + max_pages = sis->max - bsi->nr_pages; first_ppage = ALIGN(bsi->block_start, PAGE_SIZE) >> PAGE_SHIFT; next_ppage = ALIGN_DOWN(bsi->block_start + bsi->block_len, PAGE_SIZE) >> PAGE_SHIFT; @@ -10605,6 +10615,7 @@ static int btrfs_add_swap_extent(struct if (first_ppage >= next_ppage) return 0; nr_pages = next_ppage - first_ppage; + nr_pages = min(nr_pages, max_pages);
first_ppage_reported = first_ppage; if (bsi->start == 0)