From 1aaac38c83a23cd31df551b3f84d3c7f5067a7fe Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Wed, 2 Dec 2020 14:48:02 +0800 Subject: btrfs: don't allow tree block to cross page boundary for subpage support As a preparation for subpage sector size support (allowing filesystem with sector size smaller than page size to be mounted) if the sector size is smaller than page size, we don't allow tree block to be read if it crosses 64K(*) boundary. The 64K is selected because: - we are only going to support 64K page size for subpage for now - 64K is also the maximum supported node size This ensures that tree blocks are always contained in one page for a system with 64K page size, which can greatly simplify the handling. Otherwise we would have to do complex multi-page handling of tree blocks. Currently there is no way to create such tree blocks. In kernel we have avoided such tree blocks allocation even on 4K page size, as it can lead to RAID56 stripe scrubbing. While btrfs-progs have fixed its chunk allocator since 2016 for convert, and has extra checks to do the same behavior as the kernel. Just add such graceful checks in case of an ancient filesystem. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_io.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'fs/btrfs') diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 86b2a483c1ab..76e0b5ed75dd 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5273,6 +5273,14 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, return ERR_PTR(-EINVAL); } + if (fs_info->sectorsize < PAGE_SIZE && + offset_in_page(start) + len > PAGE_SIZE) { + btrfs_err(fs_info, + "tree block crosses page boundary, start %llu nodesize %lu", + start, len); + return ERR_PTR(-EINVAL); + } + eb = find_extent_buffer(fs_info, start); if (eb) return eb; -- cgit v1.2.3-59-g8ed1b