diff options
| -rw-r--r-- | fs/btrfs/relocation.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 9c8cea5cabe4..914d403b4415 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2782,10 +2782,70 @@ static noinline_for_stack int prealloc_file_extent_cluster( u64 num_bytes; int nr; int ret = 0; + u64 i_size = i_size_read(&inode->vfs_inode); u64 prealloc_start = cluster->start - offset; u64 prealloc_end = cluster->end - offset; u64 cur_offset = prealloc_start; + /* + * For subpage case, previous i_size may not be aligned to PAGE_SIZE. + * This means the range [i_size, PAGE_END + 1) is filled with zeros by + * btrfs_do_readpage() call of previously relocated file cluster. + * + * If the current cluster starts in the above range, btrfs_do_readpage() + * will skip the read, and relocate_one_page() will later writeback + * the padding zeros as new data, causing data corruption. + * + * Here we have to manually invalidate the range (i_size, PAGE_END + 1). + */ + if (!IS_ALIGNED(i_size, PAGE_SIZE)) { + struct address_space *mapping = inode->vfs_inode.i_mapping; + struct btrfs_fs_info *fs_info = inode->root->fs_info; + const u32 sectorsize = fs_info->sectorsize; + struct page *page; + + ASSERT(sectorsize < PAGE_SIZE); + ASSERT(IS_ALIGNED(i_size, sectorsize)); + + /* + * Subpage can't handle page with DIRTY but without UPTODATE + * bit as it can lead to the following deadlock: + * + * btrfs_readpage() + * | Page already *locked* + * |- btrfs_lock_and_flush_ordered_range() + * |- btrfs_start_ordered_extent() + * |- extent_write_cache_pages() + * |- lock_page() + * We try to lock the page we already hold. + * + * Here we just writeback the whole data reloc inode, so that + * we will be ensured to have no dirty range in the page, and + * are safe to clear the uptodate bits. + * + * This shouldn't cause too much overhead, as we need to write + * the data back anyway. + */ + ret = filemap_write_and_wait(mapping); + if (ret < 0) + return ret; + + clear_extent_bits(&inode->io_tree, i_size, + round_up(i_size, PAGE_SIZE) - 1, + EXTENT_UPTODATE); + page = find_lock_page(mapping, i_size >> PAGE_SHIFT); + /* + * If page is freed we don't need to do anything then, as we + * will re-read the whole page anyway. + */ + if (page) { + btrfs_subpage_clear_uptodate(fs_info, page, i_size, + round_up(i_size, PAGE_SIZE) - i_size); + unlock_page(page); + put_page(page); + } + } + BUG_ON(cluster->start != cluster->boundary[0]); ret = btrfs_alloc_data_chunk_ondemand(inode, prealloc_end + 1 - prealloc_start); |