From affc5424338682641829cc84293ec90f36425034 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Fri, 16 Sep 2022 15:28:36 +0800 Subject: [PATCH] btrfs: make inline extent read calculation much simpler Currently we calculate inline extent read in a way that inline extent can start at non-zero offset. This is consistent with the inode selftests, which puts an inline extent at file offset 5. Meanwhile the inline extent creation code will only create inline extent at file offset 0. Furthermore with the introduction of tree-checker on file extents, we are actively rejecting inline extent which starts at non-zero file offset. And so far we haven't yet seen any report of rejected inline extents at non-zero file offset. This all means, the extra calculation to support inline extents at non-zero file offset is mostly paper weight, and damaging the readability of the code. Thus this patch will: - Add extra ASSERT()s to make sure involved file offset are all 0 - Remove @extent_offset calculation - Simplify the involved code As several variables are now single-use, no need to declare them as a variable anymore. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/inode.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+), 18 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 9abed40ade11..a374dd718315 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7064,41 +7064,43 @@ next: extent_type == BTRFS_FILE_EXTENT_PREALLOC) { goto insert; } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { - unsigned long ptr; char *map; - size_t size; - size_t extent_offset; size_t copy_size; if (!page) goto out; - size = btrfs_file_extent_ram_bytes(leaf, item); - extent_offset = page_offset(page) + pg_offset - extent_start; - copy_size = min_t(u64, PAGE_SIZE - pg_offset, - size - extent_offset); - em->start = extent_start + extent_offset; + /* + * Inline extent can only exist at file offset 0. This is + * ensured by tree-checker and inline extent creation path. + * Thus all members representing file offsets should be zero. + */ + ASSERT(page_offset(page) == 0); + ASSERT(pg_offset == 0); + ASSERT(extent_start == 0); + ASSERT(em->start == 0); + + copy_size = min_t(u64, PAGE_SIZE, + btrfs_file_extent_ram_bytes(leaf, item)); + em->start = extent_start; em->len = ALIGN(copy_size, fs_info->sectorsize); em->orig_block_len = em->len; em->orig_start = em->start; - ptr = btrfs_file_extent_inline_start(item) + extent_offset; if (!PageUptodate(page)) { if (btrfs_file_extent_compression(leaf, item) != BTRFS_COMPRESS_NONE) { - ret = uncompress_inline(path, page, pg_offset, - extent_offset, item); + ret = uncompress_inline(path, page, 0, 0, item); if (ret) goto out; } else { map = kmap_local_page(page); - read_extent_buffer(leaf, map + pg_offset, ptr, - copy_size); - if (pg_offset + copy_size < PAGE_SIZE) { - memset(map + pg_offset + copy_size, 0, - PAGE_SIZE - pg_offset - - copy_size); - } + read_extent_buffer(leaf, map, + btrfs_file_extent_inline_start(item), + copy_size); + if (copy_size < PAGE_SIZE) + memset(map + copy_size, 0, + PAGE_SIZE - copy_size); kunmap_local(map); } flush_dcache_page(page); -- 2.25.1