On 2019/11/11 下午5:49, Su Yue wrote: > > > On 2019/11/11 5:28 PM, Qu Wenruo wrote: >> >> >> On 2019/11/11 下午4:42, damenly.su@xxxxxxxxx wrote: >>> From: Su Yue <Damenly_Su@xxxxxxx> >>> >>> The progs side function btrfs_lookup_first_block_group() calls >>> find_first_extent_bit() to find block group which contains bytenr >>> or after the bytenr. This behavior differs from kernel code, so >>> add the comments. >>> >>> Add the coments of btrfs_lookup_block_group() too, this one works >>> like kernel side. >>> >>> Signed-off-by: Su Yue <Damenly_Su@xxxxxxx> >>> --- >>> extent-tree.c | 6 ++++++ >>> 1 file changed, 6 insertions(+) >>> >>> diff --git a/extent-tree.c b/extent-tree.c >>> index d67e4098351f..f690ae999f37 100644 >>> --- a/extent-tree.c >>> +++ b/extent-tree.c >>> @@ -164,6 +164,9 @@ err: >>> return 0; >>> } >>> >>> +/* >>> + * Return the block group that contains or after bytenr >>> + */ >> >> What about "Return the block group thart starts at or after @bytenr" ? >> > > That's what documented in kernel already. > The thing I try to express is "contains". > For such a block group marked as B[n, m). > btrfs_lookup_first_block_group(x) (x > n && x < m). Kernel code will > return the block group next to B. However, progs side will return the > block group B. "Contains" indeed covers your example. But the "after @bytenr" part looks strange to me. Did you mean if @bytenr is not covered by any block group, then the next block group starts after @bytenr is returned? Then the comment is good. Thanks, Qu > > Thanks. >> Thanks, >> Qu >> >>> struct btrfs_block_group_cache *btrfs_lookup_first_block_group(struct >>> btrfs_fs_info *info, >>> u64 bytenr) >>> @@ -193,6 +196,9 @@ struct btrfs_block_group_cache >>> *btrfs_lookup_first_block_group(struct >>> return block_group; >>> } >>> >>> +/* >>> + * Return the block group that contains the given bytenr >>> + */ >>> struct btrfs_block_group_cache *btrfs_lookup_block_group(struct >>> btrfs_fs_info *info, >>> u64 bytenr) >>> >>
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