Re: [PATCH 1/2] btrfs: use proper inclusive end in extent_fiemap()

在 2026/7/28 17:35, Daniel Vacek 写道:
> On Tue, 28 Jul 2026 at 08:46, Qu Wenruo <[email protected]> wrote:
>> The @end parameter for all extent io tree helpers is inclusive, but
>> the call site in extent_fiemap() is passing exclusive end.
>>
>> Fix it to follow the common pattern.
>>
>> Fixes: ac3c0d36a2a2 ("btrfs: make fiemap more efficient and accurate reporting extent sharedness")
>> Signed-off-by: Qu Wenruo <[email protected]>
>> ---
>>   fs/btrfs/fiemap.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/btrfs/fiemap.c b/fs/btrfs/fiemap.c
>> index ba6a360074c0..2f2ae0b76799 100644
>> --- a/fs/btrfs/fiemap.c
>> +++ b/fs/btrfs/fiemap.c
>> @@ -657,7 +657,7 @@ static int extent_fiemap(struct btrfs_inode *inode,
>>
>>   restart:
>>          range_start = round_down(start, sectorsize);
>> -       range_end = round_up(start + len, sectorsize);
>> +       range_end = round_up(start + len, sectorsize) - 1;
>>          prev_extent_end = range_start;
>>
>>          btrfs_lock_extent(&inode->io_tree, range_start, range_end, &cached_state);
>> @@ -710,7 +710,7 @@ static int extent_fiemap(struct btrfs_inode *inode,
>>
>>                  /* We have in implicit hole (NO_HOLES feature enabled). */
>>                  if (prev_extent_end < key.offset) {
>> -                       const u64 hole_end = min(key.offset, range_end) - 1;
>> +                       const u64 hole_end = min(key.offset - 1, range_end);
>>
>>                          ret = fiemap_process_hole(inode, fieinfo, &cache,
>>                                                    &delalloc_cached_state,
>> @@ -812,10 +812,10 @@ static int extent_fiemap(struct btrfs_inode *inode,
>>          if (!stopped && prev_extent_end < range_end) {
>>                  ret = fiemap_process_hole(inode, fieinfo, &cache,
>>                                            &delalloc_cached_state, backref_ctx,
>> -                                         0, 0, 0, prev_extent_end, range_end - 1);
>> +                                         0, 0, 0, prev_extent_end, range_end);
>>                  if (ret < 0)
>>                          goto out_unlock;
>> -               prev_extent_end = range_end;
>> +               prev_extent_end = range_end + 1;
>>          }
>>
>>          if (cache.cached && cache.offset + cache.len >= last_extent_end) {
>> --
>> 2.54.0
> 
> I don't really get why you left out these:
> 
> @@ -680,7 +680,7 @@ static int extent_fiemap(struct btrfs_inode *inode,
>                  goto check_eof_delalloc;
>          }
> 
> -       while (prev_extent_end < range_end) {
> +       while (prev_extent_end <= range_end) {
>                  struct extent_buffer *leaf = path->nodes[0];
>                  struct btrfs_file_extent_item *ei;
>                  struct btrfs_key key;
> @@ -809,13 +809,13 @@ static int extent_fiemap(struct btrfs_inode *inode,
>          }
> 
>   check_eof_delalloc:
> -       if (!stopped && prev_extent_end < range_end) {
> +       if (!stopped && prev_extent_end <= range_end) {
>                  ret = fiemap_process_hole(inode, fieinfo, &cache,
>                                            &delalloc_cached_state, backref_ctx,
> 
> Am I missing something?

Because we won't reach the == case at all.

The start is always increased by a value aligned to sectorsize.

For inclusive range_end, we either completely pass it by 1, or smaller 
than it.

So that "==" will never be hit.>
> --nX