Re: [PATCH 0/1] fsmonitor: skip sanity check if the index is split
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Nov 13, 2019, 01:30 UTC
- Message-ID
- <xmqqzhh0d0ma.fsf@gitster-ct.c.googlers.com>
- In-Reply-To
- <BN6PR21MB07869E8D1DCAF189C4E472A891740@BN6PR21MB0786.namprd21.prod.outlook.com>
Kevin Willford <Kevin.Willford@microsoft.com> writes:
Show 5 quoted lines
> I agree. The only 2 places that excluding the split-index make sense are in > read_fsmonitor_extension and write_fsmonitor_extension because the > index_state that is being passing into those methods could be the delta index > in which case the number of entries for the fsmonitor bitmap would almost > always be more and cause the BUG to be hit which it should not be.
Thanks. Here is what I came up with to tie the loose ends of this thread.
-- >8 -- From: Junio C Hamano <gitster@pobox.com> Subject: [PATCH] fsmonitor: do not compare bitmap size with size of split index
3444ec2e ("fsmonitor: don't fill bitmap with entries to be removed", 2019-10-11) added a handful of sanity checks that make sure that a bit position in fsmonitor bitmap does not go beyond the end of the index. As each bit in the bitmap corresponds to a path in the index, this is the right check most of the time.
Except for the case when we are in the split-index mode and looking at a delta index that is to be overlayed on the base index but before the base index has actually been merged in, namely in read_ and write_fsmonitor_extension(). In these codepaths, the entries in the split/delta index is typically a small subset of the entire set of paths (otherwise why would we be using split-index?), so the bitmap used by the fsmonitor is almost always larger than the number of entries in the partial index, and the incorrect comparison would trigger the BUG().
Reported-by: Utsav Shah <ukshah2@illinois.edu> Helped-by: Kevin Willford <Kevin.Willford@microsoft.com> Helped-by: William Baker <William.Baker@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> --- fsmonitor.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fsmonitor.c b/fsmonitor.c index 1f4aa1b150..0477500b39 100644 --- a/fsmonitor.c +++ b/fsmonitor.c @@ -55,7 +55,8 @@ int read_fsmonitor_extension(struct index_state *istate, const void *data, } istate->fsmonitor_dirty = fsmonitor_dirty; - if (istate->fsmonitor_dirty->bit_size > istate->cache_nr) + if (!istate->split_index && + istate->fsmonitor_dirty->bit_size > istate->cache_nr) BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)", (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr); @@ -83,7 +84,8 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate) uint32_t ewah_size = 0; int fixup = 0; - if (istate->fsmonitor_dirty->bit_size > istate->cache_nr) + if (!istate->split_index && + istate->fsmonitor_dirty->bit_size > istate->cache_nr) BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)", (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
-- 2.24.0-346-gee0de6d492