[PATCH] Don't update unchanged merge entries
- From
Linus Torvalds <torvalds@linux-foundation.org>
- Date
- Mar 16, 2008, 18:42 UTC
- Message-ID
- <alpine.LFD.1.00.0803161136060.3020@woody.linux-foundation.org>
- In-Reply-To
- <alpine.LFD.1.00.0803161123260.3020@woody.linux-foundation.org>
In commit 34110cd4e394e3f92c01a4709689b384c34645d8 ("Make 'unpack_trees()' have a separate source and destination index") I introduced a really stupid bug in that it would always add merged entries with the CE_UPDATE flag set. That caused us to always re-write the file, even when it was already up-to-date in the source index.
Not only is that really stupid from a performance angle, but more importantly it's actively wrong: if we have dirty state in the tree when we merge, overwriting it with the result of the merge will incorrectly overwrite that dirty state.
This trivially fixes the problem - simply don't set the CE_UPDATE flag when the merge result matches the old state.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> ---
Ok, that was a really stupid one.
On Sun, 16 Mar 2008, Linus Torvalds wrote:
Show 8 quoted lines
> > Nope, I bisected it down to > > 34110cd4e394e3f92c01a4709689b384c34645d8 is first bad commit > > Make 'unpack_trees()' have a separate source and destination index > > and I'm trying to figure out what part of that triggered this bug.
unpack-trees.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/unpack-trees.c b/unpack-trees.c index 0cdf198..46d4f6c 100644 --- a/unpack-trees.c +++ b/unpack-trees.c @@ -593,6 +593,8 @@ static int verify_absent(struct cache_entry *ce, const char *action, static int merged_entry(struct cache_entry *merge, struct cache_entry *old, struct unpack_trees_options *o) { + int update = CE_UPDATE; + if (old) { /* * See if we can re-use the old CE directly? @@ -603,6 +605,7 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old, */ if (same(old, merge)) { copy_cache_entry(merge, old); + update = 0; } else { if (verify_uptodate(old, o)) return -1; @@ -615,7 +618,7 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old, invalidate_ce_path(merge, o); } - add_entry(o, merge, CE_UPDATE, CE_STAGEMASK); + add_entry(o, merge, update, CE_STAGEMASK); return 1; }