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[3/4] fsmonitor: avoid overriding `cache_changed` bits

Message ID c1c35f0f026993c493eaae3cf643b25c339205c4.1679500859.git.gitgitgadget@gmail.com (mailing list archive)
State Accepted
Commit be6b65b91bb48c9399c8a6a358dd29b198f2bd79
Headers show
Series Fix a few split-index bugs | expand

Commit Message

Johannes Schindelin March 22, 2023, 4 p.m. UTC 
From: Johannes Schindelin <johannes.schindelin@gmx.de>

As of e636a7b4d030 (read-cache: be specific what part of the index has
changed, 2014-06-13), the paradigm `cache_changed = 1` fell out of
fashion and it became a bit field instead.

This is important because some bits have specific meaning and should not
be unset without care, e.g. `SPLIT_INDEX_ORDERED`.

However, b5a816975206 (mark_fsmonitor_valid(): mark the index as changed
if needed, 2019-05-24) did use the `cache_changed` attribute as if it
were a Boolean instead of a bit field.

That not only would override the `SPLIT_INDEX_ORDERED` bit when marking
index entries as valid via the FSMonitor, but worse: it would set the
`SOMETHING_OTHER` bit (whose value is 1). This means that Git would
unnecessarily force a full index to be written out when a split index
was asked for.

Let's instead use the bit that is specifically intended to indicate
FSMonitor-triggered changes, allowing the split-index feature to work as
designed.

Noticed-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 fsmonitor.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/fsmonitor.h b/fsmonitor.h
index edf7ce5203b..778707b131b 100644
--- a/fsmonitor.h
+++ b/fsmonitor.h
@@ -86,7 +86,7 @@  static inline void mark_fsmonitor_valid(struct index_state *istate, struct cache
 	    !(ce->ce_flags & CE_FSMONITOR_VALID)) {
 		if (S_ISGITLINK(ce->ce_mode))
 			return;
-		istate->cache_changed = 1;
+		istate->cache_changed |= FSMONITOR_CHANGED;
 		ce->ce_flags |= CE_FSMONITOR_VALID;
 		trace_printf_key(&trace_fsmonitor, "mark_fsmonitor_clean '%s'", ce->name);
 	}