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Clarify releasedir readdir synchronization barrier

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- Document the lock/unlock pair as an acquire/release barrier.
- Explain that releasedir waits for in-flight readdir calls before destroy/free.
- Warn against removing the synchronization despite it not being a critical section.
This commit is contained in:
Antonio SJ Musumeci
2026-05-14 00:22:06 -04:00
committed by trapexit
parent 1e0bd54989
commit 8608b2be46
1 changed files with 5 additions and 1 deletions
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vendored/libfuse/lib/fuse.cpp
+5 -1
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@@ -2543,7 +2543,11 @@ fuse_lib_releasedir(fuse_req_t *req_,
f.ops.releasedir(&req_->ctx,
&ffi);
/* Done to keep race condition between last readdir reply and the unlock */
// Acquire/release barrier: not a real critical section. A
// concurrent readdir may still hold dh->lock at this point. This
// lock+unlock pair blocks until the last readdir drops the lock
// guaranteeing that the subsequent destroy/free sees no in-flight
// readdir accessing dh->d. Do NOT remove.
mutex_lock(dh->lock);
mutex_unlock(dh->lock);
mutex_destroy(dh->lock);