Author: mjg
Date: Wed Aug 26 12:54:18 2020
New Revision: 364816
URL: https://svnweb.freebsd.org/changeset/base/364816
Log:
cache: relock on failure in cache_zap_locked_vnode
This gets rid of bogus scheme of yielding in hopes the blocking thread will
make progress.
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Wed Aug 26 12:53:16 2020 (r364815)
+++ head/sys/kern/vfs_cache.c Wed Aug 26 12:54:18 2020 (r364816)
@@ -1134,8 +1134,15 @@ cache_zap_locked_vnode(struct namecache *ncp, struct v
to_unlock = vlp2;
} else {
if (!mtx_trylock(vlp1)) {
- error = EAGAIN;
- goto out;
+ /*
+ * TODO: Very wasteful but rare.
+ */
+ mtx_unlock(pvlp);
+ mtx_lock(vlp1);
+ mtx_lock(vlp2);
+ mtx_unlock(vlp2);
+ mtx_unlock(vlp1);
+ return (EAGAIN);
}
to_unlock = vlp1;
}
@@ -1377,7 +1384,6 @@ negative_success:
error = cache_zap_locked_vnode(ncp, dvp);
if (__predict_false(error != 0)) {
zap_and_exit_bucket_fail2++;
- cache_maybe_yield();
goto retry;
}
cache_free(ncp);
@@ -1465,7 +1471,6 @@ retry:
error = cache_zap_locked_bucket(ncp, cnp, hash, blp);
if (__predict_false(error != 0)) {
zap_and_exit_bucket_fail++;
- cache_maybe_yield();
goto retry;
}
counter_u64_add(numposzaps, 1);
@@ -1584,7 +1589,6 @@ negative_success:
error = cache_zap_locked_vnode(ncp, dvp);
if (__predict_false(error != 0)) {
zap_and_exit_bucket_fail2++;
- cache_maybe_yield();
goto retry;
}
cache_free(ncp);
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