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author | Mateusz Guzik <mjg@FreeBSD.org> | 2020-10-17 08:48:32 +0000 |
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committer | Mateusz Guzik <mjg@FreeBSD.org> | 2020-10-17 08:48:32 +0000 |
commit | b31b5e9cfd8967e69bfb63560d21b9588cd14126 (patch) | |
tree | 77994c53a9dd4d2bb0f30c24a6d5691befe17052 | |
parent | ad89066af446052cd7fc970fb70da5db6387cf16 (diff) | |
download | src-b31b5e9cfd8967e69bfb63560d21b9588cd14126.tar.gz src-b31b5e9cfd8967e69bfb63560d21b9588cd14126.zip |
cache: remove entries before trying to add new ones, not after
Should allow positive entries to replace negative ones in case
the cache is full.
Notes
Notes:
svn path=/head/; revision=366784
-rw-r--r-- | sys/kern/vfs_cache.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c index ef79d5ca4da0..5f206c5cb64a 100644 --- a/sys/kern/vfs_cache.c +++ b/sys/kern/vfs_cache.c @@ -1923,8 +1923,21 @@ cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, /* * Avoid blowout in namecache entries. + * + * Bugs: + * 1. filesystems may end up tryng to add an already existing entry + * (for example this can happen after a cache miss during concurrent + * lookup), in which case we will call cache_negative_zap_one despite + * not adding anything. + * 2. the routine may fail to free anything and no provisions are made + * to make it try harder (see the inside for failure modes) + * 3. it only ever looks at negative entries. */ lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; + if (numneg * ncnegfactor > lnumcache) { + cache_negative_zap_one(); + lnumcache = atomic_load_long(&numcache); + } if (__predict_false(lnumcache >= ncsize)) { atomic_subtract_long(&numcache, 1); counter_u64_add(numdrops, 1); @@ -2087,8 +2100,6 @@ cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, atomic_store_char(&ncp->nc_flag, ncp->nc_flag & ~NCF_WIP); cache_enter_unlock(&cel); - if (numneg * ncnegfactor > lnumcache) - cache_negative_zap_one(); if (ndd != NULL) cache_free(ndd); return; |