From 35b72573e977ed6b18b094136a4fa3e0ffb13603 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 17 Jun 2021 14:21:00 +0100 Subject: fscache: Fix cookie key hashing The current hash algorithm used for hashing cookie keys is really bad, producing almost no dispersion (after a test kernel build, ~30000 files were split over just 18 out of the 32768 hash buckets). Borrow the full_name_hash() hash function into fscache to do the hashing for cookie keys and, in the future, volume keys. I don't want to use full_name_hash() as-is because I want the hash value to be consistent across arches and over time as the hash value produced may get used on disk. I can also optimise parts of it away as the key will always be a padded array of aligned 32-bit words. Fixes: ec0328e46d6e ("fscache: Maintain a catalogue of allocated cookies") Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/162431201844.2908479.8293647220901514696.stgit@warthog.procyon.org.uk/ --- fs/fscache/internal.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/fscache/internal.h') diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index 200082cafdda..a49136c63e4b 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -74,6 +74,8 @@ extern struct workqueue_struct *fscache_object_wq; extern struct workqueue_struct *fscache_op_wq; DECLARE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait); +extern unsigned int fscache_hash(unsigned int salt, unsigned int *data, unsigned int n); + static inline bool fscache_object_congested(void) { return workqueue_congested(WORK_CPU_UNBOUND, fscache_object_wq); -- cgit v1.2.3