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authorDavid Howells <dhowells@redhat.com>2021-06-17 14:21:00 +0100
committerDavid Howells <dhowells@redhat.com>2021-08-27 13:34:02 +0100
commit35b72573e977ed6b18b094136a4fa3e0ffb13603 (patch)
treeb297cf2571e9b264199825f0cd140acf7733e624 /fs/fscache/internal.h
parent8beabdde18d31ac10c7d211347c361f07c7cd5b0 (diff)
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 <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/162431201844.2908479.8293647220901514696.stgit@warthog.procyon.org.uk/
Diffstat (limited to 'fs/fscache/internal.h')
-rw-r--r--fs/fscache/internal.h2
1 files changed, 2 insertions, 0 deletions
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);