diff options
| author | David Howells <dhowells@redhat.com> | 2021-06-17 14:21:00 +0100 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2021-08-27 13:34:02 +0100 |
| commit | 35b72573e977ed6b18b094136a4fa3e0ffb13603 (patch) | |
| tree | b297cf2571e9b264199825f0cd140acf7733e624 /fs/fscache/internal.h | |
| parent | 8beabdde18d31ac10c7d211347c361f07c7cd5b0 (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.h | 2 |
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); |