Commit b6ccde39 authored by Eric Biggers's avatar Eric Biggers Committed by Andreas Gruenbacher
Browse files

gfs2: avoid inefficient use of crc32_le_shift() 



__get_log_header() was using crc32_le_shift() to update a CRC with four
zero bytes.  However, this is about 5x slower than just CRC'ing four
zero bytes in the normal way.  Just do that instead.

(We could instead make crc32_le_shift() faster on short lengths.  But
all its callers do just fine without it, so I'd like to just remove it.)

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 87faee38

fs/gfs2/recovery.c

+2 −1
Original line number Diff line number Diff line
@@ -118,6 +118,7 @@ void gfs2_revoke_clean(struct gfs2_jdesc *jd) 
int __get_log_header(struct gfs2_sbd *sdp, const struct gfs2_log_header *lh,

		     unsigned int blkno, struct gfs2_log_header_host *head)

{

	const u32 zero = 0;

	u32 hash, crc;



	if (lh->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
@@ -126,7 +127,7 @@ int __get_log_header(struct gfs2_sbd *sdp, const struct gfs2_log_header *lh, 
		return 1;



	hash = crc32(~0, lh, LH_V1_SIZE - 4);

	hash = ~crc32_le_shift(hash, 4); /* assume lh_hash is zero */

	hash = ~crc32(hash, &zero, 4); /* assume lh_hash is zero */



	if (be32_to_cpu(lh->lh_hash) != hash)

		return 1;