gfs2: Don't pack struct lm_lockname (972b044e) · Commits · 戴 / test

As per a suggestion by Linus, don't pack struct lm_lockname: we did that because the struct is used as a rhashtable key, but packing tells the compiler that the 64-bit fields in the struct may be unaligned, causing it to generate worse code on some architectures. Instead, rearrange the fields in the struct so that there is no padding between fields, and exclude any tail padding from the hash key size. Signed-off-by:

Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by:

Bob Peterson <rpeterso@redhat.com>

fs/gfs2/glock.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -73,7 +73,7 @@ static DEFINE_SPINLOCK(lru_lock);

		static struct rhashtable_params ht_parms = {
		.nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
		.key_len = sizeof(struct lm_lockname),
		.key_len = offsetofend(struct lm_lockname, ln_type),
		.key_offset = offsetof(struct gfs2_glock, gl_name),
		.head_offset = offsetof(struct gfs2_glock, gl_node),
		};

fs/gfs2/incore.h

+6 −2

Original line number	Diff line number	Diff line
		@@ -203,11 +203,15 @@ enum {
		DFL_DLM_RECOVERY = 6,
		};

		/*
		* We are using struct lm_lockname as an rhashtable key. Avoid holes within
		* the struct; padding at the end is fine.
		*/
		struct lm_lockname {
		struct gfs2_sbd *ln_sbd;
		u64 ln_number;
		struct gfs2_sbd *ln_sbd;
		unsigned int ln_type;
		} __packed __aligned(sizeof(int));
		};

		#define lm_name_equal(name1, name2) \
		(((name1)->ln_number == (name2)->ln_number) && \

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