erofs: simplify try_to_claim_pcluster() (473e15b0) · Commits · 戴 / test

fs/erofs/zdata.c

+24 −27

Original line number	Diff line number	Diff line
		@@ -292,34 +292,33 @@ static int z_erofs_attach_page(struct z_erofs_collector *clt,
		return ret ? 0 : -EAGAIN;
		}

		static enum z_erofs_collectmode
		try_to_claim_pcluster(struct z_erofs_pcluster *pcl,
		z_erofs_next_pcluster_t *owned_head)
		static void z_erofs_try_to_claim_pcluster(struct z_erofs_collector *clt)
		{
		/* let's claim these following types of pclusters */
		retry:
		if (pcl->next == Z_EROFS_PCLUSTER_NIL) {
		/* type 1, nil pcluster */
		if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
		*owned_head) != Z_EROFS_PCLUSTER_NIL)
		goto retry;
		struct z_erofs_pcluster *pcl = clt->pcl;
		z_erofs_next_pcluster_t *owned_head = &clt->owned_head;

		/* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
		if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
		*owned_head) == Z_EROFS_PCLUSTER_NIL) {
		*owned_head = &pcl->next;
		/* lucky, I am the followee :) */
		return COLLECT_PRIMARY_FOLLOWED;
		} else if (pcl->next == Z_EROFS_PCLUSTER_TAIL) {
		/* so we can attach this pcluster to our submission chain. */
		clt->mode = COLLECT_PRIMARY_FOLLOWED;
		return;
		}

		/*
		* type 2, link to the end of a existing open chain,
		* be careful that its submission itself is governed
		* by the original owned chain.
		* type 2, link to the end of an existing open chain, be careful
		* that its submission is controlled by the original attached chain.
		*/
		if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
		*owned_head) != Z_EROFS_PCLUSTER_TAIL)
		goto retry;
		*owned_head) == Z_EROFS_PCLUSTER_TAIL) {
		*owned_head = Z_EROFS_PCLUSTER_TAIL;
		return COLLECT_PRIMARY_HOOKED;
		clt->mode = COLLECT_PRIMARY_HOOKED;
		clt->tailpcl = NULL;
		return;
		}
		return COLLECT_PRIMARY; /* :( better luck next time */
		/* type 3, it belongs to a chain, but it isn't the end of the chain */
		clt->mode = COLLECT_PRIMARY;
		}

		static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
		@@ -364,10 +363,8 @@ static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
		/* used to check tail merging loop due to corrupted images */
		if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
		clt->tailpcl = pcl;
		clt->mode = try_to_claim_pcluster(pcl, &clt->owned_head);
		/* clean tailpcl if the current owned_head is Z_EROFS_PCLUSTER_TAIL */
		if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
		clt->tailpcl = NULL;

		z_erofs_try_to_claim_pcluster(clt);
		clt->cl = cl;
		return 0;
		}

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