rbd: bio_chain_clone() cleanups (542582fc) · Commits · 戴 / test

In bio_chain_clone(), at the end of the function the bi_next field of the tail of the new bio chain is nulled. This isn't necessary, because if "tail" is non-null, its value will be the last bio structure allocated at the top of the while loop in that function. And before that structure is added to the end of the new chain, its bi_next pointer is always made null. While touching that function, clean a few other things: - define each local variable on its own line - move the definition of "tmp" to an inner scope - move the modification of gfpmask closer to where it's used - rearrange the logic that sets the chain's tail pointer Signed-off-by:

Alex Elder <elder@inktank.com> Reviewed-by:

Yehuda Sadeh <yehuda@inktank.com>

drivers/block/rbd.c

+10 −11

Original line number	Diff line number	Diff line
		@@ -754,7 +754,9 @@ static struct bio bio_chain_clone(struct bio old, struct bio *next,
		struct bio_pair **bp,
		int len, gfp_t gfpmask)
		{
		struct bio tmp, old_chain = old, new_chain = NULL, *tail = NULL;
		struct bio old_chain = old;
		struct bio *new_chain = NULL;
		struct bio *tail;
		int total = 0;

		if (*bp) {
		@@ -763,9 +765,12 @@ static struct bio bio_chain_clone(struct bio old, struct bio *next,
		}

		while (old_chain && (total < len)) {
		struct bio *tmp;

		tmp = bio_kmalloc(gfpmask, old_chain->bi_max_vecs);
		if (!tmp)
		goto err_out;
		gfpmask &= ~__GFP_WAIT; /* can't wait after the first */

		if (total + old_chain->bi_size > len) {
		struct bio_pair *bp;
		@@ -793,15 +798,12 @@ static struct bio bio_chain_clone(struct bio old, struct bio *next,
		}

		tmp->bi_bdev = NULL;
		gfpmask &= ~__GFP_WAIT;
		tmp->bi_next = NULL;

		if (!new_chain) {
		new_chain = tail = tmp;
		} else {
		if (new_chain)
		tail->bi_next = tmp;
		else
		new_chain = tmp;
		tail = tmp;
		}
		old_chain = old_chain->bi_next;

		total += tmp->bi_size;
		@@ -809,9 +811,6 @@ static struct bio bio_chain_clone(struct bio old, struct bio *next,

		BUG_ON(total < len);

		if (tail)
		tail->bi_next = NULL;

		*old = old_chain;

		return new_chain;

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