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Commit c6d98a60 authored Dec 24, 2013 by Ilya Dryomov

crush: return CRUSH_ITEM_UNDEF for failed placements with indep

For firstn mode, if we fail to make a valid placement choice, we just
continue and return a short result to the caller. For indep mode, however,
we need to make the position stable, and return an undefined value on
failed placements to avoid shifting later results to the left.

Reflects ceph.git commit b1d4dd4eb044875874a1d01c01c7d766db5d0a80.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

parent e8ef19c4

include/linux/crush/crush.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -19,10 +19,11 @@

		#define CRUSH_MAGIC 0x00010000ul /* for detecting algorithm revisions */


		#define CRUSH_MAX_DEPTH 10 /* max crush hierarchy depth */


		#define CRUSH_ITEM_UNDEF 0x7fffffff /* undefined result */

		/*
		* CRUSH uses user-defined "rules" to describe how inputs should be
		* mapped to devices. A rule consists of sequence of steps to perform

net/ceph/crush/mapper.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -455,9 +455,13 @@ static int crush_choose(const struct crush_map *map,
		} while (retry_descent);

		if (skip_rep) {
		if (firstn) {
		dprintk("skip rep\n");
		continue;
		}
		dprintk("undef rep, continuing\n");
		item = CRUSH_ITEM_UNDEF;
		}

		dprintk("CHOOSE got %d\n", item);
		out[outpos] = item;