lightnvm: pblk: prevent race in pblk_rb_flush_point_set (3c05ef11) · Commits · 戴 / test

Make sure that we are not advancing the sync pointer while we're adding bios to the write buffer entry completion list. This race condition results in bios not completing and was identified by a hang when running xfstest generic/113. Signed-off-by:

Hans Holmberg <hans.holmberg@cnexlabs.com> Reviewed-by:

Javier González <javier@cnexlabs.com> Signed-off-by:

Matias Bjørling <mb@lightnvm.io> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

drivers/lightnvm/pblk-rb.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -355,10 +355,13 @@ static int pblk_rb_flush_point_set(struct pblk_rb rb, struct bio bio,
		struct pblk_rb_entry *entry;
		unsigned int sync, flush_point;

		pblk_rb_sync_init(rb, NULL);
		sync = READ_ONCE(rb->sync);

		if (pos == sync)
		if (pos == sync) {
		pblk_rb_sync_end(rb, NULL);
		return 0;
		}

		#ifdef CONFIG_NVM_DEBUG
		atomic_inc(&rb->inflight_flush_point);
		@@ -367,8 +370,6 @@ static int pblk_rb_flush_point_set(struct pblk_rb rb, struct bio bio,
		flush_point = (pos == 0) ? (rb->nr_entries - 1) : (pos - 1);
		entry = &rb->entries[flush_point];

		pblk_rb_sync_init(rb, NULL);

		/* Protect flush points */
		smp_store_release(&rb->flush_point, flush_point);

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