md: tidy up device searches in read_balance. (f3ac8bf7) · Commits · 戴 / test

drivers/md/raid1.c

+36 −56

Original line number	Diff line number	Diff line
		@@ -419,11 +419,13 @@ static void raid1_end_write_request(struct bio *bio, int error)
		static int read_balance(conf_t conf, r1bio_t r1_bio)
		{
		const sector_t this_sector = r1_bio->sector;
		int new_disk = conf->last_used, disk = new_disk;
		int wonly_disk = -1;
		const int sectors = r1_bio->sectors;
		int new_disk = -1;
		int start_disk;
		int i;
		sector_t new_distance, current_distance;
		mdk_rdev_t *rdev;
		int choose_first;

		rcu_read_lock();
		/*
		@@ -434,54 +436,33 @@ static int read_balance(conf_t conf, r1bio_t r1_bio)
		retry:
		if (conf->mddev->recovery_cp < MaxSector &&
		(this_sector + sectors >= conf->next_resync)) {
		/* Choose the first operational device, for consistancy */
		new_disk = 0;

		for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
		r1_bio->bios[new_disk] == IO_BLOCKED \|\|
		!rdev \|\| !test_bit(In_sync, &rdev->flags)
		\|\| test_bit(WriteMostly, &rdev->flags);
		rdev = rcu_dereference(conf->mirrors[++new_disk].rdev)) {

		if (rdev && test_bit(In_sync, &rdev->flags) &&
		r1_bio->bios[new_disk] != IO_BLOCKED)
		wonly_disk = new_disk;

		if (new_disk == conf->raid_disks - 1) {
		new_disk = wonly_disk;
		break;
		}
		}
		goto rb_out;
		choose_first = 1;
		start_disk = 0;
		} else {
		choose_first = 0;
		start_disk = conf->last_used;
		}


		/* make sure the disk is operational */
		for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
		r1_bio->bios[new_disk] == IO_BLOCKED \|\|
		!rdev \|\| !test_bit(In_sync, &rdev->flags) \|\|
		test_bit(WriteMostly, &rdev->flags);
		rdev = rcu_dereference(conf->mirrors[new_disk].rdev)) {

		if (rdev && test_bit(In_sync, &rdev->flags) &&
		r1_bio->bios[new_disk] != IO_BLOCKED)
		wonly_disk = new_disk;

		if (new_disk <= 0)
		new_disk = conf->raid_disks;
		new_disk--;
		if (new_disk == disk) {
		new_disk = wonly_disk;
		for (i = 0 ; i < conf->raid_disks ; i++) {
		int disk = start_disk + i;
		if (disk >= conf->raid_disks)
		disk -= conf->raid_disks;

		rdev = rcu_dereference(conf->mirrors[disk].rdev);
		if (r1_bio->bios[disk] == IO_BLOCKED
		\|\| rdev == NULL
		\|\| !test_bit(In_sync, &rdev->flags))
		continue;

		new_disk = disk;
		if (!test_bit(WriteMostly, &rdev->flags))
		break;
		}
		}

		if (new_disk < 0)
		if (new_disk < 0 \|\| choose_first)
		goto rb_out;

		disk = new_disk;
		/* now disk == new_disk == starting point for search */

		/*
		* Don't change to another disk for sequential reads:
		*/
		@@ -490,20 +471,21 @@ static int read_balance(conf_t conf, r1bio_t r1_bio)
		if (this_sector == conf->mirrors[new_disk].head_position)
		goto rb_out;

		current_distance = abs(this_sector - conf->mirrors[disk].head_position);
		current_distance = abs(this_sector
		- conf->mirrors[new_disk].head_position);

		/* Find the disk whose head is closest */

		do {
		if (disk <= 0)
		disk = conf->raid_disks;
		disk--;
		/* look for a better disk - i.e. head is closer */
		start_disk = new_disk;
		for (i = 1; i < conf->raid_disks; i++) {
		int disk = start_disk + 1;
		if (disk >= conf->raid_disks)
		disk -= conf->raid_disks;

		rdev = rcu_dereference(conf->mirrors[disk].rdev);

		if (!rdev \|\| r1_bio->bios[disk] == IO_BLOCKED \|\|
		!test_bit(In_sync, &rdev->flags) \|\|
		test_bit(WriteMostly, &rdev->flags))
		if (r1_bio->bios[disk] == IO_BLOCKED
		\|\| rdev == NULL
		\|\| !test_bit(In_sync, &rdev->flags)
		\|\| test_bit(WriteMostly, &rdev->flags))
		continue;

		if (!atomic_read(&rdev->nr_pending)) {
		@@ -515,11 +497,9 @@ static int read_balance(conf_t conf, r1bio_t r1_bio)
		current_distance = new_distance;
		new_disk = disk;
		}
		} while (disk != conf->last_used);
		}

		rb_out:


		if (new_disk >= 0) {
		rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
		if (!rdev)

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