Commit c17af965 authored by David Sterba's avatar David Sterba
Browse files

btrfs: raid56: simplify tracking of Q stripe presence 



There are temporary variables tracking the index of P and Q stripes, but
none of them is really used as such, merely for determining if the Q
stripe is present. This leads to compiler warnings with
-Wunused-but-set-variable and has been reported several times.

fs/btrfs/raid56.c: In function ‘finish_rmw’:
fs/btrfs/raid56.c:1199:6: warning: variable ‘p_stripe’ set but not used [-Wunused-but-set-variable]
 1199 |  int p_stripe = -1;
      |      ^~~~~~~~
fs/btrfs/raid56.c: In function ‘finish_parity_scrub’:
fs/btrfs/raid56.c:2356:6: warning: variable ‘p_stripe’ set but not used [-Wunused-but-set-variable]
 2356 |  int p_stripe = -1;
      |      ^~~~~~~~

Replace the two variables with one that has a clear meaning and also get
rid of the warnings. The logic that verifies that there are only 2
valid cases is unchanged.

Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent b25b0b87

fs/btrfs/raid56.c

+15 −22
Original line number Diff line number Diff line
@@ -1196,22 +1196,19 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio) 
	int nr_data = rbio->nr_data;

	int stripe;

	int pagenr;

	int p_stripe = -1;

	int q_stripe = -1;

	bool has_qstripe;

	struct bio_list bio_list;

	struct bio *bio;

	int ret;



	bio_list_init(&bio_list);



	if (rbio->real_stripes - rbio->nr_data == 1) {

		p_stripe = rbio->real_stripes - 1;

	} else if (rbio->real_stripes - rbio->nr_data == 2) {

		p_stripe = rbio->real_stripes - 2;

		q_stripe = rbio->real_stripes - 1;

	} else {

	if (rbio->real_stripes - rbio->nr_data == 1)

		has_qstripe = false;

	else if (rbio->real_stripes - rbio->nr_data == 2)

		has_qstripe = true;

	else

		BUG();

	}



	/* at this point we either have a full stripe,

	 * or we've read the full stripe from the drive.
@@ -1255,7 +1252,7 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio) 
		SetPageUptodate(p);

		pointers[stripe++] = kmap(p);



		if (q_stripe != -1) {

		if (has_qstripe) {



			/*

			 * raid6, add the qstripe and call the
@@ -2353,8 +2350,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, 
	int nr_data = rbio->nr_data;

	int stripe;

	int pagenr;

	int p_stripe = -1;

	int q_stripe = -1;

	bool has_qstripe;

	struct page *p_page = NULL;

	struct page *q_page = NULL;

	struct bio_list bio_list;
@@ -2364,14 +2360,12 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, 


	bio_list_init(&bio_list);



	if (rbio->real_stripes - rbio->nr_data == 1) {

		p_stripe = rbio->real_stripes - 1;

	} else if (rbio->real_stripes - rbio->nr_data == 2) {

		p_stripe = rbio->real_stripes - 2;

		q_stripe = rbio->real_stripes - 1;

	} else {

	if (rbio->real_stripes - rbio->nr_data == 1)

		has_qstripe = false;

	else if (rbio->real_stripes - rbio->nr_data == 2)

		has_qstripe = true;

	else

		BUG();

	}



	if (bbio->num_tgtdevs && bbio->tgtdev_map[rbio->scrubp]) {

		is_replace = 1;
@@ -2393,7 +2387,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, 
		goto cleanup;

	SetPageUptodate(p_page);



	if (q_stripe != -1) {

	if (has_qstripe) {

		q_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);

		if (!q_page) {

			__free_page(p_page);
@@ -2416,8 +2410,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, 
		/* then add the parity stripe */

		pointers[stripe++] = kmap(p_page);



		if (q_stripe != -1) {



		if (has_qstripe) {

			/*

			 * raid6, add the qstripe and call the

			 * library function to fill in our p/q

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