From: Greg Kroah-Hartman gregkh@linuxfoundation.org
From: David Sterba dsterba@suse.com
commit c17af96554a8a8777cbb0fd53b8497250e548b43 upstream.
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: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/raid56.c | 37 +++++++++++++++---------------------- 1 file changed, 15 insertions(+), 22 deletions(-)
--- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -1190,22 +1190,19 @@ static noinline void finish_rmw(struct b 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. @@ -1249,7 +1246,7 @@ static noinline void finish_rmw(struct b SetPageUptodate(p); pointers[stripe++] = kmap(p);
- if (q_stripe != -1) { + if (has_qstripe) {
/* * raid6, add the qstripe and call the @@ -2325,8 +2322,7 @@ static noinline void finish_parity_scrub 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; @@ -2336,14 +2332,12 @@ static noinline void finish_parity_scrub
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; @@ -2365,7 +2359,7 @@ static noinline void finish_parity_scrub 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); @@ -2388,8 +2382,7 @@ static noinline void finish_parity_scrub /* 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