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btrfs: raid56: simplify tracking of Q stripe presence

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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>
This commit is contained in:
David Sterba 2020-02-19 15:17:20 +01:00
parent b25b0b871f
commit c17af96554
1 changed files with 15 additions and 22 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

37
fs/btrfs/raid56.c
View file

@ -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