bfqd->sb_shift was attempted used as a cache for the sbitmap queue
shift, but we don't need it, as it never changes. Kill it with fire.

Signed-off-by: Jens Axboe <ax...@kernel.dk>
---
 block/bfq-iosched.c | 16 +++++++---------
 block/bfq-iosched.h |  6 ------
 2 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index cba6e82153a2..07b43ea124b0 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -5060,26 +5060,24 @@ static unsigned int bfq_update_depths(struct bfq_data 
*bfqd,
 {
        unsigned int i, j, min_shallow = UINT_MAX;
 
-       bfqd->sb_shift = bt->sb.shift;
-
        /*
         * In-word depths if no bfq_queue is being weight-raised:
         * leaving 25% of tags only for sync reads.
         *
         * In next formulas, right-shift the value
-        * (1U<<bfqd->sb_shift), instead of computing directly
-        * (1U<<(bfqd->sb_shift - something)), to be robust against
-        * any possible value of bfqd->sb_shift, without having to
+        * (1U<<bt->sb.shift), instead of computing directly
+        * (1U<<(bt->sb.shift - something)), to be robust against
+        * any possible value of bt->sb.shift, without having to
         * limit 'something'.
         */
        /* no more than 50% of tags for async I/O */
-       bfqd->word_depths[0][0] = max((1U<<bfqd->sb_shift)>>1, 1U);
+       bfqd->word_depths[0][0] = max((1U << bt->sb.shift) >> 1, 1U);
        /*
         * no more than 75% of tags for sync writes (25% extra tags
         * w.r.t. async I/O, to prevent async I/O from starving sync
         * writes)
         */
-       bfqd->word_depths[0][1] = max(((1U<<bfqd->sb_shift) * 3)>>2, 1U);
+       bfqd->word_depths[0][1] = max(((1U << bt->sb.shift) * 3) >> 2, 1U);
 
        /*
         * In-word depths in case some bfq_queue is being weight-
@@ -5089,9 +5087,9 @@ static unsigned int bfq_update_depths(struct bfq_data 
*bfqd,
         * shortage.
         */
        /* no more than ~18% of tags for async I/O */
-       bfqd->word_depths[1][0] = max(((1U<<bfqd->sb_shift) * 3)>>4, 1U);
+       bfqd->word_depths[1][0] = max(((1U << bt->sb.shift) * 3) >> 4, 1U);
        /* no more than ~37% of tags for sync writes (~20% extra tags) */
-       bfqd->word_depths[1][1] = max(((1U<<bfqd->sb_shift) * 6)>>4, 1U);
+       bfqd->word_depths[1][1] = max(((1U << bt->sb.shift) * 6) >> 4, 1U);
 
        for (i = 0; i < 2; i++)
                for (j = 0; j < 2; j++)
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 8ec7ff92cd6f..faac509cb35e 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -636,12 +636,6 @@ struct bfq_data {
        struct bfq_queue *bio_bfqq;
 
        /*
-        * Cached sbitmap shift, used to compute depth limits in
-        * bfq_update_depths.
-        */
-       unsigned int sb_shift;
-
-       /*
         * Depth limits used in bfq_limit_depth (see comments on the
         * function)
         */
-- 
2.7.4

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