From 0472a42ba1f89ec85f070c731f4440d7cc38c44c Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 15 Mar 2017 14:05:13 +1100 Subject: md/raid5: remove over-loading of ->bi_phys_segments. When a read request, which bypassed the cache, fails, we need to retry it through the cache. This involves attaching it to a sequence of stripe_heads, and it may not be possible to get all the stripe_heads we need at once. We do what we can, and record how far we got in ->bi_phys_segments so we can pick up again later. There is only ever one bio which may have a non-zero offset stored in ->bi_phys_segments, the one that is either active in the single thread which calls retry_aligned_read(), or is in conf->retry_read_aligned waiting for retry_aligned_read() to be called again. So we only need to store one offset value. This can be in a local variable passed between remove_bio_from_retry() and retry_aligned_read(), or in the r5conf structure next to the ->retry_read_aligned pointer. Storing it there allows the last usage of ->bi_phys_segments to be removed from md/raid5.c. Signed-off-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/raid5.h | 30 +----------------------------- 1 file changed, 1 insertion(+), 29 deletions(-) (limited to 'drivers/md/raid5.h') diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index 7d74fb3..cdc7f92 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -487,35 +487,6 @@ static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector) return NULL; } -/* - * We maintain a count of processed stripes in the upper 16 bits - */ -static inline int raid5_bi_processed_stripes(struct bio *bio) -{ - atomic_t *segments = (atomic_t *)&bio->bi_phys_segments; - - return (atomic_read(segments) >> 16) & 0xffff; -} - -static inline void raid5_set_bi_processed_stripes(struct bio *bio, - unsigned int cnt) -{ - atomic_t *segments = (atomic_t *)&bio->bi_phys_segments; - int old, new; - - do { - old = atomic_read(segments); - new = (old & 0xffff) | (cnt << 16); - } while (atomic_cmpxchg(segments, old, new) != old); -} - -static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt) -{ - atomic_t *segments = (atomic_t *)&bio->bi_phys_segments; - - atomic_set(segments, cnt); -} - /* NOTE NR_STRIPE_HASH_LOCKS must remain below 64. * This is because we sometimes take all the spinlocks * and creating that much locking depth can cause @@ -613,6 +584,7 @@ struct r5conf { struct list_head delayed_list; /* stripes that have plugged requests */ struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */ struct bio *retry_read_aligned; /* currently retrying aligned bios */ + unsigned int retry_read_offset; /* sector offset into retry_read_aligned */ struct bio *retry_read_aligned_list; /* aligned bios retry list */ atomic_t preread_active_stripes; /* stripes with scheduled io */ atomic_t active_aligned_reads; -- cgit v1.1