diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c index 67b71f6e3bda..fa68336560c3 100644 --- a/drivers/md/dm-zoned-metadata.c +++ b/drivers/md/dm-zoned-metadata.c @@ -339,10 +339,11 @@ static void dmz_insert_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk) } /* - * Lookup a metadata block in the rbtree. + * Lookup a metadata block in the rbtree. If the block is found, increment + * its reference count. */ -static struct dmz_mblock *dmz_lookup_mblock(struct dmz_metadata *zmd, - sector_t mblk_no) +static struct dmz_mblock *dmz_get_mblock_fast(struct dmz_metadata *zmd, + sector_t mblk_no) { struct rb_root *root = &zmd->mblk_rbtree; struct rb_node *node = root->rb_node; @@ -350,8 +351,17 @@ static struct dmz_mblock *dmz_lookup_mblock(struct dmz_metadata *zmd, while (node) { mblk = container_of(node, struct dmz_mblock, node); - if (mblk->no == mblk_no) + if (mblk->no == mblk_no) { + /* + * If this is the first reference to the block, + * remove it from the LRU list. + */ + mblk->ref++; + if (mblk->ref == 1 && + !test_bit(DMZ_META_DIRTY, &mblk->state)) + list_del_init(&mblk->link); return mblk; + } node = (mblk->no < mblk_no) ? node->rb_left : node->rb_right; } @@ -382,32 +392,47 @@ static void dmz_mblock_bio_end_io(struct bio *bio) } /* - * Read a metadata block from disk. + * Read an uncached metadata block from disk and add it to the cache. */ -static struct dmz_mblock *dmz_fetch_mblock(struct dmz_metadata *zmd, - sector_t mblk_no) +static struct dmz_mblock *dmz_get_mblock_slow(struct dmz_metadata *zmd, + sector_t mblk_no) { - struct dmz_mblock *mblk; + struct dmz_mblock *mblk, *m; sector_t block = zmd->sb[zmd->mblk_primary].block + mblk_no; struct bio *bio; - /* Get block and insert it */ + /* Get a new block and a BIO to read it */ mblk = dmz_alloc_mblock(zmd, mblk_no); if (!mblk) return NULL; - spin_lock(&zmd->mblk_lock); - mblk->ref++; - set_bit(DMZ_META_READING, &mblk->state); - dmz_insert_mblock(zmd, mblk); - spin_unlock(&zmd->mblk_lock); - bio = bio_alloc(GFP_NOIO, 1); if (!bio) { dmz_free_mblock(zmd, mblk); return NULL; } + spin_lock(&zmd->mblk_lock); + + /* + * Make sure that another context did not start reading + * the block already. + */ + m = dmz_get_mblock_fast(zmd, mblk_no); + if (m) { + spin_unlock(&zmd->mblk_lock); + dmz_free_mblock(zmd, mblk); + bio_put(bio); + return m; + } + + mblk->ref++; + set_bit(DMZ_META_READING, &mblk->state); + dmz_insert_mblock(zmd, mblk); + + spin_unlock(&zmd->mblk_lock); + + /* Submit read BIO */ bio->bi_iter.bi_sector = dmz_blk2sect(block); bio_set_dev(bio, zmd->dev->bdev); bio->bi_private = mblk; @@ -509,19 +534,12 @@ static struct dmz_mblock *dmz_get_mblock(struct dmz_metadata *zmd, /* Check rbtree */ spin_lock(&zmd->mblk_lock); - mblk = dmz_lookup_mblock(zmd, mblk_no); - if (mblk) { - /* Cache hit: remove block from LRU list */ - mblk->ref++; - if (mblk->ref == 1 && - !test_bit(DMZ_META_DIRTY, &mblk->state)) - list_del_init(&mblk->link); - } + mblk = dmz_get_mblock_fast(zmd, mblk_no); spin_unlock(&zmd->mblk_lock); if (!mblk) { /* Cache miss: read the block from disk */ - mblk = dmz_fetch_mblock(zmd, mblk_no); + mblk = dmz_get_mblock_slow(zmd, mblk_no); if (!mblk) return ERR_PTR(-ENOMEM); }