nvmet: only allocate a single slab for bvecs

There is no need to have a separate slab cache for each namespace,
and having separate ones creates duplicate debugs file names as well.

Fixes: d5eff33e ("nvmet: add simple file backed ns support")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/nvme/target/core.c

@@ -15,6 +15,7 @@
 
 #include "nvmet.h"
 
+struct kmem_cache *nvmet_bvec_cache;
 struct workqueue_struct *buffered_io_wq;
 struct workqueue_struct *zbd_wq;
 static const struct nvmet_fabrics_ops *nvmet_transports[NVMF_TRTYPE_MAX];
@@ -1630,26 +1631,28 @@ void nvmet_subsys_put(struct nvmet_subsys *subsys)
 
 static int __init nvmet_init(void)
 {
-	int error;
+	int error = -ENOMEM;
 
 	nvmet_ana_group_enabled[NVMET_DEFAULT_ANA_GRPID] = 1;
 
+	nvmet_bvec_cache = kmem_cache_create("nvmet-bvec",
+			NVMET_MAX_MPOOL_BVEC * sizeof(struct bio_vec), 0,
+			SLAB_HWCACHE_ALIGN, NULL);
+	if (!nvmet_bvec_cache)
+		return -ENOMEM;
+
 	zbd_wq = alloc_workqueue("nvmet-zbd-wq", WQ_MEM_RECLAIM, 0);
 	if (!zbd_wq)
-		return -ENOMEM;
+		goto out_destroy_bvec_cache;
 
 	buffered_io_wq = alloc_workqueue("nvmet-buffered-io-wq",
 			WQ_MEM_RECLAIM, 0);
-	if (!buffered_io_wq) {
-		error = -ENOMEM;
+	if (!buffered_io_wq)
 		goto out_free_zbd_work_queue;
-	}
 
 	nvmet_wq = alloc_workqueue("nvmet-wq", WQ_MEM_RECLAIM, 0);
-	if (!nvmet_wq) {
-		error = -ENOMEM;
+	if (!nvmet_wq)
 		goto out_free_buffered_work_queue;
-	}
 
 	error = nvmet_init_discovery();
 	if (error)
@@ -1668,6 +1671,8 @@ static int __init nvmet_init(void)
 	destroy_workqueue(buffered_io_wq);
 out_free_zbd_work_queue:
 	destroy_workqueue(zbd_wq);
+out_destroy_bvec_cache:
+	kmem_cache_destroy(nvmet_bvec_cache);
 	return error;
 }
 
@@ -1679,6 +1684,7 @@ static void __exit nvmet_exit(void)
 	destroy_workqueue(nvmet_wq);
 	destroy_workqueue(buffered_io_wq);
 	destroy_workqueue(zbd_wq);
+	kmem_cache_destroy(nvmet_bvec_cache);
 
 	BUILD_BUG_ON(sizeof(struct nvmf_disc_rsp_page_entry) != 1024);
 	BUILD_BUG_ON(sizeof(struct nvmf_disc_rsp_page_hdr) != 1024);

drivers/nvme/target/io-cmd-file.c

@@ -11,7 +11,6 @@
 #include <linux/fs.h>
 #include "nvmet.h"
 
-#define NVMET_MAX_MPOOL_BVEC		16
 #define NVMET_MIN_MPOOL_OBJ		16
 
 void nvmet_file_ns_revalidate(struct nvmet_ns *ns)
@@ -26,8 +25,6 @@ void nvmet_file_ns_disable(struct nvmet_ns *ns)
 			flush_workqueue(buffered_io_wq);
 		mempool_destroy(ns->bvec_pool);
 		ns->bvec_pool = NULL;
-		kmem_cache_destroy(ns->bvec_cache);
-		ns->bvec_cache = NULL;
 		fput(ns->file);
 		ns->file = NULL;
 	}
@@ -59,16 +56,8 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns)
 	ns->blksize_shift = min_t(u8,
 			file_inode(ns->file)->i_blkbits, 12);
 
-	ns->bvec_cache = kmem_cache_create("nvmet-bvec",
-			NVMET_MAX_MPOOL_BVEC * sizeof(struct bio_vec),
-			0, SLAB_HWCACHE_ALIGN, NULL);
-	if (!ns->bvec_cache) {
-		ret = -ENOMEM;
-		goto err;
-	}
-
 	ns->bvec_pool = mempool_create(NVMET_MIN_MPOOL_OBJ, mempool_alloc_slab,
-			mempool_free_slab, ns->bvec_cache);
+			mempool_free_slab, nvmet_bvec_cache);
 
 	if (!ns->bvec_pool) {
 		ret = -ENOMEM;
@@ -77,9 +66,10 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns)
 
 	return ret;
 err:
+	fput(ns->file);
+	ns->file = NULL;
 	ns->size = 0;
 	ns->blksize_shift = 0;
-	nvmet_file_ns_disable(ns);
 	return ret;
 }
 

drivers/nvme/target/nvmet.h

@@ -77,7 +77,6 @@ struct nvmet_ns {
 
 	struct completion	disable_done;
 	mempool_t		*bvec_pool;
-	struct kmem_cache	*bvec_cache;
 
 	int			use_p2pmem;
 	struct pci_dev		*p2p_dev;
@@ -393,6 +392,8 @@ struct nvmet_req {
 	u64			error_slba;
 };
 
+#define NVMET_MAX_MPOOL_BVEC		16
+extern struct kmem_cache *nvmet_bvec_cache;
 extern struct workqueue_struct *buffered_io_wq;
 extern struct workqueue_struct *zbd_wq;
 extern struct workqueue_struct *nvmet_wq;