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From: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
To: linux-nvme@lists.infradead.org
Cc: MRuijter@onestopsystems.com, hch@lst.de,
	Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
	sagi@grimberg.me
Subject: [PATCH RESEND V2 1/2] nvmet: allow block device to use buffered I/O
Date: Tue,  4 Feb 2020 17:56:49 -0800	[thread overview]
Message-ID: <20200205015653.21866-2-chaitanya.kulkarni@wdc.com> (raw)
In-Reply-To: <20200205015653.21866-1-chaitanya.kulkarni@wdc.com>

NVMeOF target already has a support to execute requests in the
buffered I/O mode with file backend. This patch allows block devices to
be used with file backend code so that buffered I/O parameter can be set
for a block device backed namespace when newly introduce configfs
parameter backeend. The new file defaults to the blockio user can switch
between "blockio" and "fileio" strings to enable the file backend for
the block device when buffered_io set to 1.

Following is the performance improvement when backend=fileio and
buffered_io=1 :-

Device_path = /dev/nullb0, I/O type = randread.

With this patch and buffered I/O = 0:
  read: IOPS=198k, BW=772MiB/s (809MB/s)(45.2GiB/60002msec)
  read: IOPS=198k, BW=774MiB/s (811MB/s)(45.3GiB/60002msec)
  read: IOPS=197k, BW=771MiB/s (808MB/s)(45.2GiB/60002msec)

With this patch and buffered I/O = 1:
  read: IOPS=979k, BW=3825MiB/s (4010MB/s)(224GiB/60002msec)
  read: IOPS=983k, BW=3841MiB/s (4028MB/s)(225GiB/60003msec)
  read: IOPS=980k, BW=3828MiB/s (4014MB/s)(224GiB/60002msec)

Cc: hch@lst.de
Cc: sagi@grimberg.me
Cc: MRuijter@onestopsystems.com

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
Changes from V1:-

1. Rename use_vfs -> backend.

---
 drivers/nvme/target/configfs.c    | 42 +++++++++++++++++++++++++++++++
 drivers/nvme/target/core.c        |  7 +++++-
 drivers/nvme/target/io-cmd-bdev.c |  3 +++
 drivers/nvme/target/io-cmd-file.c | 23 ++++++++++++-----
 drivers/nvme/target/nvmet.h       |  6 +++++
 5 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index fc4c8dac87fb..500cacfc715c 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -543,6 +543,47 @@ static ssize_t nvmet_ns_buffered_io_store(struct config_item *item,
 
 CONFIGFS_ATTR(nvmet_ns_, buffered_io);
 
+static ssize_t nvmet_ns_backend_show(struct config_item *item, char *page)
+{
+	if (to_nvmet_ns(item)->backend == FILEIO)
+		return sprintf(page, "fileio\n");
+
+	return sprintf(page, "blockio\n");
+}
+
+static ssize_t nvmet_ns_backend_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	unsigned int len;
+	int ret;
+
+	mutex_lock(&ns->subsys->lock);
+	if (ns->enabled) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
+	ret = -EINVAL;
+	len = strcspn(page, "\n");
+	if (!len)
+		goto out_unlock;
+
+	if (memcmp("fileio", page, strlen("fileio")) == 0)
+		ns->backend = FILEIO;
+	else if (memcmp("blockio", page, strlen("blockio")) == 0)
+		ns->backend = BLOCKIO;
+	else
+		goto out_unlock;
+
+	ret = count;
+out_unlock:
+	mutex_unlock(&ns->subsys->lock);
+	return ret;
+}
+
+CONFIGFS_ATTR(nvmet_ns_, backend);
+
 static struct configfs_attribute *nvmet_ns_attrs[] = {
 	&nvmet_ns_attr_device_path,
 	&nvmet_ns_attr_device_nguid,
@@ -550,6 +591,7 @@ static struct configfs_attribute *nvmet_ns_attrs[] = {
 	&nvmet_ns_attr_ana_grpid,
 	&nvmet_ns_attr_enable,
 	&nvmet_ns_attr_buffered_io,
+	&nvmet_ns_attr_backend,
 #ifdef CONFIG_PCI_P2PDMA
 	&nvmet_ns_attr_p2pmem,
 #endif
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index b685f99d56a1..f32c948dac38 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -530,8 +530,13 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
 		goto out_unlock;
 
 	ret = nvmet_bdev_ns_enable(ns);
-	if (ret == -ENOTBLK)
+	if (!ret)
+		pr_info("using the blockio backend\n");
+	else if (ret == -ENOTBLK) {
 		ret = nvmet_file_ns_enable(ns);
+		if (!ret)
+			pr_info("using the fileio backend\n");
+	}
 	if (ret)
 		goto out_unlock;
 
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index ea0e596be15d..3d56d5c4a4a5 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -51,6 +51,9 @@ int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
 {
 	int ret;
 
+	if (ns->backend == FILEIO)
+		return -ENOTBLK;
+
 	ns->bdev = blkdev_get_by_path(ns->device_path,
 			FMODE_READ | FMODE_WRITE, NULL);
 	if (IS_ERR(ns->bdev)) {
diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c
index cd5670b83118..8a642cda123d 100644
--- a/drivers/nvme/target/io-cmd-file.c
+++ b/drivers/nvme/target/io-cmd-file.c
@@ -29,7 +29,9 @@ void nvmet_file_ns_disable(struct nvmet_ns *ns)
 
 int nvmet_file_ns_enable(struct nvmet_ns *ns)
 {
+	fmode_t mode = FMODE_READ | FMODE_WRITE;
 	int flags = O_RDWR | O_LARGEFILE;
+	struct block_device *bdev;
 	struct kstat stat;
 	int ret;
 
@@ -49,12 +51,21 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns)
 		goto err;
 
 	ns->size = stat.size;
-	/*
-	 * i_blkbits can be greater than the universally accepted upper bound,
-	 * so make sure we export a sane namespace lba_shift.
-	 */
-	ns->blksize_shift = min_t(u8,
-			file_inode(ns->file)->i_blkbits, 12);
+	if (ns->size == 0 && ns->backend == FILEIO) {
+		bdev = blkdev_get_by_path(ns->device_path, mode, NULL);
+		if (IS_ERR(bdev))
+			goto err;
+		ns->size = i_size_read(bdev->bd_inode);
+		ns->blksize_shift = blksize_bits(bdev_logical_block_size(bdev));
+		blkdev_put(bdev, mode);
+	} else {
+		/*
+		 * i_blkbits can be greater than the universally accepted upper
+		 * bound, so make sure we export a sane namespace lba_shift.
+		 */
+		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),
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 42ba2ddd9e96..d78d9990e513 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -50,6 +50,11 @@
 #define IPO_IATTR_CONNECT_SQE(x)	\
 	(cpu_to_le32(offsetof(struct nvmf_connect_command, x)))
 
+enum nvmet_ns_backend {
+	BLOCKIO,
+	FILEIO
+};
+
 struct nvmet_ns {
 	struct list_head	dev_link;
 	struct percpu_ref	ref;
@@ -74,6 +79,7 @@ struct nvmet_ns {
 	struct completion	disable_done;
 	mempool_t		*bvec_pool;
 	struct kmem_cache	*bvec_cache;
+	enum nvmet_ns_backend	backend;
 
 	int			use_p2pmem;
 	struct pci_dev		*p2p_dev;
-- 
2.22.1


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  reply	other threads:[~2020-02-05  1:57 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05  1:56 [PATCH 0/2] nvmet: bdev-ns buffered-io and file-ns write-through Chaitanya Kulkarni
2020-02-05  1:56 ` Chaitanya Kulkarni [this message]
2020-02-05  1:56 ` [PATCH 2/2] nvmet: add file-backed ns write-through support Chaitanya Kulkarni
2020-02-05  1:56 ` [PATCH 0/2] nvmet: bdev-ns buffered-io and file-ns write-through Chaitanya Kulkarni
2020-02-05  1:56 ` [PATCH RESEND V2 1/2] nvmet: allow block device to use buffered I/O Chaitanya Kulkarni
2020-02-05  1:56 ` [PATCH 2/2] nvmet: add file-backed ns write-through support Chaitanya Kulkarni
2020-02-05  1:59 ` [PATCH 0/2] nvmet: bdev-ns buffered-io and file-ns write-through Chaitanya Kulkarni
2020-02-05  2:01 Chaitanya Kulkarni
2020-02-05  2:01 ` [PATCH RESEND V2 1/2] nvmet: allow block device to use buffered I/O Chaitanya Kulkarni
2020-02-11 17:22   ` Sagi Grimberg
2020-02-11 17:58     ` Chaitanya Kulkarni

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