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nvmet: add buffered I/O support for file backed ns

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Add a new "buffered_io" attribute, which disabled direct I/O and thus
enables page cache based caching when enabled.   The attribute can only
be changed when the namespace is disabled as the file has to be reopend
for the change to take effect.

The possibly blocking read/write are deferred to a newly introduced
global workqueue.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Chaitanya Kulkarni
2018-06-20 00:01:41 -04:00
committed by Christoph Hellwig
parent 0866bf0c37
commit 55eb942eda
4 changed files with 67 additions and 5 deletions
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31
drivers/nvme/target/io-cmd-file.c
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@@ -16,6 +16,8 @@
void nvmet_file_ns_disable(struct nvmet_ns *ns)
{
if (ns->file) {
if (ns->buffered_io)
flush_workqueue(buffered_io_wq);
mempool_destroy(ns->bvec_pool);
ns->bvec_pool = NULL;
kmem_cache_destroy(ns->bvec_cache);
@@ -27,11 +29,14 @@ void nvmet_file_ns_disable(struct nvmet_ns *ns)
int nvmet_file_ns_enable(struct nvmet_ns *ns)
{
int ret;
int flags = O_RDWR | O_LARGEFILE;
struct kstat stat;
int ret;
ns->file = filp_open(ns->device_path,
O_RDWR | O_LARGEFILE | O_DIRECT, 0);
if (!ns->buffered_io)
flags |= O_DIRECT;
ns->file = filp_open(ns->device_path, flags, 0);
if (IS_ERR(ns->file)) {
pr_err("failed to open file %s: (%ld)\n",
ns->device_path, PTR_ERR(ns->file));
@@ -100,7 +105,7 @@ static ssize_t nvmet_file_submit_bvec(struct nvmet_req *req, loff_t pos,
iocb->ki_pos = pos;
iocb->ki_filp = req->ns->file;
iocb->ki_flags = IOCB_DIRECT | ki_flags;
iocb->ki_flags = ki_flags | iocb_flags(req->ns->file);
ret = call_iter(iocb, &iter);
@@ -189,6 +194,19 @@ out:
nvmet_file_submit_bvec(req, pos, bv_cnt, total_len);
}
static void nvmet_file_buffered_io_work(struct work_struct *w)
{
struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);
nvmet_file_execute_rw(req);
}
static void nvmet_file_execute_rw_buffered_io(struct nvmet_req *req)
{
INIT_WORK(&req->f.work, nvmet_file_buffered_io_work);
queue_work(buffered_io_wq, &req->f.work);
}
static void nvmet_file_flush_work(struct work_struct *w)
{
struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);
@@ -280,7 +298,10 @@ u16 nvmet_file_parse_io_cmd(struct nvmet_req *req)
switch (cmd->common.opcode) {
case nvme_cmd_read:
case nvme_cmd_write:
req->execute = nvmet_file_execute_rw;
if (req->ns->buffered_io)
req->execute = nvmet_file_execute_rw_buffered_io;
else
req->execute = nvmet_file_execute_rw;
req->data_len = nvmet_rw_len(req);
return 0;
case nvme_cmd_flush: