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Message-Id: <20181031221311.2596-2-longli@linuxonhyperv.com>
Date: Wed, 31 Oct 2018 22:13:10 +0000
From: Long Li <longli@...uxonhyperv.com>
To: Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org
Cc: Long Li <longli@...rosoft.com>
Subject: [Patch v4 2/3] CIFS: Add support for direct I/O write
From: Long Li <longli@...rosoft.com>
With direct I/O write, user supplied buffers are pinned to the memory and data
are transferred directly from user buffers to the transport layer.
Change in v3: add support for kernel AIO
Change in v4:
Refactor common write code to __cifs_writev for direct and non-direct I/O.
Retry on direct I/O failure.
Signed-off-by: Long Li <longli@...rosoft.com>
---
fs/cifs/cifsfs.h | 1 +
fs/cifs/file.c | 194 +++++++++++++++++++++++++++++++++++++++++++------------
2 files changed, 154 insertions(+), 41 deletions(-)
diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 7fba9aa..e9c5103 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -105,6 +105,7 @@ extern ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to);
extern ssize_t cifs_direct_readv(struct kiocb *iocb, struct iov_iter *to);
extern ssize_t cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to);
extern ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from);
+extern ssize_t cifs_direct_writev(struct kiocb *iocb, struct iov_iter *from);
extern ssize_t cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from);
extern int cifs_lock(struct file *, int, struct file_lock *);
extern int cifs_fsync(struct file *, loff_t, loff_t, int);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index daab878..1a41c04 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2524,6 +2524,55 @@ wdata_fill_from_iovec(struct cifs_writedata *wdata, struct iov_iter *from,
}
static int
+cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list, struct cifs_aio_ctx *ctx)
+{
+ int wait_retry = 0;
+ unsigned int wsize, credits;
+ int rc;
+ struct TCP_Server_Info *server = tlink_tcon(wdata->cfile->tlink)->ses->server;
+
+ /*
+ * Try to resend this wdata, waiting for credits up to 3 seconds.
+ * Note: we are attempting to resend the whole wdata not in segments
+ */
+ do {
+ rc = server->ops->wait_mtu_credits(server, wdata->bytes, &wsize, &credits);
+
+ if (rc)
+ break;
+
+ if (wsize < wdata->bytes) {
+ add_credits_and_wake_if(server, credits, 0);
+ msleep(1000);
+ wait_retry++;
+ }
+ } while (wsize < wdata->bytes && wait_retry < 3);
+
+ if (wsize < wdata->bytes) {
+ rc = -EBUSY;
+ goto out;
+ }
+
+ rc = -EAGAIN;
+ while (rc == -EAGAIN)
+ if (!wdata->cfile->invalidHandle ||
+ !(rc = cifs_reopen_file(wdata->cfile, false)))
+ rc = server->ops->async_writev(wdata,
+ cifs_uncached_writedata_release);
+
+ if (!rc) {
+ list_add_tail(&wdata->list, wdata_list);
+ return 0;
+ }
+
+ add_credits_and_wake_if(server, wdata->credits, 0);
+out:
+ kref_put(&wdata->refcount, cifs_uncached_writedata_release);
+
+ return rc;
+}
+
+static int
cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
struct cifsFileInfo *open_file,
struct cifs_sb_info *cifs_sb, struct list_head *wdata_list,
@@ -2537,6 +2586,8 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
loff_t saved_offset = offset;
pid_t pid;
struct TCP_Server_Info *server;
+ struct page **pagevec;
+ size_t start;
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
pid = open_file->pid;
@@ -2553,38 +2604,74 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
if (rc)
break;
- nr_pages = get_numpages(wsize, len, &cur_len);
- wdata = cifs_writedata_alloc(nr_pages,
+ if (ctx->direct_io) {
+ cur_len = iov_iter_get_pages_alloc(
+ from, &pagevec, wsize, &start);
+ if (cur_len < 0) {
+ cifs_dbg(VFS,
+ "direct_writev couldn't get user pages "
+ "(rc=%zd) iter type %d iov_offset %zd count"
+ " %zd\n",
+ cur_len, from->type,
+ from->iov_offset, from->count);
+ dump_stack();
+ break;
+ }
+ iov_iter_advance(from, cur_len);
+
+ nr_pages = (cur_len + start + PAGE_SIZE - 1) / PAGE_SIZE;
+
+ wdata = cifs_writedata_direct_alloc(pagevec,
cifs_uncached_writev_complete);
- if (!wdata) {
- rc = -ENOMEM;
- add_credits_and_wake_if(server, credits, 0);
- break;
- }
+ if (!wdata) {
+ rc = -ENOMEM;
+ add_credits_and_wake_if(server, credits, 0);
+ break;
+ }
- rc = cifs_write_allocate_pages(wdata->pages, nr_pages);
- if (rc) {
- kfree(wdata);
- add_credits_and_wake_if(server, credits, 0);
- break;
- }
- num_pages = nr_pages;
- rc = wdata_fill_from_iovec(wdata, from, &cur_len, &num_pages);
- if (rc) {
- for (i = 0; i < nr_pages; i++)
- put_page(wdata->pages[i]);
- kfree(wdata);
- add_credits_and_wake_if(server, credits, 0);
- break;
- }
+ wdata->page_offset = start;
+ wdata->tailsz =
+ nr_pages > 1 ?
+ cur_len - (PAGE_SIZE - start) -
+ (nr_pages - 2) * PAGE_SIZE :
+ cur_len;
+ } else {
+ nr_pages = get_numpages(wsize, len, &cur_len);
+ wdata = cifs_writedata_alloc(nr_pages,
+ cifs_uncached_writev_complete);
+ if (!wdata) {
+ rc = -ENOMEM;
+ add_credits_and_wake_if(server, credits, 0);
+ break;
+ }
- /*
- * Bring nr_pages down to the number of pages we actually used,
- * and free any pages that we didn't use.
- */
- for ( ; nr_pages > num_pages; nr_pages--)
- put_page(wdata->pages[nr_pages - 1]);
+ rc = cifs_write_allocate_pages(wdata->pages, nr_pages);
+ if (rc) {
+ kfree(wdata);
+ add_credits_and_wake_if(server, credits, 0);
+ break;
+ }
+
+ num_pages = nr_pages;
+ rc = wdata_fill_from_iovec(wdata, from, &cur_len, &num_pages);
+ if (rc) {
+ for (i = 0; i < nr_pages; i++)
+ put_page(wdata->pages[i]);
+ kfree(wdata);
+ add_credits_and_wake_if(server, credits, 0);
+ break;
+ }
+
+ /*
+ * Bring nr_pages down to the number of pages we actually used,
+ * and free any pages that we didn't use.
+ */
+ for ( ; nr_pages > num_pages; nr_pages--)
+ put_page(wdata->pages[nr_pages - 1]);
+
+ wdata->tailsz = cur_len - ((nr_pages - 1) * PAGE_SIZE);
+ }
wdata->sync_mode = WB_SYNC_ALL;
wdata->nr_pages = nr_pages;
@@ -2593,7 +2680,6 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
wdata->pid = pid;
wdata->bytes = cur_len;
wdata->pagesz = PAGE_SIZE;
- wdata->tailsz = cur_len - ((nr_pages - 1) * PAGE_SIZE);
wdata->credits = credits;
wdata->ctx = ctx;
kref_get(&ctx->refcount);
@@ -2668,13 +2754,17 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
INIT_LIST_HEAD(&tmp_list);
list_del_init(&wdata->list);
- iov_iter_advance(&tmp_from,
+ if (ctx->direct_io)
+ rc = cifs_resend_wdata(wdata, &tmp_list, ctx);
+ else {
+ iov_iter_advance(&tmp_from,
wdata->offset - ctx->pos);
- rc = cifs_write_from_iter(wdata->offset,
+ rc = cifs_write_from_iter(wdata->offset,
wdata->bytes, &tmp_from,
ctx->cfile, cifs_sb, &tmp_list,
ctx);
+ }
list_splice(&tmp_list, &ctx->list);
@@ -2687,8 +2777,9 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
kref_put(&wdata->refcount, cifs_uncached_writedata_release);
}
- for (i = 0; i < ctx->npages; i++)
- put_page(ctx->bv[i].bv_page);
+ if (!ctx->direct_io)
+ for (i = 0; i < ctx->npages; i++)
+ put_page(ctx->bv[i].bv_page);
cifs_stats_bytes_written(tcon, ctx->total_len);
set_bit(CIFS_INO_INVALID_MAPPING, &CIFS_I(dentry->d_inode)->flags);
@@ -2703,7 +2794,7 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
complete(&ctx->done);
}
-ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
+static ssize_t __cifs_writev(struct kiocb *iocb, struct iov_iter *from, bool direct)
{
struct file *file = iocb->ki_filp;
ssize_t total_written = 0;
@@ -2712,13 +2803,18 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
struct cifs_sb_info *cifs_sb;
struct cifs_aio_ctx *ctx;
struct iov_iter saved_from = *from;
+ size_t len = iov_iter_count(from);
int rc;
/*
- * BB - optimize the way when signing is disabled. We can drop this
- * extra memory-to-memory copying and use iovec buffers for constructing
- * write request.
+ * iov_iter_get_pages_alloc doesn't work with ITER_KVEC.
+ * In this case, fall back to non-direct write function.
+ * this could be improved by getting pages directly in ITER_KVEC
*/
+ if (direct && from->type & ITER_KVEC) {
+ cifs_dbg(FYI, "use non-direct cifs_writev for kvec I/O\n");
+ direct = false;
+ }
rc = generic_write_checks(iocb, from);
if (rc <= 0)
@@ -2742,10 +2838,16 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
ctx->pos = iocb->ki_pos;
- rc = setup_aio_ctx_iter(ctx, from, WRITE);
- if (rc) {
- kref_put(&ctx->refcount, cifs_aio_ctx_release);
- return rc;
+ if (direct) {
+ ctx->direct_io = true;
+ ctx->iter = *from;
+ ctx->len = len;
+ } else {
+ rc = setup_aio_ctx_iter(ctx, from, WRITE);
+ if (rc) {
+ kref_put(&ctx->refcount, cifs_aio_ctx_release);
+ return rc;
+ }
}
/* grab a lock here due to read response handlers can access ctx */
@@ -2795,6 +2897,16 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
return total_written;
}
+ssize_t cifs_direct_writev(struct kiocb *iocb, struct iov_iter *from)
+{
+ return __cifs_writev(iocb, from, true);
+}
+
+ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
+{
+ return __cifs_writev(iocb, from, false);
+}
+
static ssize_t
cifs_writev(struct kiocb *iocb, struct iov_iter *from)
{
--
2.7.4
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