[v2,04/15] CIFS: Add support for direct pages in wdata

Message ID 20180530194807.31657-5-longli@linuxonhyperv.com
State New
Headers show
Series
  • CIFS: Add direct I/O support
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Commit Message

Long Li May 30, 2018, 7:47 p.m.
From: Long Li <longli@microsoft.com>

Add a function to allocate wdata without allocating pages for data
transfer. This gives the caller an option to pass a number of pages that
point to the data buffer to write to.

wdata is reponsible for free those pages after it's done.

Signed-off-by: Long Li <longli@microsoft.com>
---
 fs/cifs/cifsglob.h  |  2 +-
 fs/cifs/cifsproto.h |  2 ++
 fs/cifs/cifssmb.c   | 17 ++++++++++++++---
 3 files changed, 17 insertions(+), 4 deletions(-)

Comments

Tom Talpey June 24, 2018, 2:01 a.m. | #1
On 5/30/2018 3:47 PM, Long Li wrote:
> From: Long Li <longli@microsoft.com>
> 
> Add a function to allocate wdata without allocating pages for data
> transfer. This gives the caller an option to pass a number of pages that
> point to the data buffer to write to.
> 
> wdata is reponsible for free those pages after it's done.

Same comment as for the earlier patch. "Caller" is responsible for
"freeing" those pages? Confusing, as worded.

> 
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
>   fs/cifs/cifsglob.h  |  2 +-
>   fs/cifs/cifsproto.h |  2 ++
>   fs/cifs/cifssmb.c   | 17 ++++++++++++++---
>   3 files changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index 56864a87..7f62c98 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -1205,7 +1205,7 @@ struct cifs_writedata {
>   	unsigned int			tailsz;
>   	unsigned int			credits;
>   	unsigned int			nr_pages;
> -	struct page			*pages[];
> +	struct page			**pages;

Also same comment as for earlier patch, these are syntactically
equivalent and maybe not needed to change.

>   };
>   
>   /*
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index 1f27d8e..7933c5f 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -533,6 +533,8 @@ int cifs_async_writev(struct cifs_writedata *wdata,
>   void cifs_writev_complete(struct work_struct *work);
>   struct cifs_writedata *cifs_writedata_alloc(unsigned int nr_pages,
>   						work_func_t complete);
> +struct cifs_writedata *cifs_writedata_direct_alloc(struct page **pages,
> +						work_func_t complete);
>   void cifs_writedata_release(struct kref *refcount);
>   int cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
>   			  struct cifs_sb_info *cifs_sb,
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index c8e4278..5aca336 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -1952,6 +1952,7 @@ cifs_writedata_release(struct kref *refcount)
>   	if (wdata->cfile)
>   		cifsFileInfo_put(wdata->cfile);
>   
> +	kvfree(wdata->pages);
>   	kfree(wdata);
>   }
>   
> @@ -2075,12 +2076,22 @@ cifs_writev_complete(struct work_struct *work)
>   struct cifs_writedata *
>   cifs_writedata_alloc(unsigned int nr_pages, work_func_t complete)
>   {
> +	struct page **pages =
> +		kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);

Why do you do a GFP_NOFS here but GFP_KERNEL in the earlier patch?

> +	if (pages)
> +		return cifs_writedata_direct_alloc(pages, complete);
> +
> +	return NULL;
> +}
> +
> +struct cifs_writedata *
> +cifs_writedata_direct_alloc(struct page **pages, work_func_t complete)
> +{
>   	struct cifs_writedata *wdata;
>   
> -	/* writedata + number of page pointers */
> -	wdata = kzalloc(sizeof(*wdata) +
> -			sizeof(struct page *) * nr_pages, GFP_NOFS);
> +	wdata = kzalloc(sizeof(*wdata), GFP_NOFS);
>   	if (wdata != NULL) {
> +		wdata->pages = pages;
>   		kref_init(&wdata->refcount);
>   		INIT_LIST_HEAD(&wdata->list);
>   		init_completion(&wdata->done);
> 
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Long Li June 25, 2018, 8:34 p.m. | #2
> Subject: Re: [Patch v2 04/15] CIFS: Add support for direct pages in wdata
> 
> On 5/30/2018 3:47 PM, Long Li wrote:
> > From: Long Li <longli@microsoft.com>
> >
> > Add a function to allocate wdata without allocating pages for data
> > transfer. This gives the caller an option to pass a number of pages
> > that point to the data buffer to write to.
> >
> > wdata is reponsible for free those pages after it's done.
> 
> Same comment as for the earlier patch. "Caller" is responsible for "freeing"
> those pages? Confusing, as worded.
> 
> >
> > Signed-off-by: Long Li <longli@microsoft.com>
> > ---
> >   fs/cifs/cifsglob.h  |  2 +-
> >   fs/cifs/cifsproto.h |  2 ++
> >   fs/cifs/cifssmb.c   | 17 ++++++++++++++---
> >   3 files changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index
> > 56864a87..7f62c98 100644
> > --- a/fs/cifs/cifsglob.h
> > +++ b/fs/cifs/cifsglob.h
> > @@ -1205,7 +1205,7 @@ struct cifs_writedata {
> >   	unsigned int			tailsz;
> >   	unsigned int			credits;
> >   	unsigned int			nr_pages;
> > -	struct page			*pages[];
> > +	struct page			**pages;
> 
> Also same comment as for earlier patch, these are syntactically equivalent
> and maybe not needed to change.
> 
> >   };
> >
> >   /*
> > diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h index
> > 1f27d8e..7933c5f 100644
> > --- a/fs/cifs/cifsproto.h
> > +++ b/fs/cifs/cifsproto.h
> > @@ -533,6 +533,8 @@ int cifs_async_writev(struct cifs_writedata *wdata,
> >   void cifs_writev_complete(struct work_struct *work);
> >   struct cifs_writedata *cifs_writedata_alloc(unsigned int nr_pages,
> >   						work_func_t complete);
> > +struct cifs_writedata *cifs_writedata_direct_alloc(struct page **pages,
> > +						work_func_t complete);
> >   void cifs_writedata_release(struct kref *refcount);
> >   int cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
> >   			  struct cifs_sb_info *cifs_sb,
> > diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index
> > c8e4278..5aca336 100644
> > --- a/fs/cifs/cifssmb.c
> > +++ b/fs/cifs/cifssmb.c
> > @@ -1952,6 +1952,7 @@ cifs_writedata_release(struct kref *refcount)
> >   	if (wdata->cfile)
> >   		cifsFileInfo_put(wdata->cfile);
> >
> > +	kvfree(wdata->pages);
> >   	kfree(wdata);
> >   }
> >
> > @@ -2075,12 +2076,22 @@ cifs_writev_complete(struct work_struct
> *work)
> >   struct cifs_writedata *
> >   cifs_writedata_alloc(unsigned int nr_pages, work_func_t complete)
> >   {
> > +	struct page **pages =
> > +		kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
> 
> Why do you do a GFP_NOFS here but GFP_KERNEL in the earlier patch?

This is for the I/O write path. The earlier patch is for I/O read path. This code preserves the behavior from the buffer I/O code.

The write path is possibly used when memory is under pressure, so it's better not to call FS (and CIFS) that may result in a loop.

> 
> > +	if (pages)
> > +		return cifs_writedata_direct_alloc(pages, complete);
> > +
> > +	return NULL;
> > +}
> > +
> > +struct cifs_writedata *
> > +cifs_writedata_direct_alloc(struct page **pages, work_func_t
> > +complete) {
> >   	struct cifs_writedata *wdata;
> >
> > -	/* writedata + number of page pointers */
> > -	wdata = kzalloc(sizeof(*wdata) +
> > -			sizeof(struct page *) * nr_pages, GFP_NOFS);
> > +	wdata = kzalloc(sizeof(*wdata), GFP_NOFS);
> >   	if (wdata != NULL) {
> > +		wdata->pages = pages;
> >   		kref_init(&wdata->refcount);
> >   		INIT_LIST_HEAD(&wdata->list);
> >   		init_completion(&wdata->done);
> >
> --
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Patch

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 56864a87..7f62c98 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1205,7 +1205,7 @@  struct cifs_writedata {
 	unsigned int			tailsz;
 	unsigned int			credits;
 	unsigned int			nr_pages;
-	struct page			*pages[];
+	struct page			**pages;
 };
 
 /*
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 1f27d8e..7933c5f 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -533,6 +533,8 @@  int cifs_async_writev(struct cifs_writedata *wdata,
 void cifs_writev_complete(struct work_struct *work);
 struct cifs_writedata *cifs_writedata_alloc(unsigned int nr_pages,
 						work_func_t complete);
+struct cifs_writedata *cifs_writedata_direct_alloc(struct page **pages,
+						work_func_t complete);
 void cifs_writedata_release(struct kref *refcount);
 int cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 			  struct cifs_sb_info *cifs_sb,
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index c8e4278..5aca336 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1952,6 +1952,7 @@  cifs_writedata_release(struct kref *refcount)
 	if (wdata->cfile)
 		cifsFileInfo_put(wdata->cfile);
 
+	kvfree(wdata->pages);
 	kfree(wdata);
 }
 
@@ -2075,12 +2076,22 @@  cifs_writev_complete(struct work_struct *work)
 struct cifs_writedata *
 cifs_writedata_alloc(unsigned int nr_pages, work_func_t complete)
 {
+	struct page **pages =
+		kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
+	if (pages)
+		return cifs_writedata_direct_alloc(pages, complete);
+
+	return NULL;
+}
+
+struct cifs_writedata *
+cifs_writedata_direct_alloc(struct page **pages, work_func_t complete)
+{
 	struct cifs_writedata *wdata;
 
-	/* writedata + number of page pointers */
-	wdata = kzalloc(sizeof(*wdata) +
-			sizeof(struct page *) * nr_pages, GFP_NOFS);
+	wdata = kzalloc(sizeof(*wdata), GFP_NOFS);
 	if (wdata != NULL) {
+		wdata->pages = pages;
 		kref_init(&wdata->refcount);
 		INIT_LIST_HEAD(&wdata->list);
 		init_completion(&wdata->done);