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