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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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