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    Subject[Patch v2 02/15] CIFS: Add support for direct pages in rdata
    Date
    From: Long Li <longli@microsoft.com>

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

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

    Signed-off-by: Long Li <longli@microsoft.com>
    ---
    fs/cifs/cifsglob.h | 2 +-
    fs/cifs/file.c | 23 ++++++++++++++++++++---
    2 files changed, 21 insertions(+), 4 deletions(-)

    diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
    index 8d16c3e..56864a87 100644
    --- a/fs/cifs/cifsglob.h
    +++ b/fs/cifs/cifsglob.h
    @@ -1179,7 +1179,7 @@ struct cifs_readdata {
    unsigned int tailsz;
    unsigned int credits;
    unsigned int nr_pages;
    - struct page *pages[];
    + struct page **pages;
    };

    struct cifs_writedata;
    diff --git a/fs/cifs/file.c b/fs/cifs/file.c
    index 23fd430..1c98293 100644
    --- a/fs/cifs/file.c
    +++ b/fs/cifs/file.c
    @@ -2880,13 +2880,13 @@ cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from)
    }

    static struct cifs_readdata *
    -cifs_readdata_alloc(unsigned int nr_pages, work_func_t complete)
    +cifs_readdata_direct_alloc(struct page **pages, work_func_t complete)
    {
    struct cifs_readdata *rdata;

    - rdata = kzalloc(sizeof(*rdata) + (sizeof(struct page *) * nr_pages),
    - GFP_KERNEL);
    + rdata = kzalloc(sizeof(*rdata), GFP_KERNEL);
    if (rdata != NULL) {
    + rdata->pages = pages;
    kref_init(&rdata->refcount);
    INIT_LIST_HEAD(&rdata->list);
    init_completion(&rdata->done);
    @@ -2896,6 +2896,22 @@ cifs_readdata_alloc(unsigned int nr_pages, work_func_t complete)
    return rdata;
    }

    +static struct cifs_readdata *
    +cifs_readdata_alloc(unsigned int nr_pages, work_func_t complete)
    +{
    + struct page **pages =
    + kzalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL);
    + struct cifs_readdata *ret = NULL;
    +
    + if (pages) {
    + ret = cifs_readdata_direct_alloc(pages, complete);
    + if (!ret)
    + kfree(pages);
    + }
    +
    + return ret;
    +}
    +
    void
    cifs_readdata_release(struct kref *refcount)
    {
    @@ -2910,6 +2926,7 @@ cifs_readdata_release(struct kref *refcount)
    if (rdata->cfile)
    cifsFileInfo_put(rdata->cfile);

    + kvfree(rdata->pages);
    kfree(rdata);
    }

    --
    2.7.4
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