[Patch v2 02/15] CIFS: Add support for direct pages in rdata

From: Long Li
Date: Wed May 30 2018 - 15:53:38 EST


From: Long Li <longli@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
---
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