On Wed, 15 Dec 2010, Sage Weil wrote:
> From: Henry C Chang <henry_c_chang@xxxxxxxxxxxxxxxxxxx>
>
> For read operation, we have to set the argument _write_ of get_user_pages
> to 1 since we will write data to pages. Also, we need to SetPageDirty before
> releasing these pages.
I made one small change from your version (see below).
That aside, I have no idea if this patch is the right thing to do. I
thought the page bits were mainly important for the page cache... what do
we accomplish by marking user pages dirty this way?
sage
>
> Signed-off-by: Henry C Chang <henry_c_chang@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sage Weil <sage@xxxxxxxxxxxx>
> ---
> fs/ceph/file.c | 4 ++--
> include/linux/ceph/libceph.h | 3 ++-
> net/ceph/pagevec.c | 6 +++---
> 3 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index e860d8f..e0f136d 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -384,7 +384,7 @@ static ssize_t ceph_sync_read(struct file *file, char __user *data,
>
> if (file->f_flags & O_DIRECT) {
> num_pages = calc_pages_for((unsigned long)data, len);
> - pages = ceph_get_direct_page_vector(data, num_pages);
> + pages = ceph_get_direct_page_vector(data, num_pages, true);
> } else {
> num_pages = calc_pages_for(off, len);
> pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
> @@ -522,7 +522,7 @@ more:
> return -ENOMEM;
>
> if (file->f_flags & O_DIRECT) {
> - pages = ceph_get_direct_page_vector(data, num_pages);
> + pages = ceph_get_direct_page_vector(data, num_pages, false);
> if (IS_ERR(pages)) {
> ret = PTR_ERR(pages);
> goto out;
> diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
> index 9e76d35..11992e8 100644
> --- a/include/linux/ceph/libceph.h
> +++ b/include/linux/ceph/libceph.h
> @@ -227,7 +227,8 @@ extern int ceph_open_session(struct ceph_client *client);
> extern void ceph_release_page_vector(struct page **pages, int num_pages);
>
> extern struct page **ceph_get_direct_page_vector(const char __user *data,
> - int num_pages);
> + int num_pages,
> + bool write_page);
> extern void ceph_put_page_vector(struct page **pages, int num_pages);
> extern void ceph_release_page_vector(struct page **pages, int num_pages);
> extern struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags);
> diff --git a/net/ceph/pagevec.c b/net/ceph/pagevec.c
> index ac34fee..128d5ba 100644
> --- a/net/ceph/pagevec.c
> +++ b/net/ceph/pagevec.c
> @@ -13,18 +13,18 @@
> * build a vector of user pages
> */
> struct page **ceph_get_direct_page_vector(const char __user *data,
> - int num_pages)
> + int num_pages, bool write_page)
> {
> struct page **pages;
> int rc;
>
> - pages = kmalloc(sizeof(*pages) * num_pages, GFP_NOFS);
> + pages = kzalloc(sizeof(*pages) * num_pages, GFP_NOFS);
> if (!pages)
> return ERR_PTR(-ENOMEM);
>
> down_read(¤t->mm->mmap_sem);
> rc = get_user_pages(current, current->mm, (unsigned long)data,
> - num_pages, 0, 0, pages, NULL);
> + num_pages, write_page, 0, pages, NULL);
> up_read(¤t->mm->mmap_sem);
> if (rc < 0)
Your version had this as
if (rc < num_pages)
but as far as I can see get_user_pages always returns either the full
result, or nothing (the __get_user_pages fail path releases what it has so
far). Hmm, that actually means the kzalloc change isn't needed too,
right?
> goto fail;
> --
> 1.7.1
>
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