Re: [PATCH 03/15] mm: Add file_offset_of_ helpers
On Thu, Sep 26, 2019 at 05:02:11PM +0300, Kirill A. Shutemov wrote:
> On Tue, Sep 24, 2019 at 05:52:02PM -0700, Matthew Wilcox wrote:
> > From: "Matthew Wilcox (Oracle)"
> >
> > The page_offset function is badly named for people reading the functions
> > which call it. The natural meaning of a function with this name would
> > be 'offset within a page', not 'page offset in bytes within a file'.
> > Dave Chinner suggests file_offset_of_page() as a replacement function
> > name and I'm also adding file_offset_of_next_page() as a helper for the
> > large page work. Also add kernel-doc for these functions so they show
> > up in the kernel API book.
> >
> > page_offset() is retained as a compatibility define for now.
>
> This should be trivial for coccinelle, right?
Yes, should be. I'd prefer not to do conversions for now to minimise
conflicts when rebasing.
> > +static inline loff_t file_offset_of_next_page(struct page *page)
> > +{
> > + return ((loff_t)page->index + compound_nr(page)) << PAGE_SHIFT;
>
> Wouldn't it be more readable as
>
> return file_offset_of_page(page) + page_size(page);
>
> ?
Good idea. I'll fix that up.
Re: [PATCH 03/15] mm: Add file_offset_of_ helpers
Your mail program is still broken. This shows up as a reply to the 0/15
email instead of as a reply to the 3/15 email.
On Wed, Oct 02, 2019 at 09:07:53PM +0800, Hillf Danton wrote:
> On Tue, 24 Sep 2019 17:52:02 -0700 From: Matthew Wilcox (Oracle)
> > +/**
> > + * file_offset_of_page - File offset of this page.
> > + * @page: Page cache page.
> > + *
> > + * Context: Any context.
> > + * Return: The offset of the first byte of this page.
> > */
> > -static inline loff_t page_offset(struct page *page)
> > +static inline loff_t file_offset_of_page(struct page *page)
> > {
> > return ((loff_t)page->index) << PAGE_SHIFT;
> > }
> >
> > static inline loff_t page_file_offset(struct page *page)
> > {
> > return ((loff_t)page_index(page)) << PAGE_SHIFT;
>
> Would you like to specify the need to build a moon on the moon,
> with another name though?
I have no idea what you mean. Is this an idiom in your native language,
perhaps?
Re: [PATCH 03/15] mm: Add file_offset_of_ helpers
On Tue, Sep 24, 2019 at 05:52:02PM -0700, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)"
>
> The page_offset function is badly named for people reading the functions
> which call it. The natural meaning of a function with this name would
> be 'offset within a page', not 'page offset in bytes within a file'.
> Dave Chinner suggests file_offset_of_page() as a replacement function
> name and I'm also adding file_offset_of_next_page() as a helper for the
> large page work. Also add kernel-doc for these functions so they show
> up in the kernel API book.
>
> page_offset() is retained as a compatibility define for now.
This should be trivial for coccinelle, right?
> ---
> drivers/net/ethernet/ibm/ibmveth.c | 2 --
> include/linux/pagemap.h| 25 ++---
> 2 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/ibm/ibmveth.c
> b/drivers/net/ethernet/ibm/ibmveth.c
> index c5be4ebd8437..bf98aeaf9a45 100644
> --- a/drivers/net/ethernet/ibm/ibmveth.c
> +++ b/drivers/net/ethernet/ibm/ibmveth.c
> @@ -978,8 +978,6 @@ static int ibmveth_ioctl(struct net_device *dev, struct
> ifreq *ifr, int cmd)
> return -EOPNOTSUPP;
> }
>
> -#define page_offset(v) ((unsigned long)(v) & ((1 << 12) - 1))
> -
> static int ibmveth_send(struct ibmveth_adapter *adapter,
> union ibmveth_buf_desc *descs, unsigned long mss)
> {
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 750770a2c685..103205494ea0 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -428,14 +428,33 @@ static inline pgoff_t page_to_pgoff(struct page *page)
> return page_to_index(page);
> }
>
> -/*
> - * Return byte-offset into filesystem object for page.
> +/**
> + * file_offset_of_page - File offset of this page.
> + * @page: Page cache page.
> + *
> + * Context: Any context.
> + * Return: The offset of the first byte of this page.
> */
> -static inline loff_t page_offset(struct page *page)
> +static inline loff_t file_offset_of_page(struct page *page)
> {
> return ((loff_t)page->index) << PAGE_SHIFT;
> }
>
> +/* Legacy; please convert callers */
> +#define page_offset(page)file_offset_of_page(page)
> +
> +/**
> + * file_offset_of_next_page - File offset of the next page.
> + * @page: Page cache page.
> + *
> + * Context: Any context.
> + * Return: The offset of the first byte after this page.
> + */
> +static inline loff_t file_offset_of_next_page(struct page *page)
> +{
> + return ((loff_t)page->index + compound_nr(page)) << PAGE_SHIFT;
Wouldn't it be more readable as
return file_offset_of_page(page) + page_size(page);
?
> +}
> +
> static inline loff_t page_file_offset(struct page *page)
> {
> return ((loff_t)page_index(page)) << PAGE_SHIFT;
> --
> 2.23.0
>
>
--
Kirill A. Shutemov
[PATCH 03/15] mm: Add file_offset_of_ helpers
From: "Matthew Wilcox (Oracle)"
The page_offset function is badly named for people reading the functions
which call it. The natural meaning of a function with this name would
be 'offset within a page', not 'page offset in bytes within a file'.
Dave Chinner suggests file_offset_of_page() as a replacement function
name and I'm also adding file_offset_of_next_page() as a helper for the
large page work. Also add kernel-doc for these functions so they show
up in the kernel API book.
page_offset() is retained as a compatibility define for now.
---
drivers/net/ethernet/ibm/ibmveth.c | 2 --
include/linux/pagemap.h| 25 ++---
2 files changed, 22 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/ibm/ibmveth.c
b/drivers/net/ethernet/ibm/ibmveth.c
index c5be4ebd8437..bf98aeaf9a45 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -978,8 +978,6 @@ static int ibmveth_ioctl(struct net_device *dev, struct
ifreq *ifr, int cmd)
return -EOPNOTSUPP;
}
-#define page_offset(v) ((unsigned long)(v) & ((1 << 12) - 1))
-
static int ibmveth_send(struct ibmveth_adapter *adapter,
union ibmveth_buf_desc *descs, unsigned long mss)
{
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 750770a2c685..103205494ea0 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -428,14 +428,33 @@ static inline pgoff_t page_to_pgoff(struct page *page)
return page_to_index(page);
}
-/*
- * Return byte-offset into filesystem object for page.
+/**
+ * file_offset_of_page - File offset of this page.
+ * @page: Page cache page.
+ *
+ * Context: Any context.
+ * Return: The offset of the first byte of this page.
*/
-static inline loff_t page_offset(struct page *page)
+static inline loff_t file_offset_of_page(struct page *page)
{
return ((loff_t)page->index) << PAGE_SHIFT;
}
+/* Legacy; please convert callers */
+#define page_offset(page) file_offset_of_page(page)
+
+/**
+ * file_offset_of_next_page - File offset of the next page.
+ * @page: Page cache page.
+ *
+ * Context: Any context.
+ * Return: The offset of the first byte after this page.
+ */
+static inline loff_t file_offset_of_next_page(struct page *page)
+{
+ return ((loff_t)page->index + compound_nr(page)) << PAGE_SHIFT;
+}
+
static inline loff_t page_file_offset(struct page *page)
{
return ((loff_t)page_index(page)) << PAGE_SHIFT;
--
2.23.0
