| Message ID | 1670381359-53-1-git-send-email-ruansy.fnst@fujitsu.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2.2,1/8] fsdax: introduce page->share for fsdax in reflink mode | expand |
On Wed, Dec 07, 2022 at 02:49:19AM +0000, Shiyang Ruan wrote: > fsdax page is used not only when CoW, but also mapread. To make the it > easily understood, use 'share' to indicate that the dax page is shared > by more than one extent. And add helper functions to use it. > > Also, the flag needs to be renamed to PAGE_MAPPING_DAX_SHARED. > > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> > Reviewed-by: Allison Henderson <allison.henderson@oracle.com> Looks fine to me, Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > --- > fs/dax.c | 38 ++++++++++++++++++++++---------------- > include/linux/mm_types.h | 5 ++++- > include/linux/page-flags.h | 2 +- > 3 files changed, 27 insertions(+), 18 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 1c6867810cbd..84fadea08705 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -334,35 +334,41 @@ static unsigned long dax_end_pfn(void *entry) > for (pfn = dax_to_pfn(entry); \ > pfn < dax_end_pfn(entry); pfn++) > > -static inline bool dax_mapping_is_cow(struct address_space *mapping) > +static inline bool dax_page_is_shared(struct page *page) > { > - return (unsigned long)mapping == PAGE_MAPPING_DAX_COW; > + return page->mapping == PAGE_MAPPING_DAX_SHARED; > } > > /* > - * Set the page->mapping with FS_DAX_MAPPING_COW flag, increase the refcount. > + * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the > + * refcount. > */ > -static inline void dax_mapping_set_cow(struct page *page) > +static inline void dax_page_share_get(struct page *page) > { > - if ((uintptr_t)page->mapping != PAGE_MAPPING_DAX_COW) { > + if (page->mapping != PAGE_MAPPING_DAX_SHARED) { > /* > * Reset the index if the page was already mapped > * regularly before. > */ > if (page->mapping) > - page->index = 1; > - page->mapping = (void *)PAGE_MAPPING_DAX_COW; > + page->share = 1; > + page->mapping = PAGE_MAPPING_DAX_SHARED; > } > - page->index++; > + page->share++; > +} > + > +static inline unsigned long dax_page_share_put(struct page *page) > +{ > + return --page->share; > } > > /* > - * When it is called in dax_insert_entry(), the cow flag will indicate that > + * When it is called in dax_insert_entry(), the shared flag will indicate that > * whether this entry is shared by multiple files. If so, set the page->mapping > - * FS_DAX_MAPPING_COW, and use page->index as refcount. > + * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount. > */ > static void dax_associate_entry(void *entry, struct address_space *mapping, > - struct vm_area_struct *vma, unsigned long address, bool cow) > + struct vm_area_struct *vma, unsigned long address, bool shared) > { > unsigned long size = dax_entry_size(entry), pfn, index; > int i = 0; > @@ -374,8 +380,8 @@ static void dax_associate_entry(void *entry, struct address_space *mapping, > for_each_mapped_pfn(entry, pfn) { > struct page *page = pfn_to_page(pfn); > > - if (cow) { > - dax_mapping_set_cow(page); > + if (shared) { > + dax_page_share_get(page); > } else { > WARN_ON_ONCE(page->mapping); > page->mapping = mapping; > @@ -396,9 +402,9 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, > struct page *page = pfn_to_page(pfn); > > WARN_ON_ONCE(trunc && page_ref_count(page) > 1); > - if (dax_mapping_is_cow(page->mapping)) { > - /* keep the CoW flag if this page is still shared */ > - if (page->index-- > 0) > + if (dax_page_is_shared(page)) { > + /* keep the shared flag if this page is still shared */ > + if (dax_page_share_put(page) > 0) > continue; > } else > WARN_ON_ONCE(page->mapping && page->mapping != mapping); > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 500e536796ca..f46cac3657ad 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -103,7 +103,10 @@ struct page { > }; > /* See page-flags.h for PAGE_MAPPING_FLAGS */ > struct address_space *mapping; > - pgoff_t index; /* Our offset within mapping. */ > + union { > + pgoff_t index; /* Our offset within mapping. */ > + unsigned long share; /* share count for fsdax */ > + }; > /** > * @private: Mapping-private opaque data. > * Usually used for buffer_heads if PagePrivate. > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index 0b0ae5084e60..d8e94f2f704a 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -641,7 +641,7 @@ PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted) > * Different with flags above, this flag is used only for fsdax mode. It > * indicates that this page->mapping is now under reflink case. > */ > -#define PAGE_MAPPING_DAX_COW 0x1 > +#define PAGE_MAPPING_DAX_SHARED ((void *)0x1) > > static __always_inline bool folio_mapping_flags(struct folio *folio) > { > -- > 2.38.1 >
diff --git a/fs/dax.c b/fs/dax.c index 1c6867810cbd..84fadea08705 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -334,35 +334,41 @@ static unsigned long dax_end_pfn(void *entry) for (pfn = dax_to_pfn(entry); \ pfn < dax_end_pfn(entry); pfn++) -static inline bool dax_mapping_is_cow(struct address_space *mapping) +static inline bool dax_page_is_shared(struct page *page) { - return (unsigned long)mapping == PAGE_MAPPING_DAX_COW; + return page->mapping == PAGE_MAPPING_DAX_SHARED; } /* - * Set the page->mapping with FS_DAX_MAPPING_COW flag, increase the refcount. + * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the + * refcount. */ -static inline void dax_mapping_set_cow(struct page *page) +static inline void dax_page_share_get(struct page *page) { - if ((uintptr_t)page->mapping != PAGE_MAPPING_DAX_COW) { + if (page->mapping != PAGE_MAPPING_DAX_SHARED) { /* * Reset the index if the page was already mapped * regularly before. */ if (page->mapping) - page->index = 1; - page->mapping = (void *)PAGE_MAPPING_DAX_COW; + page->share = 1; + page->mapping = PAGE_MAPPING_DAX_SHARED; } - page->index++; + page->share++; +} + +static inline unsigned long dax_page_share_put(struct page *page) +{ + return --page->share; } /* - * When it is called in dax_insert_entry(), the cow flag will indicate that + * When it is called in dax_insert_entry(), the shared flag will indicate that * whether this entry is shared by multiple files. If so, set the page->mapping - * FS_DAX_MAPPING_COW, and use page->index as refcount. + * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount. */ static void dax_associate_entry(void *entry, struct address_space *mapping, - struct vm_area_struct *vma, unsigned long address, bool cow) + struct vm_area_struct *vma, unsigned long address, bool shared) { unsigned long size = dax_entry_size(entry), pfn, index; int i = 0; @@ -374,8 +380,8 @@ static void dax_associate_entry(void *entry, struct address_space *mapping, for_each_mapped_pfn(entry, pfn) { struct page *page = pfn_to_page(pfn); - if (cow) { - dax_mapping_set_cow(page); + if (shared) { + dax_page_share_get(page); } else { WARN_ON_ONCE(page->mapping); page->mapping = mapping; @@ -396,9 +402,9 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, struct page *page = pfn_to_page(pfn); WARN_ON_ONCE(trunc && page_ref_count(page) > 1); - if (dax_mapping_is_cow(page->mapping)) { - /* keep the CoW flag if this page is still shared */ - if (page->index-- > 0) + if (dax_page_is_shared(page)) { + /* keep the shared flag if this page is still shared */ + if (dax_page_share_put(page) > 0) continue; } else WARN_ON_ONCE(page->mapping && page->mapping != mapping); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 500e536796ca..f46cac3657ad 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -103,7 +103,10 @@ struct page { }; /* See page-flags.h for PAGE_MAPPING_FLAGS */ struct address_space *mapping; - pgoff_t index; /* Our offset within mapping. */ + union { + pgoff_t index; /* Our offset within mapping. */ + unsigned long share; /* share count for fsdax */ + }; /** * @private: Mapping-private opaque data. * Usually used for buffer_heads if PagePrivate. diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 0b0ae5084e60..d8e94f2f704a 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -641,7 +641,7 @@ PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted) * Different with flags above, this flag is used only for fsdax mode. It * indicates that this page->mapping is now under reflink case. */ -#define PAGE_MAPPING_DAX_COW 0x1 +#define PAGE_MAPPING_DAX_SHARED ((void *)0x1) static __always_inline bool folio_mapping_flags(struct folio *folio) {