Re: [PATCH v2 01/28] csky,sparc: Declare flush_dcache_folio()
From: Christoph Hellwig <hch@infradead.org>
Date: 2021-11-16 06:38:22
Also in:
linux-fsdevel, linux-xfs, lkml
Subsystem:
arm port, c-sky architecture, filesystems (vfs and infrastructure), filesystems [iomap], generic include/asm header files, m68k architecture, memory management, memory management - core, mips, nios2 architecture, parisc architecture, sparc + ultrasparc (sparc/sparc64), superh, synopsys arc architecture, tensilica xtensa port (xtensa), the rest · Maintainers:
Russell King, Guo Ren, Alexander Viro, Christian Brauner, Arnd Bergmann, Geert Uytterhoeven, Andrew Morton, David Hildenbrand, Thomas Bogendoerfer, Dinh Nguyen, Simon Schuster, "James E.J. Bottomley", Helge Deller, "David S. Miller", Andreas Larsson, Yoshinori Sato, Rich Felker, John Paul Adrian Glaubitz, Vineet Gupta, Chris Zankel, Max Filippov, Linus Torvalds
On Mon, Nov 15, 2021 at 03:54:47PM +0000, Matthew Wilcox wrote:
There are three ways to implement flush_dcache_folio(). The first is as a noop (this is what xtensa does, which is the only architecture to define ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO; it's also done automatically by asm-generic if the architecture doesn't define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE). The second is as a loop which calls flush_dcache_page() for each page in the folio. That's the default implementation which you found in mm/util.c. The third way, which I hope architecture maintainers actually implement, is to just set the needs-flush bit on the head page. But that requires knowledge of each architecture; they need to check the needs-flush bit on the head page instead of the precise page. So I've done the safe, slow thing for all architectures. The only reason that csky and sparc are "special" is that they don't include asm-generic/cacheflush.h and the buildbots didn't catch that before the merge window. I'm doing the exact same thing for csky and sparc that I did for arc/arm/m68k/mips/nds32/nios2/parisc/sh. Nothing more, nothing less.
I see how this works no, but it is pretty horrible. Why not something simple like the patch below? If/when an architecture actually wants to override flush_dcache_folio we can find out how to best do it:
diff --git a/arch/arc/include/asm/cacheflush.h b/arch/arc/include/asm/cacheflush.h
index e8c2c7469e107..e201b4b1655af 100644
--- a/arch/arc/include/asm/cacheflush.h
+++ b/arch/arc/include/asm/cacheflush.h@@ -36,7 +36,6 @@ void __flush_dcache_page(phys_addr_t paddr, unsigned long vaddr); #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 void flush_dcache_page(struct page *page); -void flush_dcache_folio(struct folio *folio); void dma_cache_wback_inv(phys_addr_t start, unsigned long sz); void dma_cache_inv(phys_addr_t start, unsigned long sz);
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index e68fb879e4f9d..5e56288e343bb 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h@@ -290,7 +290,6 @@ extern void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr */ #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 extern void flush_dcache_page(struct page *); -void flush_dcache_folio(struct folio *folio); #define ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE 1 static inline void flush_kernel_vmap_range(void *addr, int size)
diff --git a/arch/csky/abiv1/inc/abi/cacheflush.h b/arch/csky/abiv1/inc/abi/cacheflush.h
index 432aef1f1dc23..ed62e2066ba76 100644
--- a/arch/csky/abiv1/inc/abi/cacheflush.h
+++ b/arch/csky/abiv1/inc/abi/cacheflush.h@@ -9,7 +9,6 @@ #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 extern void flush_dcache_page(struct page *); -void flush_dcache_folio(struct folio *folio); #define flush_cache_mm(mm) dcache_wbinv_all() #define flush_cache_page(vma, page, pfn) cache_wbinv_all()
diff --git a/arch/csky/abiv2/inc/abi/cacheflush.h b/arch/csky/abiv2/inc/abi/cacheflush.h
index 7e8bef60958c6..a565e00c3f70b 100644
--- a/arch/csky/abiv2/inc/abi/cacheflush.h
+++ b/arch/csky/abiv2/inc/abi/cacheflush.h@@ -25,8 +25,6 @@ static inline void flush_dcache_page(struct page *page) clear_bit(PG_dcache_clean, &page->flags); } -void flush_dcache_folio(struct folio *folio); - #define flush_dcache_mmap_lock(mapping) do { } while (0) #define flush_dcache_mmap_unlock(mapping) do { } while (0) #define flush_icache_page(vma, page) do { } while (0)
diff --git a/arch/m68k/include/asm/cacheflush_mm.h b/arch/m68k/include/asm/cacheflush_mm.h
index 8ab46625ddd32..1ac55e7b47f01 100644
--- a/arch/m68k/include/asm/cacheflush_mm.h
+++ b/arch/m68k/include/asm/cacheflush_mm.h@@ -250,7 +250,6 @@ static inline void __flush_page_to_ram(void *vaddr) #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 #define flush_dcache_page(page) __flush_page_to_ram(page_address(page)) -void flush_dcache_folio(struct folio *folio); #define flush_dcache_mmap_lock(mapping) do { } while (0) #define flush_dcache_mmap_unlock(mapping) do { } while (0) #define flush_icache_page(vma, page) __flush_page_to_ram(page_address(page))
diff --git a/arch/mips/include/asm/cacheflush.h b/arch/mips/include/asm/cacheflush.h
index f207388541d50..b3dc9c589442a 100644
--- a/arch/mips/include/asm/cacheflush.h
+++ b/arch/mips/include/asm/cacheflush.h@@ -61,8 +61,6 @@ static inline void flush_dcache_page(struct page *page) SetPageDcacheDirty(page); } -void flush_dcache_folio(struct folio *folio); - #define flush_dcache_mmap_lock(mapping) do { } while (0) #define flush_dcache_mmap_unlock(mapping) do { } while (0)
diff --git a/arch/nds32/include/asm/cacheflush.h b/arch/nds32/include/asm/cacheflush.h
index 3fc0bb7d6487c..c2a222ebfa2af 100644
--- a/arch/nds32/include/asm/cacheflush.h
+++ b/arch/nds32/include/asm/cacheflush.h@@ -27,7 +27,6 @@ void flush_cache_vunmap(unsigned long start, unsigned long end); #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 void flush_dcache_page(struct page *page); -void flush_dcache_folio(struct folio *folio); void copy_to_user_page(struct vm_area_struct *vma, struct page *page, unsigned long vaddr, void *dst, void *src, int len); void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
diff --git a/arch/nios2/include/asm/cacheflush.h b/arch/nios2/include/asm/cacheflush.h
index 1999561b22aa5..d0b71dd712872 100644
--- a/arch/nios2/include/asm/cacheflush.h
+++ b/arch/nios2/include/asm/cacheflush.h@@ -29,7 +29,6 @@ extern void flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long pfn); #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 void flush_dcache_page(struct page *page); -void flush_dcache_folio(struct folio *folio); extern void flush_icache_range(unsigned long start, unsigned long end); extern void flush_icache_page(struct vm_area_struct *vma, struct page *page);
diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index da0cd4b3a28f2..859b8a34adcfb 100644
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h@@ -50,7 +50,6 @@ void invalidate_kernel_vmap_range(void *vaddr, int size); #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 void flush_dcache_page(struct page *page); -void flush_dcache_folio(struct folio *folio); #define flush_dcache_mmap_lock(mapping) xa_lock_irq(&mapping->i_pages) #define flush_dcache_mmap_unlock(mapping) xa_unlock_irq(&mapping->i_pages)
diff --git a/arch/sh/include/asm/cacheflush.h b/arch/sh/include/asm/cacheflush.h
index c7a97f32432fb..481a664287e2e 100644
--- a/arch/sh/include/asm/cacheflush.h
+++ b/arch/sh/include/asm/cacheflush.h@@ -43,7 +43,6 @@ extern void flush_cache_range(struct vm_area_struct *vma, unsigned long start, unsigned long end); #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 void flush_dcache_page(struct page *page); -void flush_dcache_folio(struct folio *folio); extern void flush_icache_range(unsigned long start, unsigned long end); #define flush_icache_user_range flush_icache_range extern void flush_icache_page(struct vm_area_struct *vma,
diff --git a/arch/sparc/include/asm/cacheflush_32.h b/arch/sparc/include/asm/cacheflush_32.h
index 9991c18f4980c..41c6d734a4741 100644
--- a/arch/sparc/include/asm/cacheflush_32.h
+++ b/arch/sparc/include/asm/cacheflush_32.h@@ -37,7 +37,6 @@ void sparc_flush_page_to_ram(struct page *page); -void flush_dcache_folio(struct folio *folio); #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 #define flush_dcache_page(page) sparc_flush_page_to_ram(page) #define flush_dcache_mmap_lock(mapping) do { } while (0)
diff --git a/arch/sparc/include/asm/cacheflush_64.h b/arch/sparc/include/asm/cacheflush_64.h
index 9ab59a73c28b1..b9341836597ec 100644
--- a/arch/sparc/include/asm/cacheflush_64.h
+++ b/arch/sparc/include/asm/cacheflush_64.h@@ -47,7 +47,6 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page); void __flush_dcache_range(unsigned long start, unsigned long end); #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 void flush_dcache_page(struct page *page); -void flush_dcache_folio(struct folio *folio); #define flush_icache_page(vma, pg) do { } while(0)
diff --git a/arch/xtensa/include/asm/cacheflush.h b/arch/xtensa/include/asm/cacheflush.h
index a8a041609c5d0..7b4359312c257 100644
--- a/arch/xtensa/include/asm/cacheflush.h
+++ b/arch/xtensa/include/asm/cacheflush.h@@ -121,7 +121,6 @@ void flush_cache_page(struct vm_area_struct*, #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1 void flush_dcache_page(struct page *); -void flush_dcache_folio(struct folio *); void local_flush_cache_range(struct vm_area_struct *vma, unsigned long start, unsigned long end);
@@ -138,9 +137,7 @@ void local_flush_cache_page(struct vm_area_struct *vma, #define flush_cache_vunmap(start,end) do { } while (0) #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0 -#define ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO #define flush_dcache_page(page) do { } while (0) -static inline void flush_dcache_folio(struct folio *folio) { } #define flush_icache_range local_flush_icache_range #define flush_cache_page(vma, addr, pfn) do { } while (0)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 265c7f8e71342..218df77641802 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c@@ -4,6 +4,7 @@ * Copyright (C) 2016-2019 Christoph Hellwig. */ #include <linux/module.h> +#include <linux/cacheflush.h> #include <linux/compiler.h> #include <linux/fs.h> #include <linux/iomap.h>
@@ -658,6 +659,7 @@ static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len, size_t copied, struct folio *folio) { struct iomap_page *iop = to_iomap_page(folio); + flush_dcache_folio(folio); /*
diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h
index fedc0dfa4877c..eeaea7bd97bbf 100644
--- a/include/asm-generic/cacheflush.h
+++ b/include/asm-generic/cacheflush.h@@ -49,14 +49,7 @@ static inline void flush_cache_page(struct vm_area_struct *vma, static inline void flush_dcache_page(struct page *page) { } - -static inline void flush_dcache_folio(struct folio *folio) { } #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0 -#define ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO -#endif - -#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO -void flush_dcache_folio(struct folio *folio); #endif #ifndef flush_dcache_mmap_lock
diff --git a/include/linux/cacheflush.h b/include/linux/cacheflush.h
new file mode 100644
index 0000000000000..c28359bac8aa5
--- /dev/null
+++ b/include/linux/cacheflush.h@@ -0,0 +1,15 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CACHEFLUSH_H +#define _LINUX_CACHEFLUSH_H + +#include <asm/cacheflush.h> + +#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE +void flush_dcache_folio(struct folio *folio); +#else +static inline void flush_dcache_folio(struct folio *folio) +{ +} +#endif /* ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE */ + +#endif /* _LINUX_CACHEFLUSH_H */
diff --git a/mm/util.c b/mm/util.c
index e58151a612555..61ffa71adb644 100644
--- a/mm/util.c
+++ b/mm/util.c@@ -1090,7 +1090,7 @@ void page_offline_end(void) } EXPORT_SYMBOL(page_offline_end); -#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO +#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE void flush_dcache_folio(struct folio *folio) { long i, nr = folio_nr_pages(folio);
@@ -1098,5 +1098,4 @@ void flush_dcache_folio(struct folio *folio) for (i = 0; i < nr; i++) flush_dcache_page(folio_page(folio, i)); } -EXPORT_SYMBOL(flush_dcache_folio); #endif