From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 19:20:30 -0300 Subject: netfs: zero the tail of a short DIO/unbuffered read The buffered read collector zero-fills the tail of a short read that stops below the inode's i_size (netfs_clear_unread()), so a read that races an extending write still returns the expected number of bytes. The non-buffered collector path does no such thing: it just records how much was transferred. Add the same zero-fill for the non-buffered case, gated on NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short result from it is known to be safe to treat as a hole, as opposed to NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of the file and should be reported short as-is. Only CLEAR_TAIL should zero-fill here; a real EOF must stay a real short read. No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest, so this is inert on its own -- a following change teaches cifs to set it in the one case that needs it. Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- include/asm-generic/cacheflush.h | 127 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 127 insertions(+) create mode 100644 include/asm-generic/cacheflush.h (limited to 'include/asm-generic/cacheflush.h') diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h new file mode 100644 index 000000000..7ee8a179d --- /dev/null +++ b/include/asm-generic/cacheflush.h @@ -0,0 +1,127 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_GENERIC_CACHEFLUSH_H +#define _ASM_GENERIC_CACHEFLUSH_H + +#include + +struct mm_struct; +struct vm_area_struct; +struct page; +struct address_space; + +/* + * The cache doesn't need to be flushed when TLB entries change when + * the cache is mapped to physical memory, not virtual memory + */ +#ifndef flush_cache_all +static inline void flush_cache_all(void) +{ +} +#endif + +#ifndef flush_cache_mm +static inline void flush_cache_mm(struct mm_struct *mm) +{ +} +#endif + +#ifndef flush_cache_dup_mm +static inline void flush_cache_dup_mm(struct mm_struct *mm) +{ +} +#endif + +#ifndef flush_cache_range +static inline void flush_cache_range(struct vm_area_struct *vma, + unsigned long start, + unsigned long end) +{ +} +#endif + +#ifndef flush_cache_page +static inline void flush_cache_page(struct vm_area_struct *vma, + unsigned long vmaddr, + unsigned long pfn) +{ +} +#endif + +#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE +static inline void flush_dcache_page(struct page *page) +{ +} + +#define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0 +#endif + +#ifndef flush_dcache_mmap_lock +static inline void flush_dcache_mmap_lock(struct address_space *mapping) +{ +} +#endif + +#ifndef flush_dcache_mmap_unlock +static inline void flush_dcache_mmap_unlock(struct address_space *mapping) +{ +} +#endif + +#ifndef flush_icache_range +static inline void flush_icache_range(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef flush_icache_user_range +#define flush_icache_user_range flush_icache_range +#endif + +#ifndef flush_icache_user_page +static inline void flush_icache_user_page(struct vm_area_struct *vma, + struct page *page, + unsigned long addr, int len) +{ +} +#endif + +#ifndef flush_cache_vmap +static inline void flush_cache_vmap(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef flush_cache_vmap_early +static inline void flush_cache_vmap_early(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef flush_cache_vunmap +static inline void flush_cache_vunmap(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef copy_to_user_page +#define copy_to_user_page(vma, page, vaddr, dst, src, len) \ + do { \ + instrument_copy_to_user((void __user *)dst, src, len); \ + memcpy(dst, src, len); \ + flush_icache_user_page(vma, page, vaddr, len); \ + } while (0) +#endif + + +#ifndef copy_from_user_page +#define copy_from_user_page(vma, page, vaddr, dst, src, len) \ + do { \ + instrument_copy_from_user_before(dst, (void __user *)src, \ + len); \ + memcpy(dst, src, len); \ + instrument_copy_from_user_after(dst, (void __user *)src, len, \ + 0); \ + } while (0) +#endif + +#endif /* _ASM_GENERIC_CACHEFLUSH_H */ -- cgit v1.3.1