From 74d2fad1334d12bac8fe017aba598dd66c86628b Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Fri, 7 Oct 2016 16:59:56 -0700 Subject: [PATCH] thp, dax: add thp_get_unmapped_area for pmd mappings When CONFIG_FS_DAX_PMD is set, DAX supports mmap() using pmd page size. This feature relies on both mmap virtual address and FS block (i.e. physical address) to be aligned by the pmd page size. Users can use mkfs options to specify FS to align block allocations. However, aligning mmap address requires code changes to existing applications for providing a pmd-aligned address to mmap(). For instance, fio with "ioengine=mmap" performs I/Os with mmap() [1]. It calls mmap() with a NULL address, which needs to be changed to provide a pmd-aligned address for testing with DAX pmd mappings. Changing all applications that call mmap() with NULL is undesirable. Add thp_get_unmapped_area(), which can be called by filesystem's get_unmapped_area to align an mmap address by the pmd size for a DAX file. It calls the default handler, mm->get_unmapped_area(), to find a range and then aligns it for a DAX file. The patch is based on Matthew Wilcox's change that allows adding support of the pud page size easily. [1]: https://github.com/axboe/fio/blob/master/engines/mmap.c Link: http://lkml.kernel.org/r/1472497881-9323-2-git-send-email-toshi.kani@hpe.com Signed-off-by: Toshi Kani Reviewed-by: Dan Williams Cc: Matthew Wilcox Cc: Ross Zwisler Cc: Kirill A. Shutemov Cc: Dave Chinner Cc: Jan Kara Cc: Theodore Ts'o Cc: Andreas Dilger Cc: Mike Kravetz Cc: "Kirill A. Shutemov" Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/huge_mm.h | 7 +++++++ mm/huge_memory.c | 43 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 50 insertions(+) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 6f14de45b5ce..4fca5263fd42 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -87,6 +87,10 @@ extern bool is_vma_temporary_stack(struct vm_area_struct *vma); extern unsigned long transparent_hugepage_flags; +extern unsigned long thp_get_unmapped_area(struct file *filp, + unsigned long addr, unsigned long len, unsigned long pgoff, + unsigned long flags); + extern void prep_transhuge_page(struct page *page); extern void free_transhuge_page(struct page *page); @@ -169,6 +173,9 @@ void put_huge_zero_page(void); static inline void prep_transhuge_page(struct page *page) {} #define transparent_hugepage_flags 0UL + +#define thp_get_unmapped_area NULL + static inline int split_huge_page_to_list(struct page *page, struct list_head *list) { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 283583fcb1e7..a0b0e562407d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -469,6 +469,49 @@ void prep_transhuge_page(struct page *page) set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); } +unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, + loff_t off, unsigned long flags, unsigned long size) +{ + unsigned long addr; + loff_t off_end = off + len; + loff_t off_align = round_up(off, size); + unsigned long len_pad; + + if (off_end <= off_align || (off_end - off_align) < size) + return 0; + + len_pad = len + size; + if (len_pad < len || (off + len_pad) < off) + return 0; + + addr = current->mm->get_unmapped_area(filp, 0, len_pad, + off >> PAGE_SHIFT, flags); + if (IS_ERR_VALUE(addr)) + return 0; + + addr += (off - addr) & (size - 1); + return addr; +} + +unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + loff_t off = (loff_t)pgoff << PAGE_SHIFT; + + if (addr) + goto out; + if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) + goto out; + + addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); + if (addr) + return addr; + + out: + return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); +} +EXPORT_SYMBOL_GPL(thp_get_unmapped_area); + static int __do_huge_pmd_anonymous_page(struct fault_env *fe, struct page *page, gfp_t gfp) { -- 2.20.1