/* * linux/mm/msync.c * * Copyright (C) 1994-1999 Linus Torvalds */ /* * The msync() system call. */ #include <linux/slab.h> #include <linux/pagemap.h> #include <linux/mm.h> #include <linux/mman.h> #include <linux/hugetlb.h> #include <linux/syscalls.h> #include <asm/pgtable.h> #include <asm/tlbflush.h> /* * Called with mm->page_table_lock held to protect against other * threads/the swapper from ripping pte's out from under us. */ static void sync_pte_range(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end) { pte_t *pte; pte = pte_offset_map(pmd, addr); do { unsigned long pfn; struct page *page; if (!pte_present(*pte)) continue; if (!pte_maybe_dirty(*pte)) continue; pfn = pte_pfn(*pte); if (!pfn_valid(pfn)) continue; page = pfn_to_page(pfn); if (PageReserved(page)) continue; if (ptep_clear_flush_dirty(vma, addr, pte) || page_test_and_clear_dirty(page)) set_page_dirty(page); } while (pte++, addr += PAGE_SIZE, addr != end); pte_unmap(pte - 1); } static inline void sync_pmd_range(struct vm_area_struct *vma, pud_t *pud, unsigned long addr, unsigned long end) { pmd_t *pmd; unsigned long next; pmd = pmd_offset(pud, addr); do { next = pmd_addr_end(addr, end); if (pmd_none_or_clear_bad(pmd)) continue; sync_pte_range(vma, pmd, addr, next); } while (pmd++, addr = next, addr != end); } static inline void sync_pud_range(struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, unsigned long end) { pud_t *pud; unsigned long next; pud = pud_offset(pgd, addr); do { next = pud_addr_end(addr, end); if (pud_none_or_clear_bad(pud)) continue; sync_pmd_range(vma, pud, addr, next); } while (pud++, addr = next, addr != end); } static void sync_page_range(struct vm_area_struct *vma, unsigned long addr, unsigned long end) { struct mm_struct *mm = vma->vm_mm; pgd_t *pgd; unsigned long next; /* For hugepages we can't go walking the page table normally, * but that's ok, hugetlbfs is memory based, so we don't need * to do anything more on an msync() */ if (is_vm_hugetlb_page(vma)) return; BUG_ON(addr >= end); pgd = pgd_offset(mm, addr); flush_cache_range(vma, addr, end); spin_lock(&mm->page_table_lock); do { next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) continue; sync_pud_range(vma, pgd, addr, next); } while (pgd++, addr = next, addr != end); spin_unlock(&mm->page_table_lock); } #ifdef CONFIG_PREEMPT static inline void filemap_sync(struct vm_area_struct *vma, unsigned long addr, unsigned long end) { const size_t chunk = 64 * 1024; /* bytes */ unsigned long next; do { next = addr + chunk; if (next > end || next < addr) next = end; sync_page_range(vma, addr, next); cond_resched(); } while (addr = next, addr != end); } #else static inline void filemap_sync(struct vm_area_struct *vma, unsigned long addr, unsigned long end) { sync_page_range(vma, addr, end); } #endif /* * MS_SYNC syncs the entire file - including mappings. * * MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just * marks the relevant pages dirty. The application may now run fsync() to * write out the dirty pages and wait on the writeout and check the result. * Or the application may run fadvise(FADV_DONTNEED) against the fd to start * async writeout immediately. * So my _not_ starting I/O in MS_ASYNC we provide complete flexibility to * applications. */ static int msync_interval(struct vm_area_struct *vma, unsigned long addr, unsigned long end, int flags) { int ret = 0; struct file *file = vma->vm_file; if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED)) return -EBUSY; if (file && (vma->vm_flags & VM_SHARED)) { filemap_sync(vma, addr, end); if (flags & MS_SYNC) { struct address_space *mapping = file->f_mapping; int err; ret = filemap_fdatawrite(mapping); if (file->f_op && file->f_op->fsync) { /* * We don't take i_sem here because mmap_sem * is already held. */ err = file->f_op->fsync(file,file->f_dentry,1); if (err && !ret) ret = err; } err = filemap_fdatawait(mapping); if (!ret) ret = err; } } return ret; } asmlinkage long sys_msync(unsigned long start, size_t len, int flags) { unsigned long end; struct vm_area_struct *vma; int unmapped_error, error = -EINVAL; if (flags & MS_SYNC) current->flags |= PF_SYNCWRITE; down_read(¤t->mm->mmap_sem); if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC)) goto out; if (start & ~PAGE_MASK) goto out; if ((flags & MS_ASYNC) && (flags & MS_SYNC)) goto out; error = -ENOMEM; len = (len + ~PAGE_MASK) & PAGE_MASK; end = start + len; if (end < start) goto out; error = 0; if (end == start) goto out; /* * If the interval [start,end) covers some unmapped address ranges, * just ignore them, but return -ENOMEM at the end. */ vma = find_vma(current->mm, start); unmapped_error = 0; for (;;) { /* Still start < end. */ error = -ENOMEM; if (!vma) goto out; /* Here start < vma->vm_end. */ if (start < vma->vm_start) { unmapped_error = -ENOMEM; start = vma->vm_start; } /* Here vma->vm_start <= start < vma->vm_end. */ if (end <= vma->vm_end) { if (start < end) { error = msync_interval(vma, start, end, flags); if (error) goto out; } error = unmapped_error; goto out; } /* Here vma->vm_start <= start < vma->vm_end < end. */ error = msync_interval(vma, start, vma->vm_end, flags); if (error) goto out; start = vma->vm_end; vma = vma->vm_next; } out: up_read(¤t->mm->mmap_sem); current->flags &= ~PF_SYNCWRITE; return error; }