diff options
Diffstat (limited to 'mm/msync.c')
| -rw-r--r-- | mm/msync.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/mm/msync.c b/mm/msync.c new file mode 100644 index 000000000000..090f426bca7d --- /dev/null +++ b/mm/msync.c @@ -0,0 +1,236 @@ +/* + * 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; + 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; +} |