Update shared mappings

Zlatko Calusic
1998-11-20T04:10:17Z

Should this patch be applied to kernel?

Index: 129.2/mm/filemap.c
--- 129.2/mm/filemap.c Thu, 19 Nov 1998 18:20:34 +0100 zcalusic (linux-2.1/y/b/29_filemap.c 1.2.4.1.1.1.1.1 644)
+++ 129.3/mm/filemap.c Fri, 20 Nov 1998 05:07:24 +0100 zcalusic (linux-2.1/y/b/29_filemap.c 1.2.4.1.1.1.1.2 644)
@@ -5,6 +5,10 @@
*/

/*
+ * update_shared_mappings(), 1998 Andrea Arcangeli
+ */
+
+/*
* This file handles the generic file mmap semantics used by
* most "normal" filesystems (but you don't /have/ to use this:
* the NFS filesystem used to do this differently, for example)
@@ -1216,6 +1220,75 @@
return mk_pte(page,vma->vm_page_prot);
}

+static void update_one_shared_mapping(struct vm_area_struct *shared,
+ unsigned long address, pte_t orig_pte)
+{
+ pgd_t *pgd;
+ pmd_t *pmd;
+ pte_t *pte;
+ struct semaphore * mmap_sem = &shared->vm_mm->mmap_sem;
+
+ down(mmap_sem);
+
+ pgd = pgd_offset(shared->vm_mm, address);
+ if (pgd_none(*pgd))
+ goto out;
+ if (pgd_bad(*pgd)) {
+ printk(KERN_ERR "update_shared_mappings: bad pgd (%08lx)\n",
+ pgd_val(*pgd));
+ pgd_clear(pgd);
+ goto out;
+ }
+
+ pmd = pmd_offset(pgd, address);
+ if (pmd_none(*pmd))
+ goto out;
+ if (pmd_bad(*pmd))
+ {
+ printk(KERN_ERR "update_shared_mappings: bad pmd (%08lx)\n",
+ pmd_val(*pmd));
+ pmd_clear(pmd);
+ goto out;
+ }
+
+ pte = pte_offset(pmd, address);
+
+ if (pte_val(pte_mkclean(pte_mkyoung(*pte))) !=
+ pte_val(pte_mkclean(pte_mkyoung(orig_pte))))
+ goto out;
+
+ flush_page_to_ram(page(pte));
+ flush_cache_page(shared, address);
+ set_pte(pte, pte_mkclean(*pte));
+ flush_tlb_page(shared, address);
+
+ out:
+ up(mmap_sem);
+}
+
+static void update_shared_mappings(struct vm_area_struct *this,
+ unsigned long address,
+ pte_t orig_pte)
+{
+ if (this->vm_flags & VM_SHARED)
+ {
+ struct file * filp = this->vm_file;
+ if (filp)
+ {
+ struct inode * inode = filp->f_dentry->d_inode;
+ struct vm_area_struct * shared;
+
+ for (shared = inode->i_mmap; shared;
+ shared = shared->vm_next_share)
+ {
+ if (shared == this)
+ continue;
+ update_one_shared_mapping(shared, address,
+ orig_pte);
+ }
+ }
+ }
+}

static inline int filemap_sync_pte(pte_t * ptep, struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
@@ -1233,6 +1306,7 @@
flush_cache_page(vma, address);
set_pte(ptep, pte_mkclean(pte));
flush_tlb_page(vma, address);
+ update_shared_mappings(vma, address, pte);
page = pte_page(pte);
atomic_inc(&mem_map[MAP_NR(page)].count);
} else {

--
Posted by Zlatko Calusic E-mail: <Zlatko.Calusic@CARNet.hr>
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