Messages in this thread | | | Subject | Re: [PATCH -v8 3/4] Enable the MS_ASYNC functionality in sys_msync() | From | Miklos Szeredi <> | Date | Wed, 23 Jan 2008 10:34:52 +0100 |
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> On Wed, 2008-01-23 at 09:47 +0100, Peter Zijlstra wrote: > > On Wed, 2008-01-23 at 02:21 +0300, Anton Salikhmetov wrote: > > > > +static void vma_wrprotect(struct vm_area_struct *vma) > > > +{ > > > + unsigned long addr = vma->vm_start; > > > + pgd_t *pgd = pgd_offset(vma->vm_mm, addr); > > > + > > > + while (addr < vma->vm_end) { > > > + unsigned long next = pgd_addr_end(addr, vma->vm_end); > > > + > > > + if (!pgd_none_or_clear_bad(pgd)) > > > + vma_wrprotect_pgd_range(vma, pgd, addr, next); > > > + > > > + ++pgd; > > > + addr = next; > > > + } > > > +} > > > > I think you want to pass start, end here too, you might not need to > > sweep the whole vma. > > Also, it still doesn't make sense to me why we'd not need to walk the > rmap, it is all the same file after all.
It's the same file, but not the same memory map. It basically depends on how you define msync:
a) sync _file_ on region defined by this mmap/start/end-address b) sync _memory_region_ defined by start/end-address
b) is a perfectly fine definition, and it's consistent with what this code does. The fact that POSIX probably implies a) (in a rather poorly defined way) doesn't make much difference, I think.
Miklos
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