On Fri, Mar 14, 2014 at 05:03:19PM -0600, Toshi Kani wrote:
> +void dax_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf,
> + get_block_t get_block)
> +{
> + struct file *file = vma->vm_file;
> + struct inode *inode = file_inode(file);
> + struct buffer_head bh;
> + struct address_space *mapping = file->f_mapping;
> + unsigned long vaddr = (unsigned long)vmf->virtual_address;
> + pgoff_t pgoff = vmf->pgoff;
> + sector_t block;
> + pgoff_t size;
> + unsigned long pfn;
> + pte_t *pte = vmf->pte;
> + int error;
> +
> + while (pgoff < vmf->max_pgoff) {
> + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
> + if (pgoff >= size)
> + return;
> +
> + memset(&bh, 0, sizeof(bh));
> + block = (sector_t)pgoff << (PAGE_SHIFT - inode->i_blkbits);
> + bh.b_size = PAGE_SIZE;
> + error = get_block(inode, block, &bh, 0);
> + if (error || bh.b_size < PAGE_SIZE)
> + goto next;
> +
> + if (!buffer_mapped(&bh) || buffer_unwritten(&bh) ||
> + buffer_new(&bh))
> + goto next;
> +
> + /* Recheck i_size under i_mmap_mutex */
> + mutex_lock(&mapping->i_mmap_mutex);
NAK. Have you tested this with lockdep enabled?
->map_pages() called with page table lock taken and ->i_mmap_mutex
should be taken before it. It seems we need to take ->i_mmap_mutex in
do_read_fault() before calling ->map_pages().
Side note: I'm sceptical about whole idea to use i_mmap_mutux to protect
against truncate. It will not scale good enough comparing lock_page()
with its granularity.
> + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
> + if (unlikely(pgoff >= size)) {
> + mutex_unlock(&mapping->i_mmap_mutex);
> + return;
> + }
> +
> + error = dax_get_pfn(inode, &bh, &pfn);
> + if (error > 0)
> + dax_set_pte(vma, vaddr, pfn, pte);
> +
> + mutex_unlock(&mapping->i_mmap_mutex);
> +next:
> + vaddr += PAGE_SIZE;
> + pgoff++;
> + pte++;
> + }
> +}
> +EXPORT_SYMBOL_GPL(dax_map_pages);
--
Kirill A. Shutemov
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