ClabureDB: Classified Bug-Reports Database

static ssize_t
__xip_file_write(struct file *filp, const char __user *buf,
                  size_t count, loff_t pos, loff_t *ppos)
{
        struct address_space * mapping = filp->f_mapping;
        const struct address_space_operations *a_ops = mapping->a_ops;
        struct inode         *inode = mapping->host;
        long                status = 0;
        size_t                bytes;
        ssize_t                written = 0;

        BUG_ON(!mapping->a_ops->get_xip_mem);

        do {
                unsigned long index;
                unsigned long offset;
                size_t copied;
                void *xip_mem;
                unsigned long xip_pfn;

                offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
                index = pos >> PAGE_CACHE_SHIFT;
                bytes = PAGE_CACHE_SIZE - offset;
                if (bytes > count)
                        bytes = count;

                status = a_ops->get_xip_mem(mapping, index, 0,
                                                &xip_mem, &xip_pfn);
                if (status == -ENODATA) {
                        /* we allocate a new page unmap it */
                        mutex_lock(&xip_sparse_mutex);
                        status = a_ops->get_xip_mem(mapping, index, 1,
                                                        &xip_mem, &xip_pfn);
                        mutex_unlock(&xip_sparse_mutex);
                        if (!status)
                                /* unmap page at pgoff from all other vmas */
                                __xip_unmap(mapping, index);
                }

                if (status)
                        break;