Hang in filemap_fdatasync on SMP machine

Hang in filemap_fdatasync on SMP machine

[Deepa Chacko Pillai]

Hi

I have written a kernel API to flush data to the disk. Whenever I call this API on an SMP machine, it causes the system to hang. The code looks like:

		    down(&inode->i_sem);
                ret = filemap_fdatasync(inode->i_mapping);
                err = file->f_op->fsync(file, dentry, 0);
                if (err && !ret)
                        ret = err;
                err = filemap_fdatawait(inode->i_mapping);
                if (err && !ret)
                        ret = err;
                up(&inode->i_sem);

This code works perfectly fine on uniprocessor systems. But it hangs in filemap_fdatasync on SMP systems. It goes in an infinite loop in filemap_fdatasync (). Inside filemap_fdatasync (), it finds that the page is not dirty and keeps going in a loop.

	while (!list_empty(&mapping->dirty_pages)) {
                struct page *page = list_entry(mapping->dirty_pages.prev, struct page, list);

                list_del(&page->list);
                list_add(&page->list, &mapping->locked_pages);

                if (!PageDirty(page))
                        continue;

	....
	}

I am using Red Hat Linux with kernel version 2.4.19. Any help would be much appreciated.

Thanks
Deepa


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