Messages in this thread | | | Date | Wed, 22 Oct 2008 22:39:28 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Add block device speciffic splice write method |
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On Mon, 20 Oct 2008 20:11:56 +0200 Jens Axboe <jens.axboe@oracle.com> wrote:
> +ssize_t generic_file_splice_write_file_nolock(struct pipe_inode_info *pipe, > + struct file *out, loff_t *ppos, > + size_t len, unsigned int flags) > +{ > + struct address_space *mapping = out->f_mapping; > + struct inode *inode = mapping->host; > + struct splice_desc sd = { > + .total_len = len, > + .flags = flags, > + .pos = *ppos, > + .u.file = out, > + }; > + ssize_t ret; > + > + mutex_lock(&pipe->inode->i_mutex); > + ret = __splice_from_pipe(pipe, &sd, pipe_to_file); > + mutex_unlock(&pipe->inode->i_mutex); > + > + if (ret > 0) { > + unsigned long nr_pages; > + > + *ppos += ret; > + nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; > + > + if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { > + int er; > + > + er = sync_page_range_nolock(inode, mapping, *ppos, ret); > + if (er) > + ret = er; > + } > + balance_dirty_pages_ratelimited_nr(mapping, nr_pages); > + } > + > + return ret; > +} > +EXPORT_SYMBOL(generic_file_splice_write_file_nolock);
I don't think the balance_dirty_pages() is needed if we just did the sync_page_range().
But really it'd be better if the throttling happened down in pipe_to_file(), on a per-page basis. As it stands we can dirty an arbitrary number of pagecache pages without throttling. I think?
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