From patchwork Wed Nov 4 08:27:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11879923 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 621C2139F for ; Wed, 4 Nov 2020 08:32:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B2712074B for ; Wed, 4 Nov 2020 08:32:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mW2BzPoS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727857AbgKDIcM (ORCPT ); Wed, 4 Nov 2020 03:32:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725812AbgKDIcL (ORCPT ); Wed, 4 Nov 2020 03:32:11 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A4869C0613D3; Wed, 4 Nov 2020 00:32:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=qwoS/ldP8oxvQDl6Sqqe37ZwIbpdpdCdtB8HHVc24Ec=; b=mW2BzPoSpKXihmEZAjG+QFYUSq FxvVTagg1vofgsm8BF/7KkBQ7l3d1jmMQgczWlH7qDchs9jHxDpZnICXCzTnTJGggq9w3CswT6OxL fhH++/i9oPy6VwJF0pAHTnwmN3LDlq3XhU0LkJhXLGqLSUaOW1sCu2wnkkQr6U+lwtMOsOiYsOlts C1ii/AwUYNxdaBrQkOmIUkL5PvqmfubpmufolrbHgY1KW6SEgZYGTwnK2zalqoRef7Yz31oiOQH7c ED6dX+dUDMZ3+zTUGfZmsX/wDvAWd0dyhnitn4t2L1VwS6y03itn4h6EIphfVpprP5N8jI6pUjgm0 7a9DmqbQ==; Received: from 089144208145.atnat0017.highway.a1.net ([89.144.208.145] helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kaED5-0004OC-Qx; Wed, 04 Nov 2020 08:32:07 +0000 From: Christoph Hellwig To: Al Viro Cc: Greg KH , Linus Torvalds , Alexey Dobriyan , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/6] seq_file: add seq_read_iter Date: Wed, 4 Nov 2020 09:27:33 +0100 Message-Id: <20201104082738.1054792-2-hch@lst.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201104082738.1054792-1-hch@lst.de> References: <20201104082738.1054792-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org iov_iter based variant for reading a seq_file. seq_read is reimplemented on top of the iter variant. Signed-off-by: Christoph Hellwig Tested-by: Greg Kroah-Hartman Signed-off-by: Al Viro Tested-by: Nathan Chancellor Tested-by: Nathan Chancellor --- fs/seq_file.c | 45 ++++++++++++++++++++++++++++------------ include/linux/seq_file.h | 1 + 2 files changed, 33 insertions(+), 13 deletions(-) diff --git a/fs/seq_file.c b/fs/seq_file.c index 31219c1db17de3..3b20e21604e74a 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -146,7 +147,28 @@ static int traverse(struct seq_file *m, loff_t offset) */ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) { - struct seq_file *m = file->private_data; + struct iovec iov = { .iov_base = buf, .iov_len = size}; + struct kiocb kiocb; + struct iov_iter iter; + ssize_t ret; + + init_sync_kiocb(&kiocb, file); + iov_iter_init(&iter, READ, &iov, 1, size); + + kiocb.ki_pos = *ppos; + ret = seq_read_iter(&kiocb, &iter); + *ppos = kiocb.ki_pos; + return ret; +} +EXPORT_SYMBOL(seq_read); + +/* + * Ready-made ->f_op->read_iter() + */ +ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter) +{ + struct seq_file *m = iocb->ki_filp->private_data; + size_t size = iov_iter_count(iter); size_t copied = 0; size_t n; void *p; @@ -158,14 +180,14 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) * if request is to read from zero offset, reset iterator to first * record as it might have been already advanced by previous requests */ - if (*ppos == 0) { + if (iocb->ki_pos == 0) { m->index = 0; m->count = 0; } - /* Don't assume *ppos is where we left it */ - if (unlikely(*ppos != m->read_pos)) { - while ((err = traverse(m, *ppos)) == -EAGAIN) + /* Don't assume ki_pos is where we left it */ + if (unlikely(iocb->ki_pos != m->read_pos)) { + while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN) ; if (err) { /* With prejudice... */ @@ -174,7 +196,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) m->count = 0; goto Done; } else { - m->read_pos = *ppos; + m->read_pos = iocb->ki_pos; } } @@ -187,13 +209,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) /* if not empty - flush it first */ if (m->count) { n = min(m->count, size); - err = copy_to_user(buf, m->buf + m->from, n); - if (err) + if (copy_to_iter(m->buf + m->from, n, iter) != n) goto Efault; m->count -= n; m->from += n; size -= n; - buf += n; copied += n; if (!size) goto Done; @@ -254,8 +274,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) } m->op->stop(m, p); n = min(m->count, size); - err = copy_to_user(buf, m->buf, n); - if (err) + if (copy_to_iter(m->buf, n, iter) != n) goto Efault; copied += n; m->count -= n; @@ -264,7 +283,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) if (!copied) copied = err; else { - *ppos += copied; + iocb->ki_pos += copied; m->read_pos += copied; } mutex_unlock(&m->lock); @@ -276,7 +295,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) err = -EFAULT; goto Done; } -EXPORT_SYMBOL(seq_read); +EXPORT_SYMBOL(seq_read_iter); /** * seq_lseek - ->llseek() method for sequential files. diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index 813614d4b71fbc..b83b3ae3c877f3 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -107,6 +107,7 @@ void seq_pad(struct seq_file *m, char c); char *mangle_path(char *s, const char *p, const char *esc); int seq_open(struct file *, const struct seq_operations *); ssize_t seq_read(struct file *, char __user *, size_t, loff_t *); +ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter); loff_t seq_lseek(struct file *, loff_t, int); int seq_release(struct inode *, struct file *); int seq_write(struct seq_file *seq, const void *data, size_t len);