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From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Ian Kent <raven@themaw.net>, David Howells <dhowells@redhat.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	netfilter-devel@vger.kernel.org
Subject: [PATCH 14/14] fs: don't change the address limit for ->read_iter in __kernel_read
Date: Wed, 24 Jun 2020 18:13:35 +0200	[thread overview]
Message-ID: <20200624161335.1810359-15-hch@lst.de> (raw)
In-Reply-To: <20200624161335.1810359-1-hch@lst.de>

If we read to a file that implements ->read_iter there is no need
to change the address limit if we send a kvec down.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/read_write.c | 40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 1c41c25e548d8c..e7f36b15683049 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -421,7 +421,6 @@ static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo
 
 ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 {
-	mm_segment_t old_fs = get_fs();
 	ssize_t ret;
 
 	if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ)))
@@ -431,14 +430,25 @@ ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 
 	if (count > MAX_RW_COUNT)
 		count =  MAX_RW_COUNT;
-	set_fs(KERNEL_DS);
-	if (file->f_op->read)
+	if (file->f_op->read) {
+		mm_segment_t old_fs = get_fs();
+
+		set_fs(KERNEL_DS);
 		ret = file->f_op->read(file, (void __user *)buf, count, pos);
-	else if (file->f_op->read_iter)
-		ret = new_sync_read(file, (void __user *)buf, count, pos);
-	else
+		set_fs(old_fs);
+	} else if (file->f_op->read_iter) {
+		struct kvec iov = { .iov_base = buf, .iov_len = count };
+		struct kiocb kiocb;
+		struct iov_iter iter;
+
+		init_sync_kiocb(&kiocb, file);
+		kiocb.ki_pos = *pos;
+		iov_iter_kvec(&iter, READ, &iov, 1, count);
+		ret = file->f_op->read_iter(&kiocb, &iter);
+		*pos = kiocb.ki_pos;
+	} else {
 		ret = -EINVAL;
-	set_fs(old_fs);
+	}
 	if (ret > 0) {
 		fsnotify_access(file);
 		add_rchar(current, ret);
@@ -520,7 +530,14 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count,
 
 	if (count > MAX_RW_COUNT)
 		count =  MAX_RW_COUNT;
-	if (file->f_op->write_iter) {
+	if (file->f_op->write) {
+		mm_segment_t old_fs = get_fs();
+
+		set_fs(KERNEL_DS);
+		ret = file->f_op->write(file, (__force const char __user *)buf,
+				count, pos);
+		set_fs(old_fs);
+	} else if (file->f_op->write_iter) {
 		struct kvec iov = { .iov_base = (void *)buf, .iov_len = count };
 		struct kiocb kiocb;
 		struct iov_iter iter;
@@ -531,13 +548,6 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count,
 		ret = file->f_op->write_iter(&kiocb, &iter);
 		if (ret > 0)
 			*pos = kiocb.ki_pos;
-	} else if (file->f_op->write) {
-		mm_segment_t old_fs = get_fs();
-
-		set_fs(KERNEL_DS);
-		ret = file->f_op->write(file, (__force const char __user *)buf,
-				count, pos);
-		set_fs(old_fs);
 	} else {
 		ret = -EINVAL;
 	}
-- 
2.26.2


  parent reply	other threads:[~2020-06-24 16:14 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24 16:13 clean up kernel_{read,write} & friends v5 Christoph Hellwig
2020-06-24 16:13 ` [PATCH 01/14] cachefiles: switch to kernel_write Christoph Hellwig
2020-06-24 16:13 ` [PATCH 02/14] autofs: " Christoph Hellwig
2020-06-24 16:13 ` [PATCH 03/14] bpfilter: " Christoph Hellwig
2020-06-24 16:13 ` [PATCH 04/14] fs: unexport __kernel_write Christoph Hellwig
2020-06-24 16:13 ` [PATCH 05/14] fs: check FMODE_WRITE in __kernel_write Christoph Hellwig
2020-06-24 16:13 ` [PATCH 06/14] fs: implement kernel_write using __kernel_write Christoph Hellwig
2020-06-24 16:13 ` [PATCH 07/14] fs: remove __vfs_write Christoph Hellwig
2020-06-24 16:13 ` [PATCH 08/14] fs: don't change the address limit for ->write_iter in __kernel_write Christoph Hellwig
2020-06-24 16:13 ` [PATCH 09/14] fs: add a __kernel_read helper Christoph Hellwig
2020-06-24 16:13 ` [PATCH 10/14] integrity/ima: switch to using __kernel_read Christoph Hellwig
2020-06-24 16:13 ` [PATCH 11/14] fs: implement kernel_read " Christoph Hellwig
2020-06-24 16:13 ` [PATCH 12/14] fs: remove __vfs_read Christoph Hellwig
2020-06-24 16:13 ` [PATCH 13/14] fs: implement default_file_splice_read using __kernel_read Christoph Hellwig
2020-07-01  9:19   ` [fs] 140402bab8: stress-ng.splice.ops_per_sec -100.0% regression kernel test robot
2020-07-01 12:13     ` Christoph Hellwig
2020-07-01 20:32       ` Linus Torvalds
2020-06-24 16:13 ` Christoph Hellwig [this message]
  -- strict thread matches above, loose matches on Subject: below --
2020-05-28  5:40 clean up kernel_{read,write} & friends v2 Christoph Hellwig
2020-05-28  5:40 ` [PATCH 14/14] fs: don't change the address limit for ->read_iter in __kernel_read Christoph Hellwig
2020-05-28 19:03   ` Al Viro
2020-05-13  6:56 clean up kernel_{read,write} & friends v2 Christoph Hellwig
2020-05-13  6:56 ` [PATCH 14/14] fs: don't change the address limit for ->read_iter in __kernel_read Christoph Hellwig

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