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: Thu, 28 May 2020 07:40:43 +0200 [thread overview]
Message-ID: <20200528054043.621510-15-hch@lst.de> (raw)
In-Reply-To: <20200528054043.621510-1-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. Implement that
case, and prefer it over using plain ->read with a changed address
limit if available.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/read_write.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 46ddfce17e839..c93acbd8bf5a3 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 (!(file->f_mode & FMODE_CAN_READ))
@@ -429,14 +428,25 @@ 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_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 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 {
ret = -EINVAL;
- set_fs(old_fs);
+ }
if (ret > 0) {
fsnotify_access(file);
add_rchar(current, ret);
--
2.26.2
next prev parent reply other threads:[~2020-05-28 5:41 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 5:40 clean up kernel_{read,write} & friends v2 Christoph Hellwig
2020-05-28 5:40 ` [PATCH 01/14] cachefiles: switch to kernel_write Christoph Hellwig
2020-05-28 5:40 ` [PATCH 02/14] autofs: " Christoph Hellwig
2020-05-28 5:40 ` [PATCH 03/14] bpfilter: " Christoph Hellwig
2020-05-28 5:40 ` [PATCH 04/14] fs: unexport __kernel_write Christoph Hellwig
2020-05-28 5:40 ` [PATCH 05/14] fs: check FMODE_WRITE in __kernel_write Christoph Hellwig
2020-05-28 5:40 ` [PATCH 06/14] fs: remove the call_{read,write}_iter functions Christoph Hellwig
2020-05-28 18:56 ` Al Viro
2020-05-29 5:51 ` Christoph Hellwig
2020-05-28 5:40 ` [PATCH 07/14] fs: implement kernel_write using __kernel_write Christoph Hellwig
2020-05-28 5:40 ` [PATCH 08/14] fs: remove __vfs_write Christoph Hellwig
2020-05-28 5:40 ` [PATCH 09/14] fs: don't change the address limit for ->write_iter in __kernel_write Christoph Hellwig
2020-05-28 18:43 ` Linus Torvalds
2020-05-29 12:32 ` Christoph Hellwig
2020-05-31 23:59 ` Logan Gunthorpe
2020-05-28 19:00 ` Al Viro
2020-05-29 5:57 ` Christoph Hellwig
2020-05-29 13:37 ` Christoph Hellwig
2020-05-28 5:40 ` [PATCH 10/14] fs: add a __kernel_read helper Christoph Hellwig
2020-05-28 5:40 ` [PATCH 11/14] integrity/ima: switch to using __kernel_read Christoph Hellwig
2020-05-28 5:40 ` [PATCH 12/14] fs: implement kernel_read " Christoph Hellwig
2020-05-28 5:40 ` [PATCH 13/14] fs: remove __vfs_read Christoph Hellwig
2020-05-28 5:40 ` Christoph Hellwig [this message]
2020-05-28 19:03 ` [PATCH 14/14] fs: don't change the address limit for ->read_iter in __kernel_read Al Viro
2020-05-28 18:51 ` clean up kernel_{read,write} & friends v2 Linus Torvalds
2020-05-28 18:57 ` Sedat Dilek
2020-05-28 19:22 ` Joe Perches
2020-05-28 19:33 ` Al Viro
2020-05-28 19:44 ` Matthew Wilcox
2020-05-28 20:06 ` Al Viro
2020-05-28 20:14 ` Deucher, Alexander
2020-05-28 20:18 ` Joe Perches
2020-05-28 20:29 ` Dave Airlie
2020-05-28 21:03 ` Joe Perches
2020-05-28 20:17 ` David Howells
2020-05-28 21:20 ` Casey Schaufler
2020-05-29 13:08 ` David Laight
2020-05-29 19:19 ` Linus Torvalds
2020-05-29 22:02 ` Casey Schaufler
2020-05-29 23:12 ` [PATCH] checkpatch/coding-style: Allow 100 column lines Joe Perches
2020-05-30 22:14 ` Andreas Dilger
2020-05-30 23:15 ` Joe Perches
2020-06-05 6:36 ` clean up kernel_{read,write} & friends v2 Philippe Mathieu-Daudé
2020-06-05 15:00 ` Nicolas Pitre
-- strict thread matches above, loose matches on Subject: below --
2020-06-24 16:13 clean up kernel_{read,write} & friends v5 Christoph Hellwig
2020-06-24 16:13 ` [PATCH 14/14] fs: don't change the address limit for ->read_iter in __kernel_read Christoph Hellwig
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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