From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Kees Cook <keescook@chromium.org>,
Iurii Zaikin <yzaikin@google.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH 08/23] fs: don't change the address limit for ->write_iter in __kernel_write
Date: Wed, 1 Jul 2020 22:09:36 +0200 [thread overview]
Message-ID: <20200701200951.3603160-9-hch@lst.de> (raw)
In-Reply-To: <20200701200951.3603160-1-hch@lst.de>
If we write to a file that implements ->write_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 ->write with a changed address
limit if available.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/read_write.c | 34 ++++++++++++++++++++++------------
1 file changed, 22 insertions(+), 12 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 96e8e354f99b45..bd46c959799e97 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -489,10 +489,9 @@ static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t
}
/* caller is responsible for file_start_write/file_end_write */
-ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos)
+ssize_t __kernel_write(struct file *file, const void *buf, size_t count,
+ loff_t *pos)
{
- mm_segment_t old_fs;
- const char __user *p;
ssize_t ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_WRITE)))
@@ -500,18 +499,29 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t
if (!(file->f_mode & FMODE_CAN_WRITE))
return -EINVAL;
- old_fs = get_fs();
- set_fs(KERNEL_DS);
- p = (__force const char __user *)buf;
if (count > MAX_RW_COUNT)
count = MAX_RW_COUNT;
- if (file->f_op->write)
- ret = file->f_op->write(file, p, count, pos);
- else if (file->f_op->write_iter)
- ret = new_sync_write(file, p, count, pos);
- else
+ if (file->f_op->write_iter) {
+ struct kvec iov = { .iov_base = (void *)buf, .iov_len = count };
+ struct kiocb kiocb;
+ struct iov_iter iter;
+
+ init_sync_kiocb(&kiocb, file);
+ kiocb.ki_pos = *pos;
+ iov_iter_kvec(&iter, WRITE, &iov, 1, 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;
- set_fs(old_fs);
+ }
if (ret > 0) {
fsnotify_modify(file);
add_wchar(current, ret);
--
2.26.2
next prev parent reply other threads:[~2020-07-01 20:23 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 20:09 [RFC] stop using ->read and ->write for kernel access v3 Christoph Hellwig
2020-07-01 20:09 ` [PATCH 01/23] cachefiles: switch to kernel_write Christoph Hellwig
2020-07-01 20:09 ` [PATCH 02/23] autofs: " Christoph Hellwig
2020-07-01 20:09 ` [PATCH 03/23] bpfilter: " Christoph Hellwig
2020-07-01 20:09 ` [PATCH 04/23] fs: unexport __kernel_write Christoph Hellwig
2020-07-01 20:09 ` [PATCH 05/23] fs: check FMODE_WRITE in __kernel_write Christoph Hellwig
2020-07-01 20:09 ` [PATCH 06/23] fs: implement kernel_write using __kernel_write Christoph Hellwig
2020-07-01 20:09 ` [PATCH 07/23] fs: remove __vfs_write Christoph Hellwig
2020-07-01 20:09 ` Christoph Hellwig [this message]
2020-07-01 20:09 ` [PATCH 09/23] fs: add a __kernel_read helper Christoph Hellwig
2020-07-01 20:09 ` [PATCH 10/23] integrity/ima: switch to using __kernel_read Christoph Hellwig
2020-07-01 20:09 ` [PATCH 11/23] fs: implement kernel_read " Christoph Hellwig
2020-07-01 20:09 ` [PATCH 12/23] fs: remove __vfs_read Christoph Hellwig
2020-07-01 20:09 ` [PATCH 13/23] fs: don't change the address limit for ->read_iter in __kernel_read Christoph Hellwig
2020-07-01 20:09 ` [PATCH 14/23] fs: refactor new_sync_read Christoph Hellwig
2020-07-01 20:09 ` [PATCH 15/23] seq_file: add seq_read_iter Christoph Hellwig
2020-07-01 20:09 ` [PATCH 16/23] seq_file: switch over direct seq_read method calls to seq_read_iter Christoph Hellwig
2020-07-02 9:46 ` Miguel Ojeda
2020-07-02 13:50 ` Christoph Hellwig
2020-07-03 5:56 ` Miguel Ojeda
2020-07-03 7:44 ` Joe Perches
2020-07-03 9:35 ` Miguel Ojeda
2020-07-03 9:43 ` Joe Perches
2020-07-01 20:09 ` [PATCH 17/23] proc: add a read_iter method to proc proc_ops Christoph Hellwig
2020-07-01 21:27 ` Al Viro
2020-07-02 5:18 ` Christoph Hellwig
2020-07-02 7:30 ` Christoph Hellwig
2020-07-01 20:09 ` [PATCH 18/23] proc: switch over direct seq_read method calls to seq_read_iter Christoph Hellwig
2020-07-01 20:09 ` [PATCH 19/23] sysctl: Call sysctl_head_finish on error Christoph Hellwig
2020-07-02 0:32 ` Matthew Wilcox
2020-07-02 5:15 ` Christoph Hellwig
2020-07-03 1:34 ` Al Viro
2020-07-01 20:09 ` [PATCH 20/23] sysctl: Convert to iter interfaces Christoph Hellwig
2020-07-01 20:09 ` [PATCH 21/23] fs: don't allow kernel reads and writes without iter ops Christoph Hellwig
2020-07-01 20:09 ` [PATCH 22/23] fs: default to generic_file_splice_read for files having ->read_iter Christoph Hellwig
2020-07-01 20:09 ` [PATCH 23/23] fs: don't allow splice read/write without explicit ops Christoph Hellwig
2020-07-07 17:47 stop using ->read and ->write for kernel access v3 Christoph Hellwig
2020-07-07 17:47 ` [PATCH 08/23] fs: don't change the address limit for ->write_iter in __kernel_write Christoph Hellwig
2020-07-29 20:50 ` Al Viro
2020-07-30 7:02 ` Christoph Hellwig
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