From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: [PATCH 11/11] fs: don't change the address limit for ->read_iter in __kernel_read
Date: Fri, 8 May 2020 11:22:22 +0200 [thread overview]
Message-ID: <20200508092222.2097-12-hch@lst.de> (raw)
In-Reply-To: <20200508092222.2097-1-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 f0009b506014c..70715a0e2375d 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
prev parent reply other threads:[~2020-05-08 9:22 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 9:22 clean up kernel_{read,write} & friends Christoph Hellwig
2020-05-08 9:22 ` [PATCH 01/11] fs: call file_{start,end}_write from __kernel_write Christoph Hellwig
2020-05-08 9:22 ` [PATCH 02/11] fs: check FMODE_WRITE in __kernel_write Christoph Hellwig
2020-05-08 9:22 ` [PATCH 03/11] fs: remove the call_{read,write}_iter functions Christoph Hellwig
2020-05-08 9:22 ` [PATCH 04/11] fs: implement kernel_write using __kernel_write Christoph Hellwig
2020-05-08 9:22 ` [PATCH 05/11] fs: remove __vfs_write Christoph Hellwig
2020-05-08 9:22 ` [PATCH 06/11] fs: don't change the address limit for ->write_iter in __kernel_write Christoph Hellwig
2020-05-08 9:22 ` [PATCH 07/11] fs: add a __kernel_read helper Christoph Hellwig
2020-05-08 9:22 ` [PATCH 08/11] integrity/ima: switch to using __kernel_read Christoph Hellwig
2020-05-08 9:22 ` [PATCH 09/11] fs: implement kernel_read " Christoph Hellwig
2020-05-08 9:22 ` [PATCH 10/11] fs: remove __vfs_read Christoph Hellwig
2020-05-08 15:45 ` Ira Weiny
2020-05-08 15:46 ` Christoph Hellwig
2020-05-08 9:22 ` Christoph Hellwig [this message]
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