Commit 06ae43f3 authored by Al Viro's avatar Al Viro
Browse files

Don't bother with redoing rw_verify_area() from default_file_splice_from() 



default_file_splice_from() ends up calling vfs_write() (via very convoluted
callchain).  It's an overkill, since we already have done rw_verify_area()
in the caller by the time we call vfs_write() we are under set_fs(KERNEL_DS),
so access_ok() is also pointless.  Add a new helper (__kernel_write()),
use it instead of kernel_write() in there.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent f6161aa1

fs/internal.h

+5 −0
Original line number Diff line number Diff line
@@ -125,3 +125,8 @@ extern int invalidate_inodes(struct super_block *, bool); 
 * dcache.c

 */

extern struct dentry *__d_alloc(struct super_block *, const struct qstr *);



/*

 * read_write.c

 */

extern ssize_t __kernel_write(struct file *, const char *, size_t, loff_t *);

fs/read_write.c

+25 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/splice.h>

#include <linux/compat.h>

#include "read_write.h"

#include "internal.h"



#include <asm/uaccess.h>

#include <asm/unistd.h>
@@ -417,6 +418,30 @@ ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, lof 


EXPORT_SYMBOL(do_sync_write);



ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t *pos)

{

	mm_segment_t old_fs;

	const char __user *p;

	ssize_t ret;



	old_fs = get_fs();

	set_fs(get_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

		ret = do_sync_write(file, p, count, pos);

	set_fs(old_fs);

	if (ret > 0) {

		fsnotify_modify(file);

		add_wchar(current, ret);

	}

	inc_syscw(current);

	return ret;

}



ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)

{

	ssize_t ret;

fs/splice.c

+3 −1
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/security.h>

#include <linux/gfp.h>

#include <linux/socket.h>

#include "internal.h"



/*

 * Attempt to steal a page from a pipe buffer. This should perhaps go into
@@ -1048,9 +1049,10 @@ static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, 
{

	int ret;

	void *data;

	loff_t tmp = sd->pos;



	data = buf->ops->map(pipe, buf, 0);

	ret = kernel_write(sd->u.file, data + buf->offset, sd->len, sd->pos);

	ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);

	buf->ops->unmap(pipe, buf, data);



	return ret;

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