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Commit 4f6c9caf authored by Murphy Zhou's avatar Murphy Zhou Committed by Sasha Levin
Browse files

ovl: add splice file read write helper 



[ Upstream commit 1a980b8cbf0059a5308eea61522f232fd03002e2 ]

Now overlayfs falls back to use default file splice read
and write, which is not compatiple with overlayfs, returning
EFAULT. xfstests generic/591 can reproduce part of this.

Tested this patch with xfstests auto group tests.

Signed-off-by: default avatarMurphy Zhou <jencce.kernel@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 85813f1f

fs/overlayfs/file.c

+47 −0
Original line number Diff line number Diff line
@@ -9,6 +9,9 @@ 
#include <linux/xattr.h>

#include <linux/uio.h>

#include <linux/uaccess.h>

#include <linux/splice.h>

#include <linux/mm.h>

#include <linux/fs.h>

#include "overlayfs.h"



static char ovl_whatisit(struct inode *inode, struct inode *realinode)
@@ -293,6 +296,48 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) 
	return ret;

}



static ssize_t ovl_splice_read(struct file *in, loff_t *ppos,

			 struct pipe_inode_info *pipe, size_t len,

			 unsigned int flags)

{

	ssize_t ret;

	struct fd real;

	const struct cred *old_cred;



	ret = ovl_real_fdget(in, &real);

	if (ret)

		return ret;



	old_cred = ovl_override_creds(file_inode(in)->i_sb);

	ret = generic_file_splice_read(real.file, ppos, pipe, len, flags);

	revert_creds(old_cred);



	ovl_file_accessed(in);

	fdput(real);

	return ret;

}



static ssize_t

ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,

			  loff_t *ppos, size_t len, unsigned int flags)

{

	struct fd real;

	const struct cred *old_cred;

	ssize_t ret;



	ret = ovl_real_fdget(out, &real);

	if (ret)

		return ret;



	old_cred = ovl_override_creds(file_inode(out)->i_sb);

	ret = iter_file_splice_write(pipe, real.file, ppos, len, flags);

	revert_creds(old_cred);



	ovl_file_accessed(out);

	fdput(real);

	return ret;

}



static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)

{

	struct fd real;
@@ -649,6 +694,8 @@ const struct file_operations ovl_file_operations = { 
	.fadvise	= ovl_fadvise,

	.unlocked_ioctl	= ovl_ioctl,

	.compat_ioctl	= ovl_compat_ioctl,

	.splice_read    = ovl_splice_read,

	.splice_write   = ovl_splice_write,



	.copy_file_range	= ovl_copy_file_range,

	.remap_file_range	= ovl_remap_file_range,