[PATCH v2 3/8] vfs: introduce generic_file_rw_checks()

Amir Goldstein
2019-05-26T06:11:19Z

Factor out helper with some checks on in/out file that are
common to clone_file_range and copy_file_range.

Suggested-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/read_write.c | 38 +++++++++++---------------------------
include/linux/fs.h | 1 +
mm/filemap.c | 24 ++++++++++++++++++++++++
3 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index b63dcb4e4fe9..f1900bdb3127 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1617,17 +1617,18 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
size_t len, unsigned int flags)
{
- struct inode *inode_in = file_inode(file_in);
- struct inode *inode_out = file_inode(file_out);
ssize_t ret;

if (flags != 0)
return -EINVAL;

- if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
- return -EISDIR;
- if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
- return -EINVAL;
+ /* this could be relaxed once a method supports cross-fs copies */
+ if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
+ return -EXDEV;
+
+ ret = generic_file_rw_checks(file_in, file_out);
+ if (unlikely(ret))
+ return ret;

ret = rw_verify_area(READ, file_in, &pos_in, len);
if (unlikely(ret))
@@ -1637,15 +1638,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (unlikely(ret))
return ret;

- if (!(file_in->f_mode & FMODE_READ) ||
- !(file_out->f_mode & FMODE_WRITE) ||
- (file_out->f_flags & O_APPEND))
- return -EBADF;
-
- /* this could be relaxed once a method supports cross-fs copies */
- if (inode_in->i_sb != inode_out->i_sb)
- return -EXDEV;
-
if (len == 0)
return 0;

@@ -2013,29 +2005,21 @@ loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t len, unsigned int remap_flags)
{
- struct inode *inode_in = file_inode(file_in);
- struct inode *inode_out = file_inode(file_out);
loff_t ret;

WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);

- if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
- return -EISDIR;
- if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
- return -EINVAL;
-
/*
* FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
* the same mount. Practically, they only need to be on the same file
* system.
*/
- if (inode_in->i_sb != inode_out->i_sb)
+ if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
return -EXDEV;

- if (!(file_in->f_mode & FMODE_READ) ||
- !(file_out->f_mode & FMODE_WRITE) ||
- (file_out->f_flags & O_APPEND))
- return -EBADF;
+ ret = generic_file_rw_checks(file_in, file_out);
+ if (ret < 0)
+ return ret;

if (!file_in->f_op->remap_file_range)
return -EOPNOTSUPP;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ea17858310ff..89b9b73eb581 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3049,6 +3049,7 @@ extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t *count, unsigned int remap_flags);
+extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
diff --git a/mm/filemap.c b/mm/filemap.c
index c5af80c43d36..798aac92cd76 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3040,6 +3040,30 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in,
return 0;
}

+
+/*
+ * Performs common checks before doing a file copy/clone
+ * from @file_in to @file_out.
+ */
+int generic_file_rw_checks(struct file *file_in, struct file *file_out)
+{
+ struct inode *inode_in = file_inode(file_in);
+ struct inode *inode_out = file_inode(file_out);
+
+ /* Don't copy dirs, pipes, sockets... */
+ if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
+ return -EISDIR;
+ if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
+ return -EINVAL;
+
+ if (!(file_in->f_mode & FMODE_READ) ||
+ !(file_out->f_mode & FMODE_WRITE) ||
+ (file_out->f_flags & O_APPEND))
+ return -EBADF;
+
+ return 0;
+}
+
int pagecache_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
--
2.17.1