vfs: introduce generic_file_rw_checks()

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>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

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 df2006ba0cfa..a38619a4a6af 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3041,6 +3041,30 @@ 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)