vfs: pull btrfs clone API to vfs layer

[cascardo/linux.git] / fs / read_write.c

diff --git a/fs/read_write.c b/fs/read_write.c
index 6cfad47..c75d02c 100644 (file)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1451,3 +1451,75 @@ out1:
 out2:
        return ret;
 }
+
+static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write)
+{
+       struct inode *inode = file_inode(file);
+
+       if (unlikely(pos < 0))
+               return -EINVAL;
+
+        if (unlikely((loff_t) (pos + len) < 0))
+               return -EINVAL;
+
+       if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
+               loff_t end = len ? pos + len - 1 : OFFSET_MAX;
+               int retval;
+
+               retval = locks_mandatory_area(inode, file, pos, end,
+                               write ? F_WRLCK : F_RDLCK);
+               if (retval < 0)
+                       return retval;
+       }
+
+       return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
+}
+
+int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
+               struct file *file_out, loff_t pos_out, u64 len)
+{
+       struct inode *inode_in = file_inode(file_in);
+       struct inode *inode_out = file_inode(file_out);
+       int ret;
+
+       if (inode_in->i_sb != inode_out->i_sb ||
+           file_in->f_path.mnt != file_out->f_path.mnt)
+               return -EXDEV;
+
+       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 -EOPNOTSUPP;
+
+       if (!(file_in->f_mode & FMODE_READ) ||
+           !(file_out->f_mode & FMODE_WRITE) ||
+           (file_out->f_flags & O_APPEND) ||
+           !file_in->f_op->clone_file_range)
+               return -EBADF;
+
+       ret = clone_verify_area(file_in, pos_in, len, false);
+       if (ret)
+               return ret;
+
+       ret = clone_verify_area(file_out, pos_out, len, true);
+       if (ret)
+               return ret;
+
+       if (pos_in + len > i_size_read(inode_in))
+               return -EINVAL;
+
+       ret = mnt_want_write_file(file_out);
+       if (ret)
+               return ret;
+
+       ret = file_in->f_op->clone_file_range(file_in, pos_in,
+                       file_out, pos_out, len);
+       if (!ret) {
+               fsnotify_access(file_in);
+               fsnotify_modify(file_out);
+       }
+
+       mnt_drop_write_file(file_out);
+       return ret;
+}
+EXPORT_SYMBOL(vfs_clone_file_range);