1 files changed, 8 insertions, 2 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4482cf35522e..80fe3c654612 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2928,8 +2928,14 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
                 ret = btrfs_defrag_root(root);
                 break;
         case S_IFREG:
-                if (!(file->f_mode & FMODE_WRITE)) {
-                        ret = -EINVAL;
+                /*
+                 * Note that this does not check the file descriptor for write
+                 * access. This prevents defragmenting executables that are
+                 * running and allows defrag on files open in read-only mode.
+                 */
+                if (!capable(CAP_SYS_ADMIN) &&
+                    inode_permission(inode, MAY_WRITE)) {
+                        ret = -EPERM;
                         goto out;
                 }