ext4: elevate write count for migrate ioctl
The migrate ioctl writes to the filsystem, so we need to elevate the
write count.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index ca09dd10..9f3044a 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -267,7 +267,26 @@
}
case EXT4_IOC_MIGRATE:
- return ext4_ext_migrate(inode, filp, cmd, arg);
+ {
+ int err;
+ if (!is_owner_or_cap(inode))
+ return -EACCES;
+
+ err = mnt_want_write(filp->f_path.mnt);
+ if (err)
+ return err;
+ /*
+ * inode_mutex prevent write and truncate on the file.
+ * Read still goes through. We take i_data_sem in
+ * ext4_ext_swap_inode_data before we switch the
+ * inode format to prevent read.
+ */
+ mutex_lock(&(inode->i_mutex));
+ err = ext4_ext_migrate(inode);
+ mutex_unlock(&(inode->i_mutex));
+ mnt_drop_write(filp->f_path.mnt);
+ return err;
+ }
default:
return -ENOTTY;