xfs: add XFS_IOC_FREE_EOFBLOCKS ioctl

The XFS_IOC_FREE_EOFBLOCKS ioctl allows users to invoke an EOFBLOCKS
scan. The xfs_eofblocks structure is defined to support the command
parameters (scan mode).

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index c1df3c6..5b20ab0 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -42,6 +42,7 @@
 #include "xfs_inode_item.h"
 #include "xfs_export.h"
 #include "xfs_trace.h"
+#include "xfs_icache.h"
 
 #include <linux/capability.h>
 #include <linux/dcache.h>
@@ -1602,6 +1603,25 @@
 		error = xfs_errortag_clearall(mp, 1);
 		return -error;
 
+	case XFS_IOC_FREE_EOFBLOCKS: {
+		struct xfs_eofblocks eofb;
+
+		if (copy_from_user(&eofb, arg, sizeof(eofb)))
+			return -XFS_ERROR(EFAULT);
+
+		if (eofb.eof_version != XFS_EOFBLOCKS_VERSION)
+			return -XFS_ERROR(EINVAL);
+
+		if (eofb.eof_flags & ~XFS_EOF_FLAGS_VALID)
+			return -XFS_ERROR(EINVAL);
+
+		if (memchr_inv(eofb.pad, 0, sizeof(eofb.pad)))
+			return -XFS_ERROR(EINVAL);
+
+		error = xfs_icache_free_eofblocks(mp, &eofb);
+		return -error;
+	}
+
 	default:
 		return -ENOTTY;
 	}