ext4: online defrag -- Add EXT4_IOC_MOVE_EXT ioctl

The EXT4_IOC_MOVE_EXT exchanges the blocks between orig_fd and donor_fd,
and then write the file data of orig_fd to donor_fd.
ext4_mext_move_extent() is the main fucntion of ext4 online defrag,
and this patch includes all functions related to ext4 online defrag.

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 36 insertions, 0 deletions

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 91e75f7a9e73..bb415408fdb6 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -14,6 +14,7 @@
 #include <linux/compat.h>
 #include <linux/smp_lock.h>
 #include <linux/mount.h>
+#include <linux/file.h>
 #include <asm/uaccess.h>
 #include "ext4_jbd2.h"
 #include "ext4.h"
@@ -213,6 +214,41 @@ setversion_out:
 
                 return err;
         }
+
+        case EXT4_IOC_MOVE_EXT: {
+                struct move_extent me;
+                struct file *donor_filp;
+                int err;
+
+                if (copy_from_user(&me,
+                        (struct move_extent __user *)arg, sizeof(me)))
+                        return -EFAULT;
+
+                donor_filp = fget(me.donor_fd);
+                if (!donor_filp)
+                        return -EBADF;
+
+                if (!capable(CAP_DAC_OVERRIDE)) {
+                        if ((current->real_cred->fsuid != inode->i_uid) ||
+                                !(inode->i_mode & S_IRUSR) ||
+                                !(donor_filp->f_dentry->d_inode->i_mode &
+                                S_IRUSR)) {
+                                fput(donor_filp);
+                                return -EACCES;
+                        }
+                }
+
+                err = ext4_move_extents(filp, donor_filp, me.orig_start,
+                                        me.donor_start, me.len, &me.moved_len);
+                fput(donor_filp);
+
+                if (!err)
+                        if (copy_to_user((struct move_extent *)arg,
+                                &me, sizeof(me)))
+                                return -EFAULT;
+                return err;
+        }
+
         case EXT4_IOC_GROUP_ADD: {
                 struct ext4_new_group_data input;
                 struct super_block *sb = inode->i_sb;