1 files changed, 36 insertions, 7 deletions

diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 5c1e27de7755..b9e077ba07e9 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -13,8 +13,8 @@
  */
 
 #include <linux/module.h>
-#include <linux/ext4_jbd2.h>
-#include <linux/ext4_fs_extents.h>
+#include "ext4_jbd2.h"
+#include "ext4_extents.h"
 
 /*
  * The contiguous blocks details which can be
@@ -327,7 +327,7 @@ static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 }
 
 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
-                                struct inode *tmp_inode)
+                                                struct inode *tmp_inode)
 {
         int retval;
         __le32  i_data[3];
@@ -339,7 +339,7 @@ static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
          * i_data field of the original inode
          */
         retval = ext4_journal_extend(handle, 1);
-        if (retval != 0) {
+        if (retval) {
                 retval = ext4_journal_restart(handle, 1);
                 if (retval)
                         goto err_out;
@@ -351,6 +351,18 @@ static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 
         down_write(&EXT4_I(inode)->i_data_sem);
         /*
+         * if EXT4_EXT_MIGRATE is cleared a block allocation
+         * happened after we started the migrate. We need to
+         * fail the migrate
+         */
+        if (!(EXT4_I(inode)->i_flags & EXT4_EXT_MIGRATE)) {
+                retval = -EAGAIN;
+                up_write(&EXT4_I(inode)->i_data_sem);
+                goto err_out;
+        } else
+                EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags &
+                                                        ~EXT4_EXT_MIGRATE;
+        /*
          * We have the extent map build with the tmp inode.
          * Now copy the i_data across
          */
@@ -508,6 +520,17 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
          * switch the inode format to prevent read.
          */
         mutex_lock(&(inode->i_mutex));
+        /*
+         * Even though we take i_mutex we can still cause block allocation
+         * via mmap write to holes. If we have allocated new blocks we fail
+         * migrate.  New block allocation will clear EXT4_EXT_MIGRATE flag.
+         * The flag is updated with i_data_sem held to prevent racing with
+         * block allocation.
+         */
+        down_read((&EXT4_I(inode)->i_data_sem));
+        EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags | EXT4_EXT_MIGRATE;
+        up_read((&EXT4_I(inode)->i_data_sem));
+
         handle = ext4_journal_start(inode, 1);
 
         ei = EXT4_I(inode);
@@ -559,9 +582,15 @@ err_out:
                  * tmp_inode
                  */
                 free_ext_block(handle, tmp_inode);
-        else
-                retval = ext4_ext_swap_inode_data(handle, inode,
-                                                        tmp_inode);
+        else {
+                retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
+                if (retval)
+                        /*
+                         * if we fail to swap inode data free the extent
+                         * details of the tmp inode
+                         */
+                        free_ext_block(handle, tmp_inode);
+        }
 
         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
         if (ext4_journal_extend(handle, 1) != 0)