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>

3 files changed, 22 insertions, 12 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3e47b99a763c..9b6ad8f19bc9 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1084,8 +1084,7 @@ extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
 extern long ext4_compat_ioctl(struct file *, unsigned int, unsigned long);
 
 /* migrate.c */
-extern int ext4_ext_migrate(struct inode *, struct file *, unsigned int,
-                       unsigned long);
+extern int ext4_ext_migrate(struct inode *);
 /* namei.c */
 extern int ext4_orphan_add(handle_t *, struct inode *);
 extern int ext4_orphan_del(handle_t *, struct inode *);
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index ca09dd1039ec..9f3044ac6994 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -267,7 +267,26 @@ setversion_out:
         }
 
         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;
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 46fc0b5b12ba..f2a9cf498ecd 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -447,8 +447,7 @@ static int free_ext_block(handle_t *handle, struct inode *inode)
 
 }
 
-int ext4_ext_migrate(struct inode *inode, struct file *filp,
-                                unsigned int cmd, unsigned long arg)
+int ext4_ext_migrate(struct inode *inode)
 {
         handle_t *handle;
         int retval = 0, i;
@@ -516,12 +515,6 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
          * when we add extents we extent the journal
          */
         /*
-         * 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));
-        /*
          * 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.
@@ -623,7 +616,6 @@ err_out:
         tmp_inode->i_nlink = 0;
 
         ext4_journal_stop(handle);
-        mutex_unlock(&(inode->i_mutex));
 
         if (tmp_inode)
                 iput(tmp_inode);