ext4: elevate write count for migrate ioctl

(cherry picked from commit 2a43a878001cc5cb7c3c7be2e8dad0a1aeb939b0)

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2950032..9f62743 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1083,8 +1083,7 @@ 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 7a6c2f1..306bfd4 100644 (file)
--- 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 46fc0b5..f2a9cf4 100644 (file)
--- 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;
@@ -515,12 +514,6 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
         * trascation that created the inode. Later as and
         * 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
@@ -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);