smb3: missing inode locks in punch hole

smb3 fallocate punch hole was not grabbing the inode or filemap_invalidate
locks so could have race with pagemap reinstantiating the page.

Cc: stable@vger.kernel.org
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index a6fe542..4810bd6 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3384,7 +3384,7 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon,
 static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon,
                            loff_t offset, loff_t len)
 {
-       struct inode *inode;
+       struct inode *inode = file_inode(file);
        struct cifsFileInfo *cfile = file->private_data;
        struct file_zero_data_information fsctl_buf;
        long rc;
@@ -3393,14 +3393,12 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon,
 
        xid = get_xid();
 
-       inode = d_inode(cfile->dentry);
-
+       inode_lock(inode);
        /* Need to make file sparse, if not already, before freeing range. */
        /* Consider adding equivalent for compressed since it could also work */
        if (!smb2_set_sparse(xid, tcon, cfile, inode, set_sparse)) {
                rc = -EOPNOTSUPP;
-               free_xid(xid);
-               return rc;
+               goto out;
        }
 
        filemap_invalidate_lock(inode->i_mapping);
@@ -3420,8 +3418,10 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon,
                        (char *)&fsctl_buf,
                        sizeof(struct file_zero_data_information),
                        CIFSMaxBufSize, NULL, NULL);
-       free_xid(xid);
        filemap_invalidate_unlock(inode->i_mapping);
+out:
+       inode_unlock(inode);
+       free_xid(xid);
        return rc;
 }