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[RFC 09/17] xfs: (parent ptr) add parent pointer support to xfs_link

To: xfs@xxxxxxxxxxx
Subject: [RFC 09/17] xfs: (parent ptr) add parent pointer support to xfs_link
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Wed, 15 Jan 2014 16:00:21 -0600
Delivered-to: xfs@xxxxxxxxxxx
References: <20140115220012.624438534@xxxxxxx>
User-agent: quilt/0.51-1
Add the parent inode / offset entry for a new link. If the
parent inode pointer entries are not free, then add the
entry as an extended attribute of ATTR_PARENT type. The
entry uses an unique name composed of the 64 bit inode
and the 32 bit offsets. No extend attribute value is used.

---
 fs/xfs/xfs_inode.c  |   43 ++++++++++++++++++++++++++++++++++++++++---
 fs/xfs/xfs_parent.h |   39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+), 3 deletions(-)

Index: b/fs/xfs/xfs_inode.c
===================================================================
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -51,6 +51,7 @@
 #include "xfs_trans_priv.h"
 #include "xfs_log.h"
 #include "xfs_bmap_btree.h"
+#include "xfs_parent.h"
 
 kmem_zone_t *xfs_inode_zone;
 
@@ -1358,6 +1359,7 @@ xfs_link(
        int                     cancel_flags;
        int                     committed;
        int                     resblks;
+       uint                    offset;
 
        trace_xfs_link(tdp, target_name);
 
@@ -1407,12 +1409,26 @@ xfs_link(
        if (error)
                goto error_return;
 
-       xfs_bmap_init(&free_list, &first_block);
+       xfs_bmap_init(&free_list, &first_block);
 
        error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
-                                  &first_block, &free_list, resblks, NULL);
+                                  &first_block, &free_list, resblks, &offset);
        if (error)
                goto abort_return;
+
+       if (xfs_sb_version_hasparent(&mp->m_sb) &&
+           sip->i_d.di_parent == NULLFSINO) {
+               /*
+                * store the parent information in the inode if the fields
+                * are empty. zero the offset as a flag to not add the
+                * information in an extended attribute.
+                */
+               sip->i_d.di_parent = cpu_to_be64(tdp->i_ino);
+               sip->i_d.di_poffset = cpu_to_be32(offset);
+               xfs_trans_log_inode(tp, sip, XFS_ILOG_CORE);
+               offset = 0;
+       }
+
        xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);
 
@@ -1435,7 +1451,28 @@ xfs_link(
                goto abort_return;
        }
 
-       return xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
+       error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
+       if (error)
+               return error;
+
+       if (xfs_sb_version_hasparent(&mp->m_sb) && offset) {
+               struct xfs_pattr        p_entry;
+               struct xfs_name         p_name;
+
+               /*
+                * The parent pointer information could not be stored
+                * inode core, and must be stored in an extended attribute.
+                */
+               xfs_parent_pname(tdp->i_ino, offset, &p_entry, &p_name);
+               error = xfs_attr_set(sip, (char *) &p_name, NULL, 0,
+                                    ATTR_PARENT|ATTR_CREATE);
+               if (error)
+                       xfs_notice(mp,
+                          "%s: attr %llx/%x failed inode %llx %d\n",
+                          __func__, tdp->i_ino, offset, sip->i_ino,
+                          error);
+       }
+       return error;
 
  abort_return:
        cancel_flags |= XFS_TRANS_ABORT;
Index: b/fs/xfs/xfs_parent.h
===================================================================
--- /dev/null
+++ b/fs/xfs/xfs_parent.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2014 SGI
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef        __XFS_PARENT_H__
+#define        __XFS_PARENT_H__
+
+#define XFSREMOVESRC   (1 << 0)
+#define XFSREMOVETAR   (1 << 1)
+#define XFSADD         (1 << 2)
+
+struct xfs_pattr {
+       __be64  p_ino;
+       __be32  p_offset;
+} __attribute__((packed));
+
+static inline void xfs_parent_pname(xfs_ino_t ino, __uint32_t off, struct 
xfs_pattr *pe, struct xfs_name *pn)
+{
+       pe->p_ino = cpu_to_be64(ino);
+       pe->p_offset = cpu_to_be32(off);
+       pn->name = (char *)pe;
+       pn->len = sizeof(struct xfs_pattr);
+}
+#endif /* __XFS_PARENT_H__ */
+


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