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[PATCH] log replay should not overwrite newer ondisk inodes

To: xfs-dev <xfs-dev@xxxxxxx>
Subject: [PATCH] log replay should not overwrite newer ondisk inodes
From: Lachlan McIlroy <lachlan@xxxxxxx>
Date: Thu, 30 Aug 2007 12:12:47 +1000
Cc: xfs-oss <xfs@xxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Thunderbird 2.0.0.4 (X11/20070604)
Log replay of clustered inodes currently ignores the flushiter
field in the inode that is used to determine if the on-disk inode
is more up to date than the copy in the log.  As a result during
log replay the newer inode is being overwritten with an older
version and file size updates are being lost.

I haven't handled the case of the flushiter counter overflowing
but that shouldn't be a problem in this case.  The log buffer
contains newly created inodes so their flushiter values will be 0
and the on-disk inodes should not be much greater.

Lachlan
--- fs/xfs/xfs_log_recover.c_1.322      2007-08-27 17:45:45.000000000 +1000
+++ fs/xfs/xfs_log_recover.c    2007-08-30 11:50:44.000000000 +1000
@@ -1866,6 +1866,27 @@ xlog_recover_do_inode_buffer(
 }
 
 /*
+ * Check if we need to recover an inode from a buffer
+ */
+int
+xfs_recover_inode(
+       char    *dest,
+       char    *src)
+{
+       xfs_dinode_t    *dip = (xfs_dinode_t *)dest;
+       xfs_dinode_t    *dilp = (xfs_dinode_t*)src;
+
+       if ((be16_to_cpu(dip->di_core.di_magic) == XFS_DINODE_MAGIC) &&
+               (be16_to_cpu(dilp->di_core.di_magic) == XFS_DINODE_MAGIC) &&
+               (be16_to_cpu(dilp->di_core.di_flushiter) <
+                       be16_to_cpu(dip->di_core.di_flushiter))) {
+               return 1;
+       }
+
+       return 0;
+}
+
+/*
  * Perform a 'normal' buffer recovery.  Each logged region of the
  * buffer should be copied over the corresponding region in the
  * given buffer.  The bitmap in the buf log format structure indicates
@@ -1917,6 +1938,13 @@ xlog_recover_do_reg_buffer(
                                               -1, 0, XFS_QMOPT_DOWARN,
                                               "dquot_buf_recover");
                }
+               /*
+                * Sanity check if this is an inode buffer.
+                */
+               if (!error)
+                       error = xfs_recover_inode(xfs_buf_offset(bp,
+                                       (uint)bit << XFS_BLI_SHIFT),
+                                       item->ri_buf[i].i_addr);
                if (!error)
                        memcpy(xfs_buf_offset(bp,
                                (uint)bit << XFS_BLI_SHIFT),    /* dest */
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