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Re: [PATCH 4/5] xfs: free inodes on log recovery error

To: Brian Foster <bfoster@xxxxxxxxxx>
Subject: Re: [PATCH 4/5] xfs: free inodes on log recovery error
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Mon, 07 Jul 2014 10:18:39 -0500
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20140707143027.GB4123@xxxxxxxxxxxxxx>
References: <20140702143206.438456679@xxxxxxx> <20140702144139.894251516@xxxxxxx> <20140707143027.GB4123@xxxxxxxxxxxxxx>
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20120122 Thunderbird/9.0
On 07/07/14 09:30, Brian Foster wrote:
On Wed, Jul 02, 2014 at 09:32:10AM -0500, Mark Tinguely wrote:
Recovery may free inodes that end up on the inode
reclaim RCU. If recovery fails, we leak these inodes.
The filesystem should be in forced shutdown at this
point, so a call to xfs_reclaim_inode is a fast path
to freeing the inodes and RCU entries.

Signed-off-by: Mark Tinguely<tinguely@xxxxxxx>
  fs/xfs/xfs_log.c   |    2 ++
  fs/xfs/xfs_mount.c |    1 +
  2 files changed, 3 insertions(+)

Index: b/fs/xfs/xfs_log.c
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -31,6 +31,7 @@
  #include "xfs_log_priv.h"
  #include "xfs_log_recover.h"
  #include "xfs_inode.h"
+#include "xfs_icache.h"
  #include "xfs_trace.h"
  #include "xfs_fsops.h"
  #include "xfs_cksum.h"
@@ -720,6 +721,7 @@ xfs_log_mount(
        return 0;

+       xfs_reclaim_inodes(mp, SYNC_WAIT);

So an inode in the perag cache means an xfs_iget(). I see that in
xlog_recover_process_one_iunlink(), which is via
xfs_log_mount_finish(). Assuming I'm following that correctly, why the
reclaim here (and in response to failure here by the caller) as opposed
to closer to a failure of xfs_log_mount_finish()?


Index: b/fs/xfs/xfs_mount.c
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -980,6 +980,7 @@ xfs_mountfs(
+       xfs_reclaim_inodes(mp, SYNC_WAIT);
        if (mp->m_logdev_targp&&  mp->m_logdev_targp != mp->m_ddev_targp)


You are right, the reclaim in xfs_log_mount() is now redundant.

The xfs_reclaim_inodes call location in xfs_mount error path had changed when I learned that the xfs_log_unmount() left inodes in the RCU. I did not notice that with the new location that they were the same.


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