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Re: [PATCH] make inode reclaim wait for log I/O to complete

To: David Chinner <dgc@xxxxxxx>
Subject: Re: [PATCH] make inode reclaim wait for log I/O to complete
From: Lachlan McIlroy <lachlan@xxxxxxx>
Date: Thu, 22 May 2008 13:42:47 +1000
Cc: xfs-dev <xfs-dev@xxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
In-reply-to: <20080514064451.GF155679365@xxxxxxx>
References: <482A77A9.5040806@xxxxxxx> <20080514064451.GF155679365@xxxxxxx>
Reply-to: lachlan@xxxxxxx
Sender: xfs-bounce@xxxxxxxxxxx
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David Chinner wrote:
On Wed, May 14, 2008 at 03:24:57PM +1000, Lachlan McIlroy wrote:
An xfs inode can be destroyed before log I/O involving that inode
is complete.  We need to wait for the inode to be unpinned before
tearing it down.

Lachlan

--- fs/xfs/xfs_inode.c_1.501    2008-05-12 14:45:17.000000000 +1000
+++ fs/xfs/xfs_inode.c  2008-05-12 12:23:48.000000000 +1000
@@ -2787,7 +2787,7 @@ __xfs_iunpin_wait(
wait_event(ip->i_ipin_wait, (atomic_read(&ip->i_pincount) == 0));
}

-static inline void
+inline void
xfs_iunpin_wait(
        xfs_inode_t     *ip)
{

You want to kill the inline on this.

Done.


--- fs/xfs/xfs_inode.h_1.245    2008-05-12 14:45:20.000000000 +1000
+++ fs/xfs/xfs_inode.h  2008-05-12 12:31:37.000000000 +1000
@@ -481,6 +481,7 @@ void                xfs_ifunlock(xfs_inode_t *);
void            xfs_ireclaim(xfs_inode_t *);
int             xfs_finish_reclaim(xfs_inode_t *, int, int);
int             xfs_finish_reclaim_all(struct xfs_mount *, int);
+void           xfs_iunpin_wait(xfs_inode_t *);

/*
 * xfs_inode.c prototypes.
--- fs/xfs/xfs_vnodeops.c_1.757 2008-05-12 12:02:45.000000000 +1000
+++ fs/xfs/xfs_vnodeops.c       2008-05-12 12:28:15.000000000 +1000
@@ -3324,6 +3324,7 @@ xfs_finish_reclaim(
                         * because we're gonna reclaim the inode anyway.
                         */
                        if (error) {
+                               xfs_iunpin_wait(ip);
                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                                goto reclaim;
                        }

We can't get an error from xfs_iflush() from here that hasn't
already passed through xfs_iunpin_wait() in xfs_iflush().
Hence we should never see a pinned inode through this path.

Okay, good point.  I'll remove that one.  I thought about removing
the XFS_FORCED_SHUTDOWN() and dirty inode checks from xfs_finish_reclaim()
and calling xfs_iflush() anyway.  It will abort if it's a clean inode
or it will do the unpin and then abort if it's a forced shutdown.
It would make the code in xfs_finish_reclaim() a bit cleaner.  I also
wouldn't need to export xfs_iunpin_wait().  Thoughts?


@@ -3336,6 +3337,7 @@ xfs_finish_reclaim(
        }

        xfs_ifunlock(ip);
+       xfs_iunpin_wait(ip);

If we are not shutting down the filesystem, how do we get a pinned
inode here?  A pinned inode is a dirty inode and should be caught by
the above code. Is the crash occurring when a force shutdown is in
progress?

Yes, sorry, forgot to mention this was during a forced shutdown.


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