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Re: [PATCH] Unlock inode before calling xfs_idestroy()

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH] Unlock inode before calling xfs_idestroy()
From: Lachlan McIlroy <lachlan@xxxxxxx>
Date: Mon, 22 Sep 2008 13:57:11 +1000
Cc: xfs-oss <xfs@xxxxxxxxxxx>, xfs-dev <xfs-dev@xxxxxxx>
In-reply-to: <20080919072603.GA26903@xxxxxxxxxxxxx>
References: <48D3193C.6060201@xxxxxxx> <20080919072603.GA26903@xxxxxxxxxxxxx>
Reply-to: lachlan@xxxxxxx
User-agent: Thunderbird 2.0.0.16 (X11/20080707)
Christoph Hellwig wrote:
On Fri, Sep 19, 2008 at 01:15:08PM +1000, Lachlan McIlroy wrote:
Lock debugging reported the ilock was being destroyed
without being unlocked.

--- a/fs/xfs/xfs_iget.c 2008-09-19 13:03:57.000000000 +1000
+++ b/fs/xfs/xfs_iget.c 2008-09-19 13:12:38.000000000 +1000
@@ -214,6 +214,7 @@ finish_inode:
                xfs_ilock(ip, lock_flags);

        if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
+               xfs_iunlock(ip, lock_flags);
                xfs_idestroy(ip);
                xfs_put_perag(mp, pag);
                return ENOENT;
@@ -224,6 +225,7 @@ finish_inode:
         * write spinlock.
         */
        if (radix_tree_preload(GFP_KERNEL)) {
+               xfs_iunlock(ip, lock_flags);
                xfs_idestroy(ip);
                delay(1);
                goto again;

Just move the xfs_ilock call after these two statements, there is no
need to have it locked before inserting it into the radix tree.
Okay, thanks.  I thought we may need it locked while doing the mode
check so I left it as is.


@@ -239,6 +241,7 @@ finish_inode:
                BUG_ON(error != -EEXIST);
                write_unlock(&pag->pag_ici_lock);
                radix_tree_preload_end();
+               xfs_iunlock(ip, lock_flags);
                xfs_idestroy(ip);
                XFS_STATS_INC(xs_ig_dup);
                goto again;

But here we still need the fix.  But as Tim mention we need to check
for lock_flags != 0 first.  Long-term it might make sense to just make
xfs_iunlock a no-op if lock_flags == 0, but let's do that separately.


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