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[PATCH] missing unused dentry in prune_dcache()?

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On the the following patch:
http://linux.bkbits.net:8080/linux-2.6/gnupatch@449b144ecSF1rYskg3q-SeR2vf88zg

# ChangeSet
#   2006/06/22 15:05:57-07:00 neilb@suse.de
#   [PATCH] Fix dcache race during umount

#   If prune_dcache finds a dentry that it cannot free, it leaves it where it
#   is (at the tail of the list) and exits, on the assumption that some other
#   thread will be removing that dentry soon.

However as far as I see this comment is not correct: when we cannot take
s_umount rw_semaphore (for example because it was taken in do_remount) this
dentry is already extracted from dentry_unused list and we do not add it
into the list again.  Therefore dentry will not be found by prune_dcache()
and shrink_dcache_sb() and will leave in memory very long time until the
partition will be unmounted.

The patch adds this dentry into tail of the dentry_unused list.

Signed-off-by: Vasily Averin <vvs@sw.ru>
Cc: Neil Brown <neilb@suse.de>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Vasily Averin 2006-10-28 10:38:44 -07:00 committed by Linus Torvalds
parent ebed4bfc8d
commit 6eac3f93f5
1 changed files with 5 additions and 4 deletions
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9
fs/dcache.c
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@ -478,11 +478,12 @@ static void prune_dcache(int count, struct super_block *sb)
up_read(s_umount);
}
spin_unlock(&dentry->d_lock);
/* Cannot remove the first dentry, and it isn't appropriate
* to move it to the head of the list, so give up, and try
* later
/*
* Insert dentry at the head of the list as inserting at the
* tail leads to a cycle.
*/
break;
list_add(&dentry->d_lru, &dentry_unused);
dentry_stat.nr_unused++;
}
spin_unlock(&dcache_lock);
}