From: Vasily Averin Date: Sat, 28 Oct 2006 17:38:44 +0000 (-0700) Subject: [PATCH] missing unused dentry in prune_dcache()? X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=6eac3f93f5e6b7256fb20b7608d62ec192da12be;p=deliverable%2Flinux.git [PATCH] missing unused dentry in prune_dcache()? 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 Cc: Neil Brown Acked-by: David Howells Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/dcache.c b/fs/dcache.c index a1ff91eef108..a5b76b647c6d 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -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); }