From 5c47e6d0ad608987b91affbcf7d1fc12dfbe8fb4 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 29 Apr 2014 16:13:18 -0400 Subject: [PATCH] fold try_prune_one_dentry() Signed-off-by: Al Viro --- fs/dcache.c | 75 ++++++++++++++++++----------------------------------- 1 file changed, 25 insertions(+), 50 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 9b15c5c37277..a5540d491954 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -787,47 +787,9 @@ restart: } EXPORT_SYMBOL(d_prune_aliases); -/* - * Try to throw away a dentry - free the inode, dput the parent. - * Requires dentry->d_lock is held, and dentry->d_count == 0. - * Releases dentry->d_lock. - * - * This may fail if locks cannot be acquired no problem, just try again. - */ -static struct dentry * try_prune_one_dentry(struct dentry *dentry) - __releases(dentry->d_lock) -{ - struct dentry *parent; - - parent = dentry_kill(dentry, 0); - /* - * If dentry_kill returns NULL, we have nothing more to do. - * if it returns the same dentry, trylocks failed. In either - * case, just loop again. - * - * Otherwise, we need to prune ancestors too. This is necessary - * to prevent quadratic behavior of shrink_dcache_parent(), but - * is also expected to be beneficial in reducing dentry cache - * fragmentation. - */ - if (!parent) - return NULL; - if (parent == dentry) - return dentry; - - /* Prune ancestors. */ - dentry = parent; - while (dentry) { - if (lockref_put_or_lock(&dentry->d_lockref)) - return NULL; - dentry = dentry_kill(dentry, 1); - } - return NULL; -} - static void shrink_dentry_list(struct list_head *list) { - struct dentry *dentry; + struct dentry *dentry, *parent; rcu_read_lock(); for (;;) { @@ -863,22 +825,35 @@ static void shrink_dentry_list(struct list_head *list) } rcu_read_unlock(); + parent = dentry_kill(dentry, 0); /* - * If 'try_to_prune()' returns a dentry, it will - * be the same one we passed in, and d_lock will - * have been held the whole time, so it will not - * have been added to any other lists. We failed - * to get the inode lock. - * - * We just add it back to the shrink list. + * If dentry_kill returns NULL, we have nothing more to do. */ - dentry = try_prune_one_dentry(dentry); - - rcu_read_lock(); - if (dentry) { + if (!parent) { + rcu_read_lock(); + continue; + } + if (unlikely(parent == dentry)) { + /* + * trylocks have failed and d_lock has been held the + * whole time, so it could not have been added to any + * other lists. Just add it back to the shrink list. + */ + rcu_read_lock(); d_shrink_add(dentry, list); spin_unlock(&dentry->d_lock); + continue; } + /* + * We need to prune ancestors too. This is necessary to prevent + * quadratic behavior of shrink_dcache_parent(), but is also + * expected to be beneficial in reducing dentry cache + * fragmentation. + */ + dentry = parent; + while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) + dentry = dentry_kill(dentry, 1); + rcu_read_lock(); } rcu_read_unlock(); } -- 2.30.2