And a followup patch for that, removing RCU locking from shrink_dentry_list().
I haven't tested any of this at this point, but I'll ask IBM to do some stress testing. Thanks, Miklos --- From: Miklos Szeredi <[email protected]> Subject: dcache: don't need rcu in shrink_dentry_list() Since now the shrink list is private and nobody can free the dentry while it is on the shrink list, we can remove RCU protection from this. Signed-off-by: Miklos Szeredi <[email protected]> --- fs/dcache.c | 29 ++++------------------------- 1 file changed, 4 insertions(+), 25 deletions(-) --- a/fs/dcache.c +++ b/fs/dcache.c @@ -822,23 +822,9 @@ static void shrink_dentry_list(struct li { struct dentry *dentry, *parent; - rcu_read_lock(); - for (;;) { - dentry = list_entry_rcu(list->prev, struct dentry, d_lru); - if (&dentry->d_lru == list) - break; /* empty */ - - /* - * Get the dentry lock, and re-verify that the dentry is - * this on the shrinking list. If it is, we know that - * DCACHE_SHRINK_LIST and DCACHE_LRU_LIST are set. - */ + while (!list_empty(list)) { + dentry = list_entry(list->prev, struct dentry, d_lru); spin_lock(&dentry->d_lock); - if (dentry != list_entry(list->prev, struct dentry, d_lru)) { - spin_unlock(&dentry->d_lock); - continue; - } - /* * The dispose list is isolated and dentries are not accounted * to the LRU here, so we can simply remove it from the list @@ -854,7 +840,6 @@ static void shrink_dentry_list(struct li spin_unlock(&dentry->d_lock); continue; } - rcu_read_unlock(); if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) { bool free_it; @@ -870,8 +855,6 @@ static void shrink_dentry_list(struct li if (free_it) dentry_free(dentry); - - rcu_read_lock(); continue; } @@ -879,17 +862,15 @@ static void shrink_dentry_list(struct li /* * If dentry_kill returns NULL, we have nothing more to do. */ - if (!parent) { - rcu_read_lock(); + if (!parent) 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; @@ -903,9 +884,7 @@ static void shrink_dentry_list(struct li dentry = parent; while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) dentry = dentry_kill(dentry, 1); - rcu_read_lock(); } - rcu_read_unlock(); } static enum lru_status -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
