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From: npiggin on 23 Jun 2010 23:30
Problem with inode reclaim is that it puts inodes into I_FREEING state
and then continues to gather more, during which it may iput,
invalidate_mapping_pages, be preempted, etc. Holding these inodes in
I_FREEING can cause pauses.

After the inode scalability work, there is not a big reason to batch
up inodes to reclaim them, so dispose them as they are found from the
LRU.

Signed-off-by: Nick Piggin <npiggin(a)suse.de>

Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -390,6 +390,19 @@ EXPORT_SYMBOL(clear_inode);

static void inode_sb_list_del(struct inode *inode);

+static void dispose_one_inode(struct inode *inode)
+{
+ clear_inode(inode);
+
+ spin_lock(&inode->i_lock);
+ __remove_inode_hash(inode);
+ inode_sb_list_del(inode);
+ spin_unlock(&inode->i_lock);
+
+ wake_up_inode(inode);
+ destroy_inode(inode);
+}
+
/*
* dispose_list - dispose of the contents of a local list
* @head: the head of the list to free
@@ -409,15 +422,8 @@ static void dispose_list(struct list_hea

if (inode->i_data.nrpages)
truncate_inode_pages(&inode->i_data, 0);
- clear_inode(inode);
-
- spin_lock(&inode->i_lock);
- __remove_inode_hash(inode);
- inode_sb_list_del(inode);
- spin_unlock(&inode->i_lock);
-
- wake_up_inode(inode);
- destroy_inode(inode);
+ dispose_one_inode(inode);
+ cond_resched();
nr_disposed++;
}
}
@@ -526,7 +532,6 @@ EXPORT_SYMBOL(invalidate_inodes);
*/
static void prune_icache(struct zone *zone, unsigned long nr_to_scan)
{
- LIST_HEAD(freeable);
unsigned long reap = 0;

down_read(&iprune_sem);
@@ -563,8 +568,6 @@ again:
__iget(inode);
spin_unlock(&inode->i_lock);

- dispose_list(&freeable);
-
if (remove_inode_buffers(inode))
reap += invalidate_mapping_pages(&inode->i_data,
0, -1);
@@ -572,11 +575,15 @@ again:
spin_lock(&zone->inode_lru_lock);
continue;
}
- list_move(&inode->i_lru, &freeable);
+ list_del_init(&inode->i_lru);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
zone->inode_nr_lru--;
+ spin_unlock(&zone->inode_lru_lock);
+ dispose_one_inode(inode);
+ cond_resched();
+ spin_lock(&zone->inode_lru_lock);
}
if (current_is_kswapd())
__count_vm_events(KSWAPD_INODESTEAL, reap);
@@ -584,7 +591,6 @@ again:
__count_vm_events(PGINODESTEAL, reap);
spin_unlock(&zone->inode_lru_lock);

- dispose_list(&freeable);
up_read(&iprune_sem);
}



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