[PATCH 07/12] inode: move to per-sb LRU locks

Dave Chinner
2011-06-02T07:01:58Z

From: Dave Chinner <dchinner@redhat.com>

With the inode LRUs moving to per-sb structures, there is no longer
a need for a global inode_lru_lock. The locking can be made more
fine-grained by moving to a per-sb LRU lock, isolating the LRU
operations of different filesytsems completely from each other.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/inode.c | 27 +++++++++++++--------------
fs/super.c | 1 +
include/linux/fs.h | 3 ++-
3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index e039115..667a29c 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -33,7 +33,7 @@
*
* inode->i_lock protects:
* inode->i_state, inode->i_hash, __iget()
- * inode_lru_lock protects:
+ * inode->i_sb->s_inode_lru_lock protects:
* inode->i_sb->s_inode_lru, inode->i_lru
* inode_sb_list_lock protects:
* sb->s_inodes, inode->i_sb_list
@@ -46,7 +46,7 @@
*
* inode_sb_list_lock
* inode->i_lock
- * inode_lru_lock
+ * inode->i_sb->s_inode_lru_lock
*
* inode_wb_list_lock
* inode->i_lock
@@ -64,8 +64,6 @@ static unsigned int i_hash_shift __read_mostly;
static struct hlist_head *inode_hashtable __read_mostly;
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);

-static DEFINE_SPINLOCK(inode_lru_lock);
-
__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_wb_list_lock);

@@ -342,24 +340,24 @@ EXPORT_SYMBOL(ihold);

static void inode_lru_list_add(struct inode *inode)
{
- spin_lock(&inode_lru_lock);
+ spin_lock(&inode->i_sb->s_inode_lru_lock);
if (list_empty(&inode->i_lru)) {
list_add(&inode->i_lru, &inode->i_sb->s_inode_lru);
inode->i_sb->s_nr_inodes_unused++;
this_cpu_inc(nr_unused);
}
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&inode->i_sb->s_inode_lru_lock);
}

static void inode_lru_list_del(struct inode *inode)
{
- spin_lock(&inode_lru_lock);
+ spin_lock(&inode->i_sb->s_inode_lru_lock);
if (!list_empty(&inode->i_lru)) {
list_del_init(&inode->i_lru);
inode->i_sb->s_nr_inodes_unused--;
this_cpu_dec(nr_unused);
}
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&inode->i_sb->s_inode_lru_lock);
}

/**
@@ -608,7 +606,8 @@ static int can_unuse(struct inode *inode)

/*
* Scan `goal' inodes on the unused list for freeable ones. They are moved to a
- * temporary list and then are freed outside inode_lru_lock by dispose_list().
+ * temporary list and then are freed outside sb->s_inode_lru_lock by
+ * dispose_list().
*
* Any inodes which are pinned purely because of attached pagecache have their
* pagecache removed. If the inode has metadata buffers attached to
@@ -628,7 +627,7 @@ static void shrink_icache_sb(struct super_block *sb, int *nr_to_scan)
int nr_scanned;
unsigned long reap = 0;

- spin_lock(&inode_lru_lock);
+ spin_lock(&sb->s_inode_lru_lock);
for (nr_scanned = *nr_to_scan; nr_scanned >= 0; nr_scanned--) {
struct inode *inode;

@@ -638,7 +637,7 @@ static void shrink_icache_sb(struct super_block *sb, int *nr_to_scan)
inode = list_entry(sb->s_inode_lru.prev, struct inode, i_lru);

/*
- * we are inverting the inode_lru_lock/inode->i_lock here,
+ * we are inverting the sb->s_inode_lru_lock/inode->i_lock here,
* so use a trylock. If we fail to get the lock, just move the
* inode to the back of the list so we don't spin on it.
*/
@@ -670,12 +669,12 @@ static void shrink_icache_sb(struct super_block *sb, int *nr_to_scan)
if (inode_has_buffers(inode) || inode->i_data.nrpages) {
__iget(inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&sb->s_inode_lru_lock);
if (remove_inode_buffers(inode))
reap += invalidate_mapping_pages(&inode->i_data,
0, -1);
iput(inode);
- spin_lock(&inode_lru_lock);
+ spin_lock(&sb->s_inode_lru_lock);

if (inode != list_entry(sb->s_inode_lru.next,
struct inode, i_lru))
@@ -700,7 +699,7 @@ static void shrink_icache_sb(struct super_block *sb, int *nr_to_scan)
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
__count_vm_events(PGINODESTEAL, reap);
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&sb->s_inode_lru_lock);
*nr_to_scan = nr_scanned;

dispose_list(&freeable);
diff --git a/fs/super.c b/fs/super.c
index ef7caf7..9c3fa1f 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -78,6 +78,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
INIT_LIST_HEAD(&s->s_inodes);
INIT_LIST_HEAD(&s->s_dentry_lru);
INIT_LIST_HEAD(&s->s_inode_lru);
+ spin_lock_init(&s->s_inode_lru_lock);
init_rwsem(&s->s_umount);
mutex_init(&s->s_lock);
lockdep_set_class(&s->s_umount, &type->s_umount_key);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a96071d..bbd478e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1393,7 +1393,8 @@ struct super_block {
struct list_head s_dentry_lru; /* unused dentry lru */
int s_nr_dentry_unused; /* # of dentry on lru */

- /* inode_lru_lock protects s_inode_lru and s_nr_inodes_unused */
+ /* s_inode_lru_lock protects s_inode_lru and s_nr_inodes_unused */
+ spinlock_t s_inode_lru_lock ____cacheline_aligned_in_smp;
struct list_head s_inode_lru; /* unused inode lru */
int s_nr_inodes_unused; /* # of inodes on lru */

--
1.7.5.1