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Subject[PATCH 11/17] fs: Factor inode hash operations into functions
Date
From: Nick Piggin <npiggin@suse.de>

Before we can replace the inode hash locking with a more scalable
mechanism, we need to remove external users of the inode_hash_lock.
Make it private by adding a function __remove_inode_hash that can be
called by filesystems instead of open-coding their own inode hash
removal operations.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/inode.c | 39 ++++++++++++++++++++++++---------------
include/linux/fs.h | 1 +
include/linux/writeback.h | 1 -
3 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 153f8d2..24141cc 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -105,7 +105,7 @@ static struct hlist_head *inode_hashtable __read_mostly;
*/
DEFINE_SPINLOCK(sb_inode_list_lock);
DEFINE_SPINLOCK(wb_inode_list_lock);
-DEFINE_SPINLOCK(inode_hash_lock);
+static DEFINE_SPINLOCK(inode_hash_lock);

/*
* iprune_sem provides exclusion between the kswapd or try_to_free_pages
@@ -371,9 +371,7 @@ static void dispose_list(struct list_head *head)

spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
- spin_lock(&inode_hash_lock);
- hlist_del_init(&inode->i_hash);
- spin_unlock(&inode_hash_lock);
+ __remove_inode_hash(inode);
list_del_init(&inode->i_sb_list);
spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
@@ -1274,6 +1272,20 @@ void __insert_inode_hash(struct inode *inode, unsigned long hashval)
EXPORT_SYMBOL(__insert_inode_hash);

/**
+ * __remove_inode_hash - remove an inode from the hash
+ * @inode: inode to unhash
+ *
+ * Remove an inode from the superblock. inode->i_lock must be
+ * held.
+ */
+void __remove_inode_hash(struct inode *inode)
+{
+ spin_lock(&inode_hash_lock);
+ hlist_del_init(&inode->i_hash);
+ spin_unlock(&inode_hash_lock);
+}
+
+/**
* remove_inode_hash - remove an inode from the hash
* @inode: inode to unhash
*
@@ -1282,9 +1294,7 @@ EXPORT_SYMBOL(__insert_inode_hash);
void remove_inode_hash(struct inode *inode)
{
spin_lock(&inode->i_lock);
- spin_lock(&inode_hash_lock);
- hlist_del_init(&inode->i_hash);
- spin_unlock(&inode_hash_lock);
+ __remove_inode_hash(inode);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(remove_inode_hash);
@@ -1348,9 +1358,7 @@ static void iput_final(struct inode *inode)
spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
- spin_lock(&inode_hash_lock);
- hlist_del_init(&inode->i_hash);
- spin_unlock(&inode_hash_lock);
+ __remove_inode_hash(inode);
atomic_dec(&inodes_stat.nr_unused);
}
spin_lock(&wb_inode_list_lock);
@@ -1363,11 +1371,12 @@ static void iput_final(struct inode *inode)
spin_unlock(&inode->i_lock);
atomic_dec(&inodes_stat.nr_inodes);
evict(inode);
- spin_lock(&inode->i_lock);
- spin_lock(&inode_hash_lock);
- hlist_del_init(&inode->i_hash);
- spin_unlock(&inode_hash_lock);
- spin_unlock(&inode->i_lock);
+
+ /*
+ * i_lock is required to delete from hash because find_inode_fast
+ * might find us but go to sleep before we run wake_up_inode.
+ */
+ remove_inode_hash(inode);
wake_up_inode(inode);
BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
destroy_inode(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 46a51b9..da0ebf1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2186,6 +2186,7 @@ extern int should_remove_suid(struct dentry *);
extern int file_remove_suid(struct file *);

extern void __insert_inode_hash(struct inode *, unsigned long hashval);
+extern void __remove_inode_hash(struct inode *);
extern void remove_inode_hash(struct inode *);
static inline void insert_inode_hash(struct inode *inode) {
__insert_inode_hash(inode, inode->i_ino);
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index d266f0d..0f6fe0c 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -11,7 +11,6 @@ struct backing_dev_info;

extern spinlock_t sb_inode_list_lock;
extern spinlock_t wb_inode_list_lock;
-extern spinlock_t inode_hash_lock;
extern struct list_head inode_in_use;
extern struct list_head inode_unused;

--
1.7.1


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