From: Nick Piggin <npiggin@xxxxxxx>
To allow removal of the inode_lock, we first need to protect the
superblock inode list with it's own lock instead of using the
inode_lock for this purpose. Nest the new sb_inode_list_lock inside
the inode_lock around the list operations it needs to protect.
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
fs/drop_caches.c | 4 ++++
fs/fs-writeback.c | 4 ++++
fs/inode.c | 19 +++++++++++++++++++
fs/notify/inode_mark.c | 2 ++
fs/quota/dquot.c | 6 ++++++
include/linux/writeback.h | 1 +
6 files changed, 36 insertions(+), 0 deletions(-)
diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 2195c21..ab69ae7 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -17,18 +17,22 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
struct inode *inode, *toput_inode = NULL;
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
continue;
if (inode->i_mapping->nrpages == 0)
continue;
__iget(inode);
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
invalidate_mapping_pages(inode->i_mapping, 0, -1);
iput(toput_inode);
toput_inode = inode;
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
}
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
iput(toput_inode);
}
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 81e086d..9adc9d9 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1021,6 +1021,7 @@ static void wait_sb_inodes(struct super_block *sb)
WARN_ON(!rwsem_is_locked(&sb->s_umount));
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
/*
* Data integrity sync. Must wait for all pages under writeback,
@@ -1038,6 +1039,7 @@ static void wait_sb_inodes(struct super_block *sb)
if (mapping->nrpages == 0)
continue;
__iget(inode);
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
/*
* We hold a reference to 'inode' so it couldn't have
@@ -1055,7 +1057,9 @@ static void wait_sb_inodes(struct super_block *sb)
cond_resched();
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
}
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
iput(old_inode);
}
diff --git a/fs/inode.c b/fs/inode.c
index 8646433..ca98254 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -26,6 +26,15 @@
#include <linux/posix_acl.h>
/*
+ * Usage:
+ * sb_inode_list_lock protects:
+ * s_inodes, i_sb_list
+ *
+ * Ordering:
+ * inode_lock
+ * sb_inode_list_lock
+ */
+/*
* This is needed for the following functions:
* - inode_has_buffers
* - invalidate_inode_buffers
@@ -83,6 +92,7 @@ static struct hlist_head *inode_hashtable __read_mostly;
* the i_state of an inode while it is in use..
*/
DEFINE_SPINLOCK(inode_lock);
+DEFINE_SPINLOCK(sb_inode_list_lock);
/*
* iprune_sem provides exclusion between the kswapd or try_to_free_pages
@@ -339,7 +349,9 @@ static void dispose_list(struct list_head *head)
spin_lock(&inode_lock);
hlist_del_init(&inode->i_hash);
+ spin_lock(&sb_inode_list_lock);
list_del_init(&inode->i_sb_list);
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
wake_up_inode(inode);
@@ -371,6 +383,7 @@ static int invalidate_list(struct list_head *head, struct list_head *dispose)
* shrink_icache_memory() away.
*/
cond_resched_lock(&inode_lock);
+ cond_resched_lock(&sb_inode_list_lock);
next = next->next;
if (tmp == head)
@@ -408,8 +421,10 @@ int invalidate_inodes(struct super_block *sb)
down_write(&iprune_sem);
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
fsnotify_unmount_inodes(&sb->s_inodes);
busy = invalidate_list(&sb->s_inodes, &throw_away);
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
dispose_list(&throw_away);
@@ -597,7 +612,9 @@ __inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
{
inodes_stat.nr_inodes++;
list_add(&inode->i_list, &inode_in_use);
+ spin_lock(&sb_inode_list_lock);
list_add(&inode->i_sb_list, &sb->s_inodes);
+ spin_unlock(&sb_inode_list_lock);
if (head)
hlist_add_head(&inode->i_hash, head);
}
@@ -1231,7 +1248,9 @@ static void iput_final(struct inode *inode)
hlist_del_init(&inode->i_hash);
}
list_del_init(&inode->i_list);
+ spin_lock(&sb_inode_list_lock);
list_del_init(&inode->i_sb_list);
+ spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
inodes_stat.nr_inodes--;
diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 33297c0..34b1585 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -283,6 +283,7 @@ void fsnotify_unmount_inodes(struct list_head *list)
* will be added since the umount has begun. Finally,
* iprune_mutex keeps shrink_icache_memory() away.
*/
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
if (need_iput_tmp)
@@ -296,5 +297,6 @@ void fsnotify_unmount_inodes(struct list_head *list)
iput(inode);
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
}
}
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index aad1316..2e3b913 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -897,6 +897,7 @@ static void add_dquot_ref(struct super_block *sb, int type)
#endif
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
continue;
@@ -910,6 +911,7 @@ static void add_dquot_ref(struct super_block *sb, int type)
continue;
__iget(inode);
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
iput(old_inode);
@@ -921,7 +923,9 @@ static void add_dquot_ref(struct super_block *sb, int type)
* keep the reference and iput it later. */
old_inode = inode;
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
}
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
iput(old_inode);
@@ -1004,6 +1008,7 @@ static void remove_dquot_ref(struct super_block *sb, int type,
int reserved = 0;
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
/*
* We have to scan also I_NEW inodes because they can already
@@ -1017,6 +1022,7 @@ static void remove_dquot_ref(struct super_block *sb, int type,
remove_inode_dquot_ref(inode, type, tofree_head);
}
}
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
#ifdef CONFIG_QUOTA_DEBUG
if (reserved) {
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 72a5d64..9974edb 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -10,6 +10,7 @@
struct backing_dev_info;
extern spinlock_t inode_lock;
+extern spinlock_t sb_inode_list_lock;
extern struct list_head inode_in_use;
extern struct list_head inode_unused;
--
1.7.1
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