Protect inodes_stat statistics with atomic ops rather than inode_lock.
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
---
fs/fs-writeback.c | 6 ++++--
fs/inode.c | 28 +++++++++++++++-------------
include/linux/fs.h | 5 +++--
3 files changed, 22 insertions(+), 17 deletions(-)
Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c
+++ linux-2.6/fs/fs-writeback.c
@@ -924,7 +924,8 @@ static long wb_check_old_data_flush(stru
wb->last_old_flush = jiffies;
nr_pages = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS) +
- (inodes_stat.nr_inodes - inodes_stat.nr_unused);
+ (atomic_read(&inodes_stat.nr_inodes) -
+ atomic_read(&inodes_stat.nr_unused));
if (nr_pages) {
struct wb_writeback_args args = {
@@ -1285,7 +1286,8 @@ void writeback_inodes_sb(struct super_bl
long nr_to_write;
nr_to_write = nr_dirty + nr_unstable +
- (inodes_stat.nr_inodes - inodes_stat.nr_unused);
+ (atomic_read(&inodes_stat.nr_inodes) -
+ atomic_read(&inodes_stat.nr_unused));
bdi_start_writeback(sb->s_bdi, sb, nr_to_write);
}
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -123,7 +123,10 @@ static DECLARE_RWSEM(iprune_sem);
/*
* Statistics gathering..
*/
-struct inodes_stat_t inodes_stat;
+struct inodes_stat_t inodes_stat = {
+ .nr_inodes = ATOMIC_INIT(0),
+ .nr_unused = ATOMIC_INIT(0),
+};
static struct kmem_cache *inode_cachep __read_mostly;
@@ -318,7 +321,7 @@ void __iget(struct inode *inode)
list_move(&inode->i_list, &inode_in_use);
spin_unlock(&wb_inode_list_lock);
}
- inodes_stat.nr_unused--;
+ atomic_dec(&inodes_stat.nr_unused);
}
/**
@@ -382,9 +385,7 @@ static void dispose_list(struct list_hea
destroy_inode(inode);
nr_disposed++;
}
- spin_lock(&inode_lock);
- inodes_stat.nr_inodes -= nr_disposed;
- spin_unlock(&inode_lock);
+ atomic_sub(nr_disposed, &inodes_stat.nr_inodes);
}
/*
@@ -433,7 +434,7 @@ static int invalidate_list(struct list_h
busy = 1;
}
/* only unused inodes may be cached with i_count zero */
- inodes_stat.nr_unused -= count;
+ atomic_sub(count, &inodes_stat.nr_unused);
return busy;
}
@@ -551,7 +552,7 @@ again2:
spin_unlock(&inode->i_lock);
nr_pruned++;
}
- inodes_stat.nr_unused -= nr_pruned;
+ atomic_sub(nr_pruned, &inodes_stat.nr_unused);
if (current_is_kswapd())
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
@@ -584,7 +585,8 @@ static int shrink_icache_memory(int nr,
return -1;
prune_icache(nr);
}
- return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
+ return (atomic_read(&inodes_stat.nr_unused) / 100) *
+ sysctl_vfs_cache_pressure;
}
static struct shrinker icache_shrinker = {
@@ -677,7 +679,7 @@ static inline void
__inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
struct inode *inode)
{
- inodes_stat.nr_inodes++;
+ atomic_inc(&inodes_stat.nr_inodes);
spin_lock(&sb_inode_list_lock);
list_add(&inode->i_sb_list, &sb->s_inodes);
spin_unlock(&sb_inode_list_lock);
@@ -1321,8 +1323,8 @@ void generic_delete_inode(struct inode *
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
- inodes_stat.nr_inodes--;
spin_unlock(&inode_lock);
+ atomic_dec(&inodes_stat.nr_inodes);
if (op->delete_inode) {
void (*delete)(struct inode *) = op->delete_inode;
@@ -1365,7 +1367,7 @@ int generic_detach_inode(struct inode *i
list_move(&inode->i_list, &inode_unused);
spin_unlock(&wb_inode_list_lock);
}
- inodes_stat.nr_unused++;
+ atomic_inc(&inodes_stat.nr_unused);
if (sb->s_flags & MS_ACTIVE) {
spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
@@ -1383,7 +1385,7 @@ int generic_detach_inode(struct inode *i
spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
- inodes_stat.nr_unused--;
+ atomic_dec(&inodes_stat.nr_unused);
spin_lock(&inode_hash_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_hash_lock);
@@ -1395,9 +1397,9 @@ int generic_detach_inode(struct inode *i
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
- inodes_stat.nr_inodes--;
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
+ atomic_dec(&inodes_stat.nr_inodes);
return 1;
}
EXPORT_SYMBOL_GPL(generic_detach_inode);
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -38,13 +38,6 @@ struct files_stat_struct {
int max_files; /* tunable */
};
-struct inodes_stat_t {
- int nr_inodes;
- int nr_unused;
- int dummy[5]; /* padding for sysctl ABI compatibility */
-};
-
-
#define NR_FILE 8192 /* this can well be larger on a larger system */
#define MAY_EXEC 1
@@ -418,6 +411,12 @@ typedef int (get_block_t)(struct inode *
typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
ssize_t bytes, void *private);
+struct inodes_stat_t {
+ atomic_t nr_inodes;
+ atomic_t nr_unused;
+ int dummy[5]; /* padding for sysctl ABI compatibility */
+};
+
/*
* Attribute flags. These should be or-ed together to figure out what
* has been changed!
Index: linux-2.6/drivers/staging/pohmelfs/inode.c
===================================================================
--- linux-2.6.orig/drivers/staging/pohmelfs/inode.c
+++ linux-2.6/drivers/staging/pohmelfs/inode.c
@@ -1283,11 +1283,11 @@ static void pohmelfs_put_super(struct su
dprintk("%s: ino: %llu, pi: %p, inode: %p, count: %u.\n",
__func__, pi->ino, pi, inode, count);
- if (atomic_read(&inode->i_count) != count) {
+ if (inode->i_count != count) {
printk("%s: ino: %llu, pi: %p, inode: %p, count: %u, i_count: %d.\n",
__func__, pi->ino, pi, inode, count,
- atomic_read(&inode->i_count));
- count = atomic_read(&inode->i_count);
+ inode->i_count);
+ count = inode->i_count;
in_drop_list++;
}
@@ -1299,7 +1299,7 @@ static void pohmelfs_put_super(struct su
pi = POHMELFS_I(inode);
dprintk("%s: ino: %llu, pi: %p, inode: %p, i_count: %u.\n",
- __func__, pi->ino, pi, inode, atomic_read(&inode->i_count));
+ __func__, pi->ino, pi, inode, inode->i_count);
/*
* These are special inodes, they were created during
@@ -1307,7 +1307,7 @@ static void pohmelfs_put_super(struct su
* so they live here with reference counter being 1 and prevent
* umount from succeed since it believes that they are busy.
*/
- count = atomic_read(&inode->i_count);
+ count = inode->i_count;
if (count) {
list_del_init(&inode->i_sb_list);
while (count--)
Index: linux-2.6/fs/btrfs/inode.c
===================================================================
--- linux-2.6.orig/fs/btrfs/inode.c
+++ linux-2.6/fs/btrfs/inode.c
@@ -1964,8 +1964,13 @@ void btrfs_add_delayed_iput(struct inode
struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
struct delayed_iput *delayed;
- if (atomic_add_unless(&inode->i_count, -1, 1))
+ spin_lock(&inode->i_lock);
+ if (inode->i_count > 1) {
+ inode->i_count--;
+ spin_unlock(&inode->i_lock);
return;
+ }
+ spin_unlock(&inode->i_lock);
delayed = kmalloc(sizeof(*delayed), GFP_NOFS | __GFP_NOFAIL);
delayed->inode = inode;
@@ -2718,10 +2723,10 @@ static struct btrfs_trans_handle *__unli
return ERR_PTR(-ENOSPC);
/* check if there is someone else holds reference */
- if (S_ISDIR(inode->i_mode) && atomic_read(&inode->i_count) > 1)
+ if (S_ISDIR(inode->i_mode) && inode->i_count > 1)
return ERR_PTR(-ENOSPC);
- if (atomic_read(&inode->i_count) > 2)
+ if (inode->i_count > 2)
return ERR_PTR(-ENOSPC);
if (xchg(&root->fs_info->enospc_unlink, 1))
@@ -3934,7 +3939,7 @@ again:
inode = igrab(&entry->vfs_inode);
if (inode) {
spin_unlock(&root->inode_lock);
- if (atomic_read(&inode->i_count) > 1)
+ if (inode->i_count > 1)
d_prune_aliases(inode);
/*
* btrfs_drop_inode will remove it from
Index: linux-2.6/fs/ceph/mds_client.c
===================================================================
--- linux-2.6.orig/fs/ceph/mds_client.c
+++ linux-2.6/fs/ceph/mds_client.c
@@ -1028,7 +1028,7 @@ static int trim_caps_cb(struct inode *in
spin_unlock(&inode->i_lock);
d_prune_aliases(inode);
dout("trim_caps_cb %p cap %p pruned, count now %d\n",
- inode, cap, atomic_read(&inode->i_count));
+ inode, cap, inode->i_count);
return 0;
}
Index: linux-2.6/fs/logfs/dir.c
===================================================================
--- linux-2.6.orig/fs/logfs/dir.c
+++ linux-2.6/fs/logfs/dir.c
@@ -566,7 +566,9 @@ static int logfs_link(struct dentry *old
return -EMLINK;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
- atomic_inc(&inode->i_count);
+ spin_lock(&inode->i_lock);
+ inode->i_count++;
+ spin_unlock(&inode->i_lock);
inode->i_nlink++;
mark_inode_dirty_sync(inode);
Index: linux-2.6/fs/logfs/readwrite.c
===================================================================
--- linux-2.6.orig/fs/logfs/readwrite.c
+++ linux-2.6/fs/logfs/readwrite.c
@@ -1002,7 +1002,7 @@ static int __logfs_is_valid_block(struct
{
struct logfs_inode *li = logfs_inode(inode);
- if ((inode->i_nlink == 0) && atomic_read(&inode->i_count) == 1)
+ if (inode->i_nlink == 0 && inode->i_count == 1)
return 0;
if (bix < I0_BLOCKS)
--
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