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Subject[patch 23/33] fs: icache atomic inodes_stat
Protect inodes_stat statistics with atomic ops rather than inode_lock.
---
fs/cifs/inode.c | 2 +-
fs/fs-writeback.c | 3 ++-
fs/hugetlbfs/inode.c | 6 +++---
fs/inode.c | 28 +++++++++++++++-------------
include/linux/fs.h | 5 +++--
mm/page-writeback.c | 3 ++-
6 files changed, 26 insertions(+), 21 deletions(-)

Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c
+++ linux-2.6/fs/fs-writeback.c
@@ -695,7 +695,8 @@ void sync_inodes_sb(struct super_block *
unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);

wbc.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));
} else
wbc.nr_to_write = LONG_MAX; /* doesn't actually matter */

Index: linux-2.6/fs/hugetlbfs/inode.c
===================================================================
--- linux-2.6.orig/fs/hugetlbfs/inode.c
+++ linux-2.6/fs/hugetlbfs/inode.c
@@ -386,7 +386,7 @@ static void hugetlbfs_forget_inode(struc
if (!hlist_unhashed(&inode->i_hash)) {
if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_unused);
- inodes_stat.nr_unused++;
+ atomic_inc(&inodes_stat.nr_unused);
if (!sb || (sb->s_flags & MS_ACTIVE)) {
spin_unlock(&inode_lock);
return;
@@ -404,7 +404,7 @@ static void hugetlbfs_forget_inode(struc
spin_lock(&inode->i_lock);
inode->i_state &= ~I_WILL_FREE;
spin_unlock(&inode->i_lock);
- 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);
@@ -416,7 +416,7 @@ static void hugetlbfs_forget_inode(struc
spin_lock(&inode->i_lock);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
- inodes_stat.nr_inodes--;
+ atomic_dec(&inodes_stat.nr_unused);
spin_unlock(&inode_lock);
truncate_hugepages(inode, 0);
clear_inode(inode);
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -101,7 +101,10 @@ static DEFINE_MUTEX(iprune_mutex);
/*
* 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;

@@ -303,7 +306,7 @@ void __iget(struct inode *inode)

if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_in_use);
- inodes_stat.nr_unused--;
+ atomic_dec(&inodes_stat.nr_unused);
}

/**
@@ -368,9 +371,7 @@ 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);
}

/*
@@ -417,7 +418,7 @@ 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;
}

@@ -524,7 +525,7 @@ static void prune_icache(int nr_to_scan)
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
@@ -556,7 +557,8 @@ 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 = {
@@ -649,7 +651,7 @@ 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);
@@ -1287,7 +1289,7 @@ 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--;
+ atomic_dec(&inodes_stat.nr_inodes);
spin_unlock(&inode_lock);

security_inode_delete(inode);
@@ -1323,7 +1325,7 @@ static void generic_forget_inode(struct
if (!hlist_unhashed(&inode->i_hash)) {
if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_unused);
- 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);
@@ -1341,7 +1343,7 @@ static void generic_forget_inode(struct
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);
@@ -1351,7 +1353,7 @@ static void generic_forget_inode(struct
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
- inodes_stat.nr_inodes--;
+ atomic_dec(&inodes_stat.nr_inodes);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
if (inode->i_data.nrpages)
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -8,6 +8,7 @@

#include <linux/limits.h>
#include <linux/ioctl.h>
+#include <asm/atomic.h>

/*
* It's silly to have NR_OPEN bigger than NR_FILE, but you can change
@@ -39,8 +40,8 @@ struct files_stat_struct {
};

struct inodes_stat_t {
- int nr_inodes;
- int nr_unused;
+ atomic_t nr_inodes;
+ atomic_t nr_unused;
int dummy[5]; /* padding for sysctl ABI compatibility */
};

Index: linux-2.6/mm/page-writeback.c
===================================================================
--- linux-2.6.orig/mm/page-writeback.c
+++ linux-2.6/mm/page-writeback.c
@@ -779,7 +779,8 @@ static void wb_kupdate(unsigned long arg
next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10);
nr_to_write = 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));
while (nr_to_write > 0) {
wbc.more_io = 0;
wbc.encountered_congestion = 0;
Index: linux-2.6/fs/cifs/inode.c
===================================================================
--- linux-2.6.orig/fs/cifs/inode.c
+++ linux-2.6/fs/cifs/inode.c
@@ -1428,7 +1428,7 @@ int cifs_revalidate(struct dentry *diren
}
cFYI(1, ("Revalidate: %s inode 0x%p count %d dentry: 0x%p d_time %ld "
"jiffies %ld", full_path, direntry->d_inode,
- direntry->d_inode->i_count.counter, direntry,
+ direntry->d_inode->i_count, direntry,
direntry->d_time, jiffies));

if (cifsInode->time == 0) {



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