[patch 08/14] fs: icache make nr_inodes and nr_unused atomic

From: npiggin
Date: Thu Oct 21 2010 - 09:22:54 EST

Next message: npiggin: "[patch 01/14] fs: icache begin inode_lock lock breaking"
Previous message: npiggin: "[patch 03/14] fs: icache lock inodes icache state"
In reply to: npiggin: "[patch 03/14] fs: icache lock inodes icache state"
Next in thread: npiggin: "[patch 01/14] fs: icache begin inode_lock lock breaking"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Also fix a theoretical bug where number of inuse inodes is
calculated to be a negative number.

[note: at this point, most of the inode_lock could be removed]

Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
---
fs/fs-writeback.c | 5 +---
fs/inode.c | 61 ++++++++++++++++++++++++++++++++++++++++-------------
include/linux/fs.h | 4 ++-
kernel/sysctl.c | 4 +--
4 files changed, 54 insertions(+), 20 deletions(-)

Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c 2010-10-21 23:50:27.000000000 +1100
+++ linux-2.6/fs/inode.c 2010-10-21 23:50:43.000000000 +1100
@@ -133,6 +133,43 @@ static DECLARE_RWSEM(iprune_sem);
*/
struct inodes_stat_t inodes_stat;

+static atomic_t nr_inodes = ATOMIC_INIT(0);
+static atomic_t nr_unused = ATOMIC_INIT(0);
+
+static int get_nr_inodes(void)
+{
+ return atomic_read(&nr_inodes);
+}
+
+static int get_nr_unused(void)
+{
+ return atomic_read(&nr_unused);
+}
+
+int get_nr_inodes_inuse(void)
+{
+ int nr;
+ nr = get_nr_inodes() - get_nr_unused();
+ if (nr < 0)
+ nr = 0;
+ return nr;
+}
+
+/*
+ * Handle nr_inodes sysctl
+ */
+int proc_nr_inodes(ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
+ inodes_stat.nr_inodes = get_nr_inodes();
+ inodes_stat.nr_unused = get_nr_unused();
+ return proc_dointvec(table, write, buffer, lenp, ppos);
+#else
+ return -ENOSYS;
+#endif
+}
+
static struct kmem_cache *inode_cachep __read_mostly;

static void wake_up_inode(struct inode *inode)
@@ -340,7 +377,7 @@ void inode_get_ilock_wblock(struct inode
if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
list_move(&inode->i_list, &inode_in_use);
}
- inodes_stat.nr_unused--;
+ atomic_dec(&nr_unused);
}

/*
@@ -360,7 +397,7 @@ void inode_get_ilock(struct inode *inode
list_move(&inode->i_list, &inode_in_use);
spin_unlock(&wb_inode_list_lock);
}
- inodes_stat.nr_unused--;
+ atomic_dec(&nr_unused);
}
EXPORT_SYMBOL(inode_get_ilock);

@@ -436,9 +473,7 @@ 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, &nr_inodes);
}

/*
@@ -484,9 +519,7 @@ static int invalidate_list(struct super_
busy = 1;
}
/* only unused inodes may be cached with i_count zero */
- spin_lock(&inode_lock);
- inodes_stat.nr_unused -= count;
- spin_unlock(&inode_lock);
+ atomic_sub(count, &nr_unused);

return busy;
}
@@ -605,7 +638,7 @@ 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, &nr_unused);
if (current_is_kswapd())
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
@@ -638,7 +671,7 @@ static int shrink_icache_memory(struct s
return -1;
prune_icache(nr);
}
- return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
+ return (get_nr_unused() / 100) * sysctl_vfs_cache_pressure;
}

static struct shrinker icache_shrinker = {
@@ -727,7 +760,7 @@ static inline void
__inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
struct inode *inode)
{
- inodes_stat.nr_inodes++;
+ atomic_inc(&nr_inodes);
spin_lock(&wb_inode_list_lock);
list_add(&inode->i_list, &inode_in_use);
spin_unlock(&wb_inode_list_lock);
@@ -1429,7 +1462,7 @@ static void iput_final(struct inode *ino
list_move(&inode->i_list, &inode_unused);
spin_unlock(&wb_inode_list_lock);
}
- inodes_stat.nr_unused++;
+ atomic_inc(&nr_unused);
if (sb->s_flags & MS_ACTIVE) {
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
@@ -1444,7 +1477,7 @@ static void iput_final(struct inode *ino
spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
- inodes_stat.nr_unused--;
+ atomic_dec(&nr_unused);
spin_lock(&inode_hash_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_hash_lock);
@@ -1457,7 +1490,7 @@ static void iput_final(struct inode *ino
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
- inodes_stat.nr_inodes--;
+ atomic_dec(&nr_inodes);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
evict(inode);
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h 2010-10-21 23:50:27.000000000 +1100
+++ linux-2.6/include/linux/fs.h 2010-10-21 23:50:42.000000000 +1100
@@ -407,6 +407,7 @@ extern struct files_stat_struct files_st
extern int get_max_files(void);
extern int sysctl_nr_open;
extern struct inodes_stat_t inodes_stat;
+extern int get_nr_inodes_inuse(void);
extern int leases_enable, lease_break_time;

struct buffer_head;
@@ -2477,7 +2478,8 @@ ssize_t simple_attr_write(struct file *f
struct ctl_table;
int proc_nr_files(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
-
+int proc_nr_inodes(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
int __init get_filesystem_list(char *buf);

#define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
Index: linux-2.6/kernel/sysctl.c
===================================================================
--- linux-2.6.orig/kernel/sysctl.c 2010-10-21 23:49:52.000000000 +1100
+++ linux-2.6/kernel/sysctl.c 2010-10-21 23:50:27.000000000 +1100
@@ -1340,14 +1340,14 @@ static struct ctl_table fs_table[] = {
.data = &inodes_stat,
.maxlen = 2*sizeof(int),
.mode = 0444,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_nr_inodes,
},
{
.procname = "inode-state",
.data = &inodes_stat,
.maxlen = 7*sizeof(int),
.mode = 0444,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_nr_inodes,
},
{
.procname = "file-nr",
Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c 2010-10-21 23:50:27.000000000 +1100
+++ linux-2.6/fs/fs-writeback.c 2010-10-21 23:50:43.000000000 +1100
@@ -774,7 +774,7 @@ 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);
+ get_nr_inodes_inuse();

if (nr_pages) {
struct wb_writeback_work work = {
@@ -1160,8 +1160,7 @@ void writeback_inodes_sb(struct super_bl

WARN_ON(!rwsem_is_locked(&sb->s_umount));

- work.nr_pages = nr_dirty + nr_unstable +
- (inodes_stat.nr_inodes - inodes_stat.nr_unused);
+ work.nr_pages = nr_dirty + nr_unstable + get_nr_inodes_inuse();

bdi_queue_work(sb->s_bdi, &work);
wait_for_completion(&done);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: npiggin: "[patch 01/14] fs: icache begin inode_lock lock breaking"
Previous message: npiggin: "[patch 03/14] fs: icache lock inodes icache state"
In reply to: npiggin: "[patch 03/14] fs: icache lock inodes icache state"
Next in thread: npiggin: "[patch 01/14] fs: icache begin inode_lock lock breaking"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]