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Date: Wed, 29 Sep 2010 22:18:48 +1000
From: Dave Chinner <david@...morbit.com>
To: linux-fsdevel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 16/17] fs: Convert nr_inodes to a per-cpu counter
From: Eric Dumazet <dada1@...mosbay.com>
The number of inodes allocated does not need to be tied to the
addition or removal of an inode to/from a list. If we are not tied
to a list lock, we could update the counters when inodes are
initialised or destroyed, but to do that we need to convert the
counters to be per-cpu (i.e. independent of a lock). This means that
we have the freedom to change the list/locking implementation
without needing to care about the counters.
Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
Signed-off-by: Nick Piggin <npiggin@...e.de>
Signed-off-by: Dave Chinner <dchinner@...hat.com>
---
fs/fs-writeback.c | 16 +++++++++++++---
fs/inode.c | 35 +++++++++++++++++++++++++++++++++--
include/linux/fs.h | 5 ++++-
kernel/sysctl.c | 4 ++--
4 files changed, 52 insertions(+), 8 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 8e390e8..348cc18 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -728,6 +728,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
{
unsigned long expired;
long nr_pages;
+ int nr_dirty_inodes;
/*
* When set to zero, disable periodic writeback
@@ -740,10 +741,15 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
if (time_before(jiffies, expired))
return 0;
+ /* approximate dirty inodes */
+ nr_dirty_inodes = get_nr_inodes() - get_nr_inodes_unused();
+ if (nr_dirty_inodes < 0)
+ nr_dirty_inodes = 0;
+
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;
+ nr_dirty_inodes;
if (nr_pages) {
struct wb_writeback_work work = {
@@ -1105,6 +1111,7 @@ void writeback_inodes_sb(struct super_block *sb)
{
unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
+ int nr_dirty_inodes;
DECLARE_COMPLETION_ONSTACK(done);
struct wb_writeback_work work = {
.sb = sb,
@@ -1114,8 +1121,11 @@ void writeback_inodes_sb(struct super_block *sb)
WARN_ON(!rwsem_is_locked(&sb->s_umount));
- work.nr_pages = nr_dirty + nr_unstable +
- inodes_stat.nr_inodes - inodes_stat.nr_unused;
+ nr_dirty_inodes = get_nr_inodes() - get_nr_inodes_unused();
+ if (nr_dirty_inodes < 0)
+ nr_dirty_inodes = 0;
+
+ work.nr_pages = nr_dirty + nr_unstable + nr_dirty_inodes;
bdi_queue_work(sb->s_bdi, &work);
wait_for_completion(&done);
diff --git a/fs/inode.c b/fs/inode.c
index 1388450..a91efab 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -143,8 +143,38 @@ struct inodes_stat_t inodes_stat = {
.nr_unused = 0,
};
+static DEFINE_PER_CPU(unsigned int, nr_inodes);
+
static struct kmem_cache *inode_cachep __read_mostly;
+int get_nr_inodes(void)
+{
+ int i;
+ int sum = 0;
+ for_each_possible_cpu(i)
+ sum += per_cpu(nr_inodes, i);
+ return sum < 0 ? 0 : sum;
+}
+
+int get_nr_inodes_unused(void)
+{
+ return inodes_stat.nr_unused;
+}
+
+/*
+ * Handle nr_dentry 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();
+ return proc_dointvec(table, write, buffer, lenp, ppos);
+#else
+ return -ENOSYS;
+#endif
+}
+
static void wake_up_inode(struct inode *inode)
{
/*
@@ -232,6 +262,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
inode->i_fsnotify_mask = 0;
#endif
+ this_cpu_inc(nr_inodes);
+
return 0;
out:
return -ENOMEM;
@@ -272,6 +304,7 @@ void __destroy_inode(struct inode *inode)
if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
posix_acl_release(inode->i_default_acl);
#endif
+ this_cpu_dec(nr_inodes);
}
EXPORT_SYMBOL(__destroy_inode);
@@ -643,7 +676,6 @@ static inline void
__inode_add_to_lists(struct super_block *sb, struct inode_hash_bucket *b,
struct inode *inode)
{
- inodes_stat.nr_inodes++;
list_add(&inode->i_sb_list, &sb->s_inodes);
spin_unlock(&sb_inode_list_lock);
if (b) {
@@ -1382,7 +1414,6 @@ static void iput_final(struct inode *inode)
spin_unlock(&wb_inode_list_lock);
}
list_del_init(&inode->i_sb_list);
- inodes_stat.nr_inodes--;
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3a43313..d2ee5d0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -407,6 +407,8 @@ extern struct files_stat_struct files_stat;
extern int get_max_files(void);
extern int sysctl_nr_open;
extern struct inodes_stat_t inodes_stat;
+extern int get_nr_inodes(void);
+extern int get_nr_inodes_unused(void);
extern int leases_enable, lease_break_time;
struct buffer_head;
@@ -2477,7 +2479,8 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf,
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])
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index f88552c..33d1733 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -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",
--
1.7.1
--
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