fs: Convert nr_inodes and nr_unused to per-cpu counters

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.

Based on a patch originally from Eric Dumazet.

[AV: cleaned up a bit, fixed build breakage on weird configs

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 78043da85e1f..a3937a8ee95e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2486,7 +2486,8 @@ 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])