Re: [PATCH V4] fs: allow for more than 2^31 files

Robin Holt
2010-10-01T13:38:56Z

Looks good.

Reviewed-by: Robin Holt <holt@sgi.com>
Tested-by: Robin Holt <holt@sgi.com>

I don't mean to flood this with my name, merely that I do find this
patch acceptable, worthy, and have tested it. Feel free to lop off any
of these lines that are offensive.

Robin

On Fri, Oct 01, 2010 at 07:29:18AM +0200, Eric Dumazet wrote:
> Le vendredi 01 octobre 2010 à 07:03 +0200, Eric Dumazet a écrit :
> > Le jeudi 30 septembre 2010 à 23:34 -0500, Robin Holt a écrit :
> >
> > > The proc_handler used to be proc_nr_files() which would call
> > > get_nr_files() and deposit the result in files_stat.nr_files then cascade
> > > to proc_dointvec() which would dump the 3 values. Now it will dump the
> > > three values, but not update the middle (nr_files) value first.
> > >
> >
> > Ah I get it now, thanks !
> >
> > I'll send a V4 shortly.
> >
> >
>
> In this v4, I call proc_nr_files() again, and proc_nr_files() calls
> proc_doulongvec_minmax() instead of proc_dointvec()
>
> Added the "cat /proc/sys/fs/file-nr" in Changelog
>
> Thanks again Robin
>
> [PATCH V3] fs: allow for more than 2^31 files
>
> Robin Holt tried to boot a 16TB system and found af_unix was overflowing
> a 32bit value :
>
> <quote>
>
> We were seeing a failure which prevented boot. The kernel was incapable
> of creating either a named pipe or unix domain socket. This comes down
> to a common kernel function called unix_create1() which does:
>
> atomic_inc(&unix_nr_socks);
> if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
> goto out;
>
> The function get_max_files() is a simple return of files_stat.max_files.
> files_stat.max_files is a signed integer and is computed in
> fs/file_table.c's files_init().
>
> n = (mempages * (PAGE_SIZE / 1024)) / 10;
> files_stat.max_files = n;
>
> In our case, mempages (total_ram_pages) is approx 3,758,096,384
> (0xe0000000). That leaves max_files at approximately 1,503,238,553.
> This causes 2 * get_max_files() to integer overflow.
>
> </quote>
>
> Fix is to let /proc/sys/fs/file-nr & /proc/sys/fs/file-max use long
> integers, and change af_unix to use an atomic_long_t instead of
> atomic_t.
>
> get_max_files() is changed to return an unsigned long.
> get_nr_files() is changed to return a long.
>
> unix_nr_socks is changed from atomic_t to atomic_long_t, while not
> strictly needed to address Robin problem.
>
> Before patch (on a 64bit kernel) :
> # echo 2147483648 >/proc/sys/fs/file-max
> # cat /proc/sys/fs/file-max
> -18446744071562067968
>
> After patch:
> # echo 2147483648 >/proc/sys/fs/file-max
> # cat /proc/sys/fs/file-max
> 2147483648
> # cat /proc/sys/fs/file-nr
> 704 0 2147483648
>
>
> Reported-by: Robin Holt <holt@sgi.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> ---
> fs/file_table.c | 17 +++++++----------
> include/linux/fs.h | 8 ++++----
> kernel/sysctl.c | 6 +++---
> net/unix/af_unix.c | 14 +++++++-------
> 4 files changed, 21 insertions(+), 24 deletions(-)
>
> diff --git a/fs/file_table.c b/fs/file_table.c
> index a04bdd8..c3dee38 100644
> --- a/fs/file_table.c
> +++ b/fs/file_table.c
> @@ -60,7 +60,7 @@ static inline void file_free(struct file *f)
> /*
> * Return the total number of open files in the system
> */
> -static int get_nr_files(void)
> +static long get_nr_files(void)
> {
> return percpu_counter_read_positive(&nr_files);
> }
> @@ -68,7 +68,7 @@ static int get_nr_files(void)
> /*
> * Return the maximum number of open files in the system
> */
> -int get_max_files(void)
> +unsigned long get_max_files(void)
> {
> return files_stat.max_files;
> }
> @@ -82,7 +82,7 @@ int proc_nr_files(ctl_table *table, int write,
> void __user *buffer, size_t *lenp, loff_t *ppos)
> {
> files_stat.nr_files = get_nr_files();
> - return proc_dointvec(table, write, buffer, lenp, ppos);
> + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
> }
> #else
> int proc_nr_files(ctl_table *table, int write,
> @@ -105,7 +105,7 @@ int proc_nr_files(ctl_table *table, int write,
> struct file *get_empty_filp(void)
> {
> const struct cred *cred = current_cred();
> - static int old_max;
> + static long old_max;
> struct file * f;
>
> /*
> @@ -140,8 +140,7 @@ struct file *get_empty_filp(void)
> over:
> /* Ran out of filps - report that */
> if (get_nr_files() > old_max) {
> - printk(KERN_INFO "VFS: file-max limit %d reached\n",
> - get_max_files());
> + pr_info("VFS: file-max limit %lu reached\n", get_max_files());
> old_max = get_nr_files();
> }
> goto fail;
> @@ -487,7 +486,7 @@ retry:
>
> void __init files_init(unsigned long mempages)
> {
> - int n;
> + unsigned long n;
>
> filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
> SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
> @@ -498,9 +497,7 @@ void __init files_init(unsigned long mempages)
> */
>
> n = (mempages * (PAGE_SIZE / 1024)) / 10;
> - files_stat.max_files = n;
> - if (files_stat.max_files < NR_FILE)
> - files_stat.max_files = NR_FILE;
> + files_stat.max_files = max_t(unsigned long, n, NR_FILE);
> files_defer_init();
> lg_lock_init(files_lglock);
> percpu_counter_init(&nr_files, 0);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 63d069b..8c06590 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -34,9 +34,9 @@
>
> /* And dynamically-tunable limits and defaults: */
> struct files_stat_struct {
> - int nr_files; /* read only */
> - int nr_free_files; /* read only */
> - int max_files; /* tunable */
> + unsigned long nr_files; /* read only */
> + unsigned long nr_free_files; /* read only */
> + unsigned long max_files; /* tunable */
> };
>
> struct inodes_stat_t {
> @@ -404,7 +404,7 @@ extern void __init inode_init_early(void);
> extern void __init files_init(unsigned long);
>
> extern struct files_stat_struct files_stat;
> -extern int get_max_files(void);
> +extern unsigned long get_max_files(void);
> extern int sysctl_nr_open;
> extern struct inodes_stat_t inodes_stat;
> extern int leases_enable, lease_break_time;
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index f88552c..f789a0a 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1352,16 +1352,16 @@ static struct ctl_table fs_table[] = {
> {
> .procname = "file-nr",
> .data = &files_stat,
> - .maxlen = 3*sizeof(int),
> + .maxlen = sizeof(files_stat),
> .mode = 0444,
> .proc_handler = proc_nr_files,
> },
> {
> .procname = "file-max",
> .data = &files_stat.max_files,
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(files_stat.max_files),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_doulongvec_minmax,
> },
> {
> .procname = "nr_open",
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 0b39b24..3e1d7d1 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -117,7 +117,7 @@
>
> static struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
> static DEFINE_SPINLOCK(unix_table_lock);
> -static atomic_t unix_nr_socks = ATOMIC_INIT(0);
> +static atomic_long_t unix_nr_socks;
>
> #define unix_sockets_unbound (&unix_socket_table[UNIX_HASH_SIZE])
>
> @@ -360,13 +360,13 @@ static void unix_sock_destructor(struct sock *sk)
> if (u->addr)
> unix_release_addr(u->addr);
>
> - atomic_dec(&unix_nr_socks);
> + atomic_long_dec(&unix_nr_socks);
> local_bh_disable();
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
> local_bh_enable();
> #ifdef UNIX_REFCNT_DEBUG
> - printk(KERN_DEBUG "UNIX %p is destroyed, %d are still alive.\n", sk,
> - atomic_read(&unix_nr_socks));
> + printk(KERN_DEBUG "UNIX %p is destroyed, %ld are still alive.\n", sk,
> + atomic_long_read(&unix_nr_socks));
> #endif
> }
>
> @@ -606,8 +606,8 @@ static struct sock *unix_create1(struct net *net, struct socket *sock)
> struct sock *sk = NULL;
> struct unix_sock *u;
>
> - atomic_inc(&unix_nr_socks);
> - if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
> + atomic_long_inc(&unix_nr_socks);
> + if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
> goto out;
>
> sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto);
> @@ -632,7 +632,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock)
> unix_insert_socket(unix_sockets_unbound, sk);
> out:
> if (sk == NULL)
> - atomic_dec(&unix_nr_socks);
> + atomic_long_dec(&unix_nr_socks);
> else {
> local_bh_disable();
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
>
>
> --
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