get rid of NR_OPEN and introduce a sysctl_nr_open

NR_OPEN (historically set to 1024*1024) actually forbids processes to open
more than 1024*1024 handles.

Unfortunatly some production servers hit the not so 'ridiculously high
value' of 1024*1024 file descriptors per process.

Changing NR_OPEN is not considered safe because of vmalloc space potential
exhaust.

This patch introduces a new sysctl (/proc/sys/fs/nr_open) wich defaults to
1024*1024, so that admins can decide to change this limit if their workload
needs it.

[akpm@linux-foundation.org: export it for sparc64]
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 5 insertions, 3 deletions

diff --git a/arch/sparc64/solaris/fs.c b/arch/sparc64/solaris/fs.c
index 61be597bf430..9311bfe4f2f7 100644
--- a/arch/sparc64/solaris/fs.c
+++ b/arch/sparc64/solaris/fs.c
@@ -624,7 +624,7 @@ asmlinkage int solaris_ulimit(int cmd, int val)
         case 3: /* UL_GMEMLIM */
                 return current->signal->rlim[RLIMIT_DATA].rlim_cur;
         case 4: /* UL_GDESLIM */
-                return NR_OPEN;
+                return sysctl_nr_open;
         }
         return -EINVAL;
 }
diff --git a/arch/sparc64/solaris/timod.c b/arch/sparc64/solaris/timod.c
index a9d32ceabf26..f53123c02c2b 100644
--- a/arch/sparc64/solaris/timod.c
+++ b/arch/sparc64/solaris/timod.c
@@ -859,7 +859,8 @@ asmlinkage int solaris_getmsg(unsigned int fd, u32 arg1, u32 arg2, u32 arg3)
 
         SOLD("entry");
         lock_kernel();
-        if(fd >= NR_OPEN) goto out;
+        if (fd >= sysctl_nr_open)
+                goto out;
 
         fdt = files_fdtable(current->files);
         filp = fdt->fd[fd];
@@ -927,7 +928,8 @@ asmlinkage int solaris_putmsg(unsigned int fd, u32 arg1, u32 arg2, u32 arg3)
 
         SOLD("entry");
         lock_kernel();
-        if(fd >= NR_OPEN) goto out;
+        if (fd >= sysctl_nr_open)
+                goto out;
 
         fdt = files_fdtable(current->files);
         filp = fdt->fd[fd];