/*
- * linux/fs/inode.c
- *
* (C) 1997 Linus Torvalds
+ * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
*/
-
+#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
-#include <linux/dcache.h>
-#include <linux/init.h>
-#include <linux/slab.h>
-#include <linux/writeback.h>
-#include <linux/module.h>
#include <linux/backing-dev.h>
-#include <linux/wait.h>
-#include <linux/rwsem.h>
#include <linux/hash.h>
#include <linux/swap.h>
#include <linux/security.h>
-#include <linux/pagemap.h>
#include <linux/cdev.h>
#include <linux/bootmem.h>
#include <linux/fsnotify.h>
#include <linux/mount.h>
-#include <linux/async.h>
#include <linux/posix_acl.h>
#include <linux/prefetch.h>
-#include <linux/ima.h>
-#include <linux/cred.h>
+#include <linux/buffer_head.h> /* for inode_has_buffers */
+#include <linux/ratelimit.h>
#include "internal.h"
/*
- * inode locking rules.
+ * Inode locking rules:
*
* inode->i_lock protects:
* inode->i_state, inode->i_hash, __iget()
- * inode_lru_lock protects:
- * inode_lru, inode->i_lru
+ * inode->i_sb->s_inode_lru_lock protects:
+ * inode->i_sb->s_inode_lru, inode->i_lru
* inode_sb_list_lock protects:
* sb->s_inodes, inode->i_sb_list
- * inode_wb_list_lock protects:
+ * bdi->wb.list_lock protects:
* bdi->wb.b_{dirty,io,more_io}, inode->i_wb_list
* inode_hash_lock protects:
* inode_hashtable, inode->i_hash
*
* inode_sb_list_lock
* inode->i_lock
- * inode_lru_lock
+ * inode->i_sb->s_inode_lru_lock
*
- * inode_wb_list_lock
+ * bdi->wb.list_lock
* inode->i_lock
*
* inode_hash_lock
* inode_hash_lock
*/
-/*
- * This is needed for the following functions:
- * - inode_has_buffers
- * - invalidate_bdev
- *
- * FIXME: remove all knowledge of the buffer layer from this file
- */
-#include <linux/buffer_head.h>
-
-/*
- * New inode.c implementation.
- *
- * This implementation has the basic premise of trying
- * to be extremely low-overhead and SMP-safe, yet be
- * simple enough to be "obviously correct".
- *
- * Famous last words.
- */
-
-/* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */
-
-/* #define INODE_PARANOIA 1 */
-/* #define INODE_DEBUG 1 */
-
-/*
- * Inode lookup is no longer as critical as it used to be:
- * most of the lookups are going to be through the dcache.
- */
-#define I_HASHBITS i_hash_shift
-#define I_HASHMASK i_hash_mask
-
static unsigned int i_hash_mask __read_mostly;
static unsigned int i_hash_shift __read_mostly;
static struct hlist_head *inode_hashtable __read_mostly;
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
-/*
- * Each inode can be on two separate lists. One is
- * the hash list of the inode, used for lookups. The
- * other linked list is the "type" list:
- * "in_use" - valid inode, i_count > 0, i_nlink > 0
- * "dirty" - as "in_use" but also dirty
- * "unused" - valid inode, i_count = 0
- *
- * A "dirty" list is maintained for each super block,
- * allowing for low-overhead inode sync() operations.
- */
-
-static LIST_HEAD(inode_lru);
-static DEFINE_SPINLOCK(inode_lru_lock);
-
__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock);
-__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_wb_list_lock);
-
-/*
- * iprune_sem provides exclusion between the icache shrinking and the
- * umount path.
- *
- * We don't actually need it to protect anything in the umount path,
- * but only need to cycle through it to make sure any inode that
- * prune_icache took off the LRU list has been fully torn down by the
- * time we are past evict_inodes.
- */
-static DECLARE_RWSEM(iprune_sem);
/*
* Empty aops. Can be used for the cases where the user does not
struct inodes_stat_t inodes_stat;
static DEFINE_PER_CPU(unsigned int, nr_inodes);
+static DEFINE_PER_CPU(unsigned int, nr_unused);
static struct kmem_cache *inode_cachep __read_mostly;
static inline int get_nr_inodes_unused(void)
{
- return inodes_stat.nr_unused;
+ int i;
+ int sum = 0;
+ for_each_possible_cpu(i)
+ sum += per_cpu(nr_unused, i);
+ return sum < 0 ? 0 : sum;
}
int get_nr_dirty_inodes(void)
void __user *buffer, size_t *lenp, loff_t *ppos)
{
inodes_stat.nr_inodes = get_nr_inodes();
+ inodes_stat.nr_unused = get_nr_inodes_unused();
return proc_dointvec(table, write, buffer, lenp, ppos);
}
#endif
atomic_set(&inode->i_count, 1);
inode->i_op = &empty_iops;
inode->i_fop = &empty_fops;
- inode->i_nlink = 1;
+ inode->__i_nlink = 1;
+ inode->i_opflags = 0;
inode->i_uid = 0;
inode->i_gid = 0;
atomic_set(&inode->i_writecount, 0);
mutex_init(&inode->i_mutex);
lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
- init_rwsem(&inode->i_alloc_sem);
- lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
+ atomic_set(&inode->i_dio_count, 0);
mapping->a_ops = &empty_aops;
mapping->host = inode;
}
inode->i_private = NULL;
inode->i_mapping = mapping;
+ INIT_LIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
#ifdef CONFIG_FS_POSIX_ACL
inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
#endif
BUG_ON(inode_has_buffers(inode));
security_inode_free(inode);
fsnotify_inode_delete(inode);
+ if (!inode->i_nlink) {
+ WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
+ atomic_long_dec(&inode->i_sb->s_remove_count);
+ }
+
#ifdef CONFIG_FS_POSIX_ACL
if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
posix_acl_release(inode->i_acl);
static void i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
- INIT_LIST_HEAD(&inode->i_dentry);
kmem_cache_free(inode_cachep, inode);
}
call_rcu(&inode->i_rcu, i_callback);
}
+/**
+ * drop_nlink - directly drop an inode's link count
+ * @inode: inode
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink. In cases
+ * where we are attempting to track writes to the
+ * filesystem, a decrement to zero means an imminent
+ * write when the file is truncated and actually unlinked
+ * on the filesystem.
+ */
+void drop_nlink(struct inode *inode)
+{
+ WARN_ON(inode->i_nlink == 0);
+ inode->__i_nlink--;
+ if (!inode->i_nlink)
+ atomic_long_inc(&inode->i_sb->s_remove_count);
+}
+EXPORT_SYMBOL(drop_nlink);
+
+/**
+ * clear_nlink - directly zero an inode's link count
+ * @inode: inode
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink. See
+ * drop_nlink() for why we care about i_nlink hitting zero.
+ */
+void clear_nlink(struct inode *inode)
+{
+ if (inode->i_nlink) {
+ inode->__i_nlink = 0;
+ atomic_long_inc(&inode->i_sb->s_remove_count);
+ }
+}
+EXPORT_SYMBOL(clear_nlink);
+
+/**
+ * set_nlink - directly set an inode's link count
+ * @inode: inode
+ * @nlink: new nlink (should be non-zero)
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink.
+ */
+void set_nlink(struct inode *inode, unsigned int nlink)
+{
+ if (!nlink) {
+ clear_nlink(inode);
+ } else {
+ /* Yes, some filesystems do change nlink from zero to one */
+ if (inode->i_nlink == 0)
+ atomic_long_dec(&inode->i_sb->s_remove_count);
+
+ inode->__i_nlink = nlink;
+ }
+}
+EXPORT_SYMBOL(set_nlink);
+
+/**
+ * inc_nlink - directly increment an inode's link count
+ * @inode: inode
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink. Currently,
+ * it is only here for parity with dec_nlink().
+ */
+void inc_nlink(struct inode *inode)
+{
+ if (WARN_ON(inode->i_nlink == 0))
+ atomic_long_dec(&inode->i_sb->s_remove_count);
+
+ inode->__i_nlink++;
+}
+EXPORT_SYMBOL(inc_nlink);
+
void address_space_init_once(struct address_space *mapping)
{
memset(mapping, 0, sizeof(*mapping));
INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
spin_lock_init(&mapping->tree_lock);
- spin_lock_init(&mapping->i_mmap_lock);
+ mutex_init(&mapping->i_mmap_mutex);
INIT_LIST_HEAD(&mapping->private_list);
spin_lock_init(&mapping->private_lock);
INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
{
memset(inode, 0, sizeof(*inode));
INIT_HLIST_NODE(&inode->i_hash);
- INIT_LIST_HEAD(&inode->i_dentry);
INIT_LIST_HEAD(&inode->i_devices);
INIT_LIST_HEAD(&inode->i_wb_list);
INIT_LIST_HEAD(&inode->i_lru);
static void inode_lru_list_add(struct inode *inode)
{
- spin_lock(&inode_lru_lock);
+ spin_lock(&inode->i_sb->s_inode_lru_lock);
if (list_empty(&inode->i_lru)) {
- list_add(&inode->i_lru, &inode_lru);
- inodes_stat.nr_unused++;
+ list_add(&inode->i_lru, &inode->i_sb->s_inode_lru);
+ inode->i_sb->s_nr_inodes_unused++;
+ this_cpu_inc(nr_unused);
}
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&inode->i_sb->s_inode_lru_lock);
}
static void inode_lru_list_del(struct inode *inode)
{
- spin_lock(&inode_lru_lock);
+ spin_lock(&inode->i_sb->s_inode_lru_lock);
if (!list_empty(&inode->i_lru)) {
list_del_init(&inode->i_lru);
- inodes_stat.nr_unused--;
+ inode->i_sb->s_nr_inodes_unused--;
+ this_cpu_dec(nr_unused);
}
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&inode->i_sb->s_inode_lru_lock);
}
/**
static inline void inode_sb_list_del(struct inode *inode)
{
- spin_lock(&inode_sb_list_lock);
- list_del_init(&inode->i_sb_list);
- spin_unlock(&inode_sb_list_lock);
+ if (!list_empty(&inode->i_sb_list)) {
+ spin_lock(&inode_sb_list_lock);
+ list_del_init(&inode->i_sb_list);
+ spin_unlock(&inode_sb_list_lock);
+ }
}
static unsigned long hash(struct super_block *sb, unsigned long hashval)
tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
L1_CACHE_BYTES;
- tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
- return tmp & I_HASHMASK;
+ tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
+ return tmp & i_hash_mask;
}
/**
EXPORT_SYMBOL(__insert_inode_hash);
/**
- * remove_inode_hash - remove an inode from the hash
+ * __remove_inode_hash - remove an inode from the hash
* @inode: inode to unhash
*
* Remove an inode from the superblock.
*/
-void remove_inode_hash(struct inode *inode)
+void __remove_inode_hash(struct inode *inode)
{
spin_lock(&inode_hash_lock);
spin_lock(&inode->i_lock);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_hash_lock);
}
-EXPORT_SYMBOL(remove_inode_hash);
+EXPORT_SYMBOL(__remove_inode_hash);
void end_writeback(struct inode *inode)
{
might_sleep();
+ /*
+ * We have to cycle tree_lock here because reclaim can be still in the
+ * process of removing the last page (in __delete_from_page_cache())
+ * and we must not free mapping under it.
+ */
+ spin_lock_irq(&inode->i_data.tree_lock);
BUG_ON(inode->i_data.nrpages);
+ spin_unlock_irq(&inode->i_data.tree_lock);
BUG_ON(!list_empty(&inode->i_data.private_list));
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(inode->i_state & I_CLEAR);
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(!list_empty(&inode->i_lru));
- inode_wb_list_del(inode);
+ if (!list_empty(&inode->i_wb_list))
+ inode_wb_list_del(inode);
+
inode_sb_list_del(inode);
if (op->evict_inode) {
spin_unlock(&inode_sb_list_lock);
dispose_list(&dispose);
-
- /*
- * Cycle through iprune_sem to make sure any inode that prune_icache
- * moved off the list before we took the lock has been fully torn
- * down.
- */
- down_write(&iprune_sem);
- up_write(&iprune_sem);
}
/**
}
/*
- * Scan `goal' inodes on the unused list for freeable ones. They are moved to a
- * temporary list and then are freed outside inode_lru_lock by dispose_list().
+ * Walk the superblock inode LRU for freeable inodes and attempt to free them.
+ * This is called from the superblock shrinker function with a number of inodes
+ * to trim from the LRU. Inodes to be freed are moved to a temporary list and
+ * then are freed outside inode_lock by dispose_list().
*
* Any inodes which are pinned purely because of attached pagecache have their
* pagecache removed. If the inode has metadata buffers attached to
* LRU does not have strict ordering. Hence we don't want to reclaim inodes
* with this flag set because they are the inodes that are out of order.
*/
-static void prune_icache(int nr_to_scan)
+void prune_icache_sb(struct super_block *sb, int nr_to_scan)
{
LIST_HEAD(freeable);
int nr_scanned;
unsigned long reap = 0;
- down_read(&iprune_sem);
- spin_lock(&inode_lru_lock);
- for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
+ spin_lock(&sb->s_inode_lru_lock);
+ for (nr_scanned = nr_to_scan; nr_scanned >= 0; nr_scanned--) {
struct inode *inode;
- if (list_empty(&inode_lru))
+ if (list_empty(&sb->s_inode_lru))
break;
- inode = list_entry(inode_lru.prev, struct inode, i_lru);
+ inode = list_entry(sb->s_inode_lru.prev, struct inode, i_lru);
/*
- * we are inverting the inode_lru_lock/inode->i_lock here,
+ * we are inverting the sb->s_inode_lru_lock/inode->i_lock here,
* so use a trylock. If we fail to get the lock, just move the
* inode to the back of the list so we don't spin on it.
*/
if (!spin_trylock(&inode->i_lock)) {
- list_move(&inode->i_lru, &inode_lru);
+ list_move_tail(&inode->i_lru, &sb->s_inode_lru);
continue;
}
(inode->i_state & ~I_REFERENCED)) {
list_del_init(&inode->i_lru);
spin_unlock(&inode->i_lock);
- inodes_stat.nr_unused--;
+ sb->s_nr_inodes_unused--;
+ this_cpu_dec(nr_unused);
continue;
}
/* recently referenced inodes get one more pass */
if (inode->i_state & I_REFERENCED) {
inode->i_state &= ~I_REFERENCED;
- list_move(&inode->i_lru, &inode_lru);
+ list_move(&inode->i_lru, &sb->s_inode_lru);
spin_unlock(&inode->i_lock);
continue;
}
if (inode_has_buffers(inode) || inode->i_data.nrpages) {
__iget(inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&sb->s_inode_lru_lock);
if (remove_inode_buffers(inode))
reap += invalidate_mapping_pages(&inode->i_data,
0, -1);
iput(inode);
- spin_lock(&inode_lru_lock);
+ spin_lock(&sb->s_inode_lru_lock);
- if (inode != list_entry(inode_lru.next,
+ if (inode != list_entry(sb->s_inode_lru.next,
struct inode, i_lru))
continue; /* wrong inode or list_empty */
/* avoid lock inversions with trylock */
spin_unlock(&inode->i_lock);
list_move(&inode->i_lru, &freeable);
- inodes_stat.nr_unused--;
+ sb->s_nr_inodes_unused--;
+ this_cpu_dec(nr_unused);
}
if (current_is_kswapd())
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
__count_vm_events(PGINODESTEAL, reap);
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&sb->s_inode_lru_lock);
+ if (current->reclaim_state)
+ current->reclaim_state->reclaimed_slab += reap;
dispose_list(&freeable);
- up_read(&iprune_sem);
-}
-
-/*
- * shrink_icache_memory() will attempt to reclaim some unused inodes. Here,
- * "unused" means that no dentries are referring to the inodes: the files are
- * not open and the dcache references to those inodes have already been
- * reclaimed.
- *
- * This function is passed the number of inodes to scan, and it returns the
- * total number of remaining possibly-reclaimable inodes.
- */
-static int shrink_icache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
-{
- if (nr) {
- /*
- * Nasty deadlock avoidance. We may hold various FS locks,
- * and we don't want to recurse into the FS that called us
- * in clear_inode() and friends..
- */
- if (!(gfp_mask & __GFP_FS))
- return -1;
- prune_icache(nr);
- }
- return (get_nr_inodes_unused() / 100) * sysctl_vfs_cache_pressure;
}
-static struct shrinker icache_shrinker = {
- .shrink = shrink_icache_memory,
- .seeks = DEFAULT_SEEKS,
-};
-
static void __wait_on_freeing_inode(struct inode *inode);
/*
* Called with the inode lock held.
EXPORT_SYMBOL(get_next_ino);
/**
+ * new_inode_pseudo - obtain an inode
+ * @sb: superblock
+ *
+ * Allocates a new inode for given superblock.
+ * Inode wont be chained in superblock s_inodes list
+ * This means :
+ * - fs can't be unmount
+ * - quotas, fsnotify, writeback can't work
+ */
+struct inode *new_inode_pseudo(struct super_block *sb)
+{
+ struct inode *inode = alloc_inode(sb);
+
+ if (inode) {
+ spin_lock(&inode->i_lock);
+ inode->i_state = 0;
+ spin_unlock(&inode->i_lock);
+ INIT_LIST_HEAD(&inode->i_sb_list);
+ }
+ return inode;
+}
+
+/**
* new_inode - obtain an inode
* @sb: superblock
*
spin_lock_prefetch(&inode_sb_list_lock);
- inode = alloc_inode(sb);
- if (inode) {
- spin_lock(&inode->i_lock);
- inode->i_state = 0;
- spin_unlock(&inode->i_lock);
+ inode = new_inode_pseudo(sb);
+ if (inode)
inode_sb_list_add(inode);
- }
return inode;
}
EXPORT_SYMBOL(new_inode);
-/**
- * unlock_new_inode - clear the I_NEW state and wake up any waiters
- * @inode: new inode to unlock
- *
- * Called when the inode is fully initialised to clear the new state of the
- * inode and wake up anyone waiting for the inode to finish initialisation.
- */
-void unlock_new_inode(struct inode *inode)
-{
#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void lockdep_annotate_inode_mutex_key(struct inode *inode)
+{
if (S_ISDIR(inode->i_mode)) {
struct file_system_type *type = inode->i_sb->s_type;
/* Set new key only if filesystem hasn't already changed it */
- if (!lockdep_match_class(&inode->i_mutex,
- &type->i_mutex_key)) {
+ if (lockdep_match_class(&inode->i_mutex, &type->i_mutex_key)) {
/*
* ensure nobody is actually holding i_mutex
*/
&type->i_mutex_dir_key);
}
}
+}
+EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
#endif
+
+/**
+ * unlock_new_inode - clear the I_NEW state and wake up any waiters
+ * @inode: new inode to unlock
+ *
+ * Called when the inode is fully initialised to clear the new state of the
+ * inode and wake up anyone waiting for the inode to finish initialisation.
+ */
+void unlock_new_inode(struct inode *inode)
+{
+ lockdep_annotate_inode_mutex_key(inode);
spin_lock(&inode->i_lock);
WARN_ON(!(inode->i_state & I_NEW));
inode->i_state &= ~I_NEW;
+ smp_mb();
wake_up_bit(&inode->i_state, __I_NEW);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(generic_delete_inode);
/*
- * Normal UNIX filesystem behaviour: delete the
- * inode when the usage count drops to zero, and
- * i_nlink is zero.
- */
-int generic_drop_inode(struct inode *inode)
-{
- return !inode->i_nlink || inode_unhashed(inode);
-}
-EXPORT_SYMBOL_GPL(generic_drop_inode);
-
-/*
* Called when we're dropping the last reference
* to an inode.
*
WARN_ON(inode->i_state & I_NEW);
- if (op && op->drop_inode)
+ if (op->drop_inode)
drop = op->drop_inode(inode);
else
drop = generic_drop_inode(inode);
}
inode->i_state |= I_FREEING;
- inode_lru_list_del(inode);
+ if (!list_empty(&inode->i_lru))
+ inode_lru_list_del(inode);
spin_unlock(&inode->i_lock);
evict(inode);
* This function automatically handles read only file systems and media,
* as well as the "noatime" flag and inode specific "noatime" markers.
*/
-void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
+void touch_atime(struct path *path)
{
- struct inode *inode = dentry->d_inode;
+ struct vfsmount *mnt = path->mnt;
+ struct inode *inode = path->dentry->d_inode;
struct timespec now;
if (inode->i_flags & S_NOATIME)
if (sync_it & S_MTIME)
inode->i_mtime = now;
mark_inode_dirty_sync(inode);
- mnt_drop_write(file->f_path.mnt);
+ mnt_drop_write_file(file);
}
EXPORT_SYMBOL(file_update_time);
*/
void __init inode_init_early(void)
{
- int loop;
+ unsigned int loop;
/* If hashes are distributed across NUMA nodes, defer
* hash allocation until vmalloc space is available.
&i_hash_mask,
0);
- for (loop = 0; loop < (1 << i_hash_shift); loop++)
+ for (loop = 0; loop < (1U << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}
void __init inode_init(void)
{
- int loop;
+ unsigned int loop;
/* inode slab cache */
inode_cachep = kmem_cache_create("inode_cache",
(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
SLAB_MEM_SPREAD),
init_once);
- register_shrinker(&icache_shrinker);
/* Hash may have been set up in inode_init_early */
if (!hashdist)
&i_hash_mask,
0);
- for (loop = 0; loop < (1 << i_hash_shift); loop++)
+ for (loop = 0; loop < (1U << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}
* @mode: mode of the new inode
*/
void inode_init_owner(struct inode *inode, const struct inode *dir,
- mode_t mode)
+ umode_t mode)
{
inode->i_uid = current_fsuid();
if (dir && dir->i_mode & S_ISGID) {