From: Nick Piggin Date: Fri, 7 Jan 2011 06:49:32 +0000 (+1100) Subject: fs: dcache scale dentry refcount X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b7ab39f631f505edc2bbdb86620d5493f995c9da;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git fs: dcache scale dentry refcount Make d_count non-atomic and protect it with d_lock. This allows us to ensure a 0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when we start protecting many other dentry members with d_lock. Signed-off-by: Nick Piggin --- diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c index 3532b92de98..29a406a7754 100644 --- a/arch/powerpc/platforms/cell/spufs/inode.c +++ b/arch/powerpc/platforms/cell/spufs/inode.c @@ -162,7 +162,7 @@ static void spufs_prune_dir(struct dentry *dir) spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); if (!(d_unhashed(dentry)) && dentry->d_inode) { - dget_locked(dentry); + dget_locked_dlock(dentry); __d_drop(dentry); spin_unlock(&dentry->d_lock); simple_unlink(dir->d_inode, dentry); diff --git a/drivers/infiniband/hw/ipath/ipath_fs.c b/drivers/infiniband/hw/ipath/ipath_fs.c index 8c8afc716b9..18aee04a841 100644 --- a/drivers/infiniband/hw/ipath/ipath_fs.c +++ b/drivers/infiniband/hw/ipath/ipath_fs.c @@ -280,7 +280,7 @@ static int remove_file(struct dentry *parent, char *name) spin_lock(&dcache_lock); spin_lock(&tmp->d_lock); if (!(d_unhashed(tmp) && tmp->d_inode)) { - dget_locked(tmp); + dget_locked_dlock(tmp); __d_drop(tmp); spin_unlock(&tmp->d_lock); spin_unlock(&dcache_lock); diff --git a/drivers/infiniband/hw/qib/qib_fs.c b/drivers/infiniband/hw/qib/qib_fs.c index f99bddc0171..fe4b242f009 100644 --- a/drivers/infiniband/hw/qib/qib_fs.c +++ b/drivers/infiniband/hw/qib/qib_fs.c @@ -456,7 +456,7 @@ static int remove_file(struct dentry *parent, char *name) spin_lock(&dcache_lock); spin_lock(&tmp->d_lock); if (!(d_unhashed(tmp) && tmp->d_inode)) { - dget_locked(tmp); + dget_locked_dlock(tmp); __d_drop(tmp); spin_unlock(&tmp->d_lock); spin_unlock(&dcache_lock); diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index a796c9417fb..413b5642e6c 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -198,7 +198,7 @@ static int autofs4_tree_busy(struct vfsmount *mnt, else ino_count++; - if (atomic_read(&p->d_count) > ino_count) { + if (p->d_count > ino_count) { top_ino->last_used = jiffies; dput(p); return 1; @@ -347,7 +347,7 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, /* Path walk currently on this dentry? */ ino_count = atomic_read(&ino->count) + 2; - if (atomic_read(&dentry->d_count) > ino_count) + if (dentry->d_count > ino_count) goto next; /* Can we umount this guy */ @@ -369,7 +369,7 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, if (!exp_leaves) { /* Path walk currently on this dentry? */ ino_count = atomic_read(&ino->count) + 1; - if (atomic_read(&dentry->d_count) > ino_count) + if (dentry->d_count > ino_count) goto next; if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) { @@ -383,7 +383,7 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, } else { /* Path walk currently on this dentry? */ ino_count = atomic_read(&ino->count) + 1; - if (atomic_read(&dentry->d_count) > ino_count) + if (dentry->d_count > ino_count) goto next; expired = autofs4_check_leaves(mnt, dentry, timeout, do_now); diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index d34896cfb19..7922509b5b2 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -436,7 +436,7 @@ static struct dentry *autofs4_lookup_active(struct dentry *dentry) spin_lock(&active->d_lock); /* Already gone? */ - if (atomic_read(&active->d_count) == 0) + if (active->d_count == 0) goto next; qstr = &active->d_name; @@ -452,7 +452,7 @@ static struct dentry *autofs4_lookup_active(struct dentry *dentry) goto next; if (d_unhashed(active)) { - dget(active); + dget_dlock(active); spin_unlock(&active->d_lock); spin_unlock(&sbi->lookup_lock); spin_unlock(&dcache_lock); @@ -507,7 +507,7 @@ static struct dentry *autofs4_lookup_expiring(struct dentry *dentry) goto next; if (d_unhashed(expiring)) { - dget(expiring); + dget_dlock(expiring); spin_unlock(&expiring->d_lock); spin_unlock(&sbi->lookup_lock); spin_unlock(&dcache_lock); diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index d902948a90d..3ecf915a455 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -150,7 +150,9 @@ more: di = ceph_dentry(dentry); } - atomic_inc(&dentry->d_count); + spin_lock(&dentry->d_lock); + dentry->d_count++; + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); dout(" %llu (%llu) dentry %p %.*s %p\n", di->offset, filp->f_pos, diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c index bf1286588f2..bb68c799074 100644 --- a/fs/ceph/inode.c +++ b/fs/ceph/inode.c @@ -879,8 +879,8 @@ static struct dentry *splice_dentry(struct dentry *dn, struct inode *in, } else if (realdn) { dout("dn %p (%d) spliced with %p (%d) " "inode %p ino %llx.%llx\n", - dn, atomic_read(&dn->d_count), - realdn, atomic_read(&realdn->d_count), + dn, dn->d_count, + realdn, realdn->d_count, realdn->d_inode, ceph_vinop(realdn->d_inode)); dput(dn); dn = realdn; diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 38800eaa81d..a50fca1e03b 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -1486,7 +1486,7 @@ retry: *base = ceph_ino(temp->d_inode); *plen = len; dout("build_path on %p %d built %llx '%.*s'\n", - dentry, atomic_read(&dentry->d_count), *base, len, path); + dentry, dentry->d_count, *base, len, path); return path; } diff --git a/fs/coda/dir.c b/fs/coda/dir.c index 4cce3b07d9d..9e37e8bc9b8 100644 --- a/fs/coda/dir.c +++ b/fs/coda/dir.c @@ -559,7 +559,7 @@ static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd) if (cii->c_flags & C_FLUSH) coda_flag_inode_children(inode, C_FLUSH); - if (atomic_read(&de->d_count) > 1) + if (de->d_count > 1) /* pretend it's valid, but don't change the flags */ goto out; diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 20024a9ef5a..e9acea440ff 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -394,8 +394,7 @@ static void remove_dir(struct dentry * d) if (d->d_inode) simple_rmdir(parent->d_inode,d); - pr_debug(" o %s removing done (%d)\n",d->d_name.name, - atomic_read(&d->d_count)); + pr_debug(" o %s removing done (%d)\n",d->d_name.name, d->d_count); dput(parent); } diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c index 253476d78ed..79b37765d8f 100644 --- a/fs/configfs/inode.c +++ b/fs/configfs/inode.c @@ -253,7 +253,7 @@ void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); if (!(d_unhashed(dentry) && dentry->d_inode)) { - dget_locked(dentry); + dget_locked_dlock(dentry); __d_drop(dentry); spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); diff --git a/fs/dcache.c b/fs/dcache.c index 3d3c843c36e..81e91502b29 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -45,6 +45,7 @@ * - d_flags * - d_name * - d_lru + * - d_count * * Ordering: * dcache_lock @@ -125,6 +126,7 @@ static void __d_free(struct rcu_head *head) */ static void d_free(struct dentry *dentry) { + BUG_ON(dentry->d_count); this_cpu_dec(nr_dentry); if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); @@ -222,8 +224,11 @@ static struct dentry *d_kill(struct dentry *dentry) struct dentry *parent; list_del(&dentry->d_u.d_child); - /*drops the locks, at that point nobody can reach this dentry */ dentry_iput(dentry); + /* + * dentry_iput drops the locks, at which point nobody (except + * transient RCU lookups) can reach this dentry. + */ if (IS_ROOT(dentry)) parent = NULL; else @@ -303,13 +308,23 @@ void dput(struct dentry *dentry) return; repeat: - if (atomic_read(&dentry->d_count) == 1) + if (dentry->d_count == 1) might_sleep(); - if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) - return; - spin_lock(&dentry->d_lock); - if (atomic_read(&dentry->d_count)) { + if (dentry->d_count == 1) { + if (!spin_trylock(&dcache_lock)) { + /* + * Something of a livelock possibility we could avoid + * by taking dcache_lock and trying again, but we + * want to reduce dcache_lock anyway so this will + * get improved. + */ + spin_unlock(&dentry->d_lock); + goto repeat; + } + } + dentry->d_count--; + if (dentry->d_count) { spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); return; @@ -389,7 +404,7 @@ int d_invalidate(struct dentry * dentry) * working directory or similar). */ spin_lock(&dentry->d_lock); - if (atomic_read(&dentry->d_count) > 1) { + if (dentry->d_count > 1) { if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); @@ -404,29 +419,61 @@ int d_invalidate(struct dentry * dentry) } EXPORT_SYMBOL(d_invalidate); -/* This should be called _only_ with dcache_lock held */ +/* This must be called with dcache_lock and d_lock held */ static inline struct dentry * __dget_locked_dlock(struct dentry *dentry) { - atomic_inc(&dentry->d_count); + dentry->d_count++; dentry_lru_del(dentry); return dentry; } +/* This should be called _only_ with dcache_lock held */ static inline struct dentry * __dget_locked(struct dentry *dentry) { - atomic_inc(&dentry->d_count); spin_lock(&dentry->d_lock); - dentry_lru_del(dentry); + __dget_locked_dlock(dentry); spin_unlock(&dentry->d_lock); return dentry; } +struct dentry * dget_locked_dlock(struct dentry *dentry) +{ + return __dget_locked_dlock(dentry); +} + struct dentry * dget_locked(struct dentry *dentry) { return __dget_locked(dentry); } EXPORT_SYMBOL(dget_locked); +struct dentry *dget_parent(struct dentry *dentry) +{ + struct dentry *ret; + +repeat: + spin_lock(&dentry->d_lock); + ret = dentry->d_parent; + if (!ret) + goto out; + if (dentry == ret) { + ret->d_count++; + goto out; + } + if (!spin_trylock(&ret->d_lock)) { + spin_unlock(&dentry->d_lock); + cpu_relax(); + goto repeat; + } + BUG_ON(!ret->d_count); + ret->d_count++; + spin_unlock(&ret->d_lock); +out: + spin_unlock(&dentry->d_lock); + return ret; +} +EXPORT_SYMBOL(dget_parent); + /** * d_find_alias - grab a hashed alias of inode * @inode: inode in question @@ -495,7 +542,7 @@ restart: spin_lock(&dcache_lock); list_for_each_entry(dentry, &inode->i_dentry, d_alias) { spin_lock(&dentry->d_lock); - if (!atomic_read(&dentry->d_count)) { + if (!dentry->d_count) { __dget_locked_dlock(dentry); __d_drop(dentry); spin_unlock(&dentry->d_lock); @@ -530,7 +577,10 @@ static void prune_one_dentry(struct dentry * dentry) */ while (dentry) { spin_lock(&dcache_lock); - if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) { + spin_lock(&dentry->d_lock); + dentry->d_count--; + if (dentry->d_count) { + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); return; } @@ -562,7 +612,7 @@ static void shrink_dentry_list(struct list_head *list) * the LRU because of laziness during lookup. Do not free * it - just keep it off the LRU list. */ - if (atomic_read(&dentry->d_count)) { + if (dentry->d_count) { spin_unlock(&dentry->d_lock); continue; } @@ -783,7 +833,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) do { struct inode *inode; - if (atomic_read(&dentry->d_count) != 0) { + if (dentry->d_count != 0) { printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%s}" " still in use (%d)" @@ -792,7 +842,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) dentry->d_inode ? dentry->d_inode->i_ino : 0UL, dentry->d_name.name, - atomic_read(&dentry->d_count), + dentry->d_count, dentry->d_sb->s_type->name, dentry->d_sb->s_id); BUG(); @@ -802,7 +852,9 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) parent = NULL; else { parent = dentry->d_parent; - atomic_dec(&parent->d_count); + spin_lock(&parent->d_lock); + parent->d_count--; + spin_unlock(&parent->d_lock); } list_del(&dentry->d_u.d_child); @@ -853,7 +905,9 @@ void shrink_dcache_for_umount(struct super_block *sb) dentry = sb->s_root; sb->s_root = NULL; - atomic_dec(&dentry->d_count); + spin_lock(&dentry->d_lock); + dentry->d_count--; + spin_unlock(&dentry->d_lock); shrink_dcache_for_umount_subtree(dentry); while (!hlist_empty(&sb->s_anon)) { @@ -950,7 +1004,7 @@ resume: * move only zero ref count dentries to the end * of the unused list for prune_dcache */ - if (!atomic_read(&dentry->d_count)) { + if (!dentry->d_count) { dentry_lru_move_tail(dentry); found++; } else { @@ -1068,7 +1122,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) memcpy(dname, name->name, name->len); dname[name->len] = 0; - atomic_set(&dentry->d_count, 1); + dentry->d_count = 1; dentry->d_flags = DCACHE_UNHASHED; spin_lock_init(&dentry->d_lock); dentry->d_inode = NULL; @@ -1556,7 +1610,7 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) goto next; } - atomic_inc(&dentry->d_count); + dentry->d_count++; found = dentry; spin_unlock(&dentry->d_lock); break; @@ -1653,7 +1707,7 @@ void d_delete(struct dentry * dentry) spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); isdir = S_ISDIR(dentry->d_inode->i_mode); - if (atomic_read(&dentry->d_count) == 1) { + if (dentry->d_count == 1) { dentry->d_flags &= ~DCACHE_CANT_MOUNT; dentry_iput(dentry); fsnotify_nameremove(dentry, isdir); @@ -2494,11 +2548,15 @@ resume: this_parent = dentry; goto repeat; } - atomic_dec(&dentry->d_count); + spin_lock(&dentry->d_lock); + dentry->d_count--; + spin_unlock(&dentry->d_lock); } if (this_parent != root) { next = this_parent->d_u.d_child.next; - atomic_dec(&this_parent->d_count); + spin_lock(&this_parent->d_lock); + this_parent->d_count--; + spin_unlock(&this_parent->d_lock); this_parent = this_parent->d_parent; goto resume; } diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index a1ed7a7cb17..5e5c7ec1fc9 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -260,7 +260,7 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry, ecryptfs_dentry->d_parent)); lower_inode = lower_dentry->d_inode; fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode); - BUG_ON(!atomic_read(&lower_dentry->d_count)); + BUG_ON(!lower_dentry->d_count); ecryptfs_set_dentry_private(ecryptfs_dentry, kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL)); diff --git a/fs/locks.c b/fs/locks.c index 8729347bcd1..08415b2a6d3 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -1389,7 +1389,7 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp) if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) goto out; if ((arg == F_WRLCK) - && ((atomic_read(&dentry->d_count) > 1) + && ((dentry->d_count > 1) || (atomic_read(&inode->i_count) > 1))) goto out; } diff --git a/fs/namei.c b/fs/namei.c index f3b5ca40465..cbfa5fb3107 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2133,7 +2133,7 @@ void dentry_unhash(struct dentry *dentry) shrink_dcache_parent(dentry); spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); - if (atomic_read(&dentry->d_count) == 2) + if (dentry->d_count == 2) __d_drop(dentry); spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 9184c7c80f7..12de824edb5 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1720,7 +1720,7 @@ static int nfs_unlink(struct inode *dir, struct dentry *dentry) spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); - if (atomic_read(&dentry->d_count) > 1) { + if (dentry->d_count > 1) { spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); /* Start asynchronous writeout of the inode */ @@ -1868,7 +1868,7 @@ static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry, dfprintk(VFS, "NFS: rename(%s/%s -> %s/%s, ct=%d)\n", old_dentry->d_parent->d_name.name, old_dentry->d_name.name, new_dentry->d_parent->d_name.name, new_dentry->d_name.name, - atomic_read(&new_dentry->d_count)); + new_dentry->d_count); /* * For non-directories, check whether the target is busy and if so, @@ -1886,7 +1886,7 @@ static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry, rehash = new_dentry; } - if (atomic_read(&new_dentry->d_count) > 2) { + if (new_dentry->d_count > 2) { int err; /* copy the target dentry's name */ diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c index 7bdec853140..8fe9eb47a97 100644 --- a/fs/nfs/unlink.c +++ b/fs/nfs/unlink.c @@ -496,7 +496,7 @@ nfs_sillyrename(struct inode *dir, struct dentry *dentry) dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n", dentry->d_parent->d_name.name, dentry->d_name.name, - atomic_read(&dentry->d_count)); + dentry->d_count); nfs_inc_stats(dir, NFSIOS_SILLYRENAME); /* diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 184938fcff0..3a359023c9f 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1756,8 +1756,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, goto out_dput_new; if (svc_msnfs(ffhp) && - ((atomic_read(&odentry->d_count) > 1) - || (atomic_read(&ndentry->d_count) > 1))) { + ((odentry->d_count > 1) || (ndentry->d_count > 1))) { host_err = -EPERM; goto out_dput_new; } @@ -1843,7 +1842,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, if (type != S_IFDIR) { /* It's UNLINK */ #ifdef MSNFS if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) && - (atomic_read(&rdentry->d_count) > 1)) { + (rdentry->d_count > 1)) { host_err = -EPERM; } else #endif diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c index f804d41ec9d..d36fc7ee615 100644 --- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -838,7 +838,7 @@ static int nilfs_attach_snapshot(struct super_block *s, __u64 cno, static int nilfs_tree_was_touched(struct dentry *root_dentry) { - return atomic_read(&root_dentry->d_count) > 1; + return root_dentry->d_count > 1; } /** diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 2feb624b67f..b0ade2d4680 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -87,7 +87,7 @@ full_name_hash(const unsigned char *name, unsigned int len) #endif struct dentry { - atomic_t d_count; + unsigned int d_count; /* protected by d_lock */ unsigned int d_flags; /* protected by d_lock */ spinlock_t d_lock; /* per dentry lock */ int d_mounted; @@ -297,17 +297,28 @@ extern char *dentry_path(struct dentry *, char *, int); * needs and they take necessary precautions) you should hold dcache_lock * and call dget_locked() instead of dget(). */ - +static inline struct dentry *dget_dlock(struct dentry *dentry) +{ + if (dentry) { + BUG_ON(!dentry->d_count); + dentry->d_count++; + } + return dentry; +} static inline struct dentry *dget(struct dentry *dentry) { if (dentry) { - BUG_ON(!atomic_read(&dentry->d_count)); - atomic_inc(&dentry->d_count); + spin_lock(&dentry->d_lock); + dget_dlock(dentry); + spin_unlock(&dentry->d_lock); } return dentry; } extern struct dentry * dget_locked(struct dentry *); +extern struct dentry * dget_locked_dlock(struct dentry *); + +extern struct dentry *dget_parent(struct dentry *dentry); /** * d_unhashed - is dentry hashed @@ -338,16 +349,6 @@ static inline void dont_mount(struct dentry *dentry) spin_unlock(&dentry->d_lock); } -static inline struct dentry *dget_parent(struct dentry *dentry) -{ - struct dentry *ret; - - spin_lock(&dentry->d_lock); - ret = dget(dentry->d_parent); - spin_unlock(&dentry->d_lock); - return ret; -} - extern void dput(struct dentry *); static inline int d_mountpoint(struct dentry *dentry) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 746055b214d..eb7af39350c 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3655,9 +3655,7 @@ again: list_del(&cgrp->sibling); cgroup_unlock_hierarchy(cgrp->root); - spin_lock(&cgrp->dentry->d_lock); d = dget(cgrp->dentry); - spin_unlock(&d->d_lock); cgroup_d_remove_dir(d); dput(d);