Merge branch 'for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:
 "There are several notable changes here:

   - Single thread migrating itself has been optimized so that it
     doesn't need threadgroup rwsem anymore.

   - Freezer optimization to avoid unnecessary frozen state changes.

   - cgroup ID unification so that cgroup fs ino is the only unique ID
     used for the cgroup and can be used to directly look up live
     cgroups through filehandle interface on 64bit ino archs. On 32bit
     archs, cgroup fs ino is still the only ID in use but it is only
     unique when combined with gen.

   - selftest and other changes"

* 'for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (24 commits)
  writeback: fix -Wformat compilation warnings
  docs: cgroup: mm: Fix spelling of "list"
  cgroup: fix incorrect WARN_ON_ONCE() in cgroup_setup_root()
  cgroup: use cgrp->kn->id as the cgroup ID
  kernfs: use 64bit inos if ino_t is 64bit
  kernfs: implement custom exportfs ops and fid type
  kernfs: combine ino/id lookup functions into kernfs_find_and_get_node_by_id()
  kernfs: convert kernfs_node->id from union kernfs_node_id to u64
  kernfs: kernfs_find_and_get_node_by_ino() should only look up activated nodes
  kernfs: use dumber locking for kernfs_find_and_get_node_by_ino()
  netprio: use css ID instead of cgroup ID
  writeback: use ino_t for inodes in tracepoints
  kernfs: fix ino wrap-around detection
  kselftests: cgroup: Avoid the reuse of fd after it is deallocated
  cgroup: freezer: don't change task and cgroups status unnecessarily
  cgroup: use cgroup->last_bstat instead of cgroup->bstat_pending for consistency
  cgroup: remove cgroup_enable_task_cg_lists() optimization
  cgroup: pids: use atomic64_t for pids->limit
  selftests: cgroup: Run test_core under interfering stress
  selftests: cgroup: Add task migration tests
  ...

1 files changed, 58 insertions, 44 deletions

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 6c12fac2c287..4d31503abaee 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -53,63 +53,85 @@ const struct super_operations kernfs_sops = {
 	.show_path	= kernfs_sop_show_path,
 };
 
-/*
- * Similar to kernfs_fh_get_inode, this one gets kernfs node from inode
- * number and generation
- */
-struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
-	const union kernfs_node_id *id)
+static int kernfs_encode_fh(struct inode *inode, __u32 *fh, int *max_len,
+			    struct inode *parent)
 {
-	struct kernfs_node *kn;
+	struct kernfs_node *kn = inode->i_private;
 
-	kn = kernfs_find_and_get_node_by_ino(root, id->ino);
-	if (!kn)
-		return NULL;
-	if (kn->id.generation != id->generation) {
-		kernfs_put(kn);
-		return NULL;
+	if (*max_len < 2) {
+		*max_len = 2;
+		return FILEID_INVALID;
 	}
-	return kn;
+
+	*max_len = 2;
+	*(u64 *)fh = kn->id;
+	return FILEID_KERNFS;
 }
 
-static struct inode *kernfs_fh_get_inode(struct super_block *sb,
-		u64 ino, u32 generation)
+static struct dentry *__kernfs_fh_to_dentry(struct super_block *sb,
+					    struct fid *fid, int fh_len,
+					    int fh_type, bool get_parent)
 {
 	struct kernfs_super_info *info = kernfs_info(sb);
-	struct inode *inode;
 	struct kernfs_node *kn;
+	struct inode *inode;
+	u64 id;
 
-	if (ino == 0)
-		return ERR_PTR(-ESTALE);
+	if (fh_len < 2)
+		return NULL;
+
+	switch (fh_type) {
+	case FILEID_KERNFS:
+		id = *(u64 *)fid;
+		break;
+	case FILEID_INO32_GEN:
+	case FILEID_INO32_GEN_PARENT:
+		/*
+		 * blk_log_action() exposes "LOW32,HIGH32" pair without
+		 * type and userland can call us with generic fid
+		 * constructed from them.  Combine it back to ID.  See
+		 * blk_log_action().
+		 */
+		id = ((u64)fid->i32.gen << 32) | fid->i32.ino;
+		break;
+	default:
+		return NULL;
+	}
 
-	kn = kernfs_find_and_get_node_by_ino(info->root, ino);
+	kn = kernfs_find_and_get_node_by_id(info->root, id);
 	if (!kn)
 		return ERR_PTR(-ESTALE);
+
+	if (get_parent) {
+		struct kernfs_node *parent;
+
+		parent = kernfs_get_parent(kn);
+		kernfs_put(kn);
+		kn = parent;
+		if (!kn)
+			return ERR_PTR(-ESTALE);
+	}
+
 	inode = kernfs_get_inode(sb, kn);
 	kernfs_put(kn);
 	if (!inode)
 		return ERR_PTR(-ESTALE);
 
-	if (generation && inode->i_generation != generation) {
-		/* we didn't find the right inode.. */
-		iput(inode);
-		return ERR_PTR(-ESTALE);
-	}
-	return inode;
+	return d_obtain_alias(inode);
 }
 
-static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
-		int fh_len, int fh_type)
+static struct dentry *kernfs_fh_to_dentry(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
 {
-	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
-				    kernfs_fh_get_inode);
+	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, false);
 }
 
-static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,
-		int fh_len, int fh_type)
+static struct dentry *kernfs_fh_to_parent(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
 {
-	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
-				    kernfs_fh_get_inode);
+	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, true);
 }
 
 static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
@@ -120,6 +142,7 @@ static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
 }
 
 static const struct export_operations kernfs_export_ops = {
+	.encode_fh	= kernfs_encode_fh,
 	.fh_to_dentry	= kernfs_fh_to_dentry,
 	.fh_to_parent	= kernfs_fh_to_parent,
 	.get_parent	= kernfs_get_parent_dentry,
@@ -363,18 +386,9 @@ void kernfs_kill_sb(struct super_block *sb)
 
 void __init kernfs_init(void)
 {
-
-	/*
-	 * the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino
-	 * can access the slab lock free. This could introduce stale nodes,
-	 * please see how kernfs_find_and_get_node_by_ino filters out stale
-	 * nodes.
-	 */
 	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
 					      sizeof(struct kernfs_node),
-					      0,
-					      SLAB_PANIC | SLAB_TYPESAFE_BY_RCU,
-					      NULL);
+					      0, SLAB_PANIC, NULL);
 
 	/* Creates slab cache for kernfs inode attributes */
 	kernfs_iattrs_cache  = kmem_cache_create("kernfs_iattrs_cache",