sysfs: make directory dentries/inodes reclaimable, take#2

index b4074ad..eb9bc0a 100644
@@ -218,9 +218,9 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
  repeat:
 	parent_sd = sd->s_parent;
 
-	if (sd->s_type & SYSFS_KOBJ_LINK)
+	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
 		sysfs_put(sd->s_elem.symlink.target_sd);
-	if (sd->s_type & SYSFS_COPY_NAME)
+	if (sysfs_type(sd) & SYSFS_COPY_NAME)
 		kfree(sd->s_name);
 	kfree(sd->s_iattr);
 	sysfs_free_ino(sd->s_ino);

@@ -282,7 +282,7 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 
 	sd->s_name = name;
 	sd->s_mode = mode;
-	sd->s_type = type;
+	sd->s_flags = type;
 
 	return sd;
 

@@ -330,7 +330,7 @@ int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
 	struct sysfs_dirent * sd;
 
 	for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
-		if (sd->s_type) {
+		if (sysfs_type(sd)) {
 			if (strcmp(sd->s_name, new))
 				continue;
 			else

@@ -446,11 +446,12 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 {
 	struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 	struct sysfs_dirent * sd;
+	struct bin_attribute *bin_attr;
 	struct inode *inode;
 	int found = 0;
 
 	for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
-		if ((sd->s_type & SYSFS_NOT_PINNED) &&
+		if ((sysfs_type(sd) & SYSFS_NOT_PINNED) &&
 		    !strcmp(sd->s_name, dentry->d_name.name)) {
 			found = 1;
 			break;

@@ -468,16 +469,22 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 
 	if (inode->i_state & I_NEW) {
 		/* initialize inode according to type */
-		if (sd->s_type & SYSFS_KOBJ_ATTR) {
+		switch (sysfs_type(sd)) {
+		case SYSFS_KOBJ_ATTR:
 			inode->i_size = PAGE_SIZE;
 			inode->i_fop = &sysfs_file_operations;
-		} else if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
-			struct bin_attribute *bin_attr =
-				sd->s_elem.bin_attr.bin_attr;
+			break;
+		case SYSFS_KOBJ_BIN_ATTR:
+			bin_attr = sd->s_elem.bin_attr.bin_attr;
 			inode->i_size = bin_attr->size;
 			inode->i_fop = &bin_fops;
-		} else if (sd->s_type & SYSFS_KOBJ_LINK)
+			break;
+		case SYSFS_KOBJ_LINK:
 			inode->i_op = &sysfs_symlink_inode_operations;
+			break;
+		default:
+			BUG();
+		}
 	}
 
 	sysfs_instantiate(dentry, inode);

@@ -532,7 +539,7 @@ static void __sysfs_remove_dir(struct dentry *dentry)
 	while (*pos) {
 		struct sysfs_dirent *sd = *pos;
 
-		if (sd->s_type && (sd->s_type & SYSFS_NOT_PINNED)) {
+		if (sysfs_type(sd) && (sysfs_type(sd) & SYSFS_NOT_PINNED)) {
 			*pos = sd->s_sibling;
 			sd->s_sibling = removed;
 			removed = sd;

@@ -775,7 +782,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 				const char * name;
 				int len;
 
-				if (!next->s_type)
+				if (!sysfs_type(next))
 					continue;
 
 				name = next->s_name;

@@ -824,7 +831,7 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 			pos = &sd->s_children;
 			while (n && *pos) {
 				struct sysfs_dirent *next = *pos;
-				if (next->s_type)
+				if (sysfs_type(next))
 					n--;
 				pos = &(*pos)->s_sibling;
 			}

index 63daa06..ee3a5d9 100644
@@ -242,7 +242,7 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 
 	dput(dentry);
 	/* XXX: unpin if directory, this will go away soon */
-	if (sd->s_type & SYSFS_DIR)
+	if (sysfs_type(sd) == SYSFS_DIR)
 		dput(dentry);
 
 	/* adjust nlink and update timestamp */

@@ -254,7 +254,7 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 
 		inode->i_ctime = curtime;
 		drop_nlink(inode);
-		if (sd->s_type & SYSFS_DIR)
+		if (sysfs_type(sd) == SYSFS_DIR)
 			drop_nlink(inode);
 
 		mutex_unlock(&inode->i_mutex);

@@ -267,7 +267,7 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 		mutex_lock(&inode->i_mutex);
 
 		inode->i_ctime = inode->i_mtime = curtime;
-		if (sd->s_type & SYSFS_DIR)
+		if (sysfs_type(sd) == SYSFS_DIR)
 			drop_nlink(inode);
 
 		mutex_unlock(&inode->i_mutex);

@@ -293,7 +293,7 @@ int sysfs_hash_and_remove(struct dentry * dir, const char * name)
 	for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
 		sd = *pos;
 
-		if (!sd->s_type)
+		if (!sysfs_type(sd))
 			continue;
 		if (!strcmp(sd->s_name, name)) {
 			*pos = sd->s_sibling;

index 4be9593..078537e 100644
@@ -26,7 +26,7 @@ static const struct super_operations sysfs_ops = {
 
 static struct sysfs_dirent sysfs_root = {
 	.s_count	= ATOMIC_INIT(1),
-	.s_type		= SYSFS_ROOT,
+	.s_flags	= SYSFS_ROOT,
 	.s_mode		= S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
 	.s_ino		= 1,
 };

index 6f8aaf3..06b5085 100644
@@ -34,7 +34,7 @@ struct sysfs_dirent {
 		struct sysfs_elem_bin_attr	bin_attr;
 	}			s_elem;
 
-	int			s_type;
+	unsigned int		s_flags;
 	umode_t			s_mode;
 	ino_t			s_ino;
 	struct dentry		* s_dentry;

@@ -86,6 +86,11 @@ extern const struct file_operations bin_fops;
 extern const struct inode_operations sysfs_dir_inode_operations;
 extern const struct inode_operations sysfs_symlink_inode_operations;
 
+static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_TYPE_MASK;
+}
+
 static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
 {
 	if (sd) {

index 161e19a..5813550 100644
@@ -74,6 +74,7 @@ struct sysfs_ops {
 	ssize_t	(*store)(struct kobject *,struct attribute *,const char *, size_t);
 };
 
+#define SYSFS_TYPE_MASK		0x00ff
 #define SYSFS_ROOT		0x0001
 #define SYSFS_DIR		0x0002
 #define SYSFS_KOBJ_ATTR 	0x0004

@@ -82,6 +83,8 @@ struct sysfs_ops {
 #define SYSFS_NOT_PINNED	(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
 #define SYSFS_COPY_NAME		(SYSFS_DIR | SYSFS_KOBJ_LINK)
 
+#define SYSFS_FLAG_MASK		~SYSFS_TYPE_MASK
+
 #ifdef CONFIG_SYSFS
 
 extern int sysfs_schedule_callback(struct kobject *kobj,

index ee31bf3..63daa06 100644
@@ -219,9 +219,9 @@ void sysfs_instantiate(struct dentry *dentry, struct inode *inode)
  */
 void sysfs_drop_dentry(struct sysfs_dirent *sd)
 {
-	struct dentry *dentry = NULL, *parent = NULL;
-	struct inode *dir;
+	struct dentry *dentry = NULL;
 	struct timespec curtime;
+	struct inode *inode;
 
 	/* We're not holding a reference to ->s_dentry dentry but the
 	 * field will stay valid as long as sysfs_lock is held.

@@ -229,19 +229,9 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 	spin_lock(&sysfs_lock);
 	spin_lock(&dcache_lock);
 
+	/* drop dentry if it's there and dput() didn't kill it yet */
 	if (sd->s_dentry && sd->s_dentry->d_inode) {
-		/* get dentry if it's there and dput() didn't kill it yet */
 		dentry = dget_locked(sd->s_dentry);
-		parent = dentry->d_parent;
-	} else if (sd->s_parent->s_dentry->d_inode) {
-		/* We need to update the parent even if dentry for the
-		 * victim itself doesn't exist.
-		 */
-		parent = dget_locked(sd->s_parent->s_dentry);
-	}
-
-	/* drop */
-	if (dentry) {
 		spin_lock(&dentry->d_lock);
 		__d_drop(dentry);
 		spin_unlock(&dentry->d_lock);

@@ -250,36 +240,39 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 	spin_unlock(&dcache_lock);
 	spin_unlock(&sysfs_lock);
 
-	/* nothing to do if the parent isn't in dcache */
-	if (!parent)
-		return;
+	dput(dentry);
+	/* XXX: unpin if directory, this will go away soon */
+	if (sd->s_type & SYSFS_DIR)
+		dput(dentry);
 
 	/* adjust nlink and update timestamp */
-	dir = parent->d_inode;
-	mutex_lock(&dir->i_mutex);
-
 	curtime = CURRENT_TIME;
 
-	dir->i_ctime = dir->i_mtime = curtime;
+	inode = ilookup(sysfs_sb, sd->s_ino);
+	if (inode) {
+		mutex_lock(&inode->i_mutex);
 
-	if (dentry) {
-		dentry->d_inode->i_ctime = curtime;
-		drop_nlink(dentry->d_inode);
-		if (sd->s_type & SYSFS_DIR) {
-			drop_nlink(dentry->d_inode);
-			drop_nlink(dir);
-			/* XXX: unpin if directory, this will go away soon */
-			dput(dentry);
-		}
+		inode->i_ctime = curtime;
+		drop_nlink(inode);
+		if (sd->s_type & SYSFS_DIR)
+			drop_nlink(inode);
+
+		mutex_unlock(&inode->i_mutex);
+		iput(inode);
 	}
 
-	mutex_unlock(&dir->i_mutex);
+	/* adjust nlink and udpate timestamp of the parent */
+	inode = ilookup(sysfs_sb, sd->s_parent->s_ino);
+	if (inode) {
+		mutex_lock(&inode->i_mutex);
 
-	/* bye bye */
-	if (dentry)
-		dput(dentry);
-	else
-		dput(parent);
+		inode->i_ctime = inode->i_mtime = curtime;
+		if (sd->s_type & SYSFS_DIR)
+			drop_nlink(inode);
+
+		mutex_unlock(&inode->i_mutex);
+		iput(inode);
+	}
 }
 
 int sysfs_hash_and_remove(struct dentry * dir, const char * name)

index f2ea006..4762a9a 100644
@@ -317,28 +317,55 @@ void sysfs_attach_dirent(struct sysfs_dirent *sd,
 	}
 }
 
-/*
+/**
+ *	sysfs_find_dirent - find sysfs_dirent with the given name
+ *	@parent_sd: sysfs_dirent to search under
+ *	@name: name to look for
  *
- * Return -EEXIST if there is already a sysfs element with the same name for
- * the same parent.
+ *	Look for sysfs_dirent with name @name under @parent_sd.
  *
- * called with parent inode's i_mutex held
+ *	LOCKING:
+ *	mutex_lock(parent->i_mutex)
+ *
+ *	RETURNS:
+ *	Pointer to sysfs_dirent if found, NULL if not.
  */
-int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
-			  const unsigned char *new)
+struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
+				       const unsigned char *name)
 {
-	struct sysfs_dirent * sd;
+	struct sysfs_dirent *sd;
 
-	for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
-		if (sysfs_type(sd)) {
-			if (strcmp(sd->s_name, new))
-				continue;
-			else
-				return -EEXIST;
-		}
-	}
+	for (sd = parent_sd->s_children; sd; sd = sd->s_sibling)
+		if (sysfs_type(sd) && !strcmp(sd->s_name, name))
+			return sd;
+	return NULL;
+}
 
-	return 0;
+/**
+ *	sysfs_get_dirent - find and get sysfs_dirent with the given name
+ *	@parent_sd: sysfs_dirent to search under
+ *	@name: name to look for
+ *
+ *	Look for sysfs_dirent with name @name under @parent_sd and get
+ *	it if found.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	Pointer to sysfs_dirent if found, NULL if not.
+ */
+struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
+				      const unsigned char *name)
+{
+	struct sysfs_dirent *sd;
+
+	mutex_lock(&parent_sd->s_dentry->d_inode->i_mutex);
+	sd = sysfs_find_dirent(parent_sd, name);
+	sysfs_get(sd);
+	mutex_unlock(&parent_sd->s_dentry->d_inode->i_mutex);
+
+	return sd;
 }
 
 static int create_dir(struct kobject *kobj, struct dentry *parent,

@@ -382,7 +409,7 @@ static int create_dir(struct kobject *kobj, struct dentry *parent,
 
 	/* link in */
 	error = -EEXIST;
-	if (sysfs_dirent_exist(parent->d_fsdata, name))
+	if (sysfs_find_dirent(parent->d_fsdata, name))
 		goto out_iput;
 
 	sysfs_instantiate(dentry, inode);

index a84b734..e448b88 100644
@@ -421,7 +421,7 @@ int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
 
 	mutex_lock(&dir->d_inode->i_mutex);
 
-	if (sysfs_dirent_exist(parent_sd, attr->name)) {
+	if (sysfs_find_dirent(parent_sd, attr->name)) {
 		error = -EEXIST;
 		goto out_unlock;
 	}

index ff605d3..45b62e2 100644
@@ -95,7 +95,7 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 		return -ENOENT;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
-	if (!sysfs_dirent_exist(dentry->d_fsdata, name))
+	if (!sysfs_find_dirent(dentry->d_fsdata, name))
 		error = sysfs_add_link(parent_sd, name, target_sd);
 	mutex_unlock(&dentry->d_inode->i_mutex);
 

index 06b5085..f1629b4 100644
@@ -59,7 +59,10 @@ extern struct inode * sysfs_get_inode(struct sysfs_dirent *sd);
 extern void sysfs_instantiate(struct dentry *dentry, struct inode *inode);
 
 extern void release_sysfs_dirent(struct sysfs_dirent * sd);
-extern int sysfs_dirent_exist(struct sysfs_dirent *, const unsigned char *);
+extern struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
+					      const unsigned char *name);
+extern struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
+					     const unsigned char *name);
 extern struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode,
 					     int type);
 extern void sysfs_attach_dirent(struct sysfs_dirent *sd,

index eb9bc0a..f2ea006 100644
@@ -171,7 +171,7 @@ void sysfs_deactivate(struct sysfs_dirent *sd)
 	DECLARE_COMPLETION_ONSTACK(wait);
 	int v;
 
-	BUG_ON(sd->s_sibling);
+	BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
 	sd->s_sibling = (void *)&wait;
 
 	/* atomic_add_return() is a mb(), put_active() will always see

@@ -506,6 +506,7 @@ static void remove_dir(struct dentry * d)
 	mutex_lock(&parent->d_inode->i_mutex);
 
 	sysfs_unlink_sibling(sd);
+	sd->s_flags |= SYSFS_FLAG_REMOVED;
 
 	pr_debug(" o %s removing done (%d)\n",d->d_name.name,
 		 atomic_read(&d->d_count));

@@ -540,6 +541,7 @@ static void __sysfs_remove_dir(struct dentry *dentry)
 		struct sysfs_dirent *sd = *pos;
 
 		if (sysfs_type(sd) && (sysfs_type(sd) & SYSFS_NOT_PINNED)) {
+			sd->s_flags |= SYSFS_FLAG_REMOVED;
 			*pos = sd->s_sibling;
 			sd->s_sibling = removed;
 			removed = sd;

index ee3a5d9..e2f6ef1 100644
@@ -296,6 +296,7 @@ int sysfs_hash_and_remove(struct dentry * dir, const char * name)
 		if (!sysfs_type(sd))
 			continue;
 		if (!strcmp(sd->s_name, name)) {
+			sd->s_flags |= SYSFS_FLAG_REMOVED;
 			*pos = sd->s_sibling;
 			sd->s_sibling = NULL;
 			found = 1;

index 5813550..2a6df64 100644
@@ -84,6 +84,7 @@ struct sysfs_ops {
 #define SYSFS_COPY_NAME		(SYSFS_DIR | SYSFS_KOBJ_LINK)
 
 #define SYSFS_FLAG_MASK		~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_REMOVED	0x0100
 
 #ifdef CONFIG_SYSFS
 

index 663acee..f10b7b8 100644
@@ -14,7 +14,7 @@
 #include <asm/semaphore.h>
 #include "sysfs.h"
 
-DECLARE_RWSEM(sysfs_rename_sem);
+DEFINE_MUTEX(sysfs_mutex);
 spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
 
 static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;

@@ -28,7 +28,7 @@ static DEFINE_IDA(sysfs_ino_ida);
  *	sd->s_parent->s_children.
  *
  *	Locking:
- *	mutex_lock(sd->s_parent->dentry->d_inode->i_mutex)
+ *	mutex_lock(sysfs_mutex)
  */
 static void sysfs_link_sibling(struct sysfs_dirent *sd)
 {

@@ -47,7 +47,7 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd)
  *	sd->s_parent->s_children.
  *
  *	Locking:
- *	mutex_lock(sd->s_parent->dentry->d_inode->i_mutex)
+ *	mutex_lock(sysfs_mutex)
  */
 static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
 {

@@ -215,6 +215,9 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
 	struct sysfs_dirent *parent_sd;
 
  repeat:
+	/* Moving/renaming is always done while holding reference.
+	 * sd->s_parent won't change beneath us.
+	 */
 	parent_sd = sd->s_parent;
 
 	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)

@@ -291,6 +294,17 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 	return NULL;
 }
 
+/**
+ *	sysfs_attach_dentry - associate sysfs_dirent with dentry
+ *	@sd: target sysfs_dirent
+ *	@dentry: dentry to associate
+ *
+ *	Associate @sd with @dentry.  This is protected by
+ *	sysfs_assoc_lock to avoid race with sysfs_d_iput().
+ *
+ *	LOCKING:
+ *	mutex_lock(sysfs_mutex)
+ */
 static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
 {
 	dentry->d_op = &sysfs_dentry_ops;

@@ -304,6 +318,17 @@ static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
 	d_rehash(dentry);
 }
 
+/**
+ *	sysfs_attach_dirent - attach sysfs_dirent to its parent and dentry
+ *	@sd: sysfs_dirent to attach
+ *	@parent_sd: parent to attach to (optional)
+ *	@dentry: dentry to be associated to @sd (optional)
+ *
+ *	Attach @sd to @parent_sd and/or @dentry.  Both are optional.
+ *
+ *	LOCKING:
+ *	mutex_lock(sysfs_mutex)
+ */
 void sysfs_attach_dirent(struct sysfs_dirent *sd,
 			 struct sysfs_dirent *parent_sd, struct dentry *dentry)
 {

@@ -324,7 +349,7 @@ void sysfs_attach_dirent(struct sysfs_dirent *sd,
  *	Look for sysfs_dirent with name @name under @parent_sd.
  *
  *	LOCKING:
- *	mutex_lock(parent->i_mutex)
+ *	mutex_lock(sysfs_mutex)
  *
  *	RETURNS:
  *	Pointer to sysfs_dirent if found, NULL if not.

@@ -349,7 +374,7 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
  *	it if found.
  *
  *	LOCKING:
- *	Kernel thread context (may sleep)
+ *	Kernel thread context (may sleep).  Grabs sysfs_mutex.
  *
  *	RETURNS:
  *	Pointer to sysfs_dirent if found, NULL if not.

@@ -359,10 +384,10 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
 {
 	struct sysfs_dirent *sd;
 
-	mutex_lock(&parent_sd->s_dentry->d_inode->i_mutex);
+	mutex_lock(&sysfs_mutex);
 	sd = sysfs_find_dirent(parent_sd, name);
 	sysfs_get(sd);
-	mutex_unlock(&parent_sd->s_dentry->d_inode->i_mutex);
+	mutex_unlock(&sysfs_mutex);
 
 	return sd;
 }

@@ -408,14 +433,20 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	}
 
 	/* link in */
+	mutex_lock(&sysfs_mutex);
+
 	error = -EEXIST;
-	if (sysfs_find_dirent(parent_sd, name))
+	if (sysfs_find_dirent(parent_sd, name)) {
+		mutex_unlock(&sysfs_mutex);
 		goto out_iput;
+	}
 
 	sysfs_instantiate(dentry, inode);
 	inc_nlink(parent->d_inode);
 	sysfs_attach_dirent(sd, parent_sd, dentry);
 
+	mutex_unlock(&sysfs_mutex);
+
 	*p_sd = sd;
 	error = 0;
 	goto out_unlock;	/* pin directory dentry in core */

@@ -493,6 +524,8 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
+	mutex_lock(&sysfs_mutex);
+
 	if (inode->i_state & I_NEW) {
 		/* initialize inode according to type */
 		switch (sysfs_type(sd)) {

@@ -516,6 +549,8 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	sysfs_instantiate(dentry, inode);
 	sysfs_attach_dentry(sd, dentry);
 
+	mutex_unlock(&sysfs_mutex);
+
 	return NULL;
 }
 

@@ -526,17 +561,13 @@ const struct inode_operations sysfs_dir_inode_operations = {
 
 static void remove_dir(struct sysfs_dirent *sd)
 {
-	struct dentry *parent = sd->s_parent->s_dentry;
-
-	mutex_lock(&parent->d_inode->i_mutex);
-
+	mutex_lock(&sysfs_mutex);
 	sysfs_unlink_sibling(sd);
 	sd->s_flags |= SYSFS_FLAG_REMOVED;
+	mutex_unlock(&sysfs_mutex);
 
 	pr_debug(" o %s removing done\n", sd->s_name);
 
-	mutex_unlock(&parent->d_inode->i_mutex);
-
 	sysfs_drop_dentry(sd);
 	sysfs_deactivate(sd);
 	sysfs_put(sd);

@@ -552,15 +583,12 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
 {
 	struct sysfs_dirent *removed = NULL;
 	struct sysfs_dirent **pos;
-	struct dentry *dir;
 
 	if (!dir_sd)
 		return;
 
-	dir = dir_sd->s_dentry;
-
 	pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
-	mutex_lock(&dir->d_inode->i_mutex);
+	mutex_lock(&sysfs_mutex);
 	pos = &dir_sd->s_children;
 	while (*pos) {
 		struct sysfs_dirent *sd = *pos;

@@ -573,7 +601,7 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
 		} else
 			pos = &(*pos)->s_sibling;
 	}
-	mutex_unlock(&dir->d_inode->i_mutex);
+	mutex_unlock(&sysfs_mutex);
 
 	while (removed) {
 		struct sysfs_dirent *sd = removed;

@@ -621,7 +649,6 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
 	if (!new_parent_sd)
 		return -EFAULT;
 
-	down_write(&sysfs_rename_sem);
 	mutex_lock(&new_parent->d_inode->i_mutex);
 
 	new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));

@@ -661,12 +688,16 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
 	d_add(new_dentry, NULL);
 	d_move(sd->s_dentry, new_dentry);
 
+	mutex_lock(&sysfs_mutex);
+
 	sysfs_unlink_sibling(sd);
 	sysfs_get(new_parent_sd);
 	sysfs_put(sd->s_parent);
 	sd->s_parent = new_parent_sd;
 	sysfs_link_sibling(sd);
 
+	mutex_unlock(&sysfs_mutex);
+
 	error = 0;
 	goto out_unlock;
 

@@ -678,7 +709,6 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
 	dput(new_dentry);
  out_unlock:
 	mutex_unlock(&new_parent->d_inode->i_mutex);
-	up_write(&sysfs_rename_sem);
 	return error;
 }
 

@@ -717,12 +747,15 @@ again:
 	dput(new_dentry);
 
 	/* Remove from old parent's list and insert into new parent's list. */
+	mutex_lock(&sysfs_mutex);
+
 	sysfs_unlink_sibling(sd);
 	sysfs_get(new_parent_sd);
 	sysfs_put(sd->s_parent);
 	sd->s_parent = new_parent_sd;
 	sysfs_link_sibling(sd);
 
+	mutex_unlock(&sysfs_mutex);
 out:
 	mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
 	mutex_unlock(&old_parent_dentry->d_inode->i_mutex);

@@ -736,11 +769,12 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
 	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 	struct sysfs_dirent * sd;
 
-	mutex_lock(&dentry->d_inode->i_mutex);
 	sd = sysfs_new_dirent("_DIR_", 0, 0);
-	if (sd)
+	if (sd) {
+		mutex_lock(&sysfs_mutex);
 		sysfs_attach_dirent(sd, parent_sd, NULL);
-	mutex_unlock(&dentry->d_inode->i_mutex);
+		mutex_unlock(&sysfs_mutex);
+	}
 
 	file->private_data = sd;
 	return sd ? 0 : -ENOMEM;

@@ -748,12 +782,11 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
 
 static int sysfs_dir_close(struct inode *inode, struct file *file)
 {
-	struct dentry * dentry = file->f_path.dentry;
 	struct sysfs_dirent * cursor = file->private_data;
 
-	mutex_lock(&dentry->d_inode->i_mutex);
+	mutex_lock(&sysfs_mutex);
 	sysfs_unlink_sibling(cursor);
-	mutex_unlock(&dentry->d_inode->i_mutex);
+	mutex_unlock(&sysfs_mutex);
 
 	release_sysfs_dirent(cursor);
 

@@ -794,6 +827,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 			i++;
 			/* fallthrough */
 		default:
+			mutex_lock(&sysfs_mutex);
+
 			pos = &parent_sd->s_children;
 			while (*pos != cursor)
 				pos = &(*pos)->s_sibling;

@@ -826,6 +861,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 			/* put cursor back in */
 			cursor->s_sibling = *pos;
 			*pos = cursor;
+
+			mutex_unlock(&sysfs_mutex);
 	}
 	return 0;
 }

@@ -834,7 +871,6 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 {
 	struct dentry * dentry = file->f_path.dentry;
 
-	mutex_lock(&dentry->d_inode->i_mutex);
 	switch (origin) {
 		case 1:
 			offset += file->f_pos;

@@ -842,10 +878,11 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 			if (offset >= 0)
 				break;
 		default:
-			mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
 			return -EINVAL;
 	}
 	if (offset != file->f_pos) {
+		mutex_lock(&sysfs_mutex);
+
 		file->f_pos = offset;
 		if (file->f_pos >= 2) {
 			struct sysfs_dirent *sd = dentry->d_fsdata;

@@ -866,8 +903,10 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 			cursor->s_sibling = *pos;
 			*pos = cursor;
 		}
+
+		mutex_unlock(&sysfs_mutex);
 	}
-	mutex_unlock(&dentry->d_inode->i_mutex);
+
 	return offset;
 }
 

@@ -933,7 +972,9 @@ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
 	sd->s_elem.dir.kobj = kobj;
 	/* point to parent_sd but don't attach to it */
 	sd->s_parent = sysfs_get(parent_sd);
+	mutex_lock(&sysfs_mutex);
 	sysfs_attach_dirent(sd, NULL, shadow);
+	mutex_unlock(&sysfs_mutex);
 
 	d_instantiate(shadow, igrab(inode));
 	inc_nlink(inode);

index acc9890..c14e607 100644
@@ -415,29 +415,28 @@ const struct file_operations sysfs_file_operations = {
 int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
 		   int type)
 {
-	struct dentry *dir = dir_sd->s_dentry;
 	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
 	struct sysfs_dirent *sd;
-	int error = 0;
 
-	mutex_lock(&dir->d_inode->i_mutex);
+	sd = sysfs_new_dirent(attr->name, mode, type);
+	if (!sd)
+		return -ENOMEM;
+	sd->s_elem.attr.attr = (void *)attr;
 
-	if (sysfs_find_dirent(dir_sd, attr->name)) {
-		error = -EEXIST;
-		goto out_unlock;
-	}
+	mutex_lock(&sysfs_mutex);
 
-	sd = sysfs_new_dirent(attr->name, mode, type);
-	if (!sd) {
-		error = -ENOMEM;
-		goto out_unlock;
+	if (!sysfs_find_dirent(dir_sd, attr->name)) {
+		sysfs_attach_dirent(sd, dir_sd, NULL);
+		sd = NULL;
 	}
-	sd->s_elem.attr.attr = (void *)attr;
-	sysfs_attach_dirent(sd, dir_sd, NULL);
 
- out_unlock:
-	mutex_unlock(&dir->d_inode->i_mutex);
-	return error;
+	mutex_unlock(&sysfs_mutex);
+
+	if (sd) {
+		sysfs_put(sd);
+		return -EEXIST;
+	}
+	return 0;
 }
 
 

index e4c2393..d439c0b 100644
@@ -277,20 +277,14 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 
 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
 {
-	struct dentry *dir;
 	struct sysfs_dirent **pos, *sd;
 	int found = 0;
 
 	if (!dir_sd)
 		return -ENOENT;
 
-	dir = dir_sd->s_dentry;
+	mutex_lock(&sysfs_mutex);
 
-	if (dir->d_inode == NULL)
-		/* no inode means this hasn't been made visible yet */
-		return -ENOENT;
-
-	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 	for (pos = &dir_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
 		sd = *pos;
 

@@ -304,7 +298,8 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
 			break;
 		}
 	}
-	mutex_unlock(&dir->d_inode->i_mutex);
+
+	mutex_unlock(&sysfs_mutex);
 
 	if (!found)
 		return -ENOENT;

87 lines not on this page · raw message

index 4572677..2605161 100644
@@ -82,7 +82,7 @@ extern void sysfs_drop_dentry(struct sysfs_dirent *sd);
 extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
 
 extern spinlock_t sysfs_assoc_lock;
-extern struct rw_semaphore sysfs_rename_sem;
+extern struct mutex sysfs_mutex;
 extern struct super_block * sysfs_sb;
 extern const struct file_operations sysfs_dir_operations;
 extern const struct file_operations sysfs_file_operations;

index 950e679..663acee 100644
@@ -15,8 +15,7 @@
 #include "sysfs.h"
 
 DECLARE_RWSEM(sysfs_rename_sem);
-spinlock_t sysfs_lock = SPIN_LOCK_UNLOCKED;
-spinlock_t kobj_sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
+spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
 
 static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
 static DEFINE_IDA(sysfs_ino_ida);

@@ -236,10 +235,10 @@ static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
 	struct sysfs_dirent * sd = dentry->d_fsdata;
 
 	if (sd) {
-		/* sd->s_dentry is protected with sysfs_lock.  This
-		 * allows sysfs_drop_dentry() to dereference it.
+		/* sd->s_dentry is protected with sysfs_assoc_lock.
+		 * This allows sysfs_drop_dentry() to dereference it.
 		 */
-		spin_lock(&sysfs_lock);
+		spin_lock(&sysfs_assoc_lock);
 
 		/* The dentry might have been deleted or another
 		 * lookup could have happened updating sd->s_dentry to

@@ -248,7 +247,7 @@ static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
 		 */
 		if (sd->s_dentry == dentry)
 			sd->s_dentry = NULL;
-		spin_unlock(&sysfs_lock);
+		spin_unlock(&sysfs_assoc_lock);
 		sysfs_put(sd);
 	}
 	iput(inode);

@@ -298,9 +297,9 @@ static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
 	dentry->d_fsdata = sysfs_get(sd);
 
 	/* protect sd->s_dentry against sysfs_d_iput */
-	spin_lock(&sysfs_lock);
+	spin_lock(&sysfs_assoc_lock);
 	sd->s_dentry = dentry;
-	spin_unlock(&sysfs_lock);
+	spin_unlock(&sysfs_assoc_lock);
 
 	d_rehash(dentry);
 }

@@ -603,9 +602,9 @@ void sysfs_remove_dir(struct kobject * kobj)
 {
 	struct sysfs_dirent *sd = kobj->sd;
 
-	spin_lock(&kobj_sysfs_assoc_lock);
+	spin_lock(&sysfs_assoc_lock);
 	kobj->sd = NULL;
-	spin_unlock(&kobj_sysfs_assoc_lock);
+	spin_unlock(&sysfs_assoc_lock);
 
 	__sysfs_remove_dir(sd);
 }

index 1be8537..e4c2393 100644
@@ -211,11 +211,11 @@ void sysfs_instantiate(struct dentry *dentry, struct inode *inode)
  *	parent on entry to this function such that it can't be looked
  *	up anymore.
  *
- *	@sd->s_dentry which is protected with sysfs_lock points to the
- *	currently associated dentry but we're not holding a reference
- *	to it and racing with dput().  Grab dcache_lock and verify
- *	dentry before dropping it.  If @sd->s_dentry is NULL or dput()
- *	beats us, no need to bother.
+ *	@sd->s_dentry which is protected with sysfs_assoc_lock points
+ *	to the currently associated dentry but we're not holding a
+ *	reference to it and racing with dput().  Grab dcache_lock and
+ *	verify dentry before dropping it.  If @sd->s_dentry is NULL or
+ *	dput() beats us, no need to bother.
  */
 void sysfs_drop_dentry(struct sysfs_dirent *sd)
 {

@@ -224,9 +224,9 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 	struct inode *inode;
 
 	/* We're not holding a reference to ->s_dentry dentry but the
-	 * field will stay valid as long as sysfs_lock is held.
+	 * field will stay valid as long as sysfs_assoc_lock is held.
 	 */
-	spin_lock(&sysfs_lock);
+	spin_lock(&sysfs_assoc_lock);
 	spin_lock(&dcache_lock);
 
 	/* drop dentry if it's there and dput() didn't kill it yet */

@@ -238,7 +238,7 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 	}
 
 	spin_unlock(&dcache_lock);
-	spin_unlock(&sysfs_lock);
+	spin_unlock(&sysfs_assoc_lock);
 
 	dput(dentry);
 	/* XXX: unpin if directory, this will go away soon */

index 43cc522..cbd95a4 100644
@@ -82,12 +82,12 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 		return -EFAULT;
 
 	/* target->sd can go away beneath us but is protected with
-	 * kobj_sysfs_assoc_lock.  Fetch target_sd from it.
+	 * sysfs_assoc_lock.  Fetch target_sd from it.
 	 */
-	spin_lock(&kobj_sysfs_assoc_lock);
+	spin_lock(&sysfs_assoc_lock);
 	if (target->sd)
 		target_sd = sysfs_get(target->sd);
-	spin_unlock(&kobj_sysfs_assoc_lock);
+	spin_unlock(&sysfs_assoc_lock);
 
 	if (!target_sd)
 		return -ENOENT;

index 27a5f4b..4572677 100644
@@ -81,8 +81,7 @@ extern void sysfs_remove_subdir(struct sysfs_dirent *sd);
 extern void sysfs_drop_dentry(struct sysfs_dirent *sd);
 extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
 
-extern spinlock_t sysfs_lock;
-extern spinlock_t kobj_sysfs_assoc_lock;
+extern spinlock_t sysfs_assoc_lock;
 extern struct rw_semaphore sysfs_rename_sem;
 extern struct super_block * sysfs_sb;
 extern const struct file_operations sysfs_dir_operations;

index f10b7b8..dce74ef 100644
@@ -30,7 +30,7 @@ static DEFINE_IDA(sysfs_ino_ida);
  *	Locking:
  *	mutex_lock(sysfs_mutex)
  */
-static void sysfs_link_sibling(struct sysfs_dirent *sd)
+void sysfs_link_sibling(struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent *parent_sd = sd->s_parent;
 

@@ -49,7 +49,7 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd)
  *	Locking:
  *	mutex_lock(sysfs_mutex)
  */
-static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
+void sysfs_unlink_sibling(struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent **pos;
 

@@ -165,7 +165,7 @@ void sysfs_put_active_two(struct sysfs_dirent *sd)
  *
  *	Deny new active references and drain existing ones.
  */
-void sysfs_deactivate(struct sysfs_dirent *sd)
+static void sysfs_deactivate(struct sysfs_dirent *sd)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	int v;

@@ -318,27 +318,164 @@ static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
 	d_rehash(dentry);
 }
 
+static int sysfs_ilookup_test(struct inode *inode, void *arg)
+{
+	struct sysfs_dirent *sd = arg;
+	return inode->i_ino == sd->s_ino;
+}
+
 /**
- *	sysfs_attach_dirent - attach sysfs_dirent to its parent and dentry
- *	@sd: sysfs_dirent to attach
- *	@parent_sd: parent to attach to (optional)
- *	@dentry: dentry to be associated to @sd (optional)
+ *	sysfs_addrm_start - prepare for sysfs_dirent add/remove
+ *	@acxt: pointer to sysfs_addrm_cxt to be used
+ *	@parent_sd: parent sysfs_dirent
  *
- *	Attach @sd to @parent_sd and/or @dentry.  Both are optional.
+ *	This function is called when the caller is about to add or
+ *	remove sysfs_dirent under @parent_sd.  This function acquires
+ *	sysfs_mutex, grabs inode for @parent_sd if available and lock
+ *	i_mutex of it.  @acxt is used to keep and pass context to
+ *	other addrm functions.
  *
  *	LOCKING:
- *	mutex_lock(sysfs_mutex)
+ *	Kernel thread context (may sleep).  sysfs_mutex is locked on
+ *	return.  i_mutex of parent inode is locked on return if
+ *	available.
  */
-void sysfs_attach_dirent(struct sysfs_dirent *sd,
-			 struct sysfs_dirent *parent_sd, struct dentry *dentry)
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
+		       struct sysfs_dirent *parent_sd)
 {
-	if (dentry)
-		sysfs_attach_dentry(sd, dentry);
+	struct inode *inode;
 
-	if (parent_sd) {
-		sd->s_parent = sysfs_get(parent_sd);
-		sysfs_link_sibling(sd);
+	memset(acxt, 0, sizeof(*acxt));
+	acxt->parent_sd = parent_sd;
+
+	/* Lookup parent inode.  inode initialization and I_NEW
+	 * clearing are protected by sysfs_mutex.  By grabbing it and
+	 * looking up with _nowait variant, inode state can be
+	 * determined reliably.
+	 */
+	mutex_lock(&sysfs_mutex);
+
+	inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
+				parent_sd);
+
+	if (inode && !(inode->i_state & I_NEW)) {
+		/* parent inode available */
+		acxt->parent_inode = inode;
+
+		/* sysfs_mutex is below i_mutex in lock hierarchy.
+		 * First, trylock i_mutex.  If fails, unlock
+		 * sysfs_mutex and lock them in order.
+		 */
+		if (!mutex_trylock(&inode->i_mutex)) {
+			mutex_unlock(&sysfs_mutex);
+			mutex_lock(&inode->i_mutex);
+			mutex_lock(&sysfs_mutex);
+		}
+	} else
+		iput(inode);
+}
+
+/**
+ *	sysfs_add_one - add sysfs_dirent to parent
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be added
+ *
+ *	Get @acxt->parent_sd and set sd->s_parent to it and increment
+ *	nlink of parent inode if @sd is a directory.  @sd is NOT
+ *	linked into the children list of the parent.  The caller
+ *	should invoke sysfs_link_sibling() after this function
+ *	completes if @sd needs to be on the children list.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ */
+void sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+{
+	sd->s_parent = sysfs_get(acxt->parent_sd);
+
+	if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
+		inc_nlink(acxt->parent_inode);
+
+	acxt->cnt++;
+}
+
+/**
+ *	sysfs_remove_one - remove sysfs_dirent from parent
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be added
+ *
+ *	Mark @sd removed and drop nlink of parent inode if @sd is a
+ *	directory.  @sd is NOT unlinked from the children list of the
+ *	parent.  The caller is repsonsible for removing @sd from the
+ *	children list before calling this function.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ */
+void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+{
+	BUG_ON(sd->s_sibling || (sd->s_flags & SYSFS_FLAG_REMOVED));
+
+	sd->s_flags |= SYSFS_FLAG_REMOVED;
+	sd->s_sibling = acxt->removed;
+	acxt->removed = sd;
+
+	if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
+		drop_nlink(acxt->parent_inode);
+
+	acxt->cnt++;
+}
+
+/**
+ *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
+ *	@acxt: addrm context to finish up
+ *
+ *	Finish up sysfs_dirent add/remove.  Resources acquired by
+ *	sysfs_addrm_start() are released and removed sysfs_dirents are
+ *	cleaned up.  Timestamps on the parent inode are updated.
+ *
+ *	LOCKING:
+ *	All mutexes acquired by sysfs_addrm_start() are released.
+ *
+ *	RETURNS:
+ *	Number of added/removed sysfs_dirents since sysfs_addrm_start().
+ */
+int sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
+{
+	/* release resources acquired by sysfs_addrm_start() */
+	mutex_unlock(&sysfs_mutex);
+	if (acxt->parent_inode) {
+		struct inode *inode = acxt->parent_inode;
+
+		/* if added/removed, update timestamps on the parent */
+		if (acxt->cnt)
+			inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+
+		mutex_unlock(&inode->i_mutex);
+		iput(inode);
+	}
+
+	/* kill removed sysfs_dirents */
+	while (acxt->removed) {
+		struct sysfs_dirent *sd = acxt->removed;
+
+		acxt->removed = sd->s_sibling;
+		sd->s_sibling = NULL;
+
+		sysfs_drop_dentry(sd);
+		sysfs_deactivate(sd);
+		sysfs_put(sd);
 	}
+
+	return acxt->cnt;
 }
 
 /**

@@ -396,19 +533,20 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 		      const char *name, struct sysfs_dirent **p_sd)
 {
 	struct dentry *parent = parent_sd->s_dentry;
+	struct sysfs_addrm_cxt acxt;
 	int error;
 	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 	struct dentry *dentry;
 	struct inode *inode;
 	struct sysfs_dirent *sd;
 
-	mutex_lock(&parent->d_inode->i_mutex);
+	sysfs_addrm_start(&acxt, parent_sd);
 
 	/* allocate */
 	dentry = lookup_one_len(name, parent, strlen(name));
 	if (IS_ERR(dentry)) {
 		error = PTR_ERR(dentry);
-		goto out_unlock;
+		goto out_finish;
 	}
 
 	error = -EEXIST;

@@ -433,23 +571,18 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	}
 
 	/* link in */
-	mutex_lock(&sysfs_mutex);
-
 	error = -EEXIST;
-	if (sysfs_find_dirent(parent_sd, name)) {
-		mutex_unlock(&sysfs_mutex);
+	if (sysfs_find_dirent(parent_sd, name))
 		goto out_iput;
-	}
 
+	sysfs_add_one(&acxt, sd);
+	sysfs_link_sibling(sd);
 	sysfs_instantiate(dentry, inode);
-	inc_nlink(parent->d_inode);
-	sysfs_attach_dirent(sd, parent_sd, dentry);
-
-	mutex_unlock(&sysfs_mutex);
+	sysfs_attach_dentry(sd, dentry);
 
 	*p_sd = sd;
 	error = 0;
-	goto out_unlock;	/* pin directory dentry in core */
+	goto out_finish;	/* pin directory dentry in core */
 
  out_iput:
 	iput(inode);

@@ -459,8 +592,8 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	d_drop(dentry);
  out_dput:
 	dput(dentry);
- out_unlock:
-	mutex_unlock(&parent->d_inode->i_mutex);
+ out_finish:
+	sysfs_addrm_finish(&acxt);
 	return error;
 }
 

@@ -561,16 +694,12 @@ const struct inode_operations sysfs_dir_inode_operations = {
 
 static void remove_dir(struct sysfs_dirent *sd)
 {
-	mutex_lock(&sysfs_mutex);
-	sysfs_unlink_sibling(sd);
-	sd->s_flags |= SYSFS_FLAG_REMOVED;
-	mutex_unlock(&sysfs_mutex);
+	struct sysfs_addrm_cxt acxt;
 
-	pr_debug(" o %s removing done\n", sd->s_name);
-
-	sysfs_drop_dentry(sd);
-	sysfs_deactivate(sd);
-	sysfs_put(sd);
+	sysfs_addrm_start(&acxt, sd->s_parent);
+	sysfs_unlink_sibling(sd);
+	sysfs_remove_one(&acxt, sd);
+	sysfs_addrm_finish(&acxt);
 }
 
 void sysfs_remove_subdir(struct sysfs_dirent *sd)

@@ -581,38 +710,26 @@ void sysfs_remove_subdir(struct sysfs_dirent *sd)
 
 static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
 {
-	struct sysfs_dirent *removed = NULL;
+	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent **pos;
 
 	if (!dir_sd)
 		return;
 
 	pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
-	mutex_lock(&sysfs_mutex);
+	sysfs_addrm_start(&acxt, dir_sd);
 	pos = &dir_sd->s_children;
 	while (*pos) {
 		struct sysfs_dirent *sd = *pos;
 
 		if (sysfs_type(sd) && (sysfs_type(sd) & SYSFS_NOT_PINNED)) {
-			sd->s_flags |= SYSFS_FLAG_REMOVED;
 			*pos = sd->s_sibling;
-			sd->s_sibling = removed;
-			removed = sd;
+			sd->s_sibling = NULL;
+			sysfs_remove_one(&acxt, sd);
 		} else
 			pos = &(*pos)->s_sibling;
 	}
-	mutex_unlock(&sysfs_mutex);
-
-	while (removed) {
-		struct sysfs_dirent *sd = removed;
-
-		removed = sd->s_sibling;
-		sd->s_sibling = NULL;
-
-		sysfs_drop_dentry(sd);
-		sysfs_deactivate(sd);
-		sysfs_put(sd);
-	}
+	sysfs_addrm_finish(&acxt);
 
 	remove_dir(dir_sd);
 }

@@ -772,7 +889,8 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
 	sd = sysfs_new_dirent("_DIR_", 0, 0);
 	if (sd) {
 		mutex_lock(&sysfs_mutex);
-		sysfs_attach_dirent(sd, parent_sd, NULL);
+		sd->s_parent = sysfs_get(parent_sd);
+		sysfs_link_sibling(sd);
 		mutex_unlock(&sysfs_mutex);
 	}
 

@@ -957,6 +1075,7 @@ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
 	struct sysfs_dirent *parent_sd = parent->d_fsdata;
 	struct dentry *shadow;
 	struct sysfs_dirent *sd;
+	struct sysfs_addrm_cxt acxt;
 
 	sd = ERR_PTR(-EINVAL);
 	if (!sysfs_is_shadowed_inode(inode))

@@ -970,15 +1089,18 @@ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
 	if (!sd)
 		goto nomem;
 	sd->s_elem.dir.kobj = kobj;
-	/* point to parent_sd but don't attach to it */
-	sd->s_parent = sysfs_get(parent_sd);
-	mutex_lock(&sysfs_mutex);
-	sysfs_attach_dirent(sd, NULL, shadow);
-	mutex_unlock(&sysfs_mutex);
 
+	sysfs_addrm_start(&acxt, parent_sd);
+
+	/* add but don't link into children list */
+	sysfs_add_one(&acxt, sd);
+
+	/* attach and instantiate dentry */
+	sysfs_attach_dentry(sd, shadow);
 	d_instantiate(shadow, igrab(inode));
-	inc_nlink(inode);
-	inc_nlink(parent->d_inode);
+	inc_nlink(inode);	/* tj: synchronization? */
+
+	sysfs_addrm_finish(&acxt);
 
 	dget(shadow);		/* Extra count - pin the dentry in core */
 

index c14e607..ccda618 100644
@@ -416,6 +416,7 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
 		   int type)
 {
 	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
+	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
 
 	sd = sysfs_new_dirent(attr->name, mode, type);

@@ -423,20 +424,18 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
 		return -ENOMEM;
 	sd->s_elem.attr.attr = (void *)attr;
 
-	mutex_lock(&sysfs_mutex);
+	sysfs_addrm_start(&acxt, dir_sd);
 
 	if (!sysfs_find_dirent(dir_sd, attr->name)) {
-		sysfs_attach_dirent(sd, dir_sd, NULL);
-		sd = NULL;
+		sysfs_add_one(&acxt, sd);
+		sysfs_link_sibling(sd);
 	}
 
-	mutex_unlock(&sysfs_mutex);
+	if (sysfs_addrm_finish(&acxt))
+		return 0;
 
-	if (sd) {
-		sysfs_put(sd);
-		return -EEXIST;
-	}
-	return 0;
+	sysfs_put(sd);
+	return -EEXIST;
 }
 
 

95 lines not on this page · raw message

index 683316f..2f86e04 100644
@@ -55,6 +55,7 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 	struct sysfs_dirent *parent_sd = NULL;
 	struct sysfs_dirent *target_sd = NULL;
 	struct sysfs_dirent *sd = NULL;
+	struct sysfs_addrm_cxt acxt;
 	int error;
 
 	BUG_ON(!name);

@@ -87,17 +88,18 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 		goto out_put;
 	sd->s_elem.symlink.target_sd = target_sd;
 
-	mutex_lock(&sysfs_mutex);
-	error = -EEXIST;
-	if (sysfs_find_dirent(parent_sd, name))
-		goto out_unlock;
-	sysfs_attach_dirent(sd, parent_sd, NULL);
-	mutex_unlock(&sysfs_mutex);
+	sysfs_addrm_start(&acxt, parent_sd);
 
-	return 0;
+	if (!sysfs_find_dirent(parent_sd, name)) {
+		sysfs_add_one(&acxt, sd);
+		sysfs_link_sibling(sd);
+	}
 
- out_unlock:
-	mutex_unlock(&sysfs_mutex);
+	if (sysfs_addrm_finish(&acxt))
+		return 0;
+
+	error = -EEXIST;
+	/* fall through */
  out_put:
 	sysfs_put(target_sd);
 	sysfs_put(sd);

index 2605161..3e9a5ee 100644
@@ -44,14 +44,29 @@ struct sysfs_dirent {
 
 #define SD_DEACTIVATED_BIAS	INT_MIN
 
+struct sysfs_addrm_cxt {
+	struct sysfs_dirent	*parent_sd;
+	struct inode		*parent_inode;
+	struct sysfs_dirent	*removed;
+	int			cnt;
+};
+
 extern struct vfsmount * sysfs_mount;
 extern struct kmem_cache *sysfs_dir_cachep;
 
+extern void sysfs_link_sibling(struct sysfs_dirent *sd);
+extern void sysfs_unlink_sibling(struct sysfs_dirent *sd);
 extern struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
 extern void sysfs_put_active(struct sysfs_dirent *sd);
 extern struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
 extern void sysfs_put_active_two(struct sysfs_dirent *sd);
-extern void sysfs_deactivate(struct sysfs_dirent *sd);
+extern void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
+			      struct sysfs_dirent *parent_sd);
+extern void sysfs_add_one(struct sysfs_addrm_cxt *acxt,
+			  struct sysfs_dirent *sd);
+extern void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
+			     struct sysfs_dirent *sd);
+extern int sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 
 extern void sysfs_delete_inode(struct inode *inode);
 extern void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode);

@@ -65,9 +80,6 @@ extern struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
 					     const unsigned char *name);
 extern struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode,
 					     int type);
-extern void sysfs_attach_dirent(struct sysfs_dirent *sd,
-				struct sysfs_dirent *parent_sd,
-				struct dentry *dentry);
 
 extern int sysfs_add_file(struct sysfs_dirent *dir_sd,
 			  const struct attribute *attr, int type);

index 3c5574a..55796bd 100644
@@ -234,9 +234,9 @@ const struct file_operations bin_fops = {
 
 int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 {
-	BUG_ON(!kobj || !kobj->dentry || !attr);
+	BUG_ON(!kobj || !kobj->sd || !attr);
 
-	return sysfs_add_file(kobj->dentry, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
+	return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
 }
 
 

@@ -248,7 +248,7 @@ int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 
 void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 {
-	if (sysfs_hash_and_remove(kobj->dentry, attr->attr.name) < 0) {
+	if (sysfs_hash_and_remove(kobj->sd, attr->attr.name) < 0) {
 		printk(KERN_ERR "%s: "
 			"bad dentry or inode or no such file: \"%s\"\n",
 			__FUNCTION__, attr->attr.name);

294 lines not on this page · raw message

112 lines not on this page · raw message

96 lines not on this page · raw message

index e2f6ef1..1be8537 100644
@@ -275,22 +275,23 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 	}
 }
 
-int sysfs_hash_and_remove(struct dentry * dir, const char * name)
+int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
 {
+	struct dentry *dir;
 	struct sysfs_dirent **pos, *sd;
-	struct sysfs_dirent *parent_sd;
 	int found = 0;
 
-	if (!dir)
+	if (!dir_sd)
 		return -ENOENT;
 
+	dir = dir_sd->s_dentry;
+
 	if (dir->d_inode == NULL)
 		/* no inode means this hasn't been made visible yet */
 		return -ENOENT;
 
-	parent_sd = dir->d_fsdata;
 	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
-	for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
+	for (pos = &dir_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
 		sd = *pos;
 
 		if (!sysfs_type(sd))

index 45b62e2..43cc522 100644
@@ -66,7 +66,6 @@ static int sysfs_add_link(struct sysfs_dirent * parent_sd, const char * name,
  */
 int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name)
 {
-	struct dentry *dentry = NULL;
 	struct sysfs_dirent *parent_sd = NULL;
 	struct sysfs_dirent *target_sd = NULL;
 	int error = -EEXIST;

@@ -75,29 +74,28 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 
 	if (!kobj) {
 		if (sysfs_mount && sysfs_mount->mnt_sb)
-			dentry = sysfs_mount->mnt_sb->s_root;
+			parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata;
 	} else
-		dentry = kobj->dentry;
+		parent_sd = kobj->sd;
 
-	if (!dentry)
+	if (!parent_sd)
 		return -EFAULT;
-	parent_sd = dentry->d_fsdata;
 
-	/* target->dentry can go away beneath us but is protected with
+	/* target->sd can go away beneath us but is protected with
 	 * kobj_sysfs_assoc_lock.  Fetch target_sd from it.
 	 */
 	spin_lock(&kobj_sysfs_assoc_lock);
-	if (target->dentry)
-		target_sd = sysfs_get(target->dentry->d_fsdata);
+	if (target->sd)
+		target_sd = sysfs_get(target->sd);
 	spin_unlock(&kobj_sysfs_assoc_lock);
 
 	if (!target_sd)
 		return -ENOENT;
 
-	mutex_lock(&dentry->d_inode->i_mutex);
-	if (!sysfs_find_dirent(dentry->d_fsdata, name))
+	mutex_lock(&parent_sd->s_dentry->d_inode->i_mutex);
+	if (!sysfs_find_dirent(parent_sd, name))
 		error = sysfs_add_link(parent_sd, name, target_sd);
-	mutex_unlock(&dentry->d_inode->i_mutex);
+	mutex_unlock(&parent_sd->s_dentry->d_inode->i_mutex);
 
 	if (error)
 		sysfs_put(target_sd);

@@ -114,7 +112,7 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 
 void sysfs_remove_link(struct kobject * kobj, const char * name)
 {
-	sysfs_hash_and_remove(kobj->dentry,name);
+	sysfs_hash_and_remove(kobj->sd, name);
 }
 
 static int sysfs_get_target_path(struct sysfs_dirent * parent_sd,

index f1629b4..27a5f4b 100644
@@ -69,12 +69,14 @@ extern void sysfs_attach_dirent(struct sysfs_dirent *sd,
 				struct sysfs_dirent *parent_sd,
 				struct dentry *dentry);
 
-extern int sysfs_add_file(struct dentry *, const struct attribute *, int);
-extern int sysfs_hash_and_remove(struct dentry * dir, const char * name);
+extern int sysfs_add_file(struct sysfs_dirent *dir_sd,
+			  const struct attribute *attr, int type);
+extern int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
 extern struct sysfs_dirent *sysfs_find(struct sysfs_dirent *dir, const char * name);
 
-extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **);
-extern void sysfs_remove_subdir(struct dentry *);
+extern int sysfs_create_subdir(struct kobject *kobj, const char *name,
+			       struct sysfs_dirent **p_sd);
+extern void sysfs_remove_subdir(struct sysfs_dirent *sd);
 
 extern void sysfs_drop_dentry(struct sysfs_dirent *sd);
 extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);

index c288e41..06cbf41 100644
@@ -55,7 +55,7 @@ struct kobject {
 	struct kobject		* parent;
 	struct kset		* kset;
 	struct kobj_type	* ktype;
-	struct dentry		* dentry;
+	struct sysfs_dirent	* sd;
 	wait_queue_head_t	poll;
 };
 

@@ -71,13 +71,14 @@ extern void kobject_init(struct kobject *);
 extern void kobject_cleanup(struct kobject *);
 
 extern int __must_check kobject_add(struct kobject *);
-extern int __must_check kobject_shadow_add(struct kobject *, struct dentry *);
+extern int __must_check kobject_shadow_add(struct kobject *kobj,
+					   struct sysfs_dirent *shadow_parent);
 extern void kobject_del(struct kobject *);
 
 extern int __must_check kobject_rename(struct kobject *, const char *new_name);
 extern int __must_check kobject_shadow_rename(struct kobject *kobj,
-						struct dentry *new_parent,
-						const char *new_name);
+					      struct sysfs_dirent *new_parent,
+					      const char *new_name);
 extern int __must_check kobject_move(struct kobject *, struct kobject *);
 
 extern int __must_check kobject_register(struct kobject *);

index 2a6df64..4c43030 100644
@@ -19,6 +19,7 @@ struct kobject;
 struct module;
 struct nameidata;
 struct dentry;
+struct sysfs_dirent;
 
 /* FIXME
  * The *owner field is no longer used, but leave around

@@ -92,13 +93,14 @@ extern int sysfs_schedule_callback(struct kobject *kobj,
 		void (*func)(void *), void *data, struct module *owner);
 
 extern int __must_check
-sysfs_create_dir(struct kobject *, struct dentry *);
+sysfs_create_dir(struct kobject *kobj, struct sysfs_dirent *shadow_parent_sd);
 
 extern void
 sysfs_remove_dir(struct kobject *);
 
 extern int __must_check
-sysfs_rename_dir(struct kobject *, struct dentry *, const char *new_name);
+sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
+		 const char *new_name);
 
 extern int __must_check
 sysfs_move_dir(struct kobject *, struct kobject *);

@@ -138,8 +140,8 @@ void sysfs_notify(struct kobject * k, char *dir, char *attr);
 
 extern int sysfs_make_shadowed_dir(struct kobject *kobj,
 	void * (*follow_link)(struct dentry *, struct nameidata *));
-extern struct dentry *sysfs_create_shadow_dir(struct kobject *kobj);
-extern void sysfs_remove_shadow_dir(struct dentry *dir);
+extern struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj);
+extern void sysfs_remove_shadow_dir(struct sysfs_dirent *shadow_sd);
 
 extern int __must_check sysfs_init(void);
 

@@ -151,7 +153,8 @@ static inline int sysfs_schedule_callback(struct kobject *kobj,
 	return -ENOSYS;
 }
 
-static inline int sysfs_create_dir(struct kobject * k, struct dentry *shadow)
+static inline int sysfs_create_dir(struct kobject *kobj,
+				   struct sysfs_dirent *shadow_parent_sd)
 {
 	return 0;
 }

@@ -161,9 +164,9 @@ static inline void sysfs_remove_dir(struct kobject * k)
 	;
 }
 
-static inline int sysfs_rename_dir(struct kobject * k,
-					struct dentry *new_parent,
-					const char *new_name)
+static inline int sysfs_rename_dir(struct kobject *kobj,
+				   struct sysfs_dirent *new_parent_sd,
+				   const char *new_name)
 {
 	return 0;
 }

index ac15206..dc2bfbb 100644
@@ -44,7 +44,7 @@ static int populate_dir(struct kobject * kobj)
 	return error;
 }
 
-static int create_dir(struct kobject * kobj, struct dentry *shadow_parent)
+static int create_dir(struct kobject * kobj, struct sysfs_dirent *shadow_parent)
 {
 	int error = 0;
 	if (kobject_name(kobj)) {

@@ -162,7 +162,7 @@ static void unlink(struct kobject * kobj)
  *	@shadow_parent: sysfs directory to add to.
  */
 
-int kobject_shadow_add(struct kobject * kobj, struct dentry *shadow_parent)
+int kobject_shadow_add(struct kobject *kobj, struct sysfs_dirent *shadow_parent)
 {
 	int error = 0;
 	struct kobject * parent;

@@ -338,7 +338,7 @@ int kobject_rename(struct kobject * kobj, const char *new_name)
 	/* Note : if we want to send the new name alone, not the full path,
 	 * we could probably use kobject_name(kobj); */
 
-	error = sysfs_rename_dir(kobj, kobj->parent->dentry, new_name);
+	error = sysfs_rename_dir(kobj, kobj->parent->sd, new_name);
 
 	/* This function is mostly/only used for network interface.
 	 * Some hotplug package track interfaces by their name and

@@ -361,8 +361,8 @@ out:
  *	@new_name: object's new name
  */
 
-int kobject_shadow_rename(struct kobject * kobj, struct dentry *new_parent,
-			  const char *new_name)
+int kobject_shadow_rename(struct kobject * kobj,
+			  struct sysfs_dirent *new_parent, const char *new_name)
 {
 	int error = 0;
 

index dce74ef..c141391 100644
@@ -435,6 +435,62 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
 }
 
 /**
+ *	sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
+ *	@sd: target sysfs_dirent
+ *
+ *	Drop dentry for @sd.  @sd must have been unlinked from its
+ *	parent on entry to this function such that it can't be looked
+ *	up anymore.
+ *
+ *	@sd->s_dentry which is protected with sysfs_assoc_lock points
+ *	to the currently associated dentry but we're not holding a
+ *	reference to it and racing with dput().  Grab dcache_lock and
+ *	verify dentry before dropping it.  If @sd->s_dentry is NULL or
+ *	dput() beats us, no need to bother.
+ */
+static void sysfs_drop_dentry(struct sysfs_dirent *sd)
+{
+	struct dentry *dentry = NULL;
+	struct inode *inode;
+
+	/* We're not holding a reference to ->s_dentry dentry but the
+	 * field will stay valid as long as sysfs_assoc_lock is held.
+	 */
+	spin_lock(&sysfs_assoc_lock);
+	spin_lock(&dcache_lock);
+
+	/* drop dentry if it's there and dput() didn't kill it yet */
+	if (sd->s_dentry && sd->s_dentry->d_inode) {
+		dentry = dget_locked(sd->s_dentry);
+		spin_lock(&dentry->d_lock);
+		__d_drop(dentry);
+		spin_unlock(&dentry->d_lock);
+	}
+
+	spin_unlock(&dcache_lock);
+	spin_unlock(&sysfs_assoc_lock);
+
+	dput(dentry);
+	/* XXX: unpin if directory, this will go away soon */
+	if (sysfs_type(sd) == SYSFS_DIR)
+		dput(dentry);
+
+	/* adjust nlink and update timestamp */
+	inode = ilookup(sysfs_sb, sd->s_ino);
+	if (inode) {
+		mutex_lock(&inode->i_mutex);
+
+		inode->i_ctime = CURRENT_TIME;
+		drop_nlink(inode);
+		if (sysfs_type(sd) == SYSFS_DIR)
+			drop_nlink(inode);
+
+		mutex_unlock(&inode->i_mutex);
+		iput(inode);
+	}
+}
+
+/**
  *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
  *	@acxt: addrm context to finish up
  *

62 lines not on this page · raw message

index 3e9a5ee..92fe1e5 100644
@@ -90,7 +90,6 @@ extern int sysfs_create_subdir(struct kobject *kobj, const char *name,
 			       struct sysfs_dirent **p_sd);
 extern void sysfs_remove_subdir(struct sysfs_dirent *sd);
 
-extern void sysfs_drop_dentry(struct sysfs_dirent *sd);
 extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
 
 extern spinlock_t sysfs_assoc_lock;

index c141391..0cd91ba 100644
@@ -63,6 +63,104 @@ void sysfs_unlink_sibling(struct sysfs_dirent *sd)
 }
 
 /**
+ *	sysfs_get_dentry - get dentry for the given sysfs_dirent
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Get dentry for @sd.  Dentry is looked up if currently not
+ *	present.  This function climbs sysfs_dirent tree till it
+ *	reaches a sysfs_dirent with valid dentry attached and descends
+ *	down from there looking up dentry for each step.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	Pointer to found dentry on success, ERR_PTR() value on error.
+ */
+struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *cur;
+	struct dentry *parent_dentry, *dentry;
+	int i, depth;
+
+	/* Find the first parent which has valid s_dentry and get the
+	 * dentry.
+	 */
+	mutex_lock(&sysfs_mutex);
+ restart0:
+	spin_lock(&sysfs_assoc_lock);
+ restart1:
+	spin_lock(&dcache_lock);
+
+	dentry = NULL;
+	depth = 0;
+	cur = sd;
+	while (!cur->s_dentry || !cur->s_dentry->d_inode) {
+		if (cur->s_flags & SYSFS_FLAG_REMOVED) {
+			dentry = ERR_PTR(-ENOENT);
+			depth = 0;
+			break;
+		}
+		cur = cur->s_parent;
+		depth++;
+	}
+	if (!IS_ERR(dentry))
+		dentry = dget_locked(cur->s_dentry);
+
+	spin_unlock(&dcache_lock);
+	spin_unlock(&sysfs_assoc_lock);
+
+	/* from the found dentry, look up depth times */
+	while (depth--) {
+		/* find and get depth'th ancestor */
+		for (cur = sd, i = 0; cur && i < depth; i++)
+			cur = cur->s_parent;
+
+		/* This can happen if tree structure was modified due
+		 * to move/rename.  Restart.
+		 */
+		if (i != depth) {
+			dput(dentry);
+			goto restart0;
+		}
+
+		sysfs_get(cur);
+
+		mutex_unlock(&sysfs_mutex);
+
+		/* look it up */
+		parent_dentry = dentry;
+		dentry = lookup_one_len_kern(cur->s_name, parent_dentry,
+					     strlen(cur->s_name));
+		dput(parent_dentry);
+
+		if (IS_ERR(dentry)) {
+			sysfs_put(cur);
+			return dentry;
+		}
+
+		mutex_lock(&sysfs_mutex);
+		spin_lock(&sysfs_assoc_lock);
+
+		/* This, again, can happen if tree structure has
+		 * changed and we looked up the wrong thing.  Restart.
+		 */
+		if (cur->s_dentry != dentry) {
+			dput(dentry);
+			sysfs_put(cur);
+			goto restart1;
+		}
+
+		spin_unlock(&sysfs_assoc_lock);
+
+		sysfs_put(cur);
+	}
+
+	mutex_unlock(&sysfs_mutex);
+	return dentry;
+}
+
+/**
  *	sysfs_get_active - get an active reference to sysfs_dirent
  *	@sd: sysfs_dirent to get an active reference to
  *

index 92fe1e5..72530dc 100644
@@ -54,6 +54,7 @@ struct sysfs_addrm_cxt {
 extern struct vfsmount * sysfs_mount;
 extern struct kmem_cache *sysfs_dir_cachep;
 
+extern struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
 extern void sysfs_link_sibling(struct sysfs_dirent *sd);
 extern void sysfs_unlink_sibling(struct sysfs_dirent *sd);
 extern struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);

index 0cd91ba..9d30fa9 100644
@@ -568,10 +568,10 @@ static void sysfs_drop_dentry(struct sysfs_dirent *sd)
 	spin_unlock(&dcache_lock);
 	spin_unlock(&sysfs_assoc_lock);
 
-	dput(dentry);
-	/* XXX: unpin if directory, this will go away soon */
-	if (sysfs_type(sd) == SYSFS_DIR)
+	/* dentries for shadowed inodes are pinned, unpin */
+	if (dentry && sysfs_is_shadowed_inode(dentry->d_inode))
 		dput(dentry);
+	dput(dentry);
 
 	/* adjust nlink and update timestamp */
 	inode = ilookup(sysfs_sb, sd->s_ino);

@@ -686,69 +686,29 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 		      const char *name, struct sysfs_dirent **p_sd)
 {
-	struct dentry *parent = parent_sd->s_dentry;
-	struct sysfs_addrm_cxt acxt;
-	int error;
 	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
-	struct dentry *dentry;
-	struct inode *inode;
+	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
 
-	sysfs_addrm_start(&acxt, parent_sd);
-
 	/* allocate */
-	dentry = lookup_one_len(name, parent, strlen(name));
-	if (IS_ERR(dentry)) {
-		error = PTR_ERR(dentry);
-		goto out_finish;
-	}
-
-	error = -EEXIST;
-	if (dentry->d_inode)
-		goto out_dput;
-
-	error = -ENOMEM;
 	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
 	if (!sd)
-		goto out_drop;
+		return -ENOMEM;
 	sd->s_elem.dir.kobj = kobj;
 
-	inode = sysfs_get_inode(sd);
-	if (!inode)
-		goto out_sput;
-
-	if (inode->i_state & I_NEW) {
-		inode->i_op = &sysfs_dir_inode_operations;
-		inode->i_fop = &sysfs_dir_operations;
-		/* directory inodes start off with i_nlink == 2 (for ".") */
-		inc_nlink(inode);
-	}
-
 	/* link in */
-	error = -EEXIST;
-	if (sysfs_find_dirent(parent_sd, name))
-		goto out_iput;
-
-	sysfs_add_one(&acxt, sd);
-	sysfs_link_sibling(sd);
-	sysfs_instantiate(dentry, inode);
-	sysfs_attach_dentry(sd, dentry);
-
-	*p_sd = sd;
-	error = 0;
-	goto out_finish;	/* pin directory dentry in core */
+	sysfs_addrm_start(&acxt, parent_sd);
+	if (!sysfs_find_dirent(parent_sd, name)) {
+		sysfs_add_one(&acxt, sd);
+		sysfs_link_sibling(sd);
+	}
+	if (sysfs_addrm_finish(&acxt)) {
+		*p_sd = sd;
+		return 0;
+	}
 
- out_iput:
-	iput(inode);
- out_sput:
 	sysfs_put(sd);
- out_drop:
-	d_drop(dentry);
- out_dput:
-	dput(dentry);
- out_finish:
-	sysfs_addrm_finish(&acxt);
-	return error;
+	return -EEXIST;
 }
 
 int sysfs_create_subdir(struct kobject *kobj, const char *name,

@@ -785,6 +745,17 @@ int sysfs_create_dir(struct kobject * kobj,
 	return error;
 }
 
+static int sysfs_count_nlink(struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *child;
+	int nr = 0;
+
+	for (child = sd->s_children; child; child = child->s_sibling)
+		if (sysfs_type(child) == SYSFS_DIR)
+			nr++;
+	return nr + 2;
+}
+
 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 				struct nameidata *nd)
 {

@@ -795,7 +766,7 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	int found = 0;
 
 	for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
-		if ((sysfs_type(sd) & SYSFS_NOT_PINNED) &&
+		if (sysfs_type(sd) &&
 		    !strcmp(sd->s_name, dentry->d_name.name)) {
 			found = 1;
 			break;

@@ -816,6 +787,11 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	if (inode->i_state & I_NEW) {
 		/* initialize inode according to type */
 		switch (sysfs_type(sd)) {
+		case SYSFS_DIR:
+			inode->i_op = &sysfs_dir_inode_operations;
+			inode->i_fop = &sysfs_dir_operations;
+			inode->i_nlink = sysfs_count_nlink(sd);
+			break;
 		case SYSFS_KOBJ_ATTR:
 			inode->i_size = PAGE_SIZE;
 			inode->i_fop = &sysfs_file_operations;

@@ -876,7 +852,7 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
 	while (*pos) {
 		struct sysfs_dirent *sd = *pos;
 
-		if (sysfs_type(sd) && (sysfs_type(sd) & SYSFS_NOT_PINNED)) {
+		if (sysfs_type(sd) && sysfs_type(sd) != SYSFS_DIR) {
 			*pos = sd->s_sibling;
 			sd->s_sibling = NULL;
 			sysfs_remove_one(&acxt, sd);

@@ -912,14 +888,25 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
 		     const char *new_name)
 {
 	struct sysfs_dirent *sd = kobj->sd;
-	struct dentry *new_parent = new_parent_sd->s_dentry;
-	struct dentry *new_dentry;
-	char *dup_name;
+	struct dentry *new_parent = NULL;
+	struct dentry *old_dentry = NULL, *new_dentry = NULL;
+	const char *dup_name = NULL;
 	int error;
 
-	if (!new_parent_sd)
-		return -EFAULT;
+	/* get dentries */
+	old_dentry = sysfs_get_dentry(sd);
+	if (IS_ERR(old_dentry)) {
+		error = PTR_ERR(old_dentry);
+		goto out_dput;
+	}
+
+	new_parent = sysfs_get_dentry(new_parent_sd);
+	if (IS_ERR(new_parent)) {
+		error = PTR_ERR(new_parent);
+		goto out_dput;
+	}
 
+	/* lock new_parent and get dentry for new name */
 	mutex_lock(&new_parent->d_inode->i_mutex);
 
 	new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));

@@ -933,14 +920,14 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
 	 * shadows of the same directory
 	 */
 	error = -EINVAL;
-	if (sd->s_parent->s_dentry->d_inode != new_parent->d_inode ||
+	if (old_dentry->d_parent->d_inode != new_parent->d_inode ||
 	    new_dentry->d_parent->d_inode != new_parent->d_inode ||
-	    new_dentry == sd->s_dentry)
-		goto out_dput;
+	    old_dentry == new_dentry)
+		goto out_unlock;
 
 	error = -EEXIST;
 	if (new_dentry->d_inode)
-		goto out_dput;
+		goto out_unlock;
 
 	/* rename kobject and sysfs_dirent */
 	error = -ENOMEM;

@@ -950,9 +937,9 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
 
 	error = kobject_set_name(kobj, "%s", new_name);
 	if (error)
-		goto out_free;
+		goto out_drop;
 
-	kfree(sd->s_name);
+	dup_name = sd->s_name;
 	sd->s_name = new_name;
 
 	/* move under the new parent */

@@ -972,45 +959,58 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
 	error = 0;
 	goto out_unlock;
 
- out_free:
-	kfree(dup_name);
  out_drop:
 	d_drop(new_dentry);
- out_dput:
-	dput(new_dentry);
  out_unlock:
 	mutex_unlock(&new_parent->d_inode->i_mutex);
+ out_dput:
+	kfree(dup_name);
+	dput(new_parent);
+	dput(old_dentry);
+	dput(new_dentry);
 	return error;
 }
 
-int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
+int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 {
-	struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
-	struct sysfs_dirent *new_parent_sd, *sd;
+	struct sysfs_dirent *sd = kobj->sd;
+	struct sysfs_dirent *new_parent_sd;
+	struct dentry *old_parent, *new_parent = NULL;
+	struct dentry *old_dentry = NULL, *new_dentry = NULL;
 	int error;
 
-	old_parent_dentry = kobj->parent ?
-		kobj->parent->sd->s_dentry : sysfs_mount->mnt_sb->s_root;
-	new_parent_dentry = new_parent ?
-		new_parent->sd->s_dentry : sysfs_mount->mnt_sb->s_root;
+	BUG_ON(!sd->s_parent);
+	new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
+
+	/* get dentries */
+	old_dentry = sysfs_get_dentry(sd);
+	if (IS_ERR(old_dentry)) {
+		error = PTR_ERR(old_dentry);
+		goto out_dput;
+	}
+	old_parent = sd->s_parent->s_dentry;
+
+	new_parent = sysfs_get_dentry(new_parent_sd);
+	if (IS_ERR(new_parent)) {
+		error = PTR_ERR(new_parent);
+		goto out_dput;
+	}
 
-	if (old_parent_dentry->d_inode == new_parent_dentry->d_inode)
-		return 0;	/* nothing to move */
+	if (old_parent->d_inode == new_parent->d_inode) {
+		error = 0;
+		goto out_dput;	/* nothing to move */
+	}
 again:
-	mutex_lock(&old_parent_dentry->d_inode->i_mutex);
-	if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
-		mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+	mutex_lock(&old_parent->d_inode->i_mutex);
+	if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
+		mutex_unlock(&old_parent->d_inode->i_mutex);
 		goto again;
 	}
 
-	new_parent_sd = new_parent_dentry->d_fsdata;
-	sd = kobj->sd;
-
-	new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
-				    strlen(kobj->name));
+	new_dentry = lookup_one_len(kobj->name, new_parent, strlen(kobj->name));
 	if (IS_ERR(new_dentry)) {
 		error = PTR_ERR(new_dentry);
-		goto out;
+		goto out_unlock;
 	} else
 		error = 0;
 	d_add(new_dentry, NULL);

@@ -1027,10 +1027,14 @@ again:
 	sysfs_link_sibling(sd);
 
 	mutex_unlock(&sysfs_mutex);
-out:
-	mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
-	mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
 
+ out_unlock:
+	mutex_unlock(&new_parent->d_inode->i_mutex);
+	mutex_unlock(&old_parent->d_inode->i_mutex);
+ out_dput:
+	dput(new_parent);
+	dput(old_dentry);
+	dput(new_dentry);
 	return error;
 }
 

@@ -1191,12 +1195,20 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 int sysfs_make_shadowed_dir(struct kobject *kobj,
 	void * (*follow_link)(struct dentry *, struct nameidata *))
 {
+	struct dentry *dentry;
 	struct inode *inode;
 	struct inode_operations *i_op;
 
-	inode = kobj->sd->s_dentry->d_inode;
-	if (inode->i_op != &sysfs_dir_inode_operations)
+	/* get dentry for @kobj->sd, dentry of a shadowed dir is pinned */
+	dentry = sysfs_get_dentry(kobj->sd);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	inode = dentry->d_inode;
+	if (inode->i_op != &sysfs_dir_inode_operations) {
+		dput(dentry);
 		return -EINVAL;
+	}
 
 	i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
 	if (!i_op)

@@ -1223,17 +1235,23 @@ int sysfs_make_shadowed_dir(struct kobject *kobj,
 
 struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
 {
-	struct dentry *dir = kobj->sd->s_dentry;
-	struct inode *inode = dir->d_inode;
-	struct dentry *parent = dir->d_parent;
-	struct sysfs_dirent *parent_sd = parent->d_fsdata;
-	struct dentry *shadow;
+	struct sysfs_dirent *parent_sd = kobj->sd->s_parent;
+	struct dentry *dir, *parent, *shadow;
+	struct inode *inode;
 	struct sysfs_dirent *sd;
 	struct sysfs_addrm_cxt acxt;
 
+	dir = sysfs_get_dentry(kobj->sd);
+	if (IS_ERR(dir)) {
+		sd = (void *)dir;
+		goto out;
+	}
+	parent = dir->d_parent;
+
+	inode = dir->d_inode;
 	sd = ERR_PTR(-EINVAL);
 	if (!sysfs_is_shadowed_inode(inode))
-		goto out;
+		goto out_dput;
 
 	shadow = d_alloc(parent, &dir->d_name);
 	if (!shadow)

@@ -1258,12 +1276,15 @@ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
 
 	dget(shadow);		/* Extra count - pin the dentry in core */
 
-out:
-	return sd;
-nomem:
+	goto out_dput;
+
+ nomem:
 	dput(shadow);
 	sd = ERR_PTR(-ENOMEM);
-	goto out;
+ out_dput:
+	dput(dir);
+ out:
+	return sd;
 }
 
 /**

162 lines not on this page · raw message

index 078537e..402cc35 100644
@@ -24,7 +24,7 @@ static const struct super_operations sysfs_ops = {
 	.drop_inode	= sysfs_delete_inode,
 };
 
-static struct sysfs_dirent sysfs_root = {
+struct sysfs_dirent sysfs_root = {
 	.s_count	= ATOMIC_INIT(1),
 	.s_flags	= SYSFS_ROOT,
 	.s_mode		= S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,

index 72530dc..6a37f23 100644
@@ -52,6 +52,7 @@ struct sysfs_addrm_cxt {
 };
 
 extern struct vfsmount * sysfs_mount;
+extern struct sysfs_dirent sysfs_root;
 extern struct kmem_cache *sysfs_dir_cachep;
 
 extern struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);

index 4c43030..2f58ca1 100644
@@ -81,7 +81,6 @@ struct sysfs_ops {
 #define SYSFS_KOBJ_ATTR 	0x0004
 #define SYSFS_KOBJ_BIN_ATTR	0x0008
 #define SYSFS_KOBJ_LINK 	0x0020
-#define SYSFS_NOT_PINNED	(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
 #define SYSFS_COPY_NAME		(SYSFS_DIR | SYSFS_KOBJ_LINK)
 
 #define SYSFS_FLAG_MASK		~SYSFS_TYPE_MASK