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Commit e2761a11 authored by OGAWA Hirofumi's avatar OGAWA Hirofumi Committed by Al Viro
Browse files

[PATCH vfs-2.6 2/6] vfs: add d_ancestor() 



This adds d_ancestor() instead of d_isparent(), then use it.

If new_dentry == old_dentry, is_subdir() returns 1, looks strange.
"new_dentry == old_dentry" is not subdir obviously. But I'm not
checking callers for now, so this keeps current behavior.

Signed-off-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
parent 871c0067

fs/dcache.c

+23 −22
Original line number Diff line number Diff line
@@ -1720,18 +1720,23 @@ void d_move(struct dentry * dentry, struct dentry * target) 
	spin_unlock(&dcache_lock);

}



/*

 * Helper that returns 1 if p1 is a parent of p2, else 0

/**

 * d_ancestor - search for an ancestor

 * @p1: ancestor dentry

 * @p2: child dentry

 *

 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is

 * an ancestor of p2, else NULL.

 */

static int d_isparent(struct dentry *p1, struct dentry *p2)

struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)

{

	struct dentry *p;



	for (p = p2; !IS_ROOT(p); p = p->d_parent) {

		if (p->d_parent == p1)

			return 1;

			return p;

	}

	return 0;

	return NULL;

}



/*
@@ -1755,7 +1760,7 @@ static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) 


	/* Check for loops */

	ret = ERR_PTR(-ELOOP);

	if (d_isparent(alias, dentry))

	if (d_ancestor(alias, dentry))

		goto out_err;



	/* See lock_rename() */
@@ -2158,28 +2163,24 @@ asmlinkage long sys_getcwd(char __user *buf, unsigned long size) 
int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)

{

	int result;

	struct dentry * saved = new_dentry;

	unsigned long seq;



	/* need rcu_readlock to protect against the d_parent trashing due to

	 * d_move

	/* FIXME: This is old behavior, needed? Please check callers. */

	if (new_dentry == old_dentry)

		return 1;



	/*

	 * Need rcu_readlock to protect against the d_parent trashing

	 * due to d_move

	 */

	rcu_read_lock();

	do {

		/* for restarting inner loop in case of seq retry */

		new_dentry = saved;

		result = 0;

		seq = read_seqbegin(&rename_lock);

		for (;;) {

			if (new_dentry != old_dentry) {

				if (IS_ROOT(new_dentry))

					break;

				new_dentry = new_dentry->d_parent;

				continue;

			}

		if (d_ancestor(old_dentry, new_dentry))

			result = 1;

			break;

		}

		else

			result = 0;

	} while (read_seqretry(&rename_lock, seq));

	rcu_read_unlock();

fs/namei.c

+10 −12
Original line number Diff line number Diff line
@@ -1454,21 +1454,19 @@ struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 


	mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);



	for (p = p1; !IS_ROOT(p); p = p->d_parent) {

		if (p->d_parent == p2) {

	p = d_ancestor(p2, p1);

	if (p) {

		mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);

		mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);

		return p;

	}

	}



	for (p = p2; !IS_ROOT(p); p = p->d_parent) {

		if (p->d_parent == p1) {

	p = d_ancestor(p1, p2);

	if (p) {

		mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);

		mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);

		return p;

	}

	}



	mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);

	mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);

include/linux/dcache.h

+1 −0
Original line number Diff line number Diff line
@@ -287,6 +287,7 @@ static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *in 


/* used for rename() and baskets */

extern void d_move(struct dentry *, struct dentry *);

extern struct dentry *d_ancestor(struct dentry *, struct dentry *);



/* appendix may either be NULL or be used for transname suffixes */

extern struct dentry * d_lookup(struct dentry *, struct qstr *);