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

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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: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
This commit is contained in:
OGAWA Hirofumi 2008-10-16 07:50:28 +09:00 committed by Al Viro
parent 871c0067d5
commit e2761a1167
3 changed files with 34 additions and 34 deletions
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45
fs/dcache.c
View File

@ -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() */
@ -2155,31 +2160,27 @@ out:
* Caller must ensure that "new_dentry" is pinned before calling is_subdir()
*/
int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry)
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 {
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();

22
fs/namei.c
View File

@ -1454,20 +1454,18 @@ 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) {
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
return p;
}
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) {
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
return p;
}
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);

1
include/linux/dcache.h
View File

@ -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 *);