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Message-ID: <e015bca83e848f5f6f2226623.ps@mail.parknet.co.jp>
Date: Wed, 15 Oct 2008 22:58:10 +0900
From: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To: viro@...iv.linux.org.uk
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
hirofumi@...l.parknet.co.jp
Subject: [PATCH 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. But
I'm not checking callers for now, so this keeps current behavior.
Signed-off-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
---
fs/dcache.c | 28 ++++++++++------------------
fs/namei.c | 22 ++++++++++------------
include/linux/dcache.h | 1 +
3 files changed, 21 insertions(+), 30 deletions(-)
diff -puN fs/dcache.c~dcache-cleanup-2 fs/dcache.c
--- linux-2.6/fs/dcache.c~dcache-cleanup-2 2008-10-13 02:26:23.000000000 +0900
+++ linux-2.6-hirofumi/fs/dcache.c 2008-10-13 02:26:55.000000000 +0900
@@ -1719,17 +1719,18 @@ void d_move(struct dentry * dentry, stru
}
/*
- * Helper that returns 1 if p1 is a parent of p2, else 0
+ * Helper that 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;
}
/*
@@ -1753,7 +1754,7 @@ static struct dentry *__d_unalias(struct
/* Check for loops */
ret = ERR_PTR(-ELOOP);
- if (d_isparent(alias, dentry))
+ if (d_ancestor(alias, dentry))
goto out_err;
/* See lock_rename() */
@@ -2156,28 +2157,19 @@ out:
int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry)
{
int result;
- struct dentry * saved = new_dentry;
unsigned long seq;
+ 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;
- }
- result = 1;
- break;
- }
+ result = (d_ancestor(old_dentry, new_dentry) != NULL);
} while (read_seqretry(&rename_lock, seq));
rcu_read_unlock();
diff -puN include/linux/dcache.h~dcache-cleanup-2 include/linux/dcache.h
--- linux-2.6/include/linux/dcache.h~dcache-cleanup-2 2008-10-13 02:26:23.000000000 +0900
+++ linux-2.6-hirofumi/include/linux/dcache.h 2008-10-13 02:26:23.000000000 +0900
@@ -287,6 +287,7 @@ static inline struct dentry *d_add_uniqu
/* 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 *);
diff -puN fs/namei.c~dcache-cleanup-2 fs/namei.c
--- linux-2.6/fs/namei.c~dcache-cleanup-2 2008-10-13 02:26:23.000000000 +0900
+++ linux-2.6-hirofumi/fs/namei.c 2008-10-13 02:26:23.000000000 +0900
@@ -1470,20 +1470,18 @@ struct dentry *lock_rename(struct dentry
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);
_
--
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