[PATCH 5/13] autofs4 - simplify expire tree traversal

From: Ian Kent
Date: Wed Jan 18 2006 - 02:26:04 EST


This patch simplifies the expire tree traversal code by using a
function from namespace.c to calculate the next entry in the top
down tree traversals carried out during the expire operation.

Signed-off-by: Ian Kent <raven@xxxxxxxxxx>


--- linux-2.6.15-mm2/fs/autofs4/expire.c.expire-traversal-cleanup 2006-01-12 15:11:55.000000000 +0800
+++ linux-2.6.15-mm2/fs/autofs4/expire.c 2006-01-12 15:14:27.000000000 +0800
@@ -72,6 +72,27 @@ done:
return status;
}

+/*
+ * Calculate next entry in top down tree traversal.
+ * From next_mnt in namespace.c - elegant.
+ */
+static struct dentry *next_dentry(struct dentry *p, struct dentry *root)
+{
+ struct list_head *next = p->d_subdirs.next;
+
+ if (next == &p->d_subdirs) {
+ while (1) {
+ if (p == root)
+ return NULL;
+ next = p->d_u.d_child.next;
+ if (next != &p->d_parent->d_subdirs)
+ break;
+ p = p->d_parent;
+ }
+ }
+ return list_entry(next, struct dentry, d_u.d_child);
+}
+
/* Check a directory tree of mount points for busyness
* The tree is not busy iff no mountpoints are busy
*/
@@ -80,8 +101,7 @@ static int autofs4_tree_busy(struct vfsm
unsigned long timeout,
int do_now)
{
- struct dentry *this_parent = top;
- struct list_head *next;
+ struct dentry *p;

DPRINTK("top %p %.*s",
top, (int)top->d_name.len, top->d_name.name);
@@ -99,49 +119,28 @@ static int autofs4_tree_busy(struct vfsm
return 1;

spin_lock(&dcache_lock);
-repeat:
- next = this_parent->d_subdirs.next;
-resume:
- while (next != &this_parent->d_subdirs) {
- struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
-
+ for (p = top; p; p = next_dentry(p, top)) {
/* Negative dentry - give up */
- if (!simple_positive(dentry)) {
- next = next->next;
+ if (!simple_positive(p))
continue;
- }

DPRINTK("dentry %p %.*s",
- dentry, (int)dentry->d_name.len, dentry->d_name.name);
-
- if (!simple_empty_nolock(dentry)) {
- this_parent = dentry;
- goto repeat;
- }
+ p, (int) p->d_name.len, p->d_name.name);

- dentry = dget(dentry);
+ p = dget(p);
spin_unlock(&dcache_lock);

- if (d_mountpoint(dentry)) {
+ if (d_mountpoint(p)) {
/* First busy => tree busy */
- if (autofs4_mount_busy(mnt, dentry)) {
- dput(dentry);
+ if (autofs4_mount_busy(mnt, p)) {
+ dput(p);
return 1;
}
}
-
- dput(dentry);
+ dput(p);
spin_lock(&dcache_lock);
- next = next->next;
- }
-
- if (this_parent != top) {
- next = this_parent->d_u.d_child.next;
- this_parent = this_parent->d_parent;
- goto resume;
}
spin_unlock(&dcache_lock);
-
return 0;
}

@@ -150,59 +149,38 @@ static struct dentry *autofs4_check_leav
unsigned long timeout,
int do_now)
{
- struct dentry *this_parent = parent;
- struct list_head *next;
+ struct dentry *p;

DPRINTK("parent %p %.*s",
parent, (int)parent->d_name.len, parent->d_name.name);

spin_lock(&dcache_lock);
-repeat:
- next = this_parent->d_subdirs.next;
-resume:
- while (next != &this_parent->d_subdirs) {
- struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
-
+ for (p = parent; p; p = next_dentry(p, parent)) {
/* Negative dentry - give up */
- if (!simple_positive(dentry)) {
- next = next->next;
+ if (!simple_positive(p))
continue;
- }

DPRINTK("dentry %p %.*s",
- dentry, (int)dentry->d_name.len, dentry->d_name.name);
+ p, (int) p->d_name.len, p->d_name.name);

- if (!list_empty(&dentry->d_subdirs)) {
- this_parent = dentry;
- goto repeat;
- }
-
- dentry = dget(dentry);
+ p = dget(p);
spin_unlock(&dcache_lock);

- if (d_mountpoint(dentry)) {
+ if (d_mountpoint(p)) {
/* Can we expire this guy */
- if (!autofs4_can_expire(dentry, timeout, do_now))
+ if (!autofs4_can_expire(p, timeout, do_now))
goto cont;

/* Can we umount this guy */
- if (!autofs4_mount_busy(mnt, dentry))
- return dentry;
+ if (!autofs4_mount_busy(mnt, p))
+ return p;

}
cont:
- dput(dentry);
+ dput(p);
spin_lock(&dcache_lock);
- next = next->next;
- }
-
- if (this_parent != parent) {
- next = this_parent->d_u.d_child.next;
- this_parent = this_parent->d_parent;
- goto resume;
}
spin_unlock(&dcache_lock);
-
return NULL;
}

-
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