autofs4: Add d_manage() dentry operation
This patch required a previous patch to add the ->d_automount()
dentry operation.
Add a function to use the newly defined ->d_manage() dentry operation
for blocking during mount and expire.
Whether the VFS calls the dentry operations d_automount() and d_manage()
is controled by the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags. autofs
uses the d_automount() operation to callback to user space to request
mount operations and the d_manage() operation to block walks into mounts
that are under construction or destruction.
In order to prevent these functions from being called unnecessarily the
DMANAGED_* flags are cleared for cases which would cause this. In the
common case the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags are both
set for dentrys waiting to be mounted. The DMANAGED_TRANSIT flag is
cleared upon successful mount request completion and set during expire
runs, both during the dentry expire check, and if selected for expire,
is left set until a subsequent successful mount request completes.
The exception to this is the so-called rootless multi-mount which has
no actual mount at its base. In this case the DMANAGED_AUTOMOUNT flag
is cleared upon successful mount request completion as well and set
again after a successful expire.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 0571ec8..3ed79d7 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -26,10 +26,6 @@
if (ino == NULL)
return 0;
- /* No point expiring a pending mount */
- if (ino->flags & AUTOFS_INF_PENDING)
- return 0;
-
if (!do_now) {
/* Too young to die */
if (!timeout || time_after(ino->last_used + timeout, now))
@@ -283,6 +279,7 @@
unsigned long timeout;
struct dentry *root = dget(sb->s_root);
int do_now = how & AUTOFS_EXP_IMMEDIATE;
+ struct autofs_info *ino;
if (!root)
return NULL;
@@ -291,20 +288,21 @@
timeout = sbi->exp_timeout;
spin_lock(&sbi->fs_lock);
+ ino = autofs4_dentry_ino(root);
+ /* No point expiring a pending mount */
+ if (ino->flags & AUTOFS_INF_PENDING) {
+ spin_unlock(&sbi->fs_lock);
+ return NULL;
+ }
+ managed_dentry_set_transit(root);
if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
struct autofs_info *ino = autofs4_dentry_ino(root);
- if (d_mountpoint(root)) {
- ino->flags |= AUTOFS_INF_MOUNTPOINT;
- spin_lock(&root->d_lock);
- root->d_flags &= ~DCACHE_MOUNTED;
- spin_unlock(&root->d_lock);
- }
ino->flags |= AUTOFS_INF_EXPIRING;
- managed_dentry_set_automount(root);
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
return root;
}
+ managed_dentry_clear_transit(root);
spin_unlock(&sbi->fs_lock);
dput(root);
@@ -341,6 +339,10 @@
while ((dentry = get_next_positive_dentry(dentry, root))) {
spin_lock(&sbi->fs_lock);
ino = autofs4_dentry_ino(dentry);
+ /* No point expiring a pending mount */
+ if (ino->flags & AUTOFS_INF_PENDING)
+ goto cont;
+ managed_dentry_set_transit(dentry);
/*
* Case 1: (i) indirect mount or top level pseudo direct mount
@@ -400,6 +402,8 @@
}
}
next:
+ managed_dentry_clear_transit(dentry);
+cont:
spin_unlock(&sbi->fs_lock);
}
return NULL;
@@ -409,7 +413,6 @@
expired, (int)expired->d_name.len, expired->d_name.name);
ino = autofs4_dentry_ino(expired);
ino->flags |= AUTOFS_INF_EXPIRING;
- managed_dentry_set_automount(expired);
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
spin_lock(&autofs4_lock);
@@ -482,7 +485,7 @@
ino = autofs4_dentry_ino(dentry);
ino->flags &= ~AUTOFS_INF_EXPIRING;
if (!d_unhashed(dentry))
- managed_dentry_clear_automount(dentry);
+ managed_dentry_clear_transit(dentry);
complete_all(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
@@ -508,20 +511,18 @@
ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
spin_lock(&sbi->fs_lock);
- if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
- spin_lock(&sb->s_root->d_lock);
- /*
- * If we haven't been expired away, then reset
- * mounted status.
- */
- if (mnt->mnt_parent != mnt)
- sb->s_root->d_flags |= DCACHE_MOUNTED;
- spin_unlock(&sb->s_root->d_lock);
- ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
- }
ino->flags &= ~AUTOFS_INF_EXPIRING;
+ spin_lock(&dentry->d_lock);
if (ret)
- managed_dentry_clear_automount(dentry);
+ __managed_dentry_clear_transit(dentry);
+ else {
+ if ((IS_ROOT(dentry) ||
+ (autofs_type_indirect(sbi->type) &&
+ IS_ROOT(dentry->d_parent))) &&
+ !(dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
+ __managed_dentry_set_automount(dentry);
+ }
+ spin_unlock(&dentry->d_lock);
complete_all(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
dput(dentry);