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Subject[RFC-2 PATCH 7/8] shared subtree
adds support for mount/umount propogation for autofs initiated operations,
RP


fs/namespace.c | 151 +++++++++++++++++---------------------------------
fs/pnode.c | 13 ++--
include/linux/pnode.h | 3
3 files changed, 61 insertions(+), 106 deletions(-)

Index: 2.6.12.work1/fs/namespace.c
===================================================================
--- 2.6.12.work1.orig/fs/namespace.c
+++ 2.6.12.work1/fs/namespace.c
@@ -215,6 +215,9 @@ struct vfsmount *do_attach_prepare_mnt(s
if(!(child_mnt = clone_mnt(template_mnt,
template_mnt->mnt_root)))
return NULL;
+ spin_lock(&vfsmount_lock);
+ list_del_init(&child_mnt->mnt_fslink);
+ spin_unlock(&vfsmount_lock);
} else
child_mnt = template_mnt;

@@ -352,38 +355,16 @@ struct seq_operations mounts_op = {
* open files, pwds, chroots or sub mounts that are
* busy.
*/
-//TOBEFIXED
int may_umount_tree(struct vfsmount *mnt)
{
- struct list_head *next;
- struct vfsmount *this_parent = mnt;
- int actual_refs;
- int minimum_refs;
+ int actual_refs=0;
+ int minimum_refs=0;
+ struct vfsmount *p;

spin_lock(&vfsmount_lock);
- actual_refs = atomic_read(&mnt->mnt_count);
- minimum_refs = 2;
-repeat:
- next = this_parent->mnt_mounts.next;
-resume:
- while (next != &this_parent->mnt_mounts) {
- struct vfsmount *p = list_entry(next, struct vfsmount, mnt_child);
-
- next = next->next;
-
+ for (p = mnt; p; p = next_mnt(p, mnt)) {
actual_refs += atomic_read(&p->mnt_count);
minimum_refs += 2;
-
- if (!list_empty(&p->mnt_mounts)) {
- this_parent = p;
- goto repeat;
- }
- }
-
- if (this_parent != mnt) {
- next = this_parent->mnt_child.next;
- this_parent = this_parent->mnt_parent;
- goto resume;
}
spin_unlock(&vfsmount_lock);

@@ -395,18 +376,18 @@ resume:

EXPORT_SYMBOL(may_umount_tree);

-int mount_busy(struct vfsmount *mnt)
+int mount_busy(struct vfsmount *mnt, int refcnt)
{
struct vfspnode *parent_pnode;

if (mnt == mnt->mnt_parent || !IS_MNT_SHARED(mnt->mnt_parent))
- return do_refcount_check(mnt, 2);
+ return do_refcount_check(mnt, refcnt);

parent_pnode = mnt->mnt_parent->mnt_pnode;
BUG_ON(!parent_pnode);
return pnode_mount_busy(parent_pnode,
mnt->mnt_mountpoint,
- mnt->mnt_root, mnt);
+ mnt->mnt_root, mnt, refcnt);
}

/**
@@ -424,7 +405,7 @@ int mount_busy(struct vfsmount *mnt)
*/
int may_umount(struct vfsmount *mnt)
{
- if (mount_busy(mnt))
+ if (mount_busy(mnt, 2))
return -EBUSY;
return 0;
}
@@ -445,6 +426,25 @@ void do_detach_mount(struct vfsmount *mn
spin_lock(&vfsmount_lock);
}

+void umount_mnt(struct vfsmount *mnt)
+{
+ if (mnt->mnt_parent != mnt &&
+ IS_MNT_SHARED(mnt->mnt_parent)) {
+ struct vfspnode *parent_pnode
+ = mnt->mnt_parent->mnt_pnode;
+ BUG_ON(!parent_pnode);
+ pnode_umount(parent_pnode,
+ mnt->mnt_mountpoint,
+ mnt->mnt_root);
+ } else {
+ if (IS_MNT_SHARED(mnt) || IS_MNT_SLAVE(mnt)) {
+ BUG_ON(!mnt->mnt_pnode);
+ pnode_disassociate_mnt(mnt);
+ }
+ do_detach_mount(mnt);
+ }
+}
+
void umount_tree(struct vfsmount *mnt)
{
struct vfsmount *p;
@@ -459,21 +459,7 @@ void umount_tree(struct vfsmount *mnt)
mnt = list_entry(kill.next, struct vfsmount, mnt_list);
list_del_init(&mnt->mnt_list);
list_del_init(&mnt->mnt_fslink);
- if (mnt->mnt_parent != mnt &&
- IS_MNT_SHARED(mnt->mnt_parent)) {
- struct vfspnode *parent_pnode
- = mnt->mnt_parent->mnt_pnode;
- BUG_ON(!parent_pnode);
- pnode_umount(parent_pnode,
- mnt->mnt_mountpoint,
- mnt->mnt_root);
- } else {
- if (IS_MNT_SHARED(mnt) || IS_MNT_SLAVE(mnt)) {
- BUG_ON(!mnt->mnt_pnode);
- pnode_disassociate_mnt(mnt);
- }
- do_detach_mount(mnt);
- }
+ umount_mnt(mnt);
}
}

@@ -568,7 +554,7 @@ int do_umount(struct vfsmount *mnt, int
spin_lock(&vfsmount_lock);
}
retval = -EBUSY;
- if (flags & MNT_DETACH || !mount_busy(mnt)) {
+ if (flags & MNT_DETACH || !mount_busy(mnt, 2)) {
if (!list_empty(&mnt->mnt_list))
umount_tree(mnt);
retval = 0;
@@ -1490,6 +1476,8 @@ void mark_mounts_for_expiry(struct list_
if (list_empty(mounts))
return;

+ down_write(&namespace_sem);
+
spin_lock(&vfsmount_lock);

/* extract from the expiration list every vfsmount that matches the
@@ -1499,8 +1487,7 @@ void mark_mounts_for_expiry(struct list_
* cleared by mntput())
*/
list_for_each_entry_safe(mnt, next, mounts, mnt_fslink) {
- if (!xchg(&mnt->mnt_expiry_mark, 1) ||
- atomic_read(&mnt->mnt_count) != 1)
+ if (!xchg(&mnt->mnt_expiry_mark, 1) || mount_busy(mnt, 1))
continue;

mntget(mnt);
@@ -1508,12 +1495,13 @@ void mark_mounts_for_expiry(struct list_
}

/*
- * go through the vfsmounts we've just consigned to the graveyard to
- * - check that they're still dead
+ * go through the vfsmounts we've just consigned to the graveyard
* - delete the vfsmount from the appropriate namespace under lock
* - dispose of the corpse
*/
while (!list_empty(&graveyard)) {
+ struct super_block *sb;
+
mnt = list_entry(graveyard.next, struct vfsmount, mnt_fslink);
list_del_init(&mnt->mnt_fslink);

@@ -1524,60 +1512,25 @@ void mark_mounts_for_expiry(struct list_
continue;
get_namespace(namespace);

- spin_unlock(&vfsmount_lock);
- down_write(&namespace_sem);
- spin_lock(&vfsmount_lock);
-
- /* check that it is still dead: the count should now be 2 - as
- * contributed by the vfsmount parent and the mntget above */
- if (atomic_read(&mnt->mnt_count) == 2) {
- struct vfsmount *xdmnt;
- struct dentry *xdentry;
-
- /* delete from the namespace */
- list_del_init(&mnt->mnt_list);
- list_del_init(&mnt->mnt_child);
- list_del_init(&mnt->mnt_hash);
- mnt->mnt_mountpoint->d_mounted--;
-
- xdentry = mnt->mnt_mountpoint;
- mnt->mnt_mountpoint = mnt->mnt_root;
- xdmnt = mnt->mnt_parent;
- mnt->mnt_parent = mnt;
-
- spin_unlock(&vfsmount_lock);
-
- mntput(xdmnt);
- dput(xdentry);
-
- /* now lay it to rest if this was the last ref on the
- * superblock */
- if (atomic_read(&mnt->mnt_sb->s_active) == 1) {
- /* last instance - try to be smart */
- lock_kernel();
- DQUOT_OFF(mnt->mnt_sb);
- acct_auto_close(mnt->mnt_sb);
- unlock_kernel();
- }
-
- mntput(mnt);
- } else {
- /* someone brought it back to life whilst we didn't
- * have any locks held so return it to the expiration
- * list */
- list_add_tail(&mnt->mnt_fslink, mounts);
- spin_unlock(&vfsmount_lock);
+ sb = mnt->mnt_sb;
+ umount_mnt(mnt);
+ /*
+ * now lay it to rest if this was the last ref on the
+ * superblock
+ */
+ if (atomic_read(&sb->s_active) == 1) {
+ /* last instance - try to be smart */
+ lock_kernel();
+ DQUOT_OFF(sb);
+ acct_auto_close(sb);
+ unlock_kernel();
}
-
- up_write(&namespace_sem);
-
mntput(mnt);
- put_namespace(namespace);

- spin_lock(&vfsmount_lock);
+ put_namespace(namespace);
}
-
spin_unlock(&vfsmount_lock);
+ up_write(&namespace_sem);
}

EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
Index: 2.6.12.work1/fs/pnode.c
===================================================================
--- 2.6.12.work1.orig/fs/pnode.c
+++ 2.6.12.work1/fs/pnode.c
@@ -34,7 +34,7 @@ enum pnode_vfs_type {
static kmem_cache_t * pnode_cachep;

/* spinlock for pnode related operations */
- __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfspnode_lock);
+ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfspnode_lock);


void __init pnode_init(unsigned long mempages)
@@ -274,7 +274,8 @@ int pnode_merge_pnode(struct vfspnode *p
}

static int vfs_busy(struct vfsmount *mnt, struct dentry *dentry,
- struct dentry *rootdentry, struct vfsmount *origmnt)
+ struct dentry *rootdentry, struct vfsmount *origmnt,
+ int refcnt)
{
struct vfsmount *child_mnt;
int ret=0;
@@ -288,16 +289,16 @@ static int vfs_busy(struct vfsmount *mnt

if (list_empty(&child_mnt->mnt_mounts)) {
if (origmnt == child_mnt)
- ret = do_refcount_check(child_mnt, 3);
- else
- ret = do_refcount_check(child_mnt, 2);
+ ret = do_refcount_check(child_mnt, refcnt+1);
+ else
+ ret = do_refcount_check(child_mnt, refcnt);
}
mntput(child_mnt);
return ret;
}

int pnode_mount_busy(struct vfspnode *pnode, struct dentry *mntpt,
- struct dentry *root, struct vfsmount *mnt)
+ struct dentry *root, struct vfsmount *mnt, int refcnt)
{
int ret=0;
struct vfsmount *slave_mnt, *member_mnt, *t_m;
Index: 2.6.12.work1/include/linux/pnode.h
===================================================================
--- 2.6.12.work1.orig/include/linux/pnode.h
+++ 2.6.12.work1/include/linux/pnode.h
@@ -86,5 +86,6 @@ int pnode_prepare_mount(struct vfspnode
struct vfsmount *, struct vfsmount *);
int pnode_real_mount(struct vfspnode *, int);
int pnode_umount(struct vfspnode *, struct dentry *, struct dentry *);
-int pnode_mount_busy(struct vfspnode *, struct dentry *, struct dentry *, struct vfsmount *);
+int pnode_mount_busy(struct vfspnode *, struct dentry *, struct dentry *,
+ struct vfsmount *, int);
#endif /* _LINUX_PNODE_H */
-
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