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Subject[patch 38/61] lock validator: special locking: i_mutex
From: Ingo Molnar <mingo@elte.hu>

teach special (recursive) locking code to the lock validator. Has no
effect on non-lockdep kernels.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
drivers/usb/core/inode.c | 2 +-
fs/namei.c | 24 ++++++++++++------------
include/linux/fs.h | 14 ++++++++++++++
3 files changed, 27 insertions(+), 13 deletions(-)

Index: linux/drivers/usb/core/inode.c
===================================================================
--- linux.orig/drivers/usb/core/inode.c
+++ linux/drivers/usb/core/inode.c
@@ -201,7 +201,7 @@ static void update_sb(struct super_block
if (!root)
return;

- mutex_lock(&root->d_inode->i_mutex);
+ mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_PARENT);

list_for_each_entry(bus, &root->d_subdirs, d_u.d_child) {
if (bus->d_inode) {
Index: linux/fs/namei.c
===================================================================
--- linux.orig/fs/namei.c
+++ linux/fs/namei.c
@@ -1422,7 +1422,7 @@ struct dentry *lock_rename(struct dentry
struct dentry *p;

if (p1 == p2) {
- mutex_lock(&p1->d_inode->i_mutex);
+ mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
return NULL;
}

@@ -1430,30 +1430,30 @@ struct dentry *lock_rename(struct dentry

for (p = p1; p->d_parent != p; p = p->d_parent) {
if (p->d_parent == p2) {
- mutex_lock(&p2->d_inode->i_mutex);
- mutex_lock(&p1->d_inode->i_mutex);
+ 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; p->d_parent != p; p = p->d_parent) {
if (p->d_parent == p1) {
- mutex_lock(&p1->d_inode->i_mutex);
- mutex_lock(&p2->d_inode->i_mutex);
+ 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(&p1->d_inode->i_mutex);
- mutex_lock(&p2->d_inode->i_mutex);
+ mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
+ mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
return NULL;
}

void unlock_rename(struct dentry *p1, struct dentry *p2)
{
- mutex_unlock(&p1->d_inode->i_mutex);
+ mutex_unlock_non_nested(&p1->d_inode->i_mutex);
if (p1 != p2) {
- mutex_unlock(&p2->d_inode->i_mutex);
+ mutex_unlock_non_nested(&p2->d_inode->i_mutex);
mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
}
}
@@ -1750,7 +1750,7 @@ struct dentry *lookup_create(struct name
{
struct dentry *dentry = ERR_PTR(-EEXIST);

- mutex_lock(&nd->dentry->d_inode->i_mutex);
+ mutex_lock_nested(&nd->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
/*
* Yucky last component or no last component at all?
* (foo/., foo/.., /////)
@@ -2007,7 +2007,7 @@ static long do_rmdir(int dfd, const char
error = -EBUSY;
goto exit1;
}
- mutex_lock(&nd.dentry->d_inode->i_mutex);
+ mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
error = PTR_ERR(dentry);
if (!IS_ERR(dentry)) {
@@ -2081,7 +2081,7 @@ static long do_unlinkat(int dfd, const c
error = -EISDIR;
if (nd.last_type != LAST_NORM)
goto exit1;
- mutex_lock(&nd.dentry->d_inode->i_mutex);
+ mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
error = PTR_ERR(dentry);
if (!IS_ERR(dentry)) {
Index: linux/include/linux/fs.h
===================================================================
--- linux.orig/include/linux/fs.h
+++ linux/include/linux/fs.h
@@ -558,6 +558,20 @@ struct inode {
};

/*
+ * inode->i_mutex nesting types for the LOCKDEP validator:
+ *
+ * 0: the object of the current VFS operation
+ * 1: parent
+ * 2: child/target
+ */
+enum inode_i_mutex_lock_type
+{
+ I_MUTEX_NORMAL,
+ I_MUTEX_PARENT,
+ I_MUTEX_CHILD
+};
+
+/*
* NOTE: in a 32bit arch with a preemptable kernel and
* an UP compile the i_size_read/write must be atomic
* with respect to the local cpu (unlike with preempt disabled),
-
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