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Message-Id: <20220410023719.1752460-5-imran.f.khan@oracle.com>
Date: Sun, 10 Apr 2022 12:37:13 +1000
From: Imran Khan <imran.f.khan@...cle.com>
To: tj@...nel.org, viro@...iv.linux.org.uk, gregkh@...uxfoundation.org,
ebiederm@...ssion.com
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH v8 04/10] kernfs: Introduce interface to access global kernfs_open_file_mutex.
This allows to change underlying mutex locking, without needing to change
the users of the lock. For example next patch modifies this interface to
use hashed mutexes in place of a single global kernfs_open_file_mutex.
Signed-off-by: Imran Khan <imran.f.khan@...cle.com>
---
fs/kernfs/file.c | 42 +++++++++++++++++++++++++++++++-----------
1 file changed, 31 insertions(+), 11 deletions(-)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index c89220dcfdc1..214b48d59148 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -47,6 +47,22 @@ struct kernfs_open_node {
#define attribute_to_node(ptr, type, member) \
container_of(ptr, type, member)
+static inline struct mutex *kernfs_open_file_mutex_ptr(struct kernfs_node *kn)
+{
+ return &kernfs_open_file_mutex;
+}
+
+static inline struct mutex *kernfs_open_file_mutex_lock(struct kernfs_node *kn)
+{
+ struct mutex *lock;
+
+ lock = kernfs_open_file_mutex_ptr(kn);
+
+ mutex_lock(lock);
+
+ return lock;
+}
+
static DEFINE_SPINLOCK(kernfs_notify_lock);
static LLIST_HEAD(kernfs_notify_list);
@@ -520,8 +536,9 @@ static int kernfs_get_open_node(struct kernfs_node *kn,
struct kernfs_open_file *of)
{
struct kernfs_open_node *on, *new_on = NULL;
+ struct mutex *mutex = NULL;
- mutex_lock(&kernfs_open_file_mutex);
+ mutex = kernfs_open_file_mutex_lock(kn);
/**
* ->attr.open changes under kernfs_open_file_mutex so we don't
@@ -531,13 +548,13 @@ static int kernfs_get_open_node(struct kernfs_node *kn,
lockdep_is_held(&kernfs_open_file_mutex));
if (on) {
list_add_tail(&of->list, &on->files);
- mutex_unlock(&kernfs_open_file_mutex);
+ mutex_unlock(mutex);
return 0;
} else {
/* not there, initialize a new one and retry */
new_on = kmalloc(sizeof(*new_on), GFP_KERNEL);
if (!new_on) {
- mutex_unlock(&kernfs_open_file_mutex);
+ mutex_unlock(mutex);
return -ENOMEM;
}
atomic_set(&new_on->event, 1);
@@ -546,7 +563,7 @@ static int kernfs_get_open_node(struct kernfs_node *kn,
list_add_tail(&of->list, &new_on->files);
rcu_assign_pointer(kn->attr.open, new_on);
}
- mutex_unlock(&kernfs_open_file_mutex);
+ mutex_unlock(mutex);
return 0;
}
@@ -567,12 +584,13 @@ static void kernfs_put_open_node(struct kernfs_node *kn,
struct kernfs_open_file *of)
{
struct kernfs_open_node *on;
+ struct mutex *mutex = NULL;
/* ->attr.open NULL means there are no more open files */
if (rcu_dereference_raw(kn->attr.open) == NULL)
return;
- mutex_lock(&kernfs_open_file_mutex);
+ mutex = kernfs_open_file_mutex_lock(kn);
on = rcu_dereference_protected(kn->attr.open,
lockdep_is_held(&kernfs_open_file_mutex));
@@ -589,7 +607,7 @@ static void kernfs_put_open_node(struct kernfs_node *kn,
rcu_assign_pointer(kn->attr.open, NULL);
kfree_rcu(on, rcu_head);
}
- mutex_unlock(&kernfs_open_file_mutex);
+ mutex_unlock(mutex);
}
static int kernfs_fop_open(struct inode *inode, struct file *file)
@@ -731,7 +749,7 @@ static void kernfs_release_file(struct kernfs_node *kn,
* here because drain path may be called from places which can
* cause circular dependency.
*/
- lockdep_assert_held(&kernfs_open_file_mutex);
+ lockdep_assert_held(kernfs_open_file_mutex_ptr(kn));
if (!of->released) {
/*
@@ -748,11 +766,12 @@ static int kernfs_fop_release(struct inode *inode, struct file *filp)
{
struct kernfs_node *kn = inode->i_private;
struct kernfs_open_file *of = kernfs_of(filp);
+ struct mutex *mutex = NULL;
if (kn->flags & KERNFS_HAS_RELEASE) {
- mutex_lock(&kernfs_open_file_mutex);
+ mutex = kernfs_open_file_mutex_lock(kn);
kernfs_release_file(kn, of);
- mutex_unlock(&kernfs_open_file_mutex);
+ mutex_unlock(mutex);
}
kernfs_put_open_node(kn, of);
@@ -767,6 +786,7 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
{
struct kernfs_open_node *on;
struct kernfs_open_file *of;
+ struct mutex *mutex = NULL;
if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE)))
return;
@@ -774,7 +794,7 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
if (rcu_dereference_raw(kn->attr.open) == NULL)
return;
- mutex_lock(&kernfs_open_file_mutex);
+ mutex = kernfs_open_file_mutex_lock(kn);
on = rcu_dereference_check(kn->attr.open,
lockdep_is_held(&kernfs_open_file_mutex));
if (!on) {
@@ -792,7 +812,7 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
kernfs_release_file(kn, of);
}
- mutex_unlock(&kernfs_open_file_mutex);
+ mutex_unlock(mutex);
}
/*
--
2.30.2
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