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| author | Imran Khan <imran.f.khan@oracle.com> | 2022-03-24 21:30:39 +1100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-27 09:51:57 +0200 |
| commit | bd900901b8d1838bf1b6e63063e0025fca42d283 (patch) | |
| tree | 85d696920282480cd55649f05009529b5f4d8a5e /fs/kernfs | |
| parent | 6423d2951087231706246f81851067f7f0593d4a (diff) | |
| download | linux-bd900901b8d1838bf1b6e63063e0025fca42d283.tar.bz2 | |
kernfs: Remove reference counting for kernfs_open_node.
The decision to free kernfs_open_node object in kernfs_put_open_node can
be taken based on whether kernfs_open_node->files list is empty or not. As
far as kernfs_drain_open_files is concerned it can't overlap with
kernfs_fops_open and hence can check for ->attr.open optimistically
(if ->attr.open is NULL) or under kernfs_open_file_mutex (if it needs to
traverse the ->files list.) Thus kernfs_drain_open_files can work w/o ref
counting involved kernfs_open_node as well.
So remove ->refcnt and modify the above mentioned users accordingly.
Suggested by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20220324103040.584491-2-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs')
| -rw-r--r-- | fs/kernfs/file.c | 23 |
1 files changed, 9 insertions, 14 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 88423069407c..aea6968c979e 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -33,7 +33,6 @@ static DEFINE_SPINLOCK(kernfs_open_node_lock); static DEFINE_MUTEX(kernfs_open_file_mutex); struct kernfs_open_node { - atomic_t refcnt; atomic_t event; wait_queue_head_t poll; struct list_head files; /* goes through kernfs_open_file.list */ @@ -530,10 +529,8 @@ static int kernfs_get_open_node(struct kernfs_node *kn, } on = kn->attr.open; - if (on) { - atomic_inc(&on->refcnt); + if (on) list_add_tail(&of->list, &on->files); - } spin_unlock_irq(&kernfs_open_node_lock); mutex_unlock(&kernfs_open_file_mutex); @@ -548,7 +545,6 @@ static int kernfs_get_open_node(struct kernfs_node *kn, if (!new_on) return -ENOMEM; - atomic_set(&new_on->refcnt, 0); atomic_set(&new_on->event, 1); init_waitqueue_head(&new_on->poll); INIT_LIST_HEAD(&new_on->files); @@ -557,11 +553,12 @@ static int kernfs_get_open_node(struct kernfs_node *kn, /** * kernfs_put_open_node - put kernfs_open_node - * @kn: target kernfs_nodet + * @kn: target kernfs_node * @of: associated kernfs_open_file * * Put @kn->attr.open and unlink @of from the files list. If - * reference count reaches zero, disassociate and free it. + * list of associated open files becomes empty, disassociate and + * free kernfs_open_node. * * LOCKING: * None. @@ -578,7 +575,7 @@ static void kernfs_put_open_node(struct kernfs_node *kn, if (of) list_del(&of->list); - if (atomic_dec_and_test(&on->refcnt)) + if (list_empty(&on->files)) kn->attr.open = NULL; else on = NULL; @@ -768,15 +765,15 @@ void kernfs_drain_open_files(struct kernfs_node *kn) if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE))) return; - spin_lock_irq(&kernfs_open_node_lock); on = kn->attr.open; - if (on) - atomic_inc(&on->refcnt); - spin_unlock_irq(&kernfs_open_node_lock); if (!on) return; mutex_lock(&kernfs_open_file_mutex); + if (!kn->attr.open) { + mutex_unlock(&kernfs_open_file_mutex); + return; + } list_for_each_entry(of, &on->files, list) { struct inode *inode = file_inode(of->file); @@ -789,8 +786,6 @@ void kernfs_drain_open_files(struct kernfs_node *kn) } mutex_unlock(&kernfs_open_file_mutex); - - kernfs_put_open_node(kn, NULL); } /* |