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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 15 Sep 2016 10:51:27 +0200
Subject: [PATCH 128/353] fs/nfs: turn rmdir_sem into a semaphore
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=a865901ab427b7d9016bdc42a706beb5a4da5903
The RW semaphore had a reader side which used the _non_owner version
because it most likely took the reader lock in one thread and released it
in another which would cause lockdep to complain if the "regular"
version was used.
On -RT we need the owner because the rw lock is turned into a rtmutex.
The semaphores on the hand are "plain simple" and should work as
expected. We can't have multiple readers but on -RT we don't allow
multiple readers anyway so that is not a loss.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
fs/nfs/dir.c | 8 ++++++++
fs/nfs/inode.c | 4 ++++
fs/nfs/unlink.c | 31 +++++++++++++++++++++++++++----
include/linux/nfs_fs.h | 4 ++++
4 files changed, 43 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 10bc04af2882..4999bd148491 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1857,7 +1857,11 @@ int nfs_rmdir(struct inode *dir, struct dentry *dentry)
trace_nfs_rmdir_enter(dir, dentry);
if (d_really_is_positive(dentry)) {
+#ifdef CONFIG_PREEMPT_RT_BASE
+ down(&NFS_I(d_inode(dentry))->rmdir_sem);
+#else
down_write(&NFS_I(d_inode(dentry))->rmdir_sem);
+#endif
error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
/* Ensure the VFS deletes this inode */
switch (error) {
@@ -1867,7 +1871,11 @@ int nfs_rmdir(struct inode *dir, struct dentry *dentry)
case -ENOENT:
nfs_dentry_handle_enoent(dentry);
}
+#ifdef CONFIG_PREEMPT_RT_BASE
+ up(&NFS_I(d_inode(dentry))->rmdir_sem);
+#else
up_write(&NFS_I(d_inode(dentry))->rmdir_sem);
+#endif
} else
error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
trace_nfs_rmdir_exit(dir, dentry, error);
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 592b95ab378b..4fc14fb50068 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -2105,7 +2105,11 @@ static void init_once(void *foo)
atomic_long_set(&nfsi->nrequests, 0);
atomic_long_set(&nfsi->commit_info.ncommit, 0);
atomic_set(&nfsi->commit_info.rpcs_out, 0);
+#ifdef CONFIG_PREEMPT_RT_BASE
+ sema_init(&nfsi->rmdir_sem, 1);
+#else
init_rwsem(&nfsi->rmdir_sem);
+#endif
mutex_init(&nfsi->commit_mutex);
nfs4_init_once(nfsi);
}
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index fd61bf0fce63..ce9100b5604d 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -52,6 +52,29 @@ static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
rpc_restart_call_prepare(task);
}
+#ifdef CONFIG_PREEMPT_RT_BASE
+static void nfs_down_anon(struct semaphore *sema)
+{
+ down(sema);
+}
+
+static void nfs_up_anon(struct semaphore *sema)
+{
+ up(sema);
+}
+
+#else
+static void nfs_down_anon(struct rw_semaphore *rwsem)
+{
+ down_read_non_owner(rwsem);
+}
+
+static void nfs_up_anon(struct rw_semaphore *rwsem)
+{
+ up_read_non_owner(rwsem);
+}
+#endif
+
/**
* nfs_async_unlink_release - Release the sillydelete data.
* @task: rpc_task of the sillydelete
@@ -65,7 +88,7 @@ static void nfs_async_unlink_release(void *calldata)
struct dentry *dentry = data->dentry;
struct super_block *sb = dentry->d_sb;
- up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
+ nfs_up_anon(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
d_lookup_done(dentry);
nfs_free_unlinkdata(data);
dput(dentry);
@@ -118,10 +141,10 @@ static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nf
struct inode *dir = d_inode(dentry->d_parent);
struct dentry *alias;
- down_read_non_owner(&NFS_I(dir)->rmdir_sem);
+ nfs_down_anon(&NFS_I(dir)->rmdir_sem);
alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
if (IS_ERR(alias)) {
- up_read_non_owner(&NFS_I(dir)->rmdir_sem);
+ nfs_up_anon(&NFS_I(dir)->rmdir_sem);
return 0;
}
if (!d_in_lookup(alias)) {
@@ -143,7 +166,7 @@ static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nf
ret = 0;
spin_unlock(&alias->d_lock);
dput(alias);
- up_read_non_owner(&NFS_I(dir)->rmdir_sem);
+ nfs_up_anon(&NFS_I(dir)->rmdir_sem);
/*
* If we'd displaced old cached devname, free it. At that
* point dentry is definitely not a root, so we won't need
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 8ea7ceed8285..d52dfae05d2a 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -164,7 +164,11 @@ struct nfs_inode {
/* Readers: in-flight sillydelete RPC calls */
/* Writers: rmdir */
+#ifdef CONFIG_PREEMPT_RT_BASE
+ struct semaphore rmdir_sem;
+#else
struct rw_semaphore rmdir_sem;
+#endif
struct mutex commit_mutex;
#if IS_ENABLED(CONFIG_NFS_V4)
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