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authorJeff Layton <jeff.layton@primarydata.com>2019-08-18 14:18:45 -0400
committerJ. Bruce Fields <bfields@redhat.com>2019-08-19 11:00:39 -0400
commit18f6622ebbdea56a83f8e553c159ce2d62d3ad0c (patch)
treedb96f78e192180c2b3460c426e2f7864e802a9d2 /fs/locks.c
parentf69d6d8eef7807f8d937b81da24bebd2e926e4d2 (diff)
locks: create a new notifier chain for lease attempts
With the new file caching infrastructure in nfsd, we can end up holding files open for an indefinite period of time, even when they are still idle. This may prevent the kernel from handing out leases on the file, which is something we don't want to block. Fix this by running a SRCU notifier call chain whenever on any lease attempt. nfsd can then purge the cache for that inode before returning. Since SRCU is only conditionally compiled in, we must only define the new chain if it's enabled, and users of the chain must ensure that SRCU is enabled. Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/locks.c')
-rw-r--r--fs/locks.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/fs/locks.c b/fs/locks.c
index 686eae21daf6..1913481bfbf7 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1990,6 +1990,64 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
}
EXPORT_SYMBOL(generic_setlease);
+#if IS_ENABLED(CONFIG_SRCU)
+/*
+ * Kernel subsystems can register to be notified on any attempt to set
+ * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
+ * to close files that it may have cached when there is an attempt to set a
+ * conflicting lease.
+ */
+static struct srcu_notifier_head lease_notifier_chain;
+
+static inline void
+lease_notifier_chain_init(void)
+{
+ srcu_init_notifier_head(&lease_notifier_chain);
+}
+
+static inline void
+setlease_notifier(long arg, struct file_lock *lease)
+{
+ if (arg != F_UNLCK)
+ srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
+}
+
+int lease_register_notifier(struct notifier_block *nb)
+{
+ return srcu_notifier_chain_register(&lease_notifier_chain, nb);
+}
+EXPORT_SYMBOL_GPL(lease_register_notifier);
+
+void lease_unregister_notifier(struct notifier_block *nb)
+{
+ srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
+}
+EXPORT_SYMBOL_GPL(lease_unregister_notifier);
+
+#else /* !IS_ENABLED(CONFIG_SRCU) */
+static inline void
+lease_notifier_chain_init(void)
+{
+}
+
+static inline void
+setlease_notifier(long arg, struct file_lock *lease)
+{
+}
+
+int lease_register_notifier(struct notifier_block *nb)
+{
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lease_register_notifier);
+
+void lease_unregister_notifier(struct notifier_block *nb)
+{
+}
+EXPORT_SYMBOL_GPL(lease_unregister_notifier);
+
+#endif /* IS_ENABLED(CONFIG_SRCU) */
+
/**
* vfs_setlease - sets a lease on an open file
* @filp: file pointer
@@ -2010,6 +2068,8 @@ EXPORT_SYMBOL(generic_setlease);
int
vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
{
+ if (lease)
+ setlease_notifier(arg, *lease);
if (filp->f_op->setlease)
return filp->f_op->setlease(filp, arg, lease, priv);
else
@@ -2923,6 +2983,7 @@ static int __init filelock_init(void)
INIT_HLIST_HEAD(&fll->hlist);
}
+ lease_notifier_chain_init();
return 0;
}
core_initcall(filelock_init);