@@ -1786,6 +1786,40 @@ 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.
+ */
+struct srcu_notifier_head lease_notifier_chain;
+EXPORT_SYMBOL_GPL(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);
+}
+#else /* !IS_ENABLED(CONFIG_SRCU) */
+static inline void
+lease_notifier_chain_init(void)
+{
+}
+
+static inline void
+setlease_notifier(long arg, struct file_lock *lease)
+{
+}
+#endif /* IS_ENABLED(CONFIG_SRCU) */
+
/**
* vfs_setlease - sets a lease on an open file
* @filp: file pointer
@@ -1806,6 +1840,8 @@ 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
@@ -2726,6 +2762,7 @@ static int __init filelock_init(void)
for_each_possible_cpu(i)
INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i));
+ lease_notifier_chain_init();
return 0;
}
@@ -1042,6 +1042,7 @@ extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
extern int fcntl_getlease(struct file *filp);
/* fs/locks.c */
+extern struct srcu_notifier_head lease_notifier_chain;
void locks_free_lock_context(struct file_lock_context *ctx);
void locks_free_lock(struct file_lock *fl);
extern void locks_init_lock(struct file_lock *);
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 any lease attempt is made. nfsd can then purge the nfsd_file cache of any entries associated with that inode, and use the fput_global infrastructure to make sure the final __fput is done. 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> --- fs/locks.c | 37 +++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 1 + 2 files changed, 38 insertions(+)