Re: [PATCH v3 1/3] NFSD: Added fault injection

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, Sep 29, 2011 at 02:59:23PM -0400, bjschuma@netapp.com wrote:
> From: Bryan Schumaker <bjschuma@netapp.com>
> 
> Fault injection on the NFS server makes it easier to test the client's
> state manager and recovery threads.  Simulating errors on the server is
> easier than finding the right conditions that cause them naturally.

You also might look at the unlock_ip interface that Wendy Cheng added a
few years ago. The fact that it doesn't remove nfsv4 state is really a
bug, it should be blowing away any relevant v4 clients as the same time.

(Though note the IP in question is a server IP, not a client IP.)

Is this the forget_n_clients scenario really a useful one to test?
I'd've thought that the client would need to deal with the entire client
diseappearing (due to network partition, for example), but not normally
individual open owners.

--b.

> This patch uses debugfs to add a simple framework for fault injection to
> the server.  This framework is a config option, and can be enabled
> through CONFIG_NFSD_FAULT_INJECTION.  Assuming you have debugfs mounted
> to /sys/debug, a set of files will be created in /sys/debug/nfsd/.
> Writing to any of these files will cause the corresponding action and
> write a log entry to dmesg.
> 
> Changes in v3:
> - Code cleanup and better use of generic functions
> - Allow the user to input the number of state objects to delete
> - Remove "forget_everything()" since forgetting a client is basically
>   the same thing
> 
> Changes in v2:
> - Replaced "forget all state owners" with "forget all open owners"
> - Include fs/nfsd/fault_inject.c in the patch
> 
> Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
> ---
>  fs/nfsd/Kconfig        |   10 ++++
>  fs/nfsd/Makefile       |    3 +-
>  fs/nfsd/fault_inject.c |  102 ++++++++++++++++++++++++++++++++++++++++++
>  fs/nfsd/nfs4state.c    |  115 ++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfsd/nfsctl.c       |    6 +++
>  fs/nfsd/nfsd.h         |   12 +++++
>  6 files changed, 247 insertions(+), 1 deletions(-)
>  create mode 100644 fs/nfsd/fault_inject.c
> 
> diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
> index 10e6366..52fdd1c 100644
> --- a/fs/nfsd/Kconfig
> +++ b/fs/nfsd/Kconfig
> @@ -80,3 +80,13 @@ config NFSD_V4
>  	  available from http://linux-nfs.org/.
>  
>  	  If unsure, say N.
> +
> +config NFSD_FAULT_INJECTION
> +	bool "NFS server manual fault injection"
> +	depends on NFSD_V4 && DEBUG_KERNEL
> +	help
> +	  This option enables support for manually injectiong faults
> +	  into the NFS server.  This is intended to be used for
> +	  testing error recovery on the NFS client.
> +
> +	  If unsure, say N.
> diff --git a/fs/nfsd/Makefile b/fs/nfsd/Makefile
> index 9b118ee..69eae75 100644
> --- a/fs/nfsd/Makefile
> +++ b/fs/nfsd/Makefile
> @@ -5,7 +5,8 @@
>  obj-$(CONFIG_NFSD)	+= nfsd.o
>  
>  nfsd-y 			:= nfssvc.o nfsctl.o nfsproc.o nfsfh.o vfs.o \
> -			   export.o auth.o lockd.o nfscache.o nfsxdr.o stats.o
> +			   export.o auth.o lockd.o nfscache.o nfsxdr.o stats.o \
> +			   fault_inject.o
>  nfsd-$(CONFIG_NFSD_V2_ACL) += nfs2acl.o
>  nfsd-$(CONFIG_NFSD_V3)	+= nfs3proc.o nfs3xdr.o
>  nfsd-$(CONFIG_NFSD_V3_ACL) += nfs3acl.o
> diff --git a/fs/nfsd/fault_inject.c b/fs/nfsd/fault_inject.c
> new file mode 100644
> index 0000000..2139883
> --- /dev/null
> +++ b/fs/nfsd/fault_inject.c
> @@ -0,0 +1,102 @@
> +#ifdef CONFIG_NFSD_FAULT_INJECTION
> +
> +#include <linux/types.h>
> +#include <linux/fs.h>
> +#include <linux/debugfs.h>
> +#include <linux/module.h>
> +
> +#include "state.h"
> +#include "nfsd.h"
> +
> +struct nfsd_fault_inject_op {
> +	char *action;
> +	char *item;
> +	char *file;
> +	int file_data;
> +	void (*func)(u64);
> +};
> +
> +#define INJECTION_OP(op_action, op_item, op_func)	\
> +{							\
> +	.action = op_action,				\
> +	.item   = op_item,				\
> +	.file   = op_action"_"op_item,			\
> +	.func   = op_func,				\
> +}
> +
> +static struct nfsd_fault_inject_op inject_ops[] = {
> +	INJECTION_OP("forget", "clients",     nfsd_forget_clients),
> +	INJECTION_OP("forget", "locks",       nfsd_forget_locks),
> +	INJECTION_OP("forget", "openowners",  nfsd_forget_openowners),
> +	INJECTION_OP("forget", "delegations", nfsd_forget_delegations),
> +	INJECTION_OP("recall", "delegations", nfsd_recall_delegations),
> +};
> +
> +static long int NUM_INJECT_OPS = sizeof(inject_ops) / sizeof(struct nfsd_fault_inject_op);
> +static struct dentry *debug_dir;
> +
> +static int nfsd_inject_set(void *data, u64 val)
> +{
> +	int i;
> +	struct nfsd_fault_inject_op *op;
> +
> +	for (i = 0; i < NUM_INJECT_OPS; i++) {
> +		op = &inject_ops[i];
> +		if (&op->file_data == data) {
> +			if (val == 0) {
> +				printk(KERN_INFO "NFSD: Server %sing all %s",
> +				op->action, op->item);
> +			} else {
> +				printk(KERN_INFO "NFSD: Server %sing at most %llu %s",
> +				op->action, val, op->item);
> +			}
> +			op->func(val);
> +		}
> +	}
> +	return 0;
> +}
> +
> +static int nfsd_inject_get(void *data, u64 *val)
> +{
> +	return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(fops_nfsd, nfsd_inject_get, nfsd_inject_set, "%llu\n");
> +
> +void nfsd_fault_inject_cleanup(void)
> +{
> +	debugfs_remove_recursive(debug_dir);
> +}
> +
> +int nfsd_fault_inject_init(void)
> +{
> +	unsigned int i;
> +	struct nfsd_fault_inject_op *op;
> +	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
> +
> +	debug_dir = debugfs_create_dir("nfsd", NULL);
> +	if (!debug_dir)
> +		goto fail;
> +
> +	for (i = 0; i < NUM_INJECT_OPS; i++) {
> +		op = &inject_ops[i];
> +		debugfs_create_file(op->file, mode, debug_dir, &op->file_data, &fops_nfsd);
> +	}
> +	return 0;
> +
> +fail:
> +	nfsd_fault_inject_cleanup();
> +	return -ENOMEM;
> +}
> +
> +#else /* CONFIG_NFSD_FAULT_INJECTION */
> +
> +inline void nfsd_fault_inject_cleanup(void)
> +{}
> +
> +inline int nfsd_fault_inject_init(void)
> +{
> +	return 0;
> +}
> +
> +#endif /* CONFIG_NFSD_FAULT_INJECTION */
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 05f4c69..64fa6b0 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4358,6 +4358,121 @@ nfs4_check_open_reclaim(clientid_t *clid)
>  	return nfs4_find_reclaim_client(clid) ? nfs_ok : nfserr_reclaim_bad;
>  }
>  
> +#ifdef CONFIG_NFSD_FAULT_INJECTION
> +
> +void nfsd_forget_clients(u64 num)
> +{
> +	struct nfs4_client *clp, *next;
> +	int count = 0;
> +
> +	nfs4_lock_state();
> +	list_for_each_entry_safe(clp, next, &client_lru, cl_lru) {
> +		nfsd4_remove_clid_dir(clp);
> +		expire_client(clp);
> +		if (++count == num)
> +			break;
> +	}
> +	nfs4_unlock_state();
> +
> +	printk(KERN_INFO "NFSD: Forgot %d clients", count);
> +}
> +
> +static void release_lockowner_sop(struct nfs4_stateowner *sop)
> +{
> +	release_lockowner(lockowner(sop));
> +}
> +
> +static void release_openowner_sop(struct nfs4_stateowner *sop)
> +{
> +	release_openowner(openowner(sop));
> +}
> +
> +static int nfsd_release_n_owners(u64 num,
> +				struct list_head hashtbl[],
> +				unsigned int hashtbl_size,
> +				void (*release_sop)(struct nfs4_stateowner *))
> +{
> +	int i, count = 0;
> +	struct nfs4_stateowner *sop, *next;
> +
> +	for (i = 0; i < hashtbl_size; i++) {
> +		list_for_each_entry_safe(sop, next, &hashtbl[i], so_strhash) {
> +			release_sop(sop);
> +			if (++count == num)
> +				return count;
> +		}
> +	}
> +	return count;
> +}
> +
> +void nfsd_forget_locks(u64 num)
> +{
> +	int count;
> +
> +	nfs4_lock_state();
> +	count = nfsd_release_n_owners(num, lock_ownerstr_hashtbl,
> +				     LOCK_HASH_SIZE, release_lockowner_sop);
> +	nfs4_unlock_state();
> +
> +	printk(KERN_INFO "NFSD: Forgot %d locks", count);
> +}
> +
> +void nfsd_forget_openowners(u64 num)
> +{
> +	int count;
> +
> +	nfs4_lock_state();
> +	count = nfsd_release_n_owners(num, open_ownerstr_hashtbl,
> +				     OPEN_OWNER_HASH_SIZE, release_openowner_sop);
> +	nfs4_unlock_state();
> +
> +	printk(KERN_INFO "NFSD: Forgot %d open owners", count);
> +}
> +
> +int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegation *))
> +{
> +	int i, count = 0;
> +	struct nfs4_file *fp;
> +	struct nfs4_delegation *dp, *next;
> +
> +	for (i = 0; i < FILE_HASH_SIZE; i++) {
> +		list_for_each_entry(fp, &file_hashtbl[i], fi_hash) {
> +			list_for_each_entry_safe(dp, next, &fp->fi_delegations, dl_perfile) {
> +				deleg_func(dp);
> +				if (++count == num)
> +					return count;
> +			}
> +		}
> +	}
> +	return count;
> +}
> +
> +void nfsd_forget_delegations(u64 num)
> +{
> +	unsigned int count;
> +
> +	nfs4_lock_state();
> +	count = nfsd_process_n_delegations(num, unhash_delegation);
> +	nfs4_unlock_state();
> +
> +	printk(KERN_INFO "NFSD: Forgot %d delegations", count);
> +}
> +
> +void nfsd_recall_delegations(u64 num)
> +{
> +	unsigned int count;
> +
> +	nfs4_lock_state();
> +	spin_lock(&recall_lock);
> +	count = nfsd_process_n_delegations(num, nfsd_break_one_deleg);
> +	spin_unlock(&recall_lock);
> +	nfs4_unlock_state();
> +
> +	printk(KERN_INFO "NFSD: Recalled %d delegations", count);
> +}
> +
> +#endif /* CONFIG_NFSD_FAULT_INJECTION */
> +
>  /* initialization to perform at module load time: */
>  
>  int
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index db34a58..e2f1b5a 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -1130,6 +1130,9 @@ static int __init init_nfsd(void)
>  	retval = nfs4_state_init(); /* nfs4 locking state */
>  	if (retval)
>  		return retval;
> +	retval = nfsd_fault_inject_init(); /* nfsd fault injection controls */
> +	if (retval)
> +		goto out_cleanup_fault_injection;
>  	nfsd_stat_init();	/* Statistics */
>  	retval = nfsd_reply_cache_init();
>  	if (retval)
> @@ -1161,6 +1164,8 @@ out_free_cache:
>  out_free_stat:
>  	nfsd_stat_shutdown();
>  	nfsd4_free_slabs();
> +out_cleanup_fault_injection:
> +	nfsd_fault_inject_cleanup();
>  	return retval;
>  }
>  
> @@ -1174,6 +1179,7 @@ static void __exit exit_nfsd(void)
>  	nfsd_lockd_shutdown();
>  	nfsd_idmap_shutdown();
>  	nfsd4_free_slabs();
> +	nfsd_fault_inject_cleanup();
>  	unregister_filesystem(&nfsd_fs_type);
>  }
>  
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 58134a2..3ea303d 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -105,11 +105,18 @@ static inline int nfsd_v4client(struct svc_rqst *rq)
>  #ifdef CONFIG_NFSD_V4
>  extern unsigned int max_delegations;
>  int nfs4_state_init(void);
> +int nfsd_fault_inject_init(void);
> +void nfsd_fault_inject_cleanup(void);
>  void nfsd4_free_slabs(void);
>  int nfs4_state_start(void);
>  void nfs4_state_shutdown(void);
>  void nfs4_reset_lease(time_t leasetime);
>  int nfs4_reset_recoverydir(char *recdir);
> +void nfsd_forget_clients(u64);
> +void nfsd_forget_locks(u64);
> +void nfsd_forget_openowners(u64);
> +void nfsd_forget_delegations(u64);
> +void nfsd_recall_delegations(u64);
>  #else
>  static inline int nfs4_state_init(void) { return 0; }
>  static inline void nfsd4_free_slabs(void) { }
> @@ -117,6 +124,11 @@ static inline int nfs4_state_start(void) { return 0; }
>  static inline void nfs4_state_shutdown(void) { }
>  static inline void nfs4_reset_lease(time_t leasetime) { }
>  static inline int nfs4_reset_recoverydir(char *recdir) { return 0; }
> +static inline void nfsd_forget_clients(u64) {}
> +static inline void nfsd_forget_locks(u64) {}
> +static inline void nfsd_forget_openowners(u64) {}
> +static inline void nfsd_forget_delegations(u64) {}
> +static inline void nfsd_recall_delegations(u64) {}
>  #endif
>  
>  /*
> -- 
> 1.7.6.4
>