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[Cluster-devel] Re: [PATCH 1/2] NLM failover unlock commands



On Tue, Jan 15, 2008 at 05:48:00PM -0500, Wendy Cheng wrote:
> Revised version of the patch:
>
> * based on comment from Neil Brown, use sscanf() to parse IP address (a  
> cool idea imo).
> * the "ret" inside nlm_traverse_files() is now the file count that can't  
> be unlocked.
> * other minor changes from latest round of review.

Thanks!

Remind me: why do we need both per-ip and per-filesystem methods?  In
practice, I assume that we'll always do *both*?

We're migrating clients by moving a server ip address from one node to
another.  And I assume we're permitting at most one node to export each
filesystem at a time.  So it *should* be the case that the set of locks
held on the filesystem(s) that are moving are the same as the set of
locks held by the virtual ip that is moving.

But presumably in some scenarios clients can get confused, and we need
to ensure that stale locks are not left behind?

We've discussed this before, but we should get the answer into comments
in the code (or on the patches).

--b.

>
> Thanks to all for the review !
>
> -- Wendy
>

> Two new NFSD procfs files are added:
>   /proc/fs/nfsd/unlock_ip
>   /proc/fs/nfsd/unlock_filesystem
> 
> They are intended to allow admin or user mode script to release NLM locks
> based on either a path name or a server in-bound ip address (ipv4 for now)
> as;
> 
> shell> echo 10.1.1.2 > /proc/fs/nfsd/unlock_ip
> shell> echo /mnt/sfs1 > /proc/fs/nfsd/unlock_filesystem
> 
> Signed-off-by: S. Wendy Cheng <wcheng redhat com>
> Signed-off-by: Lon Hohberger  <lhh redhat com>
> Signed-off-by: Christoph Hellwig <hch lst de>
> 
>  fs/lockd/svcsubs.c          |   66 +++++++++++++++++++++++++++++++++++++++-----
>  fs/nfsd/nfsctl.c            |   65 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/lockd/lockd.h |    7 ++++
>  3 files changed, 131 insertions(+), 7 deletions(-)
> 
> --- linux-o/fs/nfsd/nfsctl.c	2008-01-04 10:01:08.000000000 -0500
> +++ linux/fs/nfsd/nfsctl.c	2008-01-15 11:30:19.000000000 -0500
> @@ -22,6 +22,7 @@
>  #include <linux/seq_file.h>
>  #include <linux/pagemap.h>
>  #include <linux/init.h>
> +#include <linux/inet.h>
>  #include <linux/string.h>
>  #include <linux/smp_lock.h>
>  #include <linux/ctype.h>
> @@ -35,6 +36,7 @@
>  #include <linux/nfsd/cache.h>
>  #include <linux/nfsd/xdr.h>
>  #include <linux/nfsd/syscall.h>
> +#include <linux/lockd/lockd.h>
>  
>  #include <asm/uaccess.h>
>  
> @@ -52,6 +54,8 @@ enum {
>  	NFSD_Getfs,
>  	NFSD_List,
>  	NFSD_Fh,
> +	NFSD_FO_UnlockIP,
> +	NFSD_FO_UnlockFS,
>  	NFSD_Threads,
>  	NFSD_Pool_Threads,
>  	NFSD_Versions,
> @@ -88,6 +92,9 @@ static ssize_t write_leasetime(struct fi
>  static ssize_t write_recoverydir(struct file *file, char *buf, size_t size);
>  #endif
>  
> +static ssize_t failover_unlock_ip(struct file *file, char *buf, size_t size);
> +static ssize_t failover_unlock_fs(struct file *file, char *buf, size_t size);
> +
>  static ssize_t (*write_op[])(struct file *, char *, size_t) = {
>  	[NFSD_Svc] = write_svc,
>  	[NFSD_Add] = write_add,
> @@ -97,6 +104,8 @@ static ssize_t (*write_op[])(struct file
>  	[NFSD_Getfd] = write_getfd,
>  	[NFSD_Getfs] = write_getfs,
>  	[NFSD_Fh] = write_filehandle,
> +	[NFSD_FO_UnlockIP] = failover_unlock_ip,
> +	[NFSD_FO_UnlockFS] = failover_unlock_fs,
>  	[NFSD_Threads] = write_threads,
>  	[NFSD_Pool_Threads] = write_pool_threads,
>  	[NFSD_Versions] = write_versions,
> @@ -288,6 +297,58 @@ static ssize_t write_getfd(struct file *
>  	return err;
>  }
>  
> +static ssize_t failover_unlock_ip(struct file *file, char *buf, size_t size)
> +{
> +	__be32 server_ip;
> +	char *fo_path, c;
> +	int b1, b2, b3, b4;
> +
> +	/* sanity check */
> +	if (size == 0)
> +		return -EINVAL;
> +
> +	if (buf[size-1] != '\n')
> +		return -EINVAL;
> +
> +	fo_path = buf;
> +	if (qword_get(&buf, fo_path, size) < 0)
> +		return -EINVAL;
> +
> +	/* get ipv4 address */
> +	if (sscanf(fo_path, "%u.%u.%u.%u%c", &b1, &b2, &b3, &b4, &c) != 4)
> +		return -EINVAL;
> +	server_ip = htonl((((((b1<<8)|b2)<<8)|b3)<<8)|b4);
> +
> +	return nlmsvc_failover_ip(server_ip);
> +}
> +
> +static ssize_t failover_unlock_fs(struct file *file, char *buf, size_t size)
> +{
> +	struct nameidata nd;
> +	char *fo_path;
> +	int error;
> +
> +	/* sanity check */
> +	if (size == 0)
> +		return -EINVAL;
> +
> +	if (buf[size-1] != '\n')
> +		return -EINVAL;
> +
> +	fo_path = buf;
> +	if (qword_get(&buf, fo_path, size) < 0)
> +		return -EINVAL;
> +
> +	error = path_lookup(fo_path, 0, &nd);
> +	if (error)
> +		return error;
> +
> +	error = nlmsvc_failover_path(&nd);
> +
> +	path_release(&nd);
> +	return error;
> +}
> +
>  static ssize_t write_filehandle(struct file *file, char *buf, size_t size)
>  {
>  	/* request is:
> @@ -646,6 +707,10 @@ static int nfsd_fill_super(struct super_
>  		[NFSD_Getfd] = {".getfd", &transaction_ops, S_IWUSR|S_IRUSR},
>  		[NFSD_Getfs] = {".getfs", &transaction_ops, S_IWUSR|S_IRUSR},
>  		[NFSD_List] = {"exports", &exports_operations, S_IRUGO},
> +		[NFSD_FO_UnlockIP] = {"unlock_ip",
> +					&transaction_ops, S_IWUSR|S_IRUSR},
> +		[NFSD_FO_UnlockFS] = {"unlock_filesystem",
> +					&transaction_ops, S_IWUSR|S_IRUSR},
>  		[NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR|S_IRUSR},
>  		[NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR},
>  		[NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR},
> --- linux-o/fs/lockd/svcsubs.c	2008-01-04 10:01:08.000000000 -0500
> +++ linux/fs/lockd/svcsubs.c	2008-01-15 11:16:48.000000000 -0500
> @@ -18,6 +18,8 @@
>  #include <linux/lockd/lockd.h>
>  #include <linux/lockd/share.h>
>  #include <linux/lockd/sm_inter.h>
> +#include <linux/module.h>
> +#include <linux/mount.h>
>  
>  #define NLMDBG_FACILITY		NLMDBG_SVCSUBS
>  
> @@ -87,7 +89,7 @@ nlm_lookup_file(struct svc_rqst *rqstp, 
>  	unsigned int	hash;
>  	__be32		nfserr;
>  
> -	nlm_debug_print_fh("nlm_file_lookup", f);
> +	nlm_debug_print_fh("nlm_lookup_file", f);
>  
>  	hash = file_hash(f);
>  
> @@ -123,6 +125,9 @@ nlm_lookup_file(struct svc_rqst *rqstp, 
>  
>  	hlist_add_head(&file->f_list, &nlm_files[hash]);
>  
> +	/* fill in f_iaddr for nlm lock failover */
> +	file->f_iaddr = rqstp->rq_daddr;
> +
>  found:
>  	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
>  	*result = file;
> @@ -194,6 +199,12 @@ again:
>  	return 0;
>  }
>  
> +static int
> +nlmsvc_always_match(struct nlm_host *dummy1, struct nlm_host *dummy2)
> +{
> +	return 1;
> +}
> +
>  /*
>   * Inspect a single file
>   */
> @@ -230,7 +241,8 @@ nlm_file_inuse(struct nlm_file *file)
>   * Loop over all files in the file table.
>   */
>  static int
> -nlm_traverse_files(struct nlm_host *host, nlm_host_match_fn_t match)
> +nlm_traverse_files(void *data, nlm_host_match_fn_t match,
> +		int (*is_failover_file)(void *data, struct nlm_file *file))
>  {
>  	struct hlist_node *pos, *next;
>  	struct nlm_file	*file;
> @@ -244,8 +256,17 @@ nlm_traverse_files(struct nlm_host *host
>  
>  			/* Traverse locks, blocks and shares of this file
>  			 * and update file->f_locks count */
> -			if (nlm_inspect_file(host, file, match))
> -				ret = 1;
> +
> +			if (likely(is_failover_file == NULL) ||
> +				is_failover_file(data, file)) {
> +				/*
> +				 *  Note that nlm_inspect_file updates f_locks
> +				 *  and ret is the number of files that can't
> +				 *  be unlocked.
> +				 */
> +				ret += nlm_inspect_file(data, file, match);
> +			} else
> +				file->f_locks = nlm_file_inuse(file);
>  
>  			mutex_lock(&nlm_file_mutex);
>  			file->f_count--;
> @@ -337,7 +358,7 @@ void
>  nlmsvc_mark_resources(void)
>  {
>  	dprintk("lockd: nlmsvc_mark_resources\n");
> -	nlm_traverse_files(NULL, nlmsvc_mark_host);
> +	nlm_traverse_files(NULL, nlmsvc_mark_host, NULL);
>  }
>  
>  /*
> @@ -348,7 +369,7 @@ nlmsvc_free_host_resources(struct nlm_ho
>  {
>  	dprintk("lockd: nlmsvc_free_host_resources\n");
>  
> -	if (nlm_traverse_files(host, nlmsvc_same_host)) {
> +	if (nlm_traverse_files(host, nlmsvc_same_host, NULL)) {
>  		printk(KERN_WARNING
>  			"lockd: couldn't remove all locks held by %s\n",
>  			host->h_name);
> @@ -368,5 +389,36 @@ nlmsvc_invalidate_all(void)
>  	 * turn, which is about as inefficient as it gets.
>  	 * Now we just do it once in nlm_traverse_files.
>  	 */
> -	nlm_traverse_files(NULL, nlmsvc_is_client);
> +	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
> +}
> +
> +static int
> +nlmsvc_failover_file_ok_path(void *datap, struct nlm_file *file)
> +{
> +	struct nameidata *nd = datap;
> +	return nd->mnt == file->f_file->f_path.mnt;
> +}
> +
> +int
> +nlmsvc_failover_path(struct nameidata *nd)
> +{
> +	return nlm_traverse_files(nd, nlmsvc_always_match,
> +			nlmsvc_failover_file_ok_path);
> +}
> +EXPORT_SYMBOL_GPL(nlmsvc_failover_path);
> +
> +static int
> +nlmsvc_failover_file_ok_ip(void *datap, struct nlm_file *file)
> +{
> +	__be32 *server_addr = datap;
> +
> +	return file->f_iaddr.addr.s_addr == *server_addr;
> +}
> +
> +int
> +nlmsvc_failover_ip(__be32 server_addr)
> +{
> +	return nlm_traverse_files(&server_addr, nlmsvc_always_match,
> +			nlmsvc_failover_file_ok_ip);
>  }
> +EXPORT_SYMBOL_GPL(nlmsvc_failover_ip);
> --- linux-o/include/linux/lockd/lockd.h	2008-01-04 10:01:08.000000000 -0500
> +++ linux/include/linux/lockd/lockd.h	2008-01-15 11:13:04.000000000 -0500
> @@ -113,6 +113,7 @@ struct nlm_file {
>  	unsigned int		f_locks;	/* guesstimate # of locks */
>  	unsigned int		f_count;	/* reference count */
>  	struct mutex		f_mutex;	/* avoid concurrent access */
> +	union svc_addr_u	f_iaddr;	/* server ip for failover */
>  };
>  
>  /*
> @@ -214,6 +215,12 @@ void		  nlmsvc_mark_resources(void);
>  void		  nlmsvc_free_host_resources(struct nlm_host *);
>  void		  nlmsvc_invalidate_all(void);
>  
> +/*
> + * Cluster failover support
> + */
> +int           nlmsvc_failover_path(struct nameidata *nd);
> +int           nlmsvc_failover_ip(__be32 server_addr);
> +
>  static __inline__ struct inode *
>  nlmsvc_file_inode(struct nlm_file *file)
>  {


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