[5/8] Keep read and write fds with each nlm_file

Commit Message

Bruce Fields Aug. 20, 2021, 9:02 p.m. UTC

From: "J. Bruce Fields" <[e-mail]>

We shouldn't really be using a read-only file descriptor to take a write
lock.

Most filesystems will put up with it.  But NFS, for example, won't.

Signed-off-by: J. Bruce Fields <[e-mail]>
---
 fs/lockd/svc4proc.c         |   4 +-
 fs/lockd/svclock.c          |  25 ++++++---
 fs/lockd/svcproc.c          |   4 +-
 fs/lockd/svcsubs.c          | 104 +++++++++++++++++++++++++-----------
 fs/nfsd/lockd.c             |   8 ++-
 include/linux/lockd/bind.h  |   3 +-
 include/linux/lockd/lockd.h |   9 +++-
 7 files changed, 114 insertions(+), 43 deletions(-)

Comments

Chuck Lever Aug. 21, 2021, 4:30 p.m. UTC | #1

Nit: short description should start with "nlm:"


> On Aug 20, 2021, at 5:02 PM, J. Bruce Fields <[e-mail]> wrote:
> 
> From: "J. Bruce Fields" <[e-mail]>
> 
> We shouldn't really be using a read-only file descriptor to take a write
> lock.
> 
> Most filesystems will put up with it.  But NFS, for example, won't.

Two overall concerns:

1. Would it be easy/possible to split this patch further?

2. What kind of testing would provide a level of confidence
   that no regressions have been introduced by this change?


> Signed-off-by: J. Bruce Fields <[e-mail]>
> ---
> fs/lockd/svc4proc.c         |   4 +-
> fs/lockd/svclock.c          |  25 ++++++---
> fs/lockd/svcproc.c          |   4 +-
> fs/lockd/svcsubs.c          | 104 +++++++++++++++++++++++++-----------
> fs/nfsd/lockd.c             |   8 ++-
> include/linux/lockd/bind.h  |   3 +-
> include/linux/lockd/lockd.h |   9 +++-
> 7 files changed, 114 insertions(+), 43 deletions(-)
> 
> diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
> index aa8eca7c38a1..c7587de948e4 100644
> --- a/fs/lockd/svc4proc.c
> +++ b/fs/lockd/svc4proc.c
> @@ -40,12 +40,14 @@ nlm4svc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> 
> 	/* Obtain file pointer. Not used by FREE_ALL call. */
> 	if (filp != NULL) {
> +		int mode = lock_to_openmode(&lock->fl);
> +
> 		if ((error = nlm_lookup_file(rqstp, &file, lock)) != 0)
> 			goto no_locks;
> 		*filp = file;
> 
> 		/* Set up the missing parts of the file_lock structure */
> -		lock->fl.fl_file  = file->f_file;
> +		lock->fl.fl_file  = file->f_file[mode];
> 		lock->fl.fl_pid = current->tgid;
> 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
> 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index bc1cf31f3cce..d60e6eea2d57 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -471,6 +471,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> {
> 	struct nlm_block	*block = NULL;
> 	int			error;
> +	int			mode;
> 	__be32			ret;
> 
> 	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
> @@ -524,7 +525,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> 
> 	if (!wait)
> 		lock->fl.fl_flags &= ~FL_SLEEP;
> -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> +	mode = lock_to_openmode(&lock->fl);
> +	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
> 	lock->fl.fl_flags &= ~FL_SLEEP;
> 
> 	dprintk("lockd: vfs_lock_file returned %d\n", error);
> @@ -577,6 +579,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> 		struct nlm_lock *conflock, struct nlm_cookie *cookie)
> {
> 	int			error;
> +	int			mode;
> 	__be32			ret;
> 	struct nlm_lockowner	*test_owner;
> 
> @@ -595,7 +598,8 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> 	/* If there's a conflicting lock, remember to clean up the test lock */
> 	test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
> 
> -	error = vfs_test_lock(file->f_file, &lock->fl);
> +	mode = lock_to_openmode(&lock->fl);
> +	error = vfs_test_lock(file->f_file[mode], &lock->fl);
> 	if (error) {
> 		/* We can't currently deal with deferred test requests */
> 		if (error == FILE_LOCK_DEFERRED)
> @@ -641,7 +645,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> __be32
> nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
> {
> -	int	error;
> +	int	error = 0;
> 
> 	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
> 				nlmsvc_file_inode(file)->i_sb->s_id,
> @@ -654,7 +658,12 @@ nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
> 	nlmsvc_cancel_blocked(net, file, lock);
> 
> 	lock->fl.fl_type = F_UNLCK;
> -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> +	if (file->f_file[0])
> +		error = vfs_lock_file(file->f_file[0], F_SETLK,
> +					&lock->fl, NULL);
> +	if (file->f_file[1])
> +		error = vfs_lock_file(file->f_file[1], F_SETLK,
> +					&lock->fl, NULL);

Eschew raw integers :-) Should the f_file array be indexed
using O_ flags as the comment below suggests?


> 	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
> }
> @@ -671,6 +680,7 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
> {
> 	struct nlm_block	*block;
> 	int status = 0;
> +	int mode;
> 
> 	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
> 				nlmsvc_file_inode(file)->i_sb->s_id,
> @@ -686,7 +696,8 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
> 	block = nlmsvc_lookup_block(file, lock);
> 	mutex_unlock(&file->f_mutex);
> 	if (block != NULL) {
> -		vfs_cancel_lock(block->b_file->f_file,
> +		mode = lock_to_openmode(&lock->fl);
> +		vfs_cancel_lock(block->b_file->f_file[mode],
> 				&block->b_call->a_args.lock.fl);
> 		status = nlmsvc_unlink_block(block);
> 		nlmsvc_release_block(block);
> @@ -803,6 +814,7 @@ nlmsvc_grant_blocked(struct nlm_block *block)
> {
> 	struct nlm_file		*file = block->b_file;
> 	struct nlm_lock		*lock = &block->b_call->a_args.lock;
> +	int			mode;
> 	int			error;
> 	loff_t			fl_start, fl_end;
> 
> @@ -828,7 +840,8 @@ nlmsvc_grant_blocked(struct nlm_block *block)
> 	lock->fl.fl_flags |= FL_SLEEP;
> 	fl_start = lock->fl.fl_start;
> 	fl_end = lock->fl.fl_end;
> -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> +	mode = lock_to_openmode(&lock->fl);
> +	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
> 	lock->fl.fl_flags &= ~FL_SLEEP;
> 	lock->fl.fl_start = fl_start;
> 	lock->fl.fl_end = fl_end;
> diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
> index f4e5e0eb30fd..99696d3f6dd6 100644
> --- a/fs/lockd/svcproc.c
> +++ b/fs/lockd/svcproc.c
> @@ -55,6 +55,7 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> 	struct nlm_host		*host = NULL;
> 	struct nlm_file		*file = NULL;
> 	struct nlm_lock		*lock = &argp->lock;
> +	int			mode;
> 	__be32			error = 0;
> 
> 	/* nfsd callbacks must have been installed for this procedure */
> @@ -75,7 +76,8 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> 		*filp = file;
> 
> 		/* Set up the missing parts of the file_lock structure */
> -		lock->fl.fl_file  = file->f_file;
> +		mode = lock_to_openmode(&lock->fl);
> +		lock->fl.fl_file  = file->f_file[mode];
> 		lock->fl.fl_pid = current->tgid;
> 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
> 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
> diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
> index f43d89e89c45..a0adaee245ae 100644
> --- a/fs/lockd/svcsubs.c
> +++ b/fs/lockd/svcsubs.c
> @@ -71,14 +71,38 @@ static inline unsigned int file_hash(struct nfs_fh *f)
> 	return tmp & (FILE_NRHASH - 1);
> }
> 
> +int lock_to_openmode(struct file_lock *lock)
> +{
> +	if (lock->fl_type == F_WRLCK)
> +		return O_WRONLY;
> +	else
> +		return O_RDONLY;

Style: a ternary would be more consistent with other areas
of the code you change in this patch.


> +}
> +
> +/*
> + * Open the file. Note that if we're reexporting, for example,
> + * this could block the lockd thread for a while.
> + *
> + * We have to make sure we have the right credential to open
> + * the file.
> + */
> +static __be32 nlm_do_fopen(struct svc_rqst *rqstp,
> +			   struct nlm_file *file, int mode)
> +{
> +	struct file **fp = &file->f_file[mode];
> +	__be32	nfserr;
> +
> +	if (*fp)
> +		return 0;
> +	nfserr = nlmsvc_ops->fopen(rqstp, &file->f_handle, fp, mode);
> +	if (nfserr)
> +		dprintk("lockd: open failed (error %d)\n", nfserr);
> +	return nfserr;
> +}
> +
> /*
>  * Lookup file info. If it doesn't exist, create a file info struct
>  * and open a (VFS) file for the given inode.
> - *
> - * FIXME:
> - * Note that we open the file O_RDONLY even when creating write locks.
> - * This is not quite right, but for now, we assume the client performs
> - * the proper R/W checking.
>  */
> __be32
> nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> @@ -87,41 +111,38 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> 	struct nlm_file	*file;
> 	unsigned int	hash;
> 	__be32		nfserr;
> +	int		mode;
> 
> 	nlm_debug_print_fh("nlm_lookup_file", &lock->fh);
> 
> 	hash = file_hash(&lock->fh);
> +	mode = lock_to_openmode(&lock->fl);
> 
> 	/* Lock file table */
> 	mutex_lock(&nlm_file_mutex);
> 
> 	hlist_for_each_entry(file, &nlm_files[hash], f_list)
> -		if (!nfs_compare_fh(&file->f_handle, &lock->fh))
> +		if (!nfs_compare_fh(&file->f_handle, &lock->fh)) {
> +			mutex_lock(&file->f_mutex);
> +			nfserr = nlm_do_fopen(rqstp, file, mode);
> +			mutex_unlock(&file->f_mutex);
> 			goto found;
> -
> +		}
> 	nlm_debug_print_fh("creating file for", &lock->fh);
> 
> 	nfserr = nlm_lck_denied_nolocks;
> 	file = kzalloc(sizeof(*file), GFP_KERNEL);
> 	if (!file)
> -		goto out_unlock;
> +		goto out_free;
> 
> 	memcpy(&file->f_handle, &lock->fh, sizeof(struct nfs_fh));
> 	mutex_init(&file->f_mutex);
> 	INIT_HLIST_NODE(&file->f_list);
> 	INIT_LIST_HEAD(&file->f_blocks);
> 
> -	/*
> -	 * Open the file. Note that if we're reexporting, for example,
> -	 * this could block the lockd thread for a while.
> -	 *
> -	 * We have to make sure we have the right credential to open
> -	 * the file.
> -	 */
> -	if ((nfserr = nlmsvc_ops->fopen(rqstp, &lock->fh, &file->f_file)) != 0) {
> -		dprintk("lockd: open failed (error %d)\n", nfserr);
> -		goto out_free;
> -	}
> +	nfserr = nlm_do_fopen(rqstp, file, mode);
> +	if (nfserr)
> +		goto out_unlock;
> 
> 	hlist_add_head(&file->f_list, &nlm_files[hash]);
> 
> @@ -129,7 +150,6 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> 	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
> 	*result = file;
> 	file->f_count++;
> -	nfserr = 0;
> 
> out_unlock:
> 	mutex_unlock(&nlm_file_mutex);
> @@ -149,13 +169,34 @@ nlm_delete_file(struct nlm_file *file)
> 	nlm_debug_print_file("closing file", file);
> 	if (!hlist_unhashed(&file->f_list)) {
> 		hlist_del(&file->f_list);
> -		nlmsvc_ops->fclose(file->f_file);
> +		if (file->f_file[O_RDONLY])
> +			nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
> +		if (file->f_file[O_WRONLY])
> +			nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
> 		kfree(file);
> 	} else {
> 		printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
> 	}
> }
> 
> +static int nlm_unlock_files(struct nlm_file *file)
> +{
> +	struct file_lock lock;
> +	struct file *f;
> +
> +	lock.fl_type  = F_UNLCK;
> +	lock.fl_start = 0;
> +	lock.fl_end   = OFFSET_MAX;
> +	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
> +		if (f && vfs_lock_file(f, F_SETLK, &lock, NULL) < 0) {
> +			printk("lockd: unlock failure in %s:%d\n",
> +				__FILE__, __LINE__);

This needs a KERN_LEVEL and maybe a _once.


> +			return 1;
> +		}
> +	}
> +	return 0;
> +}
> +
> /*
>  * Loop over all locks on the given file and perform the specified
>  * action.
> @@ -183,17 +224,10 @@ nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
> 
> 		lockhost = ((struct nlm_lockowner *)fl->fl_owner)->host;
> 		if (match(lockhost, host)) {
> -			struct file_lock lock = *fl;
> 
> 			spin_unlock(&flctx->flc_lock);
> -			lock.fl_type  = F_UNLCK;
> -			lock.fl_start = 0;
> -			lock.fl_end   = OFFSET_MAX;
> -			if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
> -				printk("lockd: unlock failure in %s:%d\n",
> -						__FILE__, __LINE__);
> +			if (nlm_unlock_files(file))
> 				return 1;
> -			}
> 			goto again;
> 		}
> 	}
> @@ -247,6 +281,15 @@ nlm_file_inuse(struct nlm_file *file)
> 	return 0;
> }
> 
> +static void nlm_close_files(struct nlm_file *file)
> +{
> +	struct file *f;
> +
> +	for (f = file->f_file[0]; f <= file->f_file[1]; f++)
> +		if (f)
> +			nlmsvc_ops->fclose(f);
> +}
> +
> /*
>  * Loop over all files in the file table.
>  */
> @@ -277,7 +320,7 @@ nlm_traverse_files(void *data, nlm_host_match_fn_t match,
> 			if (list_empty(&file->f_blocks) && !file->f_locks
> 			 && !file->f_shares && !file->f_count) {
> 				hlist_del(&file->f_list);
> -				nlmsvc_ops->fclose(file->f_file);
> +				nlm_close_files(file);
> 				kfree(file);
> 			}
> 		}
> @@ -411,6 +454,7 @@ nlmsvc_invalidate_all(void)
> 	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
> }
> 
> +
> static int
> nlmsvc_match_sb(void *datap, struct nlm_file *file)
> {
> diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
> index 3f5b3d7b62b7..606fa155c28a 100644
> --- a/fs/nfsd/lockd.c
> +++ b/fs/nfsd/lockd.c
> @@ -25,9 +25,11 @@
>  * Note: we hold the dentry use count while the file is open.
>  */
> static __be32
> -nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
> +nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
> +		int mode)
> {
> 	__be32		nfserr;
> +	int		access;
> 	struct svc_fh	fh;
> 
> 	/* must initialize before using! but maxsize doesn't matter */
> @@ -36,7 +38,9 @@ nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
> 	memcpy((char*)&fh.fh_handle.fh_base, f->data, f->size);
> 	fh.fh_export = NULL;
> 
> -	nfserr = nfsd_open(rqstp, &fh, S_IFREG, NFSD_MAY_LOCK, filp);
> +	access = (mode == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
> +	access |= NFSD_MAY_LOCK;
> +	nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
> 	fh_put(&fh);
>  	/* We return nlm error codes as nlm doesn't know
> 	 * about nfsd, but nfsd does know about nlm..
> diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
> index 0520c0cd73f4..3bc9f7410e21 100644
> --- a/include/linux/lockd/bind.h
> +++ b/include/linux/lockd/bind.h
> @@ -27,7 +27,8 @@ struct rpc_task;
> struct nlmsvc_binding {
> 	__be32			(*fopen)(struct svc_rqst *,
> 						struct nfs_fh *,
> -						struct file **);
> +						struct file **,
> +						int mode);

Style: "mode_t mode" might be better internal documentation.


> 	void			(*fclose)(struct file *);
> };
> 
> diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
> index 81b71ad2040a..da319de7e557 100644
> --- a/include/linux/lockd/lockd.h
> +++ b/include/linux/lockd/lockd.h
> @@ -10,6 +10,8 @@
> #ifndef LINUX_LOCKD_LOCKD_H
> #define LINUX_LOCKD_LOCKD_H
> 
> +/* XXX: a lot of this should really be under fs/lockd. */
> +
> #include <linux/in.h>
> #include <linux/in6.h>
> #include <net/ipv6.h>
> @@ -154,7 +156,8 @@ struct nlm_rqst {
> struct nlm_file {
> 	struct hlist_node	f_list;		/* linked list */
> 	struct nfs_fh		f_handle;	/* NFS file handle */
> -	struct file *		f_file;		/* VFS file pointer */
> +	struct file *		f_file[2];	/* VFS file pointers,
> +						   indexed by O_ flags */

Right, except that the new code in this patch always indexes
f_file with raw integers, making the comment misleading. My
preference is to keep the comment and change the new code to
index f_file symbolically.


> 	struct nlm_share *	f_shares;	/* DOS shares */
> 	struct list_head	f_blocks;	/* blocked locks */
> 	unsigned int		f_locks;	/* guesstimate # of locks */
> @@ -267,6 +270,7 @@ typedef int	  (*nlm_host_match_fn_t)(void *cur, struct nlm_host *ref);
> /*
>  * Server-side lock handling
>  */
> +int		  lock_to_openmode(struct file_lock *);
> __be32		  nlmsvc_lock(struct svc_rqst *, struct nlm_file *,
> 			      struct nlm_host *, struct nlm_lock *, int,
> 			      struct nlm_cookie *, int);
> @@ -301,7 +305,8 @@ int           nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
> 
> static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
> {
> -	return locks_inode(file->f_file);
> +	return locks_inode(file->f_file[0] ?
> +				file->f_file[0] : file->f_file[1]);
> }
> 
> static inline int __nlm_privileged_request4(const struct sockaddr *sap)
> -- 
> 2.31.1
> 

--
Chuck Lever

J. Bruce Fields Aug. 23, 2021, 4:08 p.m. UTC | #2

On Sat, Aug 21, 2021 at 04:30:43PM +0000, Chuck Lever III wrote:
> Nit: short description should start with "nlm:"
> 
> 
> > On Aug 20, 2021, at 5:02 PM, J. Bruce Fields <[e-mail]> wrote:
> > 
> > From: "J. Bruce Fields" <[e-mail]>
> > 
> > We shouldn't really be using a read-only file descriptor to take a write
> > lock.
> > 
> > Most filesystems will put up with it.  But NFS, for example, won't.
> 
> Two overall concerns:
> 
> 1. Would it be easy/possible to split this patch further?

I'm not sure.

> 2. What kind of testing would provide a level of confidence
>    that no regressions have been introduced by this change?

I've just run my usual tests; the only ones relevant to this are
"cthon -a" over v3 (with and without krb5), and a few tests of my own I
wrote for some long-ago regressions
(http://git.linux-nfs.org/?p=bfields/lock-tests.git;a=summary).

(And I also did the same over v3 re-export of a 4.2 mount, but that's
more to check for the fix than for regressions.)

--b.

> 
> 
> > Signed-off-by: J. Bruce Fields <[e-mail]>
> > ---
> > fs/lockd/svc4proc.c         |   4 +-
> > fs/lockd/svclock.c          |  25 ++++++---
> > fs/lockd/svcproc.c          |   4 +-
> > fs/lockd/svcsubs.c          | 104 +++++++++++++++++++++++++-----------
> > fs/nfsd/lockd.c             |   8 ++-
> > include/linux/lockd/bind.h  |   3 +-
> > include/linux/lockd/lockd.h |   9 +++-
> > 7 files changed, 114 insertions(+), 43 deletions(-)
> > 
> > diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
> > index aa8eca7c38a1..c7587de948e4 100644
> > --- a/fs/lockd/svc4proc.c
> > +++ b/fs/lockd/svc4proc.c
> > @@ -40,12 +40,14 @@ nlm4svc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> > 
> > 	/* Obtain file pointer. Not used by FREE_ALL call. */
> > 	if (filp != NULL) {
> > +		int mode = lock_to_openmode(&lock->fl);
> > +
> > 		if ((error = nlm_lookup_file(rqstp, &file, lock)) != 0)
> > 			goto no_locks;
> > 		*filp = file;
> > 
> > 		/* Set up the missing parts of the file_lock structure */
> > -		lock->fl.fl_file  = file->f_file;
> > +		lock->fl.fl_file  = file->f_file[mode];
> > 		lock->fl.fl_pid = current->tgid;
> > 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
> > 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
> > diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> > index bc1cf31f3cce..d60e6eea2d57 100644
> > --- a/fs/lockd/svclock.c
> > +++ b/fs/lockd/svclock.c
> > @@ -471,6 +471,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> > {
> > 	struct nlm_block	*block = NULL;
> > 	int			error;
> > +	int			mode;
> > 	__be32			ret;
> > 
> > 	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
> > @@ -524,7 +525,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> > 
> > 	if (!wait)
> > 		lock->fl.fl_flags &= ~FL_SLEEP;
> > -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> > +	mode = lock_to_openmode(&lock->fl);
> > +	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
> > 	lock->fl.fl_flags &= ~FL_SLEEP;
> > 
> > 	dprintk("lockd: vfs_lock_file returned %d\n", error);
> > @@ -577,6 +579,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> > 		struct nlm_lock *conflock, struct nlm_cookie *cookie)
> > {
> > 	int			error;
> > +	int			mode;
> > 	__be32			ret;
> > 	struct nlm_lockowner	*test_owner;
> > 
> > @@ -595,7 +598,8 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> > 	/* If there's a conflicting lock, remember to clean up the test lock */
> > 	test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
> > 
> > -	error = vfs_test_lock(file->f_file, &lock->fl);
> > +	mode = lock_to_openmode(&lock->fl);
> > +	error = vfs_test_lock(file->f_file[mode], &lock->fl);
> > 	if (error) {
> > 		/* We can't currently deal with deferred test requests */
> > 		if (error == FILE_LOCK_DEFERRED)
> > @@ -641,7 +645,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> > __be32
> > nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
> > {
> > -	int	error;
> > +	int	error = 0;
> > 
> > 	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
> > 				nlmsvc_file_inode(file)->i_sb->s_id,
> > @@ -654,7 +658,12 @@ nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
> > 	nlmsvc_cancel_blocked(net, file, lock);
> > 
> > 	lock->fl.fl_type = F_UNLCK;
> > -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> > +	if (file->f_file[0])
> > +		error = vfs_lock_file(file->f_file[0], F_SETLK,
> > +					&lock->fl, NULL);
> > +	if (file->f_file[1])
> > +		error = vfs_lock_file(file->f_file[1], F_SETLK,
> > +					&lock->fl, NULL);
> 
> Eschew raw integers :-) Should the f_file array be indexed
> using O_ flags as the comment below suggests?
> 
> 
> > 	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
> > }
> > @@ -671,6 +680,7 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
> > {
> > 	struct nlm_block	*block;
> > 	int status = 0;
> > +	int mode;
> > 
> > 	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
> > 				nlmsvc_file_inode(file)->i_sb->s_id,
> > @@ -686,7 +696,8 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
> > 	block = nlmsvc_lookup_block(file, lock);
> > 	mutex_unlock(&file->f_mutex);
> > 	if (block != NULL) {
> > -		vfs_cancel_lock(block->b_file->f_file,
> > +		mode = lock_to_openmode(&lock->fl);
> > +		vfs_cancel_lock(block->b_file->f_file[mode],
> > 				&block->b_call->a_args.lock.fl);
> > 		status = nlmsvc_unlink_block(block);
> > 		nlmsvc_release_block(block);
> > @@ -803,6 +814,7 @@ nlmsvc_grant_blocked(struct nlm_block *block)
> > {
> > 	struct nlm_file		*file = block->b_file;
> > 	struct nlm_lock		*lock = &block->b_call->a_args.lock;
> > +	int			mode;
> > 	int			error;
> > 	loff_t			fl_start, fl_end;
> > 
> > @@ -828,7 +840,8 @@ nlmsvc_grant_blocked(struct nlm_block *block)
> > 	lock->fl.fl_flags |= FL_SLEEP;
> > 	fl_start = lock->fl.fl_start;
> > 	fl_end = lock->fl.fl_end;
> > -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> > +	mode = lock_to_openmode(&lock->fl);
> > +	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
> > 	lock->fl.fl_flags &= ~FL_SLEEP;
> > 	lock->fl.fl_start = fl_start;
> > 	lock->fl.fl_end = fl_end;
> > diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
> > index f4e5e0eb30fd..99696d3f6dd6 100644
> > --- a/fs/lockd/svcproc.c
> > +++ b/fs/lockd/svcproc.c
> > @@ -55,6 +55,7 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> > 	struct nlm_host		*host = NULL;
> > 	struct nlm_file		*file = NULL;
> > 	struct nlm_lock		*lock = &argp->lock;
> > +	int			mode;
> > 	__be32			error = 0;
> > 
> > 	/* nfsd callbacks must have been installed for this procedure */
> > @@ -75,7 +76,8 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> > 		*filp = file;
> > 
> > 		/* Set up the missing parts of the file_lock structure */
> > -		lock->fl.fl_file  = file->f_file;
> > +		mode = lock_to_openmode(&lock->fl);
> > +		lock->fl.fl_file  = file->f_file[mode];
> > 		lock->fl.fl_pid = current->tgid;
> > 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
> > 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
> > diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
> > index f43d89e89c45..a0adaee245ae 100644
> > --- a/fs/lockd/svcsubs.c
> > +++ b/fs/lockd/svcsubs.c
> > @@ -71,14 +71,38 @@ static inline unsigned int file_hash(struct nfs_fh *f)
> > 	return tmp & (FILE_NRHASH - 1);
> > }
> > 
> > +int lock_to_openmode(struct file_lock *lock)
> > +{
> > +	if (lock->fl_type == F_WRLCK)
> > +		return O_WRONLY;
> > +	else
> > +		return O_RDONLY;
> 
> Style: a ternary would be more consistent with other areas
> of the code you change in this patch.
> 
> 
> > +}
> > +
> > +/*
> > + * Open the file. Note that if we're reexporting, for example,
> > + * this could block the lockd thread for a while.
> > + *
> > + * We have to make sure we have the right credential to open
> > + * the file.
> > + */
> > +static __be32 nlm_do_fopen(struct svc_rqst *rqstp,
> > +			   struct nlm_file *file, int mode)
> > +{
> > +	struct file **fp = &file->f_file[mode];
> > +	__be32	nfserr;
> > +
> > +	if (*fp)
> > +		return 0;
> > +	nfserr = nlmsvc_ops->fopen(rqstp, &file->f_handle, fp, mode);
> > +	if (nfserr)
> > +		dprintk("lockd: open failed (error %d)\n", nfserr);
> > +	return nfserr;
> > +}
> > +
> > /*
> >  * Lookup file info. If it doesn't exist, create a file info struct
> >  * and open a (VFS) file for the given inode.
> > - *
> > - * FIXME:
> > - * Note that we open the file O_RDONLY even when creating write locks.
> > - * This is not quite right, but for now, we assume the client performs
> > - * the proper R/W checking.
> >  */
> > __be32
> > nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> > @@ -87,41 +111,38 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> > 	struct nlm_file	*file;
> > 	unsigned int	hash;
> > 	__be32		nfserr;
> > +	int		mode;
> > 
> > 	nlm_debug_print_fh("nlm_lookup_file", &lock->fh);
> > 
> > 	hash = file_hash(&lock->fh);
> > +	mode = lock_to_openmode(&lock->fl);
> > 
> > 	/* Lock file table */
> > 	mutex_lock(&nlm_file_mutex);
> > 
> > 	hlist_for_each_entry(file, &nlm_files[hash], f_list)
> > -		if (!nfs_compare_fh(&file->f_handle, &lock->fh))
> > +		if (!nfs_compare_fh(&file->f_handle, &lock->fh)) {
> > +			mutex_lock(&file->f_mutex);
> > +			nfserr = nlm_do_fopen(rqstp, file, mode);
> > +			mutex_unlock(&file->f_mutex);
> > 			goto found;
> > -
> > +		}
> > 	nlm_debug_print_fh("creating file for", &lock->fh);
> > 
> > 	nfserr = nlm_lck_denied_nolocks;
> > 	file = kzalloc(sizeof(*file), GFP_KERNEL);
> > 	if (!file)
> > -		goto out_unlock;
> > +		goto out_free;
> > 
> > 	memcpy(&file->f_handle, &lock->fh, sizeof(struct nfs_fh));
> > 	mutex_init(&file->f_mutex);
> > 	INIT_HLIST_NODE(&file->f_list);
> > 	INIT_LIST_HEAD(&file->f_blocks);
> > 
> > -	/*
> > -	 * Open the file. Note that if we're reexporting, for example,
> > -	 * this could block the lockd thread for a while.
> > -	 *
> > -	 * We have to make sure we have the right credential to open
> > -	 * the file.
> > -	 */
> > -	if ((nfserr = nlmsvc_ops->fopen(rqstp, &lock->fh, &file->f_file)) != 0) {
> > -		dprintk("lockd: open failed (error %d)\n", nfserr);
> > -		goto out_free;
> > -	}
> > +	nfserr = nlm_do_fopen(rqstp, file, mode);
> > +	if (nfserr)
> > +		goto out_unlock;
> > 
> > 	hlist_add_head(&file->f_list, &nlm_files[hash]);
> > 
> > @@ -129,7 +150,6 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> > 	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
> > 	*result = file;
> > 	file->f_count++;
> > -	nfserr = 0;
> > 
> > out_unlock:
> > 	mutex_unlock(&nlm_file_mutex);
> > @@ -149,13 +169,34 @@ nlm_delete_file(struct nlm_file *file)
> > 	nlm_debug_print_file("closing file", file);
> > 	if (!hlist_unhashed(&file->f_list)) {
> > 		hlist_del(&file->f_list);
> > -		nlmsvc_ops->fclose(file->f_file);
> > +		if (file->f_file[O_RDONLY])
> > +			nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
> > +		if (file->f_file[O_WRONLY])
> > +			nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
> > 		kfree(file);
> > 	} else {
> > 		printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
> > 	}
> > }
> > 
> > +static int nlm_unlock_files(struct nlm_file *file)
> > +{
> > +	struct file_lock lock;
> > +	struct file *f;
> > +
> > +	lock.fl_type  = F_UNLCK;
> > +	lock.fl_start = 0;
> > +	lock.fl_end   = OFFSET_MAX;
> > +	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
> > +		if (f && vfs_lock_file(f, F_SETLK, &lock, NULL) < 0) {
> > +			printk("lockd: unlock failure in %s:%d\n",
> > +				__FILE__, __LINE__);
> 
> This needs a KERN_LEVEL and maybe a _once.
> 
> 
> > +			return 1;
> > +		}
> > +	}
> > +	return 0;
> > +}
> > +
> > /*
> >  * Loop over all locks on the given file and perform the specified
> >  * action.
> > @@ -183,17 +224,10 @@ nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
> > 
> > 		lockhost = ((struct nlm_lockowner *)fl->fl_owner)->host;
> > 		if (match(lockhost, host)) {
> > -			struct file_lock lock = *fl;
> > 
> > 			spin_unlock(&flctx->flc_lock);
> > -			lock.fl_type  = F_UNLCK;
> > -			lock.fl_start = 0;
> > -			lock.fl_end   = OFFSET_MAX;
> > -			if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
> > -				printk("lockd: unlock failure in %s:%d\n",
> > -						__FILE__, __LINE__);
> > +			if (nlm_unlock_files(file))
> > 				return 1;
> > -			}
> > 			goto again;
> > 		}
> > 	}
> > @@ -247,6 +281,15 @@ nlm_file_inuse(struct nlm_file *file)
> > 	return 0;
> > }
> > 
> > +static void nlm_close_files(struct nlm_file *file)
> > +{
> > +	struct file *f;
> > +
> > +	for (f = file->f_file[0]; f <= file->f_file[1]; f++)
> > +		if (f)
> > +			nlmsvc_ops->fclose(f);
> > +}
> > +
> > /*
> >  * Loop over all files in the file table.
> >  */
> > @@ -277,7 +320,7 @@ nlm_traverse_files(void *data, nlm_host_match_fn_t match,
> > 			if (list_empty(&file->f_blocks) && !file->f_locks
> > 			 && !file->f_shares && !file->f_count) {
> > 				hlist_del(&file->f_list);
> > -				nlmsvc_ops->fclose(file->f_file);
> > +				nlm_close_files(file);
> > 				kfree(file);
> > 			}
> > 		}
> > @@ -411,6 +454,7 @@ nlmsvc_invalidate_all(void)
> > 	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
> > }
> > 
> > +
> > static int
> > nlmsvc_match_sb(void *datap, struct nlm_file *file)
> > {
> > diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
> > index 3f5b3d7b62b7..606fa155c28a 100644
> > --- a/fs/nfsd/lockd.c
> > +++ b/fs/nfsd/lockd.c
> > @@ -25,9 +25,11 @@
> >  * Note: we hold the dentry use count while the file is open.
> >  */
> > static __be32
> > -nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
> > +nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
> > +		int mode)
> > {
> > 	__be32		nfserr;
> > +	int		access;
> > 	struct svc_fh	fh;
> > 
> > 	/* must initialize before using! but maxsize doesn't matter */
> > @@ -36,7 +38,9 @@ nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
> > 	memcpy((char*)&fh.fh_handle.fh_base, f->data, f->size);
> > 	fh.fh_export = NULL;
> > 
> > -	nfserr = nfsd_open(rqstp, &fh, S_IFREG, NFSD_MAY_LOCK, filp);
> > +	access = (mode == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
> > +	access |= NFSD_MAY_LOCK;
> > +	nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
> > 	fh_put(&fh);
> >  	/* We return nlm error codes as nlm doesn't know
> > 	 * about nfsd, but nfsd does know about nlm..
> > diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
> > index 0520c0cd73f4..3bc9f7410e21 100644
> > --- a/include/linux/lockd/bind.h
> > +++ b/include/linux/lockd/bind.h
> > @@ -27,7 +27,8 @@ struct rpc_task;
> > struct nlmsvc_binding {
> > 	__be32			(*fopen)(struct svc_rqst *,
> > 						struct nfs_fh *,
> > -						struct file **);
> > +						struct file **,
> > +						int mode);
> 
> Style: "mode_t mode" might be better internal documentation.
> 
> 
> > 	void			(*fclose)(struct file *);
> > };
> > 
> > diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
> > index 81b71ad2040a..da319de7e557 100644
> > --- a/include/linux/lockd/lockd.h
> > +++ b/include/linux/lockd/lockd.h
> > @@ -10,6 +10,8 @@
> > #ifndef LINUX_LOCKD_LOCKD_H
> > #define LINUX_LOCKD_LOCKD_H
> > 
> > +/* XXX: a lot of this should really be under fs/lockd. */
> > +
> > #include <linux/in.h>
> > #include <linux/in6.h>
> > #include <net/ipv6.h>
> > @@ -154,7 +156,8 @@ struct nlm_rqst {
> > struct nlm_file {
> > 	struct hlist_node	f_list;		/* linked list */
> > 	struct nfs_fh		f_handle;	/* NFS file handle */
> > -	struct file *		f_file;		/* VFS file pointer */
> > +	struct file *		f_file[2];	/* VFS file pointers,
> > +						   indexed by O_ flags */
> 
> Right, except that the new code in this patch always indexes
> f_file with raw integers, making the comment misleading. My
> preference is to keep the comment and change the new code to
> index f_file symbolically.
> 
> 
> > 	struct nlm_share *	f_shares;	/* DOS shares */
> > 	struct list_head	f_blocks;	/* blocked locks */
> > 	unsigned int		f_locks;	/* guesstimate # of locks */
> > @@ -267,6 +270,7 @@ typedef int	  (*nlm_host_match_fn_t)(void *cur, struct nlm_host *ref);
> > /*
> >  * Server-side lock handling
> >  */
> > +int		  lock_to_openmode(struct file_lock *);
> > __be32		  nlmsvc_lock(struct svc_rqst *, struct nlm_file *,
> > 			      struct nlm_host *, struct nlm_lock *, int,
> > 			      struct nlm_cookie *, int);
> > @@ -301,7 +305,8 @@ int           nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
> > 
> > static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
> > {
> > -	return locks_inode(file->f_file);
> > +	return locks_inode(file->f_file[0] ?
> > +				file->f_file[0] : file->f_file[1]);
> > }
> > 
> > static inline int __nlm_privileged_request4(const struct sockaddr *sap)
> > -- 
> > 2.31.1
> > 
> 
> --
> Chuck Lever
> 
>

J. Bruce Fields Aug. 23, 2021, 6:57 p.m. UTC | #3

On Sat, Aug 21, 2021 at 04:30:43PM +0000, Chuck Lever III wrote:
> > @@ -654,7 +658,12 @@ nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
> > 	nlmsvc_cancel_blocked(net, file, lock);
> > 
> > 	lock->fl.fl_type = F_UNLCK;
> > -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> > +	if (file->f_file[0])
> > +		error = vfs_lock_file(file->f_file[0], F_SETLK,
> > +					&lock->fl, NULL);
> > +	if (file->f_file[1])
> > +		error = vfs_lock_file(file->f_file[1], F_SETLK,
> > +					&lock->fl, NULL);
> 
> Eschew raw integers :-) Should the f_file array be indexed
> using O_ flags as the comment below suggests?

Sure, done.

> > diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
> > index f43d89e89c45..a0adaee245ae 100644
> > --- a/fs/lockd/svcsubs.c
> > +++ b/fs/lockd/svcsubs.c
> > @@ -71,14 +71,38 @@ static inline unsigned int file_hash(struct nfs_fh *f)
> > 	return tmp & (FILE_NRHASH - 1);
> > }
> > 
> > +int lock_to_openmode(struct file_lock *lock)
> > +{
> > +	if (lock->fl_type == F_WRLCK)
> > +		return O_WRONLY;
> > +	else
> > +		return O_RDONLY;
> 
> Style: a ternary would be more consistent with other areas
> of the code you change in this patch.

OK.

> > +static int nlm_unlock_files(struct nlm_file *file)
> > +{
> > +	struct file_lock lock;
> > +	struct file *f;
> > +
> > +	lock.fl_type  = F_UNLCK;
> > +	lock.fl_start = 0;
> > +	lock.fl_end   = OFFSET_MAX;
> > +	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
> > +		if (f && vfs_lock_file(f, F_SETLK, &lock, NULL) < 0) {
> > +			printk("lockd: unlock failure in %s:%d\n",
> > +				__FILE__, __LINE__);
> 
> This needs a KERN_LEVEL and maybe a _once.

How about going with pr_warn for now.  I don't *think* there's much
danger of spamming the logs from this one.  And I'm wondering there
might be some causes (unresponsive server?) that could resolve
themselves, and then come back, and that you'd still want to hear about
the second time.

> > @@ -27,7 +27,8 @@ struct rpc_task;
> > struct nlmsvc_binding {
> > 	__be32			(*fopen)(struct svc_rqst *,
> > 						struct nfs_fh *,
> > -						struct file **);
> > +						struct file **,
> > +						int mode);
> 
> Style: "mode_t mode" might be better internal documentation.

It's confusing that we use the word "mode" both for "access mode" (O_
flags) and "mode bits" (permission bits).  This is the former, and I
thought mode_t was the for the latter.

> > @@ -154,7 +156,8 @@ struct nlm_rqst {
> > struct nlm_file {
> > 	struct hlist_node	f_list;		/* linked list */
> > 	struct nfs_fh		f_handle;	/* NFS file handle */
> > -	struct file *		f_file;		/* VFS file pointer */
> > +	struct file *		f_file[2];	/* VFS file pointers,
> > +						   indexed by O_ flags */
> 
> Right, except that the new code in this patch always indexes
> f_file with raw integers, making the comment misleading. My
> preference is to keep the comment and change the new code to
> index f_file symbolically.

OK.

--b.

Chuck Lever Aug. 23, 2021, 6:59 p.m. UTC | #4

> On Aug 23, 2021, at 2:57 PM, J. Bruce Fields <[e-mail]> wrote:
> 
> On Sat, Aug 21, 2021 at 04:30:43PM +0000, Chuck Lever III wrote:
>>> @@ -654,7 +658,12 @@ nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
>>> 	nlmsvc_cancel_blocked(net, file, lock);
>>> 
>>> 	lock->fl.fl_type = F_UNLCK;
>>> -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
>>> +	if (file->f_file[0])
>>> +		error = vfs_lock_file(file->f_file[0], F_SETLK,
>>> +					&lock->fl, NULL);
>>> +	if (file->f_file[1])
>>> +		error = vfs_lock_file(file->f_file[1], F_SETLK,
>>> +					&lock->fl, NULL);
>> 
>> Eschew raw integers :-) Should the f_file array be indexed
>> using O_ flags as the comment below suggests?
> 
> Sure, done.
> 
>>> diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
>>> index f43d89e89c45..a0adaee245ae 100644
>>> --- a/fs/lockd/svcsubs.c
>>> +++ b/fs/lockd/svcsubs.c
>>> @@ -71,14 +71,38 @@ static inline unsigned int file_hash(struct nfs_fh *f)
>>> 	return tmp & (FILE_NRHASH - 1);
>>> }
>>> 
>>> +int lock_to_openmode(struct file_lock *lock)
>>> +{
>>> +	if (lock->fl_type == F_WRLCK)
>>> +		return O_WRONLY;
>>> +	else
>>> +		return O_RDONLY;
>> 
>> Style: a ternary would be more consistent with other areas
>> of the code you change in this patch.
> 
> OK.
> 
>>> +static int nlm_unlock_files(struct nlm_file *file)
>>> +{
>>> +	struct file_lock lock;
>>> +	struct file *f;
>>> +
>>> +	lock.fl_type  = F_UNLCK;
>>> +	lock.fl_start = 0;
>>> +	lock.fl_end   = OFFSET_MAX;
>>> +	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
>>> +		if (f && vfs_lock_file(f, F_SETLK, &lock, NULL) < 0) {
>>> +			printk("lockd: unlock failure in %s:%d\n",
>>> +				__FILE__, __LINE__);
>> 
>> This needs a KERN_LEVEL and maybe a _once.
> 
> How about going with pr_warn for now.

Sold.


> I don't *think* there's much
> danger of spamming the logs from this one.  And I'm wondering there
> might be some causes (unresponsive server?) that could resolve
> themselves, and then come back, and that you'd still want to hear about
> the second time.
> 
>>> @@ -27,7 +27,8 @@ struct rpc_task;
>>> struct nlmsvc_binding {
>>> 	__be32			(*fopen)(struct svc_rqst *,
>>> 						struct nfs_fh *,
>>> -						struct file **);
>>> +						struct file **,
>>> +						int mode);
>> 
>> Style: "mode_t mode" might be better internal documentation.
> 
> It's confusing that we use the word "mode" both for "access mode" (O_
> flags) and "mode bits" (permission bits).  This is the former, and I
> thought mode_t was the for the latter.

Fair enough.


> 
>>> @@ -154,7 +156,8 @@ struct nlm_rqst {
>>> struct nlm_file {
>>> 	struct hlist_node	f_list;		/* linked list */
>>> 	struct nfs_fh		f_handle;	/* NFS file handle */
>>> -	struct file *		f_file;		/* VFS file pointer */
>>> +	struct file *		f_file[2];	/* VFS file pointers,
>>> +						   indexed by O_ flags */
>> 
>> Right, except that the new code in this patch always indexes
>> f_file with raw integers, making the comment misleading. My
>> preference is to keep the comment and change the new code to
>> index f_file symbolically.
> 
> OK.
> 
> --b.

--
Chuck Lever

J. Bruce Fields Aug. 23, 2021, 8:44 p.m. UTC | #5

From: "J. Bruce Fields" <[e-mail]>
Subject: [PATCH v4] Keep read and write fds with each nlm_file

We shouldn't really be using a read-only file descriptor to take a write
lock.

Most filesystems will put up with it.  But NFS, for example, won't.

Signed-off-by: J. Bruce Fields <[e-mail]>
---
 fs/lockd/svc4proc.c         |   4 +-
 fs/lockd/svclock.c          |  25 ++++++---
 fs/lockd/svcproc.c          |   4 +-
 fs/lockd/svcsubs.c          | 102 +++++++++++++++++++++++++-----------
 fs/nfsd/lockd.c             |   8 ++-
 include/linux/lockd/bind.h  |   3 +-
 include/linux/lockd/lockd.h |   9 +++-
 7 files changed, 111 insertions(+), 44 deletions(-)

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index bc496bbd696b..e10ae2c41279 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -40,13 +40,15 @@ nlm4svc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
 
 	/* Obtain file pointer. Not used by FREE_ALL call. */
 	if (filp != NULL) {
+		int mode = lock_to_openmode(&lock->fl);
+
 		error = nlm_lookup_file(rqstp, &file, lock);
 		if (error)
 			goto no_locks;
 		*filp = file;
 
 		/* Set up the missing parts of the file_lock structure */
-		lock->fl.fl_file  = file->f_file;
+		lock->fl.fl_file  = file->f_file[mode];
 		lock->fl.fl_pid = current->tgid;
 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index bc1cf31f3cce..6abbc92b88e3 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -471,6 +471,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 {
 	struct nlm_block	*block = NULL;
 	int			error;
+	int			mode;
 	__be32			ret;
 
 	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
@@ -524,7 +525,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 
 	if (!wait)
 		lock->fl.fl_flags &= ~FL_SLEEP;
-	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+	mode = lock_to_openmode(&lock->fl);
+	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
 	lock->fl.fl_flags &= ~FL_SLEEP;
 
 	dprintk("lockd: vfs_lock_file returned %d\n", error);
@@ -577,6 +579,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 		struct nlm_lock *conflock, struct nlm_cookie *cookie)
 {
 	int			error;
+	int			mode;
 	__be32			ret;
 	struct nlm_lockowner	*test_owner;
 
@@ -595,7 +598,8 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 	/* If there's a conflicting lock, remember to clean up the test lock */
 	test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
 
-	error = vfs_test_lock(file->f_file, &lock->fl);
+	mode = lock_to_openmode(&lock->fl);
+	error = vfs_test_lock(file->f_file[mode], &lock->fl);
 	if (error) {
 		/* We can't currently deal with deferred test requests */
 		if (error == FILE_LOCK_DEFERRED)
@@ -641,7 +645,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 __be32
 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 {
-	int	error;
+	int	error = 0;
 
 	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 				nlmsvc_file_inode(file)->i_sb->s_id,
@@ -654,7 +658,12 @@ nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 	nlmsvc_cancel_blocked(net, file, lock);
 
 	lock->fl.fl_type = F_UNLCK;
-	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+	if (file->f_file[O_RDONLY])
+		error = vfs_lock_file(file->f_file[O_RDONLY], F_SETLK,
+					&lock->fl, NULL);
+	if (file->f_file[O_WRONLY])
+		error = vfs_lock_file(file->f_file[O_WRONLY], F_SETLK,
+					&lock->fl, NULL);
 
 	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 }
@@ -671,6 +680,7 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
 {
 	struct nlm_block	*block;
 	int status = 0;
+	int mode;
 
 	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 				nlmsvc_file_inode(file)->i_sb->s_id,
@@ -686,7 +696,8 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
 	block = nlmsvc_lookup_block(file, lock);
 	mutex_unlock(&file->f_mutex);
 	if (block != NULL) {
-		vfs_cancel_lock(block->b_file->f_file,
+		mode = lock_to_openmode(&lock->fl);
+		vfs_cancel_lock(block->b_file->f_file[mode],
 				&block->b_call->a_args.lock.fl);
 		status = nlmsvc_unlink_block(block);
 		nlmsvc_release_block(block);
@@ -803,6 +814,7 @@ nlmsvc_grant_blocked(struct nlm_block *block)
 {
 	struct nlm_file		*file = block->b_file;
 	struct nlm_lock		*lock = &block->b_call->a_args.lock;
+	int			mode;
 	int			error;
 	loff_t			fl_start, fl_end;
 
@@ -828,7 +840,8 @@ nlmsvc_grant_blocked(struct nlm_block *block)
 	lock->fl.fl_flags |= FL_SLEEP;
 	fl_start = lock->fl.fl_start;
 	fl_end = lock->fl.fl_end;
-	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+	mode = lock_to_openmode(&lock->fl);
+	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
 	lock->fl.fl_flags &= ~FL_SLEEP;
 	lock->fl.fl_start = fl_start;
 	lock->fl.fl_end = fl_end;
diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index f4e5e0eb30fd..99696d3f6dd6 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -55,6 +55,7 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
 	struct nlm_host		*host = NULL;
 	struct nlm_file		*file = NULL;
 	struct nlm_lock		*lock = &argp->lock;
+	int			mode;
 	__be32			error = 0;
 
 	/* nfsd callbacks must have been installed for this procedure */
@@ -75,7 +76,8 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
 		*filp = file;
 
 		/* Set up the missing parts of the file_lock structure */
-		lock->fl.fl_file  = file->f_file;
+		mode = lock_to_openmode(&lock->fl);
+		lock->fl.fl_file  = file->f_file[mode];
 		lock->fl.fl_pid = current->tgid;
 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index 13e6ffc219ec..cb3a7512c33e 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -71,14 +71,35 @@ static inline unsigned int file_hash(struct nfs_fh *f)
 	return tmp & (FILE_NRHASH - 1);
 }
 
+int lock_to_openmode(struct file_lock *lock)
+{
+	return (lock->fl_type == F_WRLCK) ? O_WRONLY : O_RDONLY;
+}
+
+/*
+ * Open the file. Note that if we're reexporting, for example,
+ * this could block the lockd thread for a while.
+ *
+ * We have to make sure we have the right credential to open
+ * the file.
+ */
+static __be32 nlm_do_fopen(struct svc_rqst *rqstp,
+			   struct nlm_file *file, int mode)
+{
+	struct file **fp = &file->f_file[mode];
+	__be32	nfserr;
+
+	if (*fp)
+		return 0;
+	nfserr = nlmsvc_ops->fopen(rqstp, &file->f_handle, fp, mode);
+	if (nfserr)
+		dprintk("lockd: open failed (error %d)\n", nfserr);
+	return nfserr;
+}
+
 /*
  * Lookup file info. If it doesn't exist, create a file info struct
  * and open a (VFS) file for the given inode.
- *
- * FIXME:
- * Note that we open the file O_RDONLY even when creating write locks.
- * This is not quite right, but for now, we assume the client performs
- * the proper R/W checking.
  */
 __be32
 nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
@@ -87,42 +108,38 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
 	struct nlm_file	*file;
 	unsigned int	hash;
 	__be32		nfserr;
+	int		mode;
 
 	nlm_debug_print_fh("nlm_lookup_file", &lock->fh);
 
 	hash = file_hash(&lock->fh);
+	mode = lock_to_openmode(&lock->fl);
 
 	/* Lock file table */
 	mutex_lock(&nlm_file_mutex);
 
 	hlist_for_each_entry(file, &nlm_files[hash], f_list)
-		if (!nfs_compare_fh(&file->f_handle, &lock->fh))
+		if (!nfs_compare_fh(&file->f_handle, &lock->fh)) {
+			mutex_lock(&file->f_mutex);
+			nfserr = nlm_do_fopen(rqstp, file, mode);
+			mutex_unlock(&file->f_mutex);
 			goto found;
-
+		}
 	nlm_debug_print_fh("creating file for", &lock->fh);
 
 	nfserr = nlm_lck_denied_nolocks;
 	file = kzalloc(sizeof(*file), GFP_KERNEL);
 	if (!file)
-		goto out_unlock;
+		goto out_free;
 
 	memcpy(&file->f_handle, &lock->fh, sizeof(struct nfs_fh));
 	mutex_init(&file->f_mutex);
 	INIT_HLIST_NODE(&file->f_list);
 	INIT_LIST_HEAD(&file->f_blocks);
 
-	/*
-	 * Open the file. Note that if we're reexporting, for example,
-	 * this could block the lockd thread for a while.
-	 *
-	 * We have to make sure we have the right credential to open
-	 * the file.
-	 */
-	nfserr = nlmsvc_ops->fopen(rqstp, &lock->fh, &file->f_file);
-	if (nfserr) {
-		dprintk("lockd: open failed (error %d)\n", nfserr);
-		goto out_free;
-	}
+	nfserr = nlm_do_fopen(rqstp, file, mode);
+	if (nfserr)
+		goto out_unlock;
 
 	hlist_add_head(&file->f_list, &nlm_files[hash]);
 
@@ -130,7 +147,6 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
 	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
 	*result = file;
 	file->f_count++;
-	nfserr = 0;
 
 out_unlock:
 	mutex_unlock(&nlm_file_mutex);
@@ -150,13 +166,34 @@ nlm_delete_file(struct nlm_file *file)
 	nlm_debug_print_file("closing file", file);
 	if (!hlist_unhashed(&file->f_list)) {
 		hlist_del(&file->f_list);
-		nlmsvc_ops->fclose(file->f_file);
+		if (file->f_file[O_RDONLY])
+			nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
+		if (file->f_file[O_WRONLY])
+			nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
 		kfree(file);
 	} else {
 		printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
 	}
 }
 
+static int nlm_unlock_files(struct nlm_file *file)
+{
+	struct file_lock lock;
+	struct file *f;
+
+	lock.fl_type  = F_UNLCK;
+	lock.fl_start = 0;
+	lock.fl_end   = OFFSET_MAX;
+	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
+		if (f && vfs_lock_file(f, F_SETLK, &lock, NULL) < 0) {
+			pr_warn("lockd: unlock failure in %s:%d\n",
+				__FILE__, __LINE__);
+			return 1;
+		}
+	}
+	return 0;
+}
+
 /*
  * Loop over all locks on the given file and perform the specified
  * action.
@@ -184,17 +221,10 @@ nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
 
 		lockhost = ((struct nlm_lockowner *)fl->fl_owner)->host;
 		if (match(lockhost, host)) {
-			struct file_lock lock = *fl;
 
 			spin_unlock(&flctx->flc_lock);
-			lock.fl_type  = F_UNLCK;
-			lock.fl_start = 0;
-			lock.fl_end   = OFFSET_MAX;
-			if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
-				printk("lockd: unlock failure in %s:%d\n",
-						__FILE__, __LINE__);
+			if (nlm_unlock_files(file))
 				return 1;
-			}
 			goto again;
 		}
 	}
@@ -248,6 +278,15 @@ nlm_file_inuse(struct nlm_file *file)
 	return 0;
 }
 
+static void nlm_close_files(struct nlm_file *file)
+{
+	struct file *f;
+
+	for (f = file->f_file[0]; f <= file->f_file[1]; f++)
+		if (f)
+			nlmsvc_ops->fclose(f);
+}
+
 /*
  * Loop over all files in the file table.
  */
@@ -278,7 +317,7 @@ nlm_traverse_files(void *data, nlm_host_match_fn_t match,
 			if (list_empty(&file->f_blocks) && !file->f_locks
 			 && !file->f_shares && !file->f_count) {
 				hlist_del(&file->f_list);
-				nlmsvc_ops->fclose(file->f_file);
+				nlm_close_files(file);
 				kfree(file);
 			}
 		}
@@ -412,6 +451,7 @@ nlmsvc_invalidate_all(void)
 	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
 }
 
+
 static int
 nlmsvc_match_sb(void *datap, struct nlm_file *file)
 {
diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
index 3f5b3d7b62b7..606fa155c28a 100644
--- a/fs/nfsd/lockd.c
+++ b/fs/nfsd/lockd.c
@@ -25,9 +25,11 @@
  * Note: we hold the dentry use count while the file is open.
  */
 static __be32
-nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
+nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
+		int mode)
 {
 	__be32		nfserr;
+	int		access;
 	struct svc_fh	fh;
 
 	/* must initialize before using! but maxsize doesn't matter */
@@ -36,7 +38,9 @@ nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
 	memcpy((char*)&fh.fh_handle.fh_base, f->data, f->size);
 	fh.fh_export = NULL;
 
-	nfserr = nfsd_open(rqstp, &fh, S_IFREG, NFSD_MAY_LOCK, filp);
+	access = (mode == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
+	access |= NFSD_MAY_LOCK;
+	nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
 	fh_put(&fh);
  	/* We return nlm error codes as nlm doesn't know
 	 * about nfsd, but nfsd does know about nlm..
diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
index 0520c0cd73f4..3bc9f7410e21 100644
--- a/include/linux/lockd/bind.h
+++ b/include/linux/lockd/bind.h
@@ -27,7 +27,8 @@ struct rpc_task;
 struct nlmsvc_binding {
 	__be32			(*fopen)(struct svc_rqst *,
 						struct nfs_fh *,
-						struct file **);
+						struct file **,
+						int mode);
 	void			(*fclose)(struct file *);
 };
 
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index 81b71ad2040a..da319de7e557 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -10,6 +10,8 @@
 #ifndef LINUX_LOCKD_LOCKD_H
 #define LINUX_LOCKD_LOCKD_H
 
+/* XXX: a lot of this should really be under fs/lockd. */
+
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <net/ipv6.h>
@@ -154,7 +156,8 @@ struct nlm_rqst {
 struct nlm_file {
 	struct hlist_node	f_list;		/* linked list */
 	struct nfs_fh		f_handle;	/* NFS file handle */
-	struct file *		f_file;		/* VFS file pointer */
+	struct file *		f_file[2];	/* VFS file pointers,
+						   indexed by O_ flags */
 	struct nlm_share *	f_shares;	/* DOS shares */
 	struct list_head	f_blocks;	/* blocked locks */
 	unsigned int		f_locks;	/* guesstimate # of locks */
@@ -267,6 +270,7 @@ typedef int	  (*nlm_host_match_fn_t)(void *cur, struct nlm_host *ref);
 /*
  * Server-side lock handling
  */
+int		  lock_to_openmode(struct file_lock *);
 __be32		  nlmsvc_lock(struct svc_rqst *, struct nlm_file *,
 			      struct nlm_host *, struct nlm_lock *, int,
 			      struct nlm_cookie *, int);
@@ -301,7 +305,8 @@ int           nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
 
 static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
 {
-	return locks_inode(file->f_file);
+	return locks_inode(file->f_file[0] ?
+				file->f_file[0] : file->f_file[1]);
 }
 
 static inline int __nlm_privileged_request4(const struct sockaddr *sap)

Chuck Lever Aug. 23, 2021, 9:54 p.m. UTC | #6

> On Aug 23, 2021, at 4:44 PM, Bruce Fields <[e-mail]> wrote:
> 
> From: "J. Bruce Fields" <[e-mail]>
> Subject: [PATCH v4] Keep read and write fds with each nlm_file
> 
> We shouldn't really be using a read-only file descriptor to take a write
> lock.
> 
> Most filesystems will put up with it.  But NFS, for example, won't.
> 
> Signed-off-by: J. Bruce Fields <[e-mail]>
> ---
> fs/lockd/svc4proc.c         |   4 +-
> fs/lockd/svclock.c          |  25 ++++++---
> fs/lockd/svcproc.c          |   4 +-
> fs/lockd/svcsubs.c          | 102 +++++++++++++++++++++++++-----------
> fs/nfsd/lockd.c             |   8 ++-
> include/linux/lockd/bind.h  |   3 +-
> include/linux/lockd/lockd.h |   9 +++-
> 7 files changed, 111 insertions(+), 44 deletions(-)
> 
> diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
> index bc496bbd696b..e10ae2c41279 100644
> --- a/fs/lockd/svc4proc.c
> +++ b/fs/lockd/svc4proc.c
> @@ -40,13 +40,15 @@ nlm4svc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> 
> 	/* Obtain file pointer. Not used by FREE_ALL call. */
> 	if (filp != NULL) {
> +		int mode = lock_to_openmode(&lock->fl);
> +
> 		error = nlm_lookup_file(rqstp, &file, lock);
> 		if (error)
> 			goto no_locks;
> 		*filp = file;
> 
> 		/* Set up the missing parts of the file_lock structure */
> -		lock->fl.fl_file  = file->f_file;
> +		lock->fl.fl_file  = file->f_file[mode];
> 		lock->fl.fl_pid = current->tgid;
> 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
> 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index bc1cf31f3cce..6abbc92b88e3 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -471,6 +471,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> {
> 	struct nlm_block	*block = NULL;
> 	int			error;
> +	int			mode;
> 	__be32			ret;
> 
> 	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
> @@ -524,7 +525,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> 
> 	if (!wait)
> 		lock->fl.fl_flags &= ~FL_SLEEP;
> -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> +	mode = lock_to_openmode(&lock->fl);
> +	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
> 	lock->fl.fl_flags &= ~FL_SLEEP;
> 
> 	dprintk("lockd: vfs_lock_file returned %d\n", error);
> @@ -577,6 +579,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> 		struct nlm_lock *conflock, struct nlm_cookie *cookie)
> {
> 	int			error;
> +	int			mode;
> 	__be32			ret;
> 	struct nlm_lockowner	*test_owner;
> 
> @@ -595,7 +598,8 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> 	/* If there's a conflicting lock, remember to clean up the test lock */
> 	test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
> 
> -	error = vfs_test_lock(file->f_file, &lock->fl);
> +	mode = lock_to_openmode(&lock->fl);
> +	error = vfs_test_lock(file->f_file[mode], &lock->fl);
> 	if (error) {
> 		/* We can't currently deal with deferred test requests */
> 		if (error == FILE_LOCK_DEFERRED)
> @@ -641,7 +645,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> __be32
> nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
> {
> -	int	error;
> +	int	error = 0;
> 
> 	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
> 				nlmsvc_file_inode(file)->i_sb->s_id,
> @@ -654,7 +658,12 @@ nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
> 	nlmsvc_cancel_blocked(net, file, lock);
> 
> 	lock->fl.fl_type = F_UNLCK;
> -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> +	if (file->f_file[O_RDONLY])
> +		error = vfs_lock_file(file->f_file[O_RDONLY], F_SETLK,
> +					&lock->fl, NULL);
> +	if (file->f_file[O_WRONLY])
> +		error = vfs_lock_file(file->f_file[O_WRONLY], F_SETLK,
> +					&lock->fl, NULL);
> 
> 	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
> }
> @@ -671,6 +680,7 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
> {
> 	struct nlm_block	*block;
> 	int status = 0;
> +	int mode;
> 
> 	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
> 				nlmsvc_file_inode(file)->i_sb->s_id,
> @@ -686,7 +696,8 @@ nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
> 	block = nlmsvc_lookup_block(file, lock);
> 	mutex_unlock(&file->f_mutex);
> 	if (block != NULL) {
> -		vfs_cancel_lock(block->b_file->f_file,
> +		mode = lock_to_openmode(&lock->fl);
> +		vfs_cancel_lock(block->b_file->f_file[mode],
> 				&block->b_call->a_args.lock.fl);
> 		status = nlmsvc_unlink_block(block);
> 		nlmsvc_release_block(block);
> @@ -803,6 +814,7 @@ nlmsvc_grant_blocked(struct nlm_block *block)
> {
> 	struct nlm_file		*file = block->b_file;
> 	struct nlm_lock		*lock = &block->b_call->a_args.lock;
> +	int			mode;
> 	int			error;
> 	loff_t			fl_start, fl_end;
> 
> @@ -828,7 +840,8 @@ nlmsvc_grant_blocked(struct nlm_block *block)
> 	lock->fl.fl_flags |= FL_SLEEP;
> 	fl_start = lock->fl.fl_start;
> 	fl_end = lock->fl.fl_end;
> -	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
> +	mode = lock_to_openmode(&lock->fl);
> +	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
> 	lock->fl.fl_flags &= ~FL_SLEEP;
> 	lock->fl.fl_start = fl_start;
> 	lock->fl.fl_end = fl_end;
> diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
> index f4e5e0eb30fd..99696d3f6dd6 100644
> --- a/fs/lockd/svcproc.c
> +++ b/fs/lockd/svcproc.c
> @@ -55,6 +55,7 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> 	struct nlm_host		*host = NULL;
> 	struct nlm_file		*file = NULL;
> 	struct nlm_lock		*lock = &argp->lock;
> +	int			mode;
> 	__be32			error = 0;
> 
> 	/* nfsd callbacks must have been installed for this procedure */
> @@ -75,7 +76,8 @@ nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
> 		*filp = file;
> 
> 		/* Set up the missing parts of the file_lock structure */
> -		lock->fl.fl_file  = file->f_file;
> +		mode = lock_to_openmode(&lock->fl);
> +		lock->fl.fl_file  = file->f_file[mode];
> 		lock->fl.fl_pid = current->tgid;
> 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
> 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
> diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
> index 13e6ffc219ec..cb3a7512c33e 100644
> --- a/fs/lockd/svcsubs.c
> +++ b/fs/lockd/svcsubs.c
> @@ -71,14 +71,35 @@ static inline unsigned int file_hash(struct nfs_fh *f)
> 	return tmp & (FILE_NRHASH - 1);
> }
> 
> +int lock_to_openmode(struct file_lock *lock)
> +{
> +	return (lock->fl_type == F_WRLCK) ? O_WRONLY : O_RDONLY;
> +}
> +
> +/*
> + * Open the file. Note that if we're reexporting, for example,
> + * this could block the lockd thread for a while.
> + *
> + * We have to make sure we have the right credential to open
> + * the file.
> + */
> +static __be32 nlm_do_fopen(struct svc_rqst *rqstp,
> +			   struct nlm_file *file, int mode)
> +{
> +	struct file **fp = &file->f_file[mode];
> +	__be32	nfserr;
> +
> +	if (*fp)
> +		return 0;
> +	nfserr = nlmsvc_ops->fopen(rqstp, &file->f_handle, fp, mode);
> +	if (nfserr)
> +		dprintk("lockd: open failed (error %d)\n", nfserr);
> +	return nfserr;
> +}
> +
> /*
>  * Lookup file info. If it doesn't exist, create a file info struct
>  * and open a (VFS) file for the given inode.
> - *
> - * FIXME:
> - * Note that we open the file O_RDONLY even when creating write locks.
> - * This is not quite right, but for now, we assume the client performs
> - * the proper R/W checking.
>  */
> __be32
> nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> @@ -87,42 +108,38 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> 	struct nlm_file	*file;
> 	unsigned int	hash;
> 	__be32		nfserr;
> +	int		mode;
> 
> 	nlm_debug_print_fh("nlm_lookup_file", &lock->fh);
> 
> 	hash = file_hash(&lock->fh);
> +	mode = lock_to_openmode(&lock->fl);
> 
> 	/* Lock file table */
> 	mutex_lock(&nlm_file_mutex);
> 
> 	hlist_for_each_entry(file, &nlm_files[hash], f_list)
> -		if (!nfs_compare_fh(&file->f_handle, &lock->fh))
> +		if (!nfs_compare_fh(&file->f_handle, &lock->fh)) {
> +			mutex_lock(&file->f_mutex);
> +			nfserr = nlm_do_fopen(rqstp, file, mode);
> +			mutex_unlock(&file->f_mutex);
> 			goto found;
> -
> +		}
> 	nlm_debug_print_fh("creating file for", &lock->fh);
> 
> 	nfserr = nlm_lck_denied_nolocks;
> 	file = kzalloc(sizeof(*file), GFP_KERNEL);
> 	if (!file)
> -		goto out_unlock;
> +		goto out_free;
> 
> 	memcpy(&file->f_handle, &lock->fh, sizeof(struct nfs_fh));
> 	mutex_init(&file->f_mutex);
> 	INIT_HLIST_NODE(&file->f_list);
> 	INIT_LIST_HEAD(&file->f_blocks);
> 
> -	/*
> -	 * Open the file. Note that if we're reexporting, for example,
> -	 * this could block the lockd thread for a while.
> -	 *
> -	 * We have to make sure we have the right credential to open
> -	 * the file.
> -	 */
> -	nfserr = nlmsvc_ops->fopen(rqstp, &lock->fh, &file->f_file);
> -	if (nfserr) {
> -		dprintk("lockd: open failed (error %d)\n", nfserr);
> -		goto out_free;
> -	}
> +	nfserr = nlm_do_fopen(rqstp, file, mode);
> +	if (nfserr)
> +		goto out_unlock;
> 
> 	hlist_add_head(&file->f_list, &nlm_files[hash]);
> 
> @@ -130,7 +147,6 @@ nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
> 	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
> 	*result = file;
> 	file->f_count++;
> -	nfserr = 0;
> 
> out_unlock:
> 	mutex_unlock(&nlm_file_mutex);
> @@ -150,13 +166,34 @@ nlm_delete_file(struct nlm_file *file)
> 	nlm_debug_print_file("closing file", file);
> 	if (!hlist_unhashed(&file->f_list)) {
> 		hlist_del(&file->f_list);
> -		nlmsvc_ops->fclose(file->f_file);
> +		if (file->f_file[O_RDONLY])
> +			nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
> +		if (file->f_file[O_WRONLY])
> +			nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
> 		kfree(file);
> 	} else {
> 		printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
> 	}
> }
> 
> +static int nlm_unlock_files(struct nlm_file *file)
> +{
> +	struct file_lock lock;
> +	struct file *f;
> +
> +	lock.fl_type  = F_UNLCK;
> +	lock.fl_start = 0;
> +	lock.fl_end   = OFFSET_MAX;
> +	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {

O_RDONLY and O_WRONLY ?


> +		if (f && vfs_lock_file(f, F_SETLK, &lock, NULL) < 0) {
> +			pr_warn("lockd: unlock failure in %s:%d\n",
> +				__FILE__, __LINE__);
> +			return 1;
> +		}
> +	}
> +	return 0;
> +}
> +
> /*
>  * Loop over all locks on the given file and perform the specified
>  * action.
> @@ -184,17 +221,10 @@ nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
> 
> 		lockhost = ((struct nlm_lockowner *)fl->fl_owner)->host;
> 		if (match(lockhost, host)) {
> -			struct file_lock lock = *fl;
> 
> 			spin_unlock(&flctx->flc_lock);
> -			lock.fl_type  = F_UNLCK;
> -			lock.fl_start = 0;
> -			lock.fl_end   = OFFSET_MAX;
> -			if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
> -				printk("lockd: unlock failure in %s:%d\n",
> -						__FILE__, __LINE__);
> +			if (nlm_unlock_files(file))
> 				return 1;
> -			}
> 			goto again;
> 		}
> 	}
> @@ -248,6 +278,15 @@ nlm_file_inuse(struct nlm_file *file)
> 	return 0;
> }
> 
> +static void nlm_close_files(struct nlm_file *file)
> +{
> +	struct file *f;
> +
> +	for (f = file->f_file[0]; f <= file->f_file[1]; f++)

O_RDONLY and O_WRONLY ?


> +		if (f)
> +			nlmsvc_ops->fclose(f);
> +}
> +
> /*
>  * Loop over all files in the file table.
>  */
> @@ -278,7 +317,7 @@ nlm_traverse_files(void *data, nlm_host_match_fn_t match,
> 			if (list_empty(&file->f_blocks) && !file->f_locks
> 			 && !file->f_shares && !file->f_count) {
> 				hlist_del(&file->f_list);
> -				nlmsvc_ops->fclose(file->f_file);
> +				nlm_close_files(file);
> 				kfree(file);
> 			}
> 		}
> @@ -412,6 +451,7 @@ nlmsvc_invalidate_all(void)
> 	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
> }
> 
> +
> static int
> nlmsvc_match_sb(void *datap, struct nlm_file *file)
> {
> diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
> index 3f5b3d7b62b7..606fa155c28a 100644
> --- a/fs/nfsd/lockd.c
> +++ b/fs/nfsd/lockd.c
> @@ -25,9 +25,11 @@
>  * Note: we hold the dentry use count while the file is open.
>  */
> static __be32
> -nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
> +nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
> +		int mode)
> {
> 	__be32		nfserr;
> +	int		access;
> 	struct svc_fh	fh;
> 
> 	/* must initialize before using! but maxsize doesn't matter */
> @@ -36,7 +38,9 @@ nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
> 	memcpy((char*)&fh.fh_handle.fh_base, f->data, f->size);
> 	fh.fh_export = NULL;
> 
> -	nfserr = nfsd_open(rqstp, &fh, S_IFREG, NFSD_MAY_LOCK, filp);
> +	access = (mode == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
> +	access |= NFSD_MAY_LOCK;
> +	nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
> 	fh_put(&fh);
>  	/* We return nlm error codes as nlm doesn't know
> 	 * about nfsd, but nfsd does know about nlm..
> diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
> index 0520c0cd73f4..3bc9f7410e21 100644
> --- a/include/linux/lockd/bind.h
> +++ b/include/linux/lockd/bind.h
> @@ -27,7 +27,8 @@ struct rpc_task;
> struct nlmsvc_binding {
> 	__be32			(*fopen)(struct svc_rqst *,
> 						struct nfs_fh *,
> -						struct file **);
> +						struct file **,
> +						int mode);
> 	void			(*fclose)(struct file *);
> };
> 
> diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
> index 81b71ad2040a..da319de7e557 100644
> --- a/include/linux/lockd/lockd.h
> +++ b/include/linux/lockd/lockd.h
> @@ -10,6 +10,8 @@
> #ifndef LINUX_LOCKD_LOCKD_H
> #define LINUX_LOCKD_LOCKD_H
> 
> +/* XXX: a lot of this should really be under fs/lockd. */
> +
> #include <linux/in.h>
> #include <linux/in6.h>
> #include <net/ipv6.h>
> @@ -154,7 +156,8 @@ struct nlm_rqst {
> struct nlm_file {
> 	struct hlist_node	f_list;		/* linked list */
> 	struct nfs_fh		f_handle;	/* NFS file handle */
> -	struct file *		f_file;		/* VFS file pointer */
> +	struct file *		f_file[2];	/* VFS file pointers,
> +						   indexed by O_ flags */
> 	struct nlm_share *	f_shares;	/* DOS shares */
> 	struct list_head	f_blocks;	/* blocked locks */
> 	unsigned int		f_locks;	/* guesstimate # of locks */
> @@ -267,6 +270,7 @@ typedef int	  (*nlm_host_match_fn_t)(void *cur, struct nlm_host *ref);
> /*
>  * Server-side lock handling
>  */
> +int		  lock_to_openmode(struct file_lock *);
> __be32		  nlmsvc_lock(struct svc_rqst *, struct nlm_file *,
> 			      struct nlm_host *, struct nlm_lock *, int,
> 			      struct nlm_cookie *, int);
> @@ -301,7 +305,8 @@ int           nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
> 
> static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
> {
> -	return locks_inode(file->f_file);
> +	return locks_inode(file->f_file[0] ?
> +				file->f_file[0] : file->f_file[1]);

O_RDONLY and O_WRONLY ?


> }
> 
> static inline int __nlm_privileged_request4(const struct sockaddr *sap)
> -- 
> 2.31.1
> 

--
Chuck Lever

J. Bruce Fields Aug. 23, 2021, 9:58 p.m. UTC | #7

On Mon, Aug 23, 2021 at 09:54:20PM +0000, Chuck Lever III wrote:
> > On Aug 23, 2021, at 4:44 PM, Bruce Fields <[e-mail]> wrote:
> > +static int nlm_unlock_files(struct nlm_file *file)
> > +{
> > +	struct file_lock lock;
> > +	struct file *f;
> > +
> > +	lock.fl_type  = F_UNLCK;
> > +	lock.fl_start = 0;
> > +	lock.fl_end   = OFFSET_MAX;
> > +	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
> 
> O_RDONLY and O_WRONLY ?

I thought they looked weird as loop boundaries.

> > @@ -301,7 +305,8 @@ int           nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
> > 
> > static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
> > {
> > -	return locks_inode(file->f_file);
> > +	return locks_inode(file->f_file[0] ?
> > +				file->f_file[0] : file->f_file[1]);
> 
> O_RDONLY and O_WRONLY ?

A little less weird.

OK, I admit, "looks weird" isn't much of an argument.

I say we leave it to whoever cares enough to make the change.

--b.

Chuck Lever Aug. 23, 2021, 10 p.m. UTC | #8

> On Aug 23, 2021, at 5:58 PM, Bruce Fields <[e-mail]> wrote:
> 
> On Mon, Aug 23, 2021 at 09:54:20PM +0000, Chuck Lever III wrote:
>>> On Aug 23, 2021, at 4:44 PM, Bruce Fields <[e-mail]> wrote:
>>> +static int nlm_unlock_files(struct nlm_file *file)
>>> +{
>>> +	struct file_lock lock;
>>> +	struct file *f;
>>> +
>>> +	lock.fl_type  = F_UNLCK;
>>> +	lock.fl_start = 0;
>>> +	lock.fl_end   = OFFSET_MAX;
>>> +	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
>> 
>> O_RDONLY and O_WRONLY ?
> 
> I thought they looked weird as loop boundaries.
> 
>>> @@ -301,7 +305,8 @@ int           nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
>>> 
>>> static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
>>> {
>>> -	return locks_inode(file->f_file);
>>> +	return locks_inode(file->f_file[0] ?
>>> +				file->f_file[0] : file->f_file[1]);
>> 
>> O_RDONLY and O_WRONLY ?
> 
> A little less weird.
> 
> OK, I admit, "looks weird" isn't much of an argument.
> 
> I say we leave it to whoever cares enough to make the change.

I can update nlmsvc_file_inode() when I apply this version
of the patch, and leave the loops alone.


--
Chuck Lever

Patch

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index aa8eca7c38a1..c7587de948e4 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -40,12 +40,14 @@  nlm4svc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
 
 	/* Obtain file pointer. Not used by FREE_ALL call. */
 	if (filp != NULL) {
+		int mode = lock_to_openmode(&lock->fl);
+
 		if ((error = nlm_lookup_file(rqstp, &file, lock)) != 0)
 			goto no_locks;
 		*filp = file;
 
 		/* Set up the missing parts of the file_lock structure */
-		lock->fl.fl_file  = file->f_file;
+		lock->fl.fl_file  = file->f_file[mode];
 		lock->fl.fl_pid = current->tgid;
 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index bc1cf31f3cce..d60e6eea2d57 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -471,6 +471,7 @@  nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 {
 	struct nlm_block	*block = NULL;
 	int			error;
+	int			mode;
 	__be32			ret;
 
 	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
@@ -524,7 +525,8 @@  nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 
 	if (!wait)
 		lock->fl.fl_flags &= ~FL_SLEEP;
-	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+	mode = lock_to_openmode(&lock->fl);
+	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
 	lock->fl.fl_flags &= ~FL_SLEEP;
 
 	dprintk("lockd: vfs_lock_file returned %d\n", error);
@@ -577,6 +579,7 @@  nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 		struct nlm_lock *conflock, struct nlm_cookie *cookie)
 {
 	int			error;
+	int			mode;
 	__be32			ret;
 	struct nlm_lockowner	*test_owner;
 
@@ -595,7 +598,8 @@  nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 	/* If there's a conflicting lock, remember to clean up the test lock */
 	test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
 
-	error = vfs_test_lock(file->f_file, &lock->fl);
+	mode = lock_to_openmode(&lock->fl);
+	error = vfs_test_lock(file->f_file[mode], &lock->fl);
 	if (error) {
 		/* We can't currently deal with deferred test requests */
 		if (error == FILE_LOCK_DEFERRED)
@@ -641,7 +645,7 @@  nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 __be32
 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 {
-	int	error;
+	int	error = 0;
 
 	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 				nlmsvc_file_inode(file)->i_sb->s_id,
@@ -654,7 +658,12 @@  nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 	nlmsvc_cancel_blocked(net, file, lock);
 
 	lock->fl.fl_type = F_UNLCK;
-	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+	if (file->f_file[0])
+		error = vfs_lock_file(file->f_file[0], F_SETLK,
+					&lock->fl, NULL);
+	if (file->f_file[1])
+		error = vfs_lock_file(file->f_file[1], F_SETLK,
+					&lock->fl, NULL);
 
 	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 }
@@ -671,6 +680,7 @@  nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
 {
 	struct nlm_block	*block;
 	int status = 0;
+	int mode;
 
 	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 				nlmsvc_file_inode(file)->i_sb->s_id,
@@ -686,7 +696,8 @@  nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *l
 	block = nlmsvc_lookup_block(file, lock);
 	mutex_unlock(&file->f_mutex);
 	if (block != NULL) {
-		vfs_cancel_lock(block->b_file->f_file,
+		mode = lock_to_openmode(&lock->fl);
+		vfs_cancel_lock(block->b_file->f_file[mode],
 				&block->b_call->a_args.lock.fl);
 		status = nlmsvc_unlink_block(block);
 		nlmsvc_release_block(block);
@@ -803,6 +814,7 @@  nlmsvc_grant_blocked(struct nlm_block *block)
 {
 	struct nlm_file		*file = block->b_file;
 	struct nlm_lock		*lock = &block->b_call->a_args.lock;
+	int			mode;
 	int			error;
 	loff_t			fl_start, fl_end;
 
@@ -828,7 +840,8 @@  nlmsvc_grant_blocked(struct nlm_block *block)
 	lock->fl.fl_flags |= FL_SLEEP;
 	fl_start = lock->fl.fl_start;
 	fl_end = lock->fl.fl_end;
-	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+	mode = lock_to_openmode(&lock->fl);
+	error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
 	lock->fl.fl_flags &= ~FL_SLEEP;
 	lock->fl.fl_start = fl_start;
 	lock->fl.fl_end = fl_end;
diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index f4e5e0eb30fd..99696d3f6dd6 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -55,6 +55,7 @@  nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
 	struct nlm_host		*host = NULL;
 	struct nlm_file		*file = NULL;
 	struct nlm_lock		*lock = &argp->lock;
+	int			mode;
 	__be32			error = 0;
 
 	/* nfsd callbacks must have been installed for this procedure */
@@ -75,7 +76,8 @@  nlmsvc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
 		*filp = file;
 
 		/* Set up the missing parts of the file_lock structure */
-		lock->fl.fl_file  = file->f_file;
+		mode = lock_to_openmode(&lock->fl);
+		lock->fl.fl_file  = file->f_file[mode];
 		lock->fl.fl_pid = current->tgid;
 		lock->fl.fl_lmops = &nlmsvc_lock_operations;
 		nlmsvc_locks_init_private(&lock->fl, host, (pid_t)lock->svid);
diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index f43d89e89c45..a0adaee245ae 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -71,14 +71,38 @@  static inline unsigned int file_hash(struct nfs_fh *f)
 	return tmp & (FILE_NRHASH - 1);
 }
 
+int lock_to_openmode(struct file_lock *lock)
+{
+	if (lock->fl_type == F_WRLCK)
+		return O_WRONLY;
+	else
+		return O_RDONLY;
+}
+
+/*
+ * Open the file. Note that if we're reexporting, for example,
+ * this could block the lockd thread for a while.
+ *
+ * We have to make sure we have the right credential to open
+ * the file.
+ */
+static __be32 nlm_do_fopen(struct svc_rqst *rqstp,
+			   struct nlm_file *file, int mode)
+{
+	struct file **fp = &file->f_file[mode];
+	__be32	nfserr;
+
+	if (*fp)
+		return 0;
+	nfserr = nlmsvc_ops->fopen(rqstp, &file->f_handle, fp, mode);
+	if (nfserr)
+		dprintk("lockd: open failed (error %d)\n", nfserr);
+	return nfserr;
+}
+
 /*
  * Lookup file info. If it doesn't exist, create a file info struct
  * and open a (VFS) file for the given inode.
- *
- * FIXME:
- * Note that we open the file O_RDONLY even when creating write locks.
- * This is not quite right, but for now, we assume the client performs
- * the proper R/W checking.
  */
 __be32
 nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
@@ -87,41 +111,38 @@  nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
 	struct nlm_file	*file;
 	unsigned int	hash;
 	__be32		nfserr;
+	int		mode;
 
 	nlm_debug_print_fh("nlm_lookup_file", &lock->fh);
 
 	hash = file_hash(&lock->fh);
+	mode = lock_to_openmode(&lock->fl);
 
 	/* Lock file table */
 	mutex_lock(&nlm_file_mutex);
 
 	hlist_for_each_entry(file, &nlm_files[hash], f_list)
-		if (!nfs_compare_fh(&file->f_handle, &lock->fh))
+		if (!nfs_compare_fh(&file->f_handle, &lock->fh)) {
+			mutex_lock(&file->f_mutex);
+			nfserr = nlm_do_fopen(rqstp, file, mode);
+			mutex_unlock(&file->f_mutex);
 			goto found;
-
+		}
 	nlm_debug_print_fh("creating file for", &lock->fh);
 
 	nfserr = nlm_lck_denied_nolocks;
 	file = kzalloc(sizeof(*file), GFP_KERNEL);
 	if (!file)
-		goto out_unlock;
+		goto out_free;
 
 	memcpy(&file->f_handle, &lock->fh, sizeof(struct nfs_fh));
 	mutex_init(&file->f_mutex);
 	INIT_HLIST_NODE(&file->f_list);
 	INIT_LIST_HEAD(&file->f_blocks);
 
-	/*
-	 * Open the file. Note that if we're reexporting, for example,
-	 * this could block the lockd thread for a while.
-	 *
-	 * We have to make sure we have the right credential to open
-	 * the file.
-	 */
-	if ((nfserr = nlmsvc_ops->fopen(rqstp, &lock->fh, &file->f_file)) != 0) {
-		dprintk("lockd: open failed (error %d)\n", nfserr);
-		goto out_free;
-	}
+	nfserr = nlm_do_fopen(rqstp, file, mode);
+	if (nfserr)
+		goto out_unlock;
 
 	hlist_add_head(&file->f_list, &nlm_files[hash]);
 
@@ -129,7 +150,6 @@  nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
 	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
 	*result = file;
 	file->f_count++;
-	nfserr = 0;
 
 out_unlock:
 	mutex_unlock(&nlm_file_mutex);
@@ -149,13 +169,34 @@  nlm_delete_file(struct nlm_file *file)
 	nlm_debug_print_file("closing file", file);
 	if (!hlist_unhashed(&file->f_list)) {
 		hlist_del(&file->f_list);
-		nlmsvc_ops->fclose(file->f_file);
+		if (file->f_file[O_RDONLY])
+			nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
+		if (file->f_file[O_WRONLY])
+			nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
 		kfree(file);
 	} else {
 		printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
 	}
 }
 
+static int nlm_unlock_files(struct nlm_file *file)
+{
+	struct file_lock lock;
+	struct file *f;
+
+	lock.fl_type  = F_UNLCK;
+	lock.fl_start = 0;
+	lock.fl_end   = OFFSET_MAX;
+	for (f = file->f_file[0]; f <= file->f_file[1]; f++) {
+		if (f && vfs_lock_file(f, F_SETLK, &lock, NULL) < 0) {
+			printk("lockd: unlock failure in %s:%d\n",
+				__FILE__, __LINE__);
+			return 1;
+		}
+	}
+	return 0;
+}
+
 /*
  * Loop over all locks on the given file and perform the specified
  * action.
@@ -183,17 +224,10 @@  nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
 
 		lockhost = ((struct nlm_lockowner *)fl->fl_owner)->host;
 		if (match(lockhost, host)) {
-			struct file_lock lock = *fl;
 
 			spin_unlock(&flctx->flc_lock);
-			lock.fl_type  = F_UNLCK;
-			lock.fl_start = 0;
-			lock.fl_end   = OFFSET_MAX;
-			if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
-				printk("lockd: unlock failure in %s:%d\n",
-						__FILE__, __LINE__);
+			if (nlm_unlock_files(file))
 				return 1;
-			}
 			goto again;
 		}
 	}
@@ -247,6 +281,15 @@  nlm_file_inuse(struct nlm_file *file)
 	return 0;
 }
 
+static void nlm_close_files(struct nlm_file *file)
+{
+	struct file *f;
+
+	for (f = file->f_file[0]; f <= file->f_file[1]; f++)
+		if (f)
+			nlmsvc_ops->fclose(f);
+}
+
 /*
  * Loop over all files in the file table.
  */
@@ -277,7 +320,7 @@  nlm_traverse_files(void *data, nlm_host_match_fn_t match,
 			if (list_empty(&file->f_blocks) && !file->f_locks
 			 && !file->f_shares && !file->f_count) {
 				hlist_del(&file->f_list);
-				nlmsvc_ops->fclose(file->f_file);
+				nlm_close_files(file);
 				kfree(file);
 			}
 		}
@@ -411,6 +454,7 @@  nlmsvc_invalidate_all(void)
 	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
 }
 
+
 static int
 nlmsvc_match_sb(void *datap, struct nlm_file *file)
 {
diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
index 3f5b3d7b62b7..606fa155c28a 100644
--- a/fs/nfsd/lockd.c
+++ b/fs/nfsd/lockd.c
@@ -25,9 +25,11 @@ 
  * Note: we hold the dentry use count while the file is open.
  */
 static __be32
-nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
+nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
+		int mode)
 {
 	__be32		nfserr;
+	int		access;
 	struct svc_fh	fh;
 
 	/* must initialize before using! but maxsize doesn't matter */
@@ -36,7 +38,9 @@  nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp)
 	memcpy((char*)&fh.fh_handle.fh_base, f->data, f->size);
 	fh.fh_export = NULL;
 
-	nfserr = nfsd_open(rqstp, &fh, S_IFREG, NFSD_MAY_LOCK, filp);
+	access = (mode == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
+	access |= NFSD_MAY_LOCK;
+	nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
 	fh_put(&fh);
  	/* We return nlm error codes as nlm doesn't know
 	 * about nfsd, but nfsd does know about nlm..
diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
index 0520c0cd73f4..3bc9f7410e21 100644
--- a/include/linux/lockd/bind.h
+++ b/include/linux/lockd/bind.h
@@ -27,7 +27,8 @@  struct rpc_task;
 struct nlmsvc_binding {
 	__be32			(*fopen)(struct svc_rqst *,
 						struct nfs_fh *,
-						struct file **);
+						struct file **,
+						int mode);
 	void			(*fclose)(struct file *);
 };
 
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index 81b71ad2040a..da319de7e557 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -10,6 +10,8 @@ 
 #ifndef LINUX_LOCKD_LOCKD_H
 #define LINUX_LOCKD_LOCKD_H
 
+/* XXX: a lot of this should really be under fs/lockd. */
+
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <net/ipv6.h>
@@ -154,7 +156,8 @@  struct nlm_rqst {
 struct nlm_file {
 	struct hlist_node	f_list;		/* linked list */
 	struct nfs_fh		f_handle;	/* NFS file handle */
-	struct file *		f_file;		/* VFS file pointer */
+	struct file *		f_file[2];	/* VFS file pointers,
+						   indexed by O_ flags */
 	struct nlm_share *	f_shares;	/* DOS shares */
 	struct list_head	f_blocks;	/* blocked locks */
 	unsigned int		f_locks;	/* guesstimate # of locks */
@@ -267,6 +270,7 @@  typedef int	  (*nlm_host_match_fn_t)(void *cur, struct nlm_host *ref);
 /*
  * Server-side lock handling
  */
+int		  lock_to_openmode(struct file_lock *);
 __be32		  nlmsvc_lock(struct svc_rqst *, struct nlm_file *,
 			      struct nlm_host *, struct nlm_lock *, int,
 			      struct nlm_cookie *, int);
@@ -301,7 +305,8 @@  int           nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr);
 
 static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
 {
-	return locks_inode(file->f_file);
+	return locks_inode(file->f_file[0] ?
+				file->f_file[0] : file->f_file[1]);
 }
 
 static inline int __nlm_privileged_request4(const struct sockaddr *sap)