linux-ext4 - Re: [PATCH 4/4] nfsd: vfs_llseek() with 32 or 64 bit offsets (hashes)

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Message-ID: <20110809173342.GB16206@fieldses.org>
Date:	Tue, 9 Aug 2011 13:33:42 -0400
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Bernd Schubert <bernd.schubert@...m.fraunhofer.de>
Cc:	linux-nfs@...r.kernel.org, linux-ext4@...r.kernel.org,
	hch@...radead.org, yong.fan@...mcloud.com,
	linux-fsdevel@...r.kernel.org, tytso@....edu, adilger@...mcloud.com
Subject: Re: [PATCH 4/4] nfsd: vfs_llseek() with 32 or 64 bit offsets
 (hashes)

On Mon, Aug 08, 2011 at 05:38:13PM +0200, Bernd Schubert wrote:
> Use 32-bit or 64-bit llseek() hashes for directory offsets depending on
> the NFS version. NFSv2 gets 32-bit hashes only.
> 
> NOTE: This patch got rather complex as Christoph asked to set the
> filp->f_mode flag in the open call or immediatly after dentry_open()
> in nfsd_open() to avoid races.
> Personally I still do not see a reason for that and in my opinion
> FMODE_32BITHASH/FMODE_64BITHASH flags could be set nfsd_readdir(), as it
> follows directly after nfsd_open() without a chance of races.

The bulk of the patch seems to be just an access->may_flags rename.
Could you please split that into a separate patch?

--b.

> 
> 
> Signed-off-by: Bernd Schubert <bernd.schubert@...m.fraunhofer.de>
> ---
>  fs/nfsd/vfs.c |   33 +++++++++++++++++++++++----------
>  fs/nfsd/vfs.h |    2 ++
>  2 files changed, 25 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index fd0acca..4bb517f 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -708,12 +708,13 @@ static int nfsd_open_break_lease(struct inode *inode, int access)
>  
>  /*
>   * Open an existing file or directory.
> - * The access argument indicates the type of open (read/write/lock)
> + * The may_flags argument indicates the type of open (read/write/lock)
> + * and additional flags.
>   * N.B. After this call fhp needs an fh_put
>   */
>  __be32
>  nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
> -			int access, struct file **filp)
> +			int may_flags, struct file **filp)
>  {
>  	struct dentry	*dentry;
>  	struct inode	*inode;
> @@ -728,7 +729,7 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
>  	 * and (hopefully) checked permission - so allow OWNER_OVERRIDE
>  	 * in case a chmod has now revoked permission.
>  	 */
> -	err = fh_verify(rqstp, fhp, type, access | NFSD_MAY_OWNER_OVERRIDE);
> +	err = fh_verify(rqstp, fhp, type, may_flags | NFSD_MAY_OWNER_OVERRIDE);
>  	if (err)
>  		goto out;
>  
> @@ -739,7 +740,7 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
>  	 * or any access when mandatory locking enabled
>  	 */
>  	err = nfserr_perm;
> -	if (IS_APPEND(inode) && (access & NFSD_MAY_WRITE))
> +	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
>  		goto out;
>  	/*
>  	 * We must ignore files (but only files) which might have mandatory
> @@ -752,12 +753,12 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
>  	if (!inode->i_fop)
>  		goto out;
>  
> -	host_err = nfsd_open_break_lease(inode, access);
> +	host_err = nfsd_open_break_lease(inode, may_flags);
>  	if (host_err) /* NOMEM or WOULDBLOCK */
>  		goto out_nfserr;
>  
> -	if (access & NFSD_MAY_WRITE) {
> -		if (access & NFSD_MAY_READ)
> +	if (may_flags & NFSD_MAY_WRITE) {
> +		if (may_flags & NFSD_MAY_READ)
>  			flags = O_RDWR|O_LARGEFILE;
>  		else
>  			flags = O_WRONLY|O_LARGEFILE;
> @@ -766,8 +767,15 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
>  			    flags, current_cred());
>  	if (IS_ERR(*filp))
>  		host_err = PTR_ERR(*filp);
> -	else
> -		host_err = ima_file_check(*filp, access);
> +	else {
> +		host_err = ima_file_check(*filp, may_flags);
> +
> +		if (may_flags & NFSD_MAY_64BIT_COOKIE)
> +			(*filp)->f_mode |= FMODE_64BITHASH;
> +		else
> +			(*filp)->f_mode |= FMODE_32BITHASH;
> +	}
> +
>  out_nfserr:
>  	err = nfserrno(host_err);
>  out:
> @@ -1989,8 +1997,13 @@ nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
>  	__be32		err;
>  	struct file	*file;
>  	loff_t		offset = *offsetp;
> +	int		flags = NFSD_MAY_READ;
> +
> +	/* NFSv2 only supports 32 bit cookies */
> +	if (rqstp->rq_vers > 2)
> +		flags |= NFSD_MAY_64BIT_COOKIE;
>  
> -	err = nfsd_open(rqstp, fhp, S_IFDIR, NFSD_MAY_READ, &file);
> +	err = nfsd_open(rqstp, fhp, S_IFDIR, flags, &file);
>  	if (err)
>  		goto out;
>  
> diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
> index e0bbac0..ecd00e1 100644
> --- a/fs/nfsd/vfs.h
> +++ b/fs/nfsd/vfs.h
> @@ -26,6 +26,8 @@
>  #define NFSD_MAY_NOT_BREAK_LEASE 512
>  #define NFSD_MAY_BYPASS_GSS	1024
>  
> +#define NFSD_MAY_64BIT_COOKIE	2048 /* 64 bit readdir cookies for >= NFSv3 */
> +
>  #define NFSD_MAY_CREATE		(NFSD_MAY_EXEC|NFSD_MAY_WRITE)
>  #define NFSD_MAY_REMOVE		(NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC)
>  
> 
> --
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