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Bruce Fields" , Chuck Lever , linux-nfs@vger.kernel.org Subject: Re: [PATCH 2/2] nfsd: Record NFSv4 pre/post-op attributes as non-atomic Message-ID: <20201201193521.GA21355@fieldses.org> References: <20201201041427.756749-1-trondmy@kernel.org> <20201201041427.756749-2-trondmy@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201201041427.756749-2-trondmy@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, Nov 30, 2020 at 11:14:27PM -0500, trondmy@kernel.org wrote: > From: Trond Myklebust > > For the case of NFSv4, specify to the client that the the pre/post-op > attributes were not recorded atomically with the main operation. > > Signed-off-by: Trond Myklebust > --- > fs/nfs/export.c | 3 ++- > fs/nfsd/nfsfh.c | 4 ++++ > fs/nfsd/nfsfh.h | 5 +++++ > fs/nfsd/xdr4.h | 2 +- > include/linux/exportfs.h | 3 +++ > 5 files changed, 15 insertions(+), 2 deletions(-) > > diff --git a/fs/nfs/export.c b/fs/nfs/export.c > index 48b879cfe6e3..7412bb164fa7 100644 > --- a/fs/nfs/export.c > +++ b/fs/nfs/export.c > @@ -172,5 +172,6 @@ const struct export_operations nfs_export_ops = { > .fh_to_dentry = nfs_fh_to_dentry, > .get_parent = nfs_get_parent, > .flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK| > - EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS, > + EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS| > + EXPORT_OP_NOATOMIC_ATTR, So I still don't understand why we need a new flag for this. Before you said it was because a filesystem might want to turn off the v4 atomic flag but still return v3 post-wcc attributes. But it seems that a) we have no example of a filesystem that wants to do that, b) it would violate the protocol anyway. Is that right? If so, then let's just stick to one flag for both. --b. > }; > diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c > index e80a7525561d..66f2ef67792a 100644 > --- a/fs/nfsd/nfsfh.c > +++ b/fs/nfsd/nfsfh.c > @@ -301,6 +301,10 @@ static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp) > fhp->fh_export = exp; > > switch (rqstp->rq_vers) { > + case 4: > + if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR) > + fhp->fh_no_atomic_attr = true; > + break; > case 3: > if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC) > fhp->fh_no_wcc = true; > diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h > index 347d10aa6265..cb20c2cd3469 100644 > --- a/fs/nfsd/nfsfh.h > +++ b/fs/nfsd/nfsfh.h > @@ -36,6 +36,11 @@ typedef struct svc_fh { > bool fh_locked; /* inode locked by us */ > bool fh_want_write; /* remount protection taken */ > bool fh_no_wcc; /* no wcc data needed */ > + bool fh_no_atomic_attr; > + /* > + * wcc data is not atomic with > + * operation > + */ > int fh_flags; /* FH flags */ > #ifdef CONFIG_NFSD_V3 > bool fh_post_saved; /* post-op attrs saved */ > diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h > index b4556e86e97c..a60ff5ce1a37 100644 > --- a/fs/nfsd/xdr4.h > +++ b/fs/nfsd/xdr4.h > @@ -748,7 +748,7 @@ static inline void > set_change_info(struct nfsd4_change_info *cinfo, struct svc_fh *fhp) > { > BUG_ON(!fhp->fh_pre_saved); > - cinfo->atomic = (u32)fhp->fh_post_saved; > + cinfo->atomic = (u32)(fhp->fh_post_saved && !fhp->fh_no_atomic_attr); > > cinfo->before_change = fhp->fh_pre_change; > cinfo->after_change = fhp->fh_post_change; > diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h > index d93e8a6737bb..9f4d4bcbf251 100644 > --- a/include/linux/exportfs.h > +++ b/include/linux/exportfs.h > @@ -217,6 +217,9 @@ struct export_operations { > #define EXPORT_OP_NOSUBTREECHK (0x2) /* no subtree checking */ > #define EXPORT_OP_CLOSE_BEFORE_UNLINK (0x4) /* close files before unlink */ > #define EXPORT_OP_REMOTE_FS (0x8) /* Filesystem is remote */ > +#define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply > + atomic attribute updates > + */ > unsigned long flags; > }; > > -- > 2.28.0