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From:   trondmy@kernel.org
To:     "J. Bruce Fields" <bfields@redhat.com>,
        Chuck Lever <chuck.lever@oracle.com>
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH 2/2] nfsd: Record NFSv4 pre/post-op attributes as non-atomic
Date:   Mon, 30 Nov 2020 23:14:27 -0500
Message-Id: <20201201041427.756749-2-trondmy@kernel.org>
In-Reply-To: <20201201041427.756749-1-trondmy@kernel.org>
References: <20201201041427.756749-1-trondmy@kernel.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

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 <trond.myklebust@hammerspace.com>
---
 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,
 };
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