[PATCH v3 1/4] nfsd/blocklayout: always ignore loca_time_modify

[Chuck Lever <cel@kernel.org>]

From: Christoph Hellwig <hch@lst.de>

RFC 8881 Section 18.42 makes it clear that the client provided timestamp
is a "may" condition, and clients that want to force a specific timestamp
should send a separate SETATTR in the compound.

Since commit b82f92d5dd1a ("fs: have setattr_copy handle multigrain
timestamps appropriately") the ia_mtime value is ignored by file
systems using multi-grain timestamps like XFS, which is the only
file system supporting blocklayout exports right now, so make that
explicit in NFSD as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/blocklayout.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index 9d829c84f374..24cc5025f649 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -179,15 +179,20 @@ static __be32
 nfsd4_block_commit_blocks(struct inode *inode, struct nfsd4_layoutcommit *lcp,
 		struct iomap *iomaps, int nr_iomaps)
 {
-	struct timespec64 mtime = inode_get_mtime(inode);
 	struct iattr iattr = { .ia_valid = 0 };
 	int error;
 
-	if (lcp->lc_mtime.tv_nsec == UTIME_NOW ||
-	    timespec64_compare(&lcp->lc_mtime, &mtime) < 0)
-		lcp->lc_mtime = current_time(inode);
+	/*
+	 * This ignores the client provided mtime in loca_time_modify, as a
+	 * fully client specified mtime doesn't really fit into the Linux
+	 * multi-grain timestamp architecture.
+	 *
+	 * RFC 8881 Section 18.42 makes it clear that the client provided
+	 * timestamp is a "may" condition, and clients that want to force a
+	 * specific timestamp should send a separate SETATTR in the compound.
+	 */
 	iattr.ia_valid |= ATTR_ATIME | ATTR_CTIME | ATTR_MTIME;
-	iattr.ia_atime = iattr.ia_ctime = iattr.ia_mtime = lcp->lc_mtime;
+	iattr.ia_atime = iattr.ia_ctime = iattr.ia_mtime = current_time(inode);
 
 	if (lcp->lc_size_chg) {
 		iattr.ia_valid |= ATTR_SIZE;
-- 
2.53.0