[PATCH 3/6] fuse: cache atime when in iomap mode

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

When we're running in iomap mode, allow the kernel to cache the access
timestamp to further reduce the number of roundtrips to the fuse server.

Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
 fs/fuse/dir.c   |    5 +++++
 fs/fuse/inode.c |   19 ++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)


diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index d2f9bcccd776f0..a3ea50b99054ff 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2030,6 +2030,11 @@ int fuse_flush_times(struct inode *inode, struct fuse_file *ff)
 		inarg.ctime = inode_get_ctime_sec(inode);
 		inarg.ctimensec = inode_get_ctime_nsec(inode);
 	}
+	if (fuse_has_iomap(inode)) {
+		inarg.valid |= FATTR_ATIME;
+		inarg.atime = inode_get_atime_sec(inode);
+		inarg.atimensec = inode_get_atime_nsec(inode);
+	}
 	if (ff) {
 		inarg.valid |= FATTR_FH;
 		inarg.fh = ff->fh;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index b1793df3cbbd1a..91143845c615c4 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -264,7 +264,8 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 	attr->mtimensec = min_t(u32, attr->mtimensec, NSEC_PER_SEC - 1);
 	attr->ctimensec = min_t(u32, attr->ctimensec, NSEC_PER_SEC - 1);
 
-	inode_set_atime(inode, attr->atime, attr->atimensec);
+	if (!(cache_mask & STATX_ATIME))
+		inode_set_atime(inode, attr->atime, attr->atimensec);
 	/* mtime from server may be stale due to local buffered write */
 	if (!(cache_mask & STATX_MTIME)) {
 		inode_set_mtime(inode, attr->mtime, attr->mtimensec);
@@ -331,8 +332,12 @@ u32 fuse_get_cache_mask(struct inode *inode)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 
-	if (S_ISREG(inode->i_mode) &&
-	    (fuse_inode_has_iomap(inode) || fc->writeback_cache))
+	if (!S_ISREG(inode->i_mode))
+		return 0;
+
+	if (fuse_inode_has_iomap(inode))
+		return STATX_MTIME | STATX_CTIME | STATX_ATIME | STATX_SIZE;
+	if (fc->writeback_cache)
 		return STATX_MTIME | STATX_CTIME | STATX_SIZE;
 
 	return 0;
@@ -451,6 +456,14 @@ static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr,
 				   new_decode_dev(attr->rdev));
 	} else
 		BUG();
+
+	/*
+	 * iomap caches atime too, so we must load it from the fuse server
+	 * at instantiation time.
+	 */
+	if (fuse_has_iomap(inode))
+		inode_set_atime(inode, attr->atime, attr->atimensec);
+
 	/*
 	 * Ensure that we don't cache acls for daemons without FUSE_POSIX_ACL
 	 * so they see the exact same behavior as before.