[PATCH v2 014/109] virtiofsd: Make fsync work even if only inode is passed in

[Dr. David Alan Gilbert (git)]

From: Vivek Goyal <vgo...@redhat.com>

If caller has not sent file handle in request, then using inode, retrieve
the fd opened using O_PATH and use that to open file again and issue
fsync. This will be needed when dax_flush() calls fsync. At that time
we only have inode information (and not file).

Signed-off-by: Vivek Goyal <vgo...@redhat.com>
Reviewed-by: Daniel P. Berrangé <berra...@redhat.com>
---
 tools/virtiofsd/fuse_lowlevel.c  |  6 +++++-
 tools/virtiofsd/passthrough_ll.c | 28 ++++++++++++++++++++++++++--
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
index efba1066a1..861a0b6c31 100644
--- a/tools/virtiofsd/fuse_lowlevel.c
+++ b/tools/virtiofsd/fuse_lowlevel.c
@@ -1076,7 +1076,11 @@ static void do_fsync(fuse_req_t req, fuse_ino_t nodeid, 
const void *inarg)
     fi.fh = arg->fh;
 
     if (req->se->op.fsync) {
-        req->se->op.fsync(req, nodeid, datasync, &fi);
+        if (fi.fh == (uint64_t)-1) {
+            req->se->op.fsync(req, nodeid, datasync, NULL);
+        } else {
+            req->se->op.fsync(req, nodeid, datasync, &fi);
+        }
     } else {
         fuse_reply_err(req, ENOSYS);
     }
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index e1f76170f6..3a8d5497c6 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -902,10 +902,34 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int 
datasync,
 {
     int res;
     (void)ino;
+    int fd;
+    char *buf;
+
+    fuse_log(FUSE_LOG_DEBUG, "lo_fsync(ino=%" PRIu64 ", fi=0x%p)\n", ino,
+             (void *)fi);
+
+    if (!fi) {
+        res = asprintf(&buf, "/proc/self/fd/%i", lo_fd(req, ino));
+        if (res == -1) {
+            return (void)fuse_reply_err(req, errno);
+        }
+
+        fd = open(buf, O_RDWR);
+        free(buf);
+        if (fd == -1) {
+            return (void)fuse_reply_err(req, errno);
+        }
+    } else {
+        fd = fi->fh;
+    }
+
     if (datasync) {
-        res = fdatasync(fi->fh);
+        res = fdatasync(fd);
     } else {
-        res = fsync(fi->fh);
+        res = fsync(fd);
+    }
+    if (!fi) {
+        close(fd);
     }
     fuse_reply_err(req, res == -1 ? errno : 0);
 }
-- 
2.24.1