[Qemu-devel] [PATCH] qemu: virtio-9p: Do not reset atime

["M. Mohan Kumar" <mohan@in.ibm.com>]

Current code resets file's atime to 0 when there is a change in mtime.
This results in resetting the atime to "1970-01-01 05:30:00". For
example, truncate -s 0 filename results in changing the mtime to the
truncate time, but resets the atime to "1970-01-01 05:30:00". utime
system call does not have any provision to set only mtime or atime. So
change v9fs_wstat_post_chmod function to use utimensat function to change
the atime and mtime fields. If tv_nsec field is set to the special value
"UTIME_OMIT", corresponding file time stamp is not updated.

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
---
 hw/file-op-9p.h      |    2 +-
 hw/virtio-9p-local.c |    8 ++++----
 hw/virtio-9p.c       |   28 ++++++++++++++++++++--------
 3 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/hw/file-op-9p.h b/hw/file-op-9p.h
index dd82ac7..120c803 100644
--- a/hw/file-op-9p.h
+++ b/hw/file-op-9p.h
@@ -52,7 +52,7 @@ typedef struct FileOperations
     int (*chmod)(FsContext *, const char *, FsCred *);
     int (*chown)(FsContext *, const char *, FsCred *);
     int (*mknod)(FsContext *, const char *, FsCred *);
-    int (*utime)(FsContext *, const char *, const struct utimbuf *);
+    int (*utimensat)(FsContext *, const char *, const struct timespec *);
     int (*remove)(FsContext *, const char *);
     int (*symlink)(FsContext *, const char *, const char *, FsCred *);
     int (*link)(FsContext *, const char *, const char *);
diff --git a/hw/virtio-9p-local.c b/hw/virtio-9p-local.c
index ecd5db9..dd60354 100644
--- a/hw/virtio-9p-local.c
+++ b/hw/virtio-9p-local.c
@@ -451,10 +451,10 @@ static int local_chown(FsContext *fs_ctx, const char *path, FsCred *credp)
     return -1;
 }
 
-static int local_utime(FsContext *ctx, const char *path,
-                        const struct utimbuf *buf)
+static int local_utimensat(FsContext *s, const char *path,
+		       const struct timespec *buf)
 {
-    return utime(rpath(ctx, path), buf);
+    return utimensat(AT_FDCWD, rpath(s, path), buf, AT_SYMLINK_NOFOLLOW);
 }
 
 static int local_remove(FsContext *ctx, const char *path)
@@ -496,7 +496,7 @@ FileOperations local_ops = {
     .truncate = local_truncate,
     .rename = local_rename,
     .chown = local_chown,
-    .utime = local_utime,
+    .utimensat = local_utimensat,
     .remove = local_remove,
     .fsync = local_fsync,
     .statfs = local_statfs,
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index 1615924..f087122 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -238,10 +238,25 @@ static int v9fs_do_chown(V9fsState *s, V9fsString *path, uid_t uid, gid_t gid)
     return s->ops->chown(&s->ctx, path->data, &cred);
 }
 
-static int v9fs_do_utime(V9fsState *s, V9fsString *path,
-                            const struct utimbuf *buf)
+static int v9fs_do_utimensat(V9fsState *s, V9fsString *path, V9fsStat v9stat)
 {
-    return s->ops->utime(&s->ctx, path->data, buf);
+    struct timespec ts[2];
+
+    if (v9stat.atime != -1) {
+        ts[0].tv_sec = v9stat.atime;
+        ts[0].tv_nsec = 0;
+    } else {
+        ts[0].tv_nsec = UTIME_OMIT;
+    }
+
+    if (v9stat.mtime != -1) {
+        ts[1].tv_sec = v9stat.mtime;
+        ts[1].tv_nsec = 0;
+    } else {
+        ts[1].tv_nsec = UTIME_OMIT;
+    }
+
+    return s->ops->utimensat(&s->ctx, path->data, ts);
 }
 
 static int v9fs_do_remove(V9fsState *s, V9fsString *path)
@@ -2184,11 +2199,8 @@ static void v9fs_wstat_post_chmod(V9fsState *s, V9fsWstatState *vs, int err)
         goto out;
     }
 
-    if (vs->v9stat.mtime != -1) {
-        struct utimbuf tb;
-        tb.actime = 0;
-        tb.modtime = vs->v9stat.mtime;
-        if (v9fs_do_utime(s, &vs->fidp->path, &tb)) {
+    if (vs->v9stat.mtime != -1 || vs->v9stat.atime != -1) {
+        if (v9fs_do_utimensat(s, &vs->fidp->path, vs->v9stat)) {
             err = -errno;
         }
     }
-- 
1.6.6.1