From: Paulo Alcantara Date: Tue, 7 Oct 2025 19:23:23 +0000 (-0300) Subject: smb: client: fix missing timestamp updates after ftruncate(2) X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=57ce9f7793b714fb14a97d502ce926162c3b96b1;p=users%2Fhch%2Fmisc.git smb: client: fix missing timestamp updates after ftruncate(2) Mask off ATTR_MTIME|ATTR_CTIME bits on ATTR_SIZE (e.g. ftruncate(2)) to prevent the client from sending set info calls and then disabling automatic timestamp updates on server side as per MS-FSA 2.1.4.17. ---8<--- import os import time filename = '/mnt/foo' def print_stat(prefix): st = os.stat(filename) print(prefix, ': ', time.ctime(st.st_atime), time.ctime(st.st_ctime)) fd = os.open(filename, os.O_CREAT|os.O_TRUNC|os.O_WRONLY, 0o644) print_stat('old') os.ftruncate(fd, 10) time.sleep(2) os.write(fd, b'foo') os.close(fd) time.sleep(2) print_stat('new') ---8<--- Before patch: $ mount.cifs //srv/share /mnt -o ... $ python3 run.py old : Fri Oct 3 13:47:03 2025 Fri Oct 3 13:47:03 2025 new : Fri Oct 3 13:47:00 2025 Fri Oct 3 13:47:03 2025 After patch: $ mount.cifs //srv/share /mnt -o ... $ python3 run.py old : Fri Oct 3 13:48:39 2025 Fri Oct 3 13:48:39 2025 new : Fri Oct 3 13:48:41 2025 Fri Oct 3 13:48:41 2025 Signed-off-by: Paulo Alcantara (Red Hat) Cc: Frank Sorenson Reviewed-by: David Howells Cc: linux-cifs@vger.kernel.org Signed-off-by: Steve French --- diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c index ce88bef4e44c..fbfd5b556815 100644 --- a/fs/smb/client/inode.c +++ b/fs/smb/client/inode.c @@ -3156,12 +3156,11 @@ cifs_setattr_unix(struct dentry *direntry, struct iattr *attrs) if (rc != 0) goto out; /* - * The man page of truncate says if the size changed, - * then the st_ctime and st_mtime fields for the file - * are updated. + * Avoid setting timestamps on the server for ftruncate(2) to + * prevent it from disabling automatic timestamp updates as per + * MS-FSA 2.1.4.17. */ - attrs->ia_ctime = attrs->ia_mtime = current_time(inode); - attrs->ia_valid |= ATTR_CTIME | ATTR_MTIME; + attrs->ia_valid &= ~(ATTR_CTIME | ATTR_MTIME); } /* skip mode change if it's just for clearing setuid/setgid */ @@ -3335,12 +3334,11 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs) if (rc != 0) goto cifs_setattr_exit; /* - * The man page of truncate says if the size changed, - * then the st_ctime and st_mtime fields for the file - * are updated. + * Avoid setting timestamps on the server for ftruncate(2) to + * prevent it from disabling automatic timestamp updates as per + * MS-FSA 2.1.4.17. */ - attrs->ia_ctime = attrs->ia_mtime = current_time(inode); - attrs->ia_valid |= ATTR_CTIME | ATTR_MTIME; + attrs->ia_valid &= ~(ATTR_CTIME | ATTR_MTIME); } if (attrs->ia_valid & ATTR_UID)