Servers can defer destaging any data and updating the mtime until close(). This means that if we do a setinfo to modify the mtime while other handles are open for write the server may overwrite our setinfo timestamps when if flushes the file on close() of the writeable handle.

To solve this we add an explicit flush when the mtime is about to be updated.

This fixes "cp -p" to preserve mtime when copying a file onto an SMB2 share.

CC: Stable stable@vger.kernel.org Signed-off-by: Ronnie Sahlberg lsahlber@redhat.com --- fs/cifs/inode.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c index 1bffe029fb66..56ca4b8ccaba 100644 --- a/fs/cifs/inode.c +++ b/fs/cifs/inode.c @@ -2406,6 +2406,8 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs) struct inode *inode = d_inode(direntry); struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb); struct cifsInodeInfo *cifsInode = CIFS_I(inode); + struct cifsFileInfo *wfile; + struct cifs_tcon *tcon; char *full_path = NULL; int rc = -EACCES; __u32 dosattr = 0; @@ -2452,6 +2454,20 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs) mapping_set_error(inode->i_mapping, rc); rc = 0;

+ if (attrs->ia_valid & ATTR_MTIME) { + rc = cifs_get_writable_file(cifsInode, false, &wfile); + if (!rc) { + tcon = tlink_tcon(wfile->tlink); + rc = tcon->ses->server->ops->flush(xid, tcon, &wfile->fid); + cifsFileInfo_put(wfile); + if (rc) + return rc; + } else if (rc != -EBADF) + return rc; + else + rc = 0; + } + if (attrs->ia_valid & ATTR_SIZE) { rc = cifs_set_file_size(inode, attrs, xid, full_path); if (rc != 0)