From: Ralph Boehme Date: Fri, 17 Jan 2020 09:56:00 +0000 (+0100) Subject: smbd: avoid calling vfs_file_id_from_sbuf() if statinfo is not valid X-Git-Tag: samba-4.12.0rc1~75 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7606800b798a31d62e69f61d441201e5db2f0d8a;p=thirdparty%2Fsamba.git smbd: avoid calling vfs_file_id_from_sbuf() if statinfo is not valid When we're about to create a file, the stat info will be all zero, so vfs_file_id_from_sbuf() would return a bogus file_id. This is normally not a problem, as open_file() itself also calls vfs_file_id_from_sbuf() after having created the file. This is however a problem when using the VFS module fileid, as that is doing caching of /etc/mtab and failing to find smb_fname->st.st_ex_dev (all zero in this case when creating a new file) in the mtab cache will trigger a mtab reload which can be *very* expensive. Copying many small files to a Samba server in this situation will result in abysimal performance. BUG: https://bugzilla.samba.org/show_bug.cgi?id=14237 Pair-Programmed-With: Jeremy Allison Signed-off-by: Ralph Boehme Autobuild-User(master): Jeremy Allison Autobuild-Date(master): Fri Jan 17 22:38:14 UTC 2020 on sn-devel-184 --- diff --git a/source3/smbd/open.c b/source3/smbd/open.c index a012e33316f..e64e22581e0 100644 --- a/source3/smbd/open.c +++ b/source3/smbd/open.c @@ -3596,7 +3596,15 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn, return NT_STATUS_ACCESS_DENIED; } - fsp->file_id = vfs_file_id_from_sbuf(conn, &smb_fname->st); + if (VALID_STAT(smb_fname->st)) { + /* + * Only try and create a file id before open + * for an existing file. For a file being created + * this won't do anything useful until the file + * exists and has a valid stat struct. + */ + fsp->file_id = vfs_file_id_from_sbuf(conn, &smb_fname->st); + } fsp->fh->private_options = private_flags; fsp->access_mask = open_access_mask; /* We change this to the * requested access_mask after