virtiofsd: Save error code early at the failure callsite

Change error code handling slightly in lo_setattr(). Right now we seem
to jump to out_err and assume that "errno" is valid and use that to
send reply.

But if caller has to do some other operations before jumping to out_err,
then it does the dance of first saving errno to saverr and the restore
errno before jumping to out_err. This makes it more confusing.

I am about to make more changes where caller will have to do some
work after error before jumping to out_err. I found it easier to
change the convention a bit. That is caller saves error in "saverr"
before jumping to out_err. And out_err uses "saverr" to send error
back and does not rely on "errno" having actual error.

v3: Resolved conflicts in lo_setattr() due to lo_inode_open() changes.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210208224024.43555-2-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Vivek Goyal 2021-02-08 17:40:23 -05:00 committed by Dr. David Alan Gilbert
parent a65963efa3
commit 1e08f164e9

View File

@ -698,6 +698,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
res = fchmodat(lo->proc_self_fd, procname, attr->st_mode, 0);
}
if (res == -1) {
saverr = errno;
goto out_err;
}
}
@ -707,6 +708,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
if (res == -1) {
saverr = errno;
goto out_err;
}
}
@ -718,16 +720,15 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
} else {
truncfd = lo_inode_open(lo, inode, O_RDWR);
if (truncfd < 0) {
errno = -truncfd;
saverr = -truncfd;
goto out_err;
}
}
res = ftruncate(truncfd, attr->st_size);
saverr = res == -1 ? errno : 0;
if (!fi) {
saverr = errno;
close(truncfd);
errno = saverr;
}
if (res == -1) {
goto out_err;
@ -760,6 +761,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
res = utimensat(lo->proc_self_fd, procname, tv, 0);
}
if (res == -1) {
saverr = errno;
goto out_err;
}
}
@ -768,7 +770,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
return lo_getattr(req, ino, fi);
out_err:
saverr = errno;
lo_inode_put(lo, &inode);
fuse_reply_err(req, saverr);
}