On 4/28/20 2:23 PM, Jeff Layton wrote:
On Mon, 2020-04-27 at 23:46 +0200, edward6@xxxxxxxxxxxxx wrote:
From: Eduard Shishkin <edward6@xxxxxxxxxxxxx>
In the function handle_session() variable @features always
contains little endian order of bytes. Just because the feature
bits are packed bytewise from left to right in
encode_supported_features().
However, test_bit(), called to check features availability, assumes
the host order of bytes in that variable. This leads to problems on
big endian architectures. Specifically it is impossible to mount
ceph volume on s390.
This patch adds conversion from little endian to the host order
of bytes, thus fixing the problem.
Signed-off-by: Eduard Shishkin <edward6@xxxxxxxxxxxxx>
---
fs/ceph/mds_client.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 486f91f..190598d 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3252,7 +3252,7 @@ static void handle_session(struct ceph_mds_session *session,
struct ceph_mds_session_head *h;
u32 op;
u64 seq;
- unsigned long features = 0;
+ __le64 features = 0;
int wake = 0;
bool blacklisted = false;
@@ -3301,7 +3301,7 @@ static void handle_session(struct ceph_mds_session *session,
if (session->s_state == CEPH_MDS_SESSION_RECONNECTING)
pr_info("mds%d reconnect success\n", session->s_mds);
session->s_state = CEPH_MDS_SESSION_OPEN;
- session->s_features = features;
+ session->s_features = le64_to_cpu(features);
renewed_caps(mdsc, session, 0);
wake = 1;
if (mdsc->stopping)
(cc'ing Zheng since he did the original patches here)
Thanks Eduard. The problem is real, but I think we can just do the
conversion during the decode.
The feature mask words sent by the MDS are 64 bits, so if it's smaller
we can assume that it's malformed. So, I don't think we need to handle
the case where it's smaller than 8 bytes.
How about this patch instead?
Hi Jeff,
This also works. Please, apply.
Thanks,
Eduard.
--------------------------8<-----------------------------
ceph: fix endianness bug when handling MDS session feature bits
Eduard reported a problem mounting cephfs on s390 arch. The feature
mask sent by the MDS is little-endian, so we need to convert it
before storing and testing against it.
Reported-by: Eduard Shishkin <edward6@xxxxxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/ceph/mds_client.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index a8a5b98148ec..6c283c52d401 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3260,8 +3260,7 @@ static void handle_session(struct ceph_mds_session *session,
void *end = p + msg->front.iov_len;
struct ceph_mds_session_head *h;
u32 op;
- u64 seq;
- unsigned long features = 0;
+ u64 seq, features = 0;
int wake = 0;
bool blacklisted = false;
@@ -3280,9 +3279,8 @@ static void handle_session(struct ceph_mds_session *session,
goto bad;
/* version >= 3, feature bits */
ceph_decode_32_safe(&p, end, len, bad);
- ceph_decode_need(&p, end, len, bad);
- memcpy(&features, p, min_t(size_t, len, sizeof(features)));
- p += len;
+ ceph_decode_64_safe(&p, end, features, bad);
+ p += len - sizeof(features);
}
mutex_lock(&mdsc->mutex);
