Re: [PATCH v6] ceph: blocklist the kclient when receiving corrupted snap trace

On 01/02/2023 03:05, Ilya Dryomov wrote:

On Thu, Jan 12, 2023 at 9:56 AM xiubli@redhat.com wrote:

...

From: Xiubo Li xiubli@redhat.com

When received corrupted snap trace we don't know what exactly has happened in MDS side. And we shouldn't continue IOs and metadatas access to MDS, which may corrupt or get incorrect contents.

This patch will just block all the further IO/MDS requests immediately and then evict the kclient itself.

The reason why we still need to evict the kclient just after blocking all the further IOs is that the MDS could revoke the caps faster.

Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/57686 Reviewed-by: Venky Shankar vshankar@redhat.com Signed-off-by: Xiubo Li xiubli@redhat.com

---

V6:

• switch to ceph_inode_is_shutdown() to check the mount state
• fix two debug logs
• use the WRITE_ONCE to set the FENCE_IO state

V5:

• s/CEPH_MOUNT_CORRUPTED/CEPH_MOUNT_FENCE_IO/g

V4:

• block all the IO/metadata requests before evicting the client.

V3:

• Fixed ERROR: spaces required around that ':' (ctx:VxW)

V2:

• Switched to WARN() to taint the Linux kernel.

  fs/ceph/addr.c | 17 +++++++++++++++-- fs/ceph/caps.c | 17 ++++++++++++++--- fs/ceph/file.c | 9 +++++++++ fs/ceph/mds_client.c | 28 +++++++++++++++++++++++++--- fs/ceph/snap.c | 38 ++++++++++++++++++++++++++++++++++++-- fs/ceph/super.h | 1 + 6 files changed, 100 insertions(+), 10 deletions(-)

Hi Xiubo,

This patch appears to be based on testing. If the intent is to get it into 6.2-rc it needs to be rebased on mainline because there is a number of contextual conflicts with SPARSEREAD, etc.

Okay, I will rebase it.

...

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 6fb329a70ac1..13d1c24d2f53 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -305,13 +305,18 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq) struct inode *inode = rreq->inode; struct ceph_inode_info *ci = ceph_inode(inode); struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

•   struct ceph_osd_request *req;
  

•   struct ceph_osd_request *req = NULL;
     struct ceph_vino vino = ceph_vino(inode);
     struct iov_iter iter;
     int err = 0;
     u64 len = subreq->len;
     bool sparse = ceph_test_mount_opt(fsc, SPARSEREAD);
  
  

•   if (ceph_inode_is_shutdown(inode)) {
  

•           err = -EIO;
  

•           goto out;
  

•   }
  

•    if (ceph_has_inline_data(ci) && ceph_netfs_issue_op_inline(subreq))
             return;
  
  

@@ -557,6 +562,9 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)

     dout("writepage %p idx %lu\n", page, page->index);

•   if (ceph_inode_is_shutdown(inode))
  

•           return -EIO;
  

•    /* verify this is a writeable snap context */
     snapc = page_snap_context(page);
     if (!snapc) {
  

@@ -1637,7 +1645,7 @@ int ceph_uninline_data(struct file *file) struct ceph_inode_info *ci = ceph_inode(inode); struct ceph_fs_client *fsc = ceph_inode_to_client(inode); struct ceph_osd_request *req = NULL;

•   struct ceph_cap_flush *prealloc_cf;
  

•   struct ceph_cap_flush *prealloc_cf = NULL;
     struct folio *folio = NULL;
     u64 inline_version = CEPH_INLINE_NONE;
     struct page *pages[1];
  

@@ -1651,6 +1659,11 @@ int ceph_uninline_data(struct file *file) dout("uninline_data %p %llx.%llx inline_version %llu\n", inode, ceph_vinop(inode), inline_version);

•   if (ceph_inode_is_shutdown(inode)) {
  

•           err = -EIO;
  

•           goto out;
  

•   }
  

•    if (inline_version == CEPH_INLINE_NONE)
             return 0;
  
  

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 948136f81fc8..5230ab64fff0 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -4134,6 +4134,7 @@ void ceph_handle_caps(struct ceph_mds_session *session, void *p, *end; struct cap_extra_info extra_info = {}; bool queue_trunc;

•   bool close_sessions = false;
  
     dout("handle_caps from mds%d\n", session->s_mds);
  
  

@@ -4275,9 +4276,13 @@ void ceph_handle_caps(struct ceph_mds_session *session, realm = NULL; if (snaptrace_len) { down_write(&mdsc->snap_rwsem);

•                   ceph_update_snap_trace(mdsc, snaptrace,
  

•                                          snaptrace + snaptrace_len,
  

•                                          false, &realm);
  

•                   if (ceph_update_snap_trace(mdsc, snaptrace,
  

•                                              snaptrace + snaptrace_len,
  

•                                              false, &realm)) {
  

•                           up_write(&mdsc->snap_rwsem);
  

•                           close_sessions = true;
  

•                           goto done;
  

•                   }
                     downgrade_write(&mdsc->snap_rwsem);
             } else {
                     down_read(&mdsc->snap_rwsem);
  

@@ -4341,6 +4346,11 @@ void ceph_handle_caps(struct ceph_mds_session *session, iput(inode); out: ceph_put_string(extra_info.pool_ns);

•   /* Defer closing the sessions after s_mutex lock being released */
  

•   if (close_sessions)
  

•           ceph_mdsc_close_sessions(mdsc);
  

•    return;
  
  

  flush_cap_releases:

@@ -4350,6 +4360,7 @@ void ceph_handle_caps(struct ceph_mds_session *session, * cap). */ ceph_flush_cap_releases(mdsc, session);

Stray whitespace?

Will remove it.

...

     goto done;

bad: diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 59c89c436185..1ba3c07e242b 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -976,6 +976,9 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *to, dout("sync_read on file %p %llu~%u %s\n", file, off, (unsigned)len, (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");

•   if (ceph_inode_is_shutdown(inode))
  

•           return -EIO;
  

•    if (!len)
             return 0;
     /*
  

@@ -1342,6 +1345,9 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter, bool should_dirty = !write && user_backed_iter(iter); bool sparse = ceph_test_mount_opt(fsc, SPARSEREAD);

•   if (ceph_inode_is_shutdown(inode))
  

•           return -EIO;
  

•    if (write && ceph_snap(file_inode(file)) != CEPH_NOSNAP)
             return -EROFS;
  
  

@@ -2078,6 +2084,9 @@ static int ceph_zero_partial_object(struct inode *inode, loff_t zero = 0; int op;

•   if (ceph_inode_is_shutdown(inode))
  

•           return -EIO;
  

•    if (!length) {
             op = offset ? CEPH_OSD_OP_DELETE : CEPH_OSD_OP_TRUNCATE;
             length = &zero;
  

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index cbbaf334b6b8..b60812707fce 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -957,6 +957,9 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc, { struct ceph_mds_session *s;

•   if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_FENCE_IO)
  

•           return ERR_PTR(-EIO);
  

•    if (mds >= mdsc->mdsmap->possible_max_rank)
             return ERR_PTR(-EINVAL);
  
  

@@ -1632,6 +1635,9 @@ static int __open_session(struct ceph_mds_client *mdsc, int mstate; int mds = session->s_mds;

•   if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_FENCE_IO)
  

•           return -EIO;
  

•    /* wait for mds to go active? */
     mstate = ceph_mdsmap_get_state(mdsc->mdsmap, mds);
     dout("open_session to mds%d (%s)\n", mds,
  

@@ -3205,6 +3211,11 @@ static void __do_request(struct ceph_mds_client *mdsc, err = -ETIMEDOUT; goto finish; }

•   if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_FENCE_IO) {
  

•           dout("do_request metadata corrupted\n");
  

•           err = -EIO;
  

•           goto finish;
  

•   }
  

In all other cases, a fencing-related condition is checked first and the associated EIO error therefore trumps all other errors (and not just errors, in some cases the error takes precedence over a potential successful return, for example when there is no inline data). However in this case ETIMEDOUT could be returned even if fsc->mount_state == CEPH_MOUNT_FENCE_IO. Should these checks be reordered?

I just followed the following "CEPH_MOUNT_SHUTDOWN" case and thought it won't that critical. But to make it the same logic with others I will fix it.

...

     if (READ_ONCE(mdsc->fsc->mount_state) == CEPH_MOUNT_SHUTDOWN) {
             dout("do_request forced umount\n");
             err = -EIO;

@@ -3584,6 +3595,7 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg) u64 tid; int err, result; int mds = session->s_mds;

•   bool close_sessions = false;
  
     if (msg->front.iov_len < sizeof(*head)) {
             pr_err("mdsc_handle_reply got corrupt (short) reply\n");
  

@@ -3698,10 +3710,15 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg) realm = NULL; if (rinfo->snapblob_len) { down_write(&mdsc->snap_rwsem);

•           ceph_update_snap_trace(mdsc, rinfo->snapblob,
  

•           err = ceph_update_snap_trace(mdsc, rinfo->snapblob,
                             rinfo->snapblob + rinfo->snapblob_len,
                             le32_to_cpu(head->op) == CEPH_MDS_OP_RMSNAP,
                             &realm);
  

•           if (err) {
  

•                   up_write(&mdsc->snap_rwsem);
  

•                   close_sessions = true;
  

•                   goto out_err;
  

•           }
             downgrade_write(&mdsc->snap_rwsem);
     } else {
             down_read(&mdsc->snap_rwsem);
  

@@ -3759,6 +3776,10 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg) req->r_end_latency, err); out: ceph_mdsc_put_request(req);

•   /* Defer closing the sessions after s_mutex lock being released */
  

•   if (close_sessions)
  

•           ceph_mdsc_close_sessions(mdsc);
     return;
  

  }

@@ -5358,7 +5379,7 @@ static bool done_closing_sessions(struct ceph_mds_client *mdsc, int skipped) }

/*

• • called after sb is ro.

• • called after sb is ro or when metadata corrupted.
  */ void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc) {

@@ -5648,7 +5669,8 @@ static void mds_peer_reset(struct ceph_connection *con) struct ceph_mds_client *mdsc = s->s_mdsc;

     pr_warn("mds%d closed our session\n", s->s_mds);

•   send_mds_reconnect(mdsc, s);
  

•   if (READ_ONCE(mdsc->fsc->mount_state) != CEPH_MOUNT_FENCE_IO)
  

•           send_mds_reconnect(mdsc, s);
  

  }

  static void mds_dispatch(struct ceph_connection *con, struct ceph_msg *msg)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index c1c452afa84d..3d417ec8da0c 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include <linux/ceph/ceph_debug.h>

+#include <linux/fs.h> #include <linux/sort.h> #include <linux/slab.h> #include <linux/iversion.h> @@ -767,8 +768,10 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc, struct ceph_snap_realm *realm; struct ceph_snap_realm *first_realm = NULL; struct ceph_snap_realm *realm_to_rebuild = NULL;

•   struct ceph_client *client = mdsc->fsc->client;
     int rebuild_snapcs;
     int err = -ENOMEM;
  

•   int ret;
     LIST_HEAD(dirty_realms);
  
     lockdep_assert_held_write(&mdsc->snap_rwsem);
  

@@ -885,6 +888,27 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc, if (first_realm) ceph_put_snap_realm(mdsc, first_realm); pr_err("%s error %d\n", __func__, err);

•   /*
  

•    * When receiving a corrupted snap trace we don't know what
  

•    * exactly has happened in MDS side. And we shouldn't continue
  

•    * writing to OSD, which may corrupt the snapshot contents.
  

•    *
  

•    * Just try to blocklist this kclient and then this kclient
  

•    * must be remounted to continue after the corrupted metadata
  

•    * fixed in the MDS side.
  

•    */
  

•   WRITE_ONCE(mdsc->fsc->mount_state, CEPH_MOUNT_FENCE_IO);
  

•   ret = ceph_monc_blocklist_add(&client->monc, &client->msgr.inst.addr);
  

•   if (ret)
  

•           pr_err("%s blocklist of %s failed: %d", __func__,
  

•                  ceph_pr_addr(&client->msgr.inst.addr), ret);
  

•   WARN(1, "%s: %s%s do remount to continue%s",
  

•        __func__, ret ? "" : ceph_pr_addr(&client->msgr.inst.addr),
  

FWIW this %s%s construct is still not right: in case blocklisting fails, the message would look like "ceph_update_snap_trace: do remount ..." with two spaces instead of one.

+ WARN(1, "%s: %s%sdo remount to continue%s", + __func__, ret ? "" : ceph_pr_addr(&client->msgr.inst.addr), + ret ? "" : " was blocklisted, ", + err == -EIO ? " after corrupted snaptrace is fixed" : ""); +

This should be okay.

Thanks,

- Xiubo

Thanks,

             Ilya