ceph: handle frag mismatch between readdir request and reply

If client has outdated directory fragments information, it may request
readdir an non-existent directory fragment. In this case, the MDS finds
an approximate directory fragment and sends its contents back to the
client. When receiving a reply with fragment that is different than the
requested one, the client need to reset the 'readdir offset'.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 868b61d..2a0bcae 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -352,8 +352,18 @@ more:
                }
 
                /* note next offset and last dentry name */
+               rinfo = &req->r_reply_info;
+               if (le32_to_cpu(rinfo->dir_dir->frag) != frag) {
+                       frag = le32_to_cpu(rinfo->dir_dir->frag);
+                       if (ceph_frag_is_leftmost(frag))
+                               fi->next_offset = 2;
+                       else
+                               fi->next_offset = 0;
+                       off = fi->next_offset;
+               }
                fi->offset = fi->next_offset;
                fi->last_readdir = req;
+               fi->frag = frag;
 
                if (req->r_reply_info.dir_end) {
                        kfree(fi->last_name);
@@ -363,7 +373,6 @@ more:
                        else
                                fi->next_offset = 0;
                } else {
-                       rinfo = &req->r_reply_info;
                        err = note_last_dentry(fi,
                                       rinfo->dir_dname[rinfo->dir_nr-1],
                                       rinfo->dir_dname_len[rinfo->dir_nr-1]);

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 1c9fea0..9a8e396 100644 (file)
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1275,8 +1275,20 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
        int err = 0, i;
        struct inode *snapdir = NULL;
        struct ceph_mds_request_head *rhead = req->r_request->front.iov_base;
-       u64 frag = le32_to_cpu(rhead->args.readdir.frag);
        struct ceph_dentry_info *di;
+       u64 r_readdir_offset = req->r_readdir_offset;
+       u32 frag = le32_to_cpu(rhead->args.readdir.frag);
+
+       if (rinfo->dir_dir &&
+           le32_to_cpu(rinfo->dir_dir->frag) != frag) {
+               dout("readdir_prepopulate got new frag %x -> %x\n",
+                    frag, le32_to_cpu(rinfo->dir_dir->frag));
+               frag = le32_to_cpu(rinfo->dir_dir->frag);
+               if (ceph_frag_is_leftmost(frag))
+                       r_readdir_offset = 2;
+               else
+                       r_readdir_offset = 0;
+       }
 
        if (req->r_aborted)
                return readdir_prepopulate_inodes_only(req, session);
@@ -1340,7 +1352,7 @@ retry_lookup:
                }
 
                di = dn->d_fsdata;
-               di->offset = ceph_make_fpos(frag, i + req->r_readdir_offset);
+               di->offset = ceph_make_fpos(frag, i + r_readdir_offset);
 
                /* inode */
                if (dn->d_inode) {

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index b7bda5d..f51ab26 100644 (file)
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2238,8 +2238,7 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
        err = ceph_fill_trace(mdsc->fsc->sb, req, req->r_session);
        if (err == 0) {
                if (result == 0 && (req->r_op == CEPH_MDS_OP_READDIR ||
-                                   req->r_op == CEPH_MDS_OP_LSSNAP) &&
-                   rinfo->dir_nr)
+                                   req->r_op == CEPH_MDS_OP_LSSNAP))
                        ceph_readdir_prepopulate(req, req->r_session);
                ceph_unreserve_caps(mdsc, &req->r_caps_reservation);
        }