LU-1996 lustre: Flexible changelog format.

[fs/lustre-release.git] / lustre / obdclass / llog_osd.c

diff --git a/lustre/obdclass/llog_osd.c b/lustre/obdclass/llog_osd.c
index 8295d39..e74f552 100644 (file)
--- a/lustre/obdclass/llog_osd.c
+++ b/lustre/obdclass/llog_osd.c
@@ -187,6 +187,7 @@ static int llog_osd_read_header(const struct lu_env *env,
        struct llog_rec_hdr     *llh_hdr;
        struct dt_object        *o;
        struct llog_thread_info *lgi;
+       enum llog_flag           flags;
        int                      rc;
 
        ENTRY;
@@ -209,6 +210,8 @@ static int llog_osd_read_header(const struct lu_env *env,
                RETURN(LLOG_EEMPTY);
        }
 
+       flags = handle->lgh_hdr->llh_flags;
+
        lgi->lgi_off = 0;
        lgi->lgi_buf.lb_buf = handle->lgh_hdr;
        lgi->lgi_buf.lb_len = LLOG_CHUNK_SIZE;
@@ -243,6 +246,7 @@ static int llog_osd_read_header(const struct lu_env *env,
                RETURN(-EIO);
        }
 
+       handle->lgh_hdr->llh_flags |= (flags & LLOG_F_EXT_MASK);
        handle->lgh_last_idx = handle->lgh_hdr->llh_tail.lrt_index;
 
        RETURN(0);
@@ -587,6 +591,32 @@ static inline void llog_skip_over(__u64 *off, int curr, int goal)
 }
 
 /**
+ * Remove optional fields that the client doesn't expect.
+ * This is typically in order to ensure compatibility with older clients.
+ * It is assumed that since we exclusively remove fields, the block will be
+ * big enough to handle the remapped records. It is also assumed that records
+ * of a block have the same format (i.e.: the same features enabled).
+ *
+ * \param[in,out]    hdr       Header of the block of records to remap.
+ * \param[in,out]    last_hdr   Last header, don't read past this point.
+ * \param[in]        flags     Flags describing the fields to keep.
+ */
+static void changelog_block_trim_ext(struct llog_rec_hdr *hdr,
+                                    struct llog_rec_hdr *last_hdr,
+                                    enum changelog_rec_flags flags)
+{
+       if (hdr->lrh_type != CHANGELOG_REC)
+               return;
+
+       do {
+               struct changelog_rec *rec = (struct changelog_rec *)(hdr + 1);
+
+               changelog_remap_rec(rec, rec->cr_flags & flags);
+               hdr = llog_rec_hdr_next(hdr);
+       } while ((char *)hdr <= (char *)last_hdr);
+}
+
+/**
  * Implementation of the llog_operations::lop_next_block
  *
  * This function finds the the next llog block to return which contains
@@ -713,6 +743,12 @@ static int llog_osd_next_block(const struct lu_env *env,
                               rec->lrh_index, next_idx);
                        GOTO(out, rc = -ENOENT);
                }
+
+               /* Trim unsupported extensions for compat w/ older clients */
+               if (!(loghandle->lgh_hdr->llh_flags & LLOG_F_EXT_JOBID))
+                       changelog_block_trim_ext(rec, last_rec,
+                                                CLF_VERSION | CLF_RENAME);
+
                GOTO(out, rc = 0);
        }
        GOTO(out, rc = -EIO);
@@ -831,6 +867,12 @@ static int llog_osd_prev_block(const struct lu_env *env,
                               rec->lrh_index, prev_idx);
                        GOTO(out, rc = -ENOENT);
                }
+
+               /* Trim unsupported extensions for compat w/ older clients */
+               if (!(loghandle->lgh_hdr->llh_flags & LLOG_F_EXT_JOBID))
+                       changelog_block_trim_ext(rec, last_rec,
+                                                CLF_VERSION | CLF_RENAME);
+
                GOTO(out, rc = 0);
        }
        GOTO(out, rc = -EIO);