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LU-7340 mdd: changelogs garbage collection
[fs/lustre-release.git] / lustre / obdclass / llog.c
index e77eb63..d3b1e04 100644 (file)
  *
  * You should have received a copy of the GNU General Public License
  * version 2 along with this program; If not, see
- * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * http://www.gnu.org/licenses/gpl-2.0.html
  *
  * GPL HEADER END
  */
@@ -27,7 +23,7 @@
  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2012, 2013, Intel Corporation.
+ * Copyright (c) 2012, 2016, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
 
 #define DEBUG_SUBSYSTEM S_LOG
 
-#ifndef __KERNEL__
-#include <liblustre.h>
-#endif
-
-#include <obd_class.h>
+#include <linux/pid_namespace.h>
+#include <linux/kthread.h>
+#include <llog_swab.h>
 #include <lustre_log.h>
+#include <obd_class.h>
 #include "llog_internal.h"
-
 /*
  * Allocate a new log or catalog handle
  * Used inside llog_open().
  */
-struct llog_handle *llog_alloc_handle(void)
+static struct llog_handle *llog_alloc_handle(void)
 {
        struct llog_handle *loghandle;
 
@@ -68,8 +62,8 @@ struct llog_handle *llog_alloc_handle(void)
                return NULL;
 
        init_rwsem(&loghandle->lgh_lock);
-       spin_lock_init(&loghandle->lgh_hdr_lock);
-       CFS_INIT_LIST_HEAD(&loghandle->u.phd.phd_entry);
+       mutex_init(&loghandle->lgh_hdr_mutex);
+       INIT_LIST_HEAD(&loghandle->u.phd.phd_entry);
        atomic_set(&loghandle->lgh_refcount, 1);
 
        return loghandle;
@@ -78,20 +72,19 @@ struct llog_handle *llog_alloc_handle(void)
 /*
  * Free llog handle and header data if exists. Used in llog_close() only
  */
-void llog_free_handle(struct llog_handle *loghandle)
+static void llog_free_handle(struct llog_handle *loghandle)
 {
        LASSERT(loghandle != NULL);
 
        /* failed llog_init_handle */
-       if (!loghandle->lgh_hdr)
+       if (loghandle->lgh_hdr == NULL)
                goto out;
 
        if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_PLAIN)
-               LASSERT(cfs_list_empty(&loghandle->u.phd.phd_entry));
+               LASSERT(list_empty(&loghandle->u.phd.phd_entry));
        else if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_CAT)
-               LASSERT(cfs_list_empty(&loghandle->u.chd.chd_head));
-       LASSERT(sizeof(*(loghandle->lgh_hdr)) == LLOG_CHUNK_SIZE);
-       OBD_FREE(loghandle->lgh_hdr, LLOG_CHUNK_SIZE);
+               LASSERT(list_empty(&loghandle->u.chd.chd_head));
+       OBD_FREE_LARGE(loghandle->lgh_hdr, loghandle->lgh_hdr_size);
 out:
        OBD_FREE_PTR(loghandle);
 }
@@ -108,73 +101,205 @@ void llog_handle_put(struct llog_handle *loghandle)
                llog_free_handle(loghandle);
 }
 
+static int llog_declare_destroy(const struct lu_env *env,
+                               struct llog_handle *handle,
+                               struct thandle *th)
+{
+       struct llog_operations *lop;
+       int rc;
+
+       ENTRY;
+
+       rc = llog_handle2ops(handle, &lop);
+       if (rc)
+               RETURN(rc);
+       if (lop->lop_declare_destroy == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       rc = lop->lop_declare_destroy(env, handle, th);
+
+       RETURN(rc);
+}
+
+int llog_trans_destroy(const struct lu_env *env, struct llog_handle *handle,
+                      struct thandle *th)
+{
+       struct llog_operations  *lop;
+       int rc;
+       ENTRY;
+
+       rc = llog_handle2ops(handle, &lop);
+       if (rc < 0)
+               RETURN(rc);
+       if (lop->lop_destroy == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       LASSERT(handle->lgh_obj != NULL);
+       if (!dt_object_exists(handle->lgh_obj))
+               RETURN(0);
+
+       rc = lop->lop_destroy(env, handle, th);
+
+       RETURN(rc);
+}
+
+int llog_destroy(const struct lu_env *env, struct llog_handle *handle)
+{
+       struct llog_operations  *lop;
+       struct dt_device        *dt;
+       struct thandle          *th;
+       int rc;
+
+       ENTRY;
+
+       rc = llog_handle2ops(handle, &lop);
+       if (rc < 0)
+               RETURN(rc);
+       if (lop->lop_destroy == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       if (handle->lgh_obj == NULL) {
+               /* if lgh_obj == NULL, then it is from client side destroy */
+               rc = lop->lop_destroy(env, handle, NULL);
+               RETURN(rc);
+       }
+
+       if (!dt_object_exists(handle->lgh_obj))
+               RETURN(0);
+
+       dt = lu2dt_dev(handle->lgh_obj->do_lu.lo_dev);
+
+       th = dt_trans_create(env, dt);
+       if (IS_ERR(th))
+               RETURN(PTR_ERR(th));
+
+       rc = llog_declare_destroy(env, handle, th);
+       if (rc != 0)
+               GOTO(out_trans, rc);
+
+       rc = dt_trans_start_local(env, dt, th);
+       if (rc < 0)
+               GOTO(out_trans, rc);
+
+       rc = lop->lop_destroy(env, handle, th);
+
+out_trans:
+       dt_trans_stop(env, dt, th);
+
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_destroy);
+
 /* returns negative on error; 0 if success; 1 if success & log destroyed */
 int llog_cancel_rec(const struct lu_env *env, struct llog_handle *loghandle,
                    int index)
 {
-        struct llog_log_hdr *llh = loghandle->lgh_hdr;
-        int rc = 0;
-        ENTRY;
+       struct llog_thread_info *lgi = llog_info(env);
+       struct dt_device        *dt;
+       struct llog_log_hdr     *llh = loghandle->lgh_hdr;
+       struct thandle          *th;
+       int                      rc;
+       int rc1;
+       bool subtract_count = false;
+
+       ENTRY;
 
-        CDEBUG(D_RPCTRACE, "Canceling %d in log "DOSTID"\n",
-               index, POSTID(&loghandle->lgh_id.lgl_oi));
+       CDEBUG(D_RPCTRACE, "Canceling %d in log "DFID"\n", index,
+              PFID(&loghandle->lgh_id.lgl_oi.oi_fid));
 
-        if (index == 0) {
-                CERROR("Can't cancel index 0 which is header\n");
-                RETURN(-EINVAL);
-        }
+       if (index == 0) {
+               CERROR("Can't cancel index 0 which is header\n");
+               RETURN(-EINVAL);
+       }
+
+       LASSERT(loghandle != NULL);
+       LASSERT(loghandle->lgh_ctxt != NULL);
+       LASSERT(loghandle->lgh_obj != NULL);
+
+       dt = lu2dt_dev(loghandle->lgh_obj->do_lu.lo_dev);
+
+       th = dt_trans_create(env, dt);
+       if (IS_ERR(th))
+               RETURN(PTR_ERR(th));
+
+       rc = llog_declare_write_rec(env, loghandle, &llh->llh_hdr, index, th);
+       if (rc < 0)
+               GOTO(out_trans, rc);
+
+       if ((llh->llh_flags & LLOG_F_ZAP_WHEN_EMPTY)) {
+               rc = llog_declare_destroy(env, loghandle, th);
+               if (rc < 0)
+                       GOTO(out_trans, rc);
+       }
 
-       spin_lock(&loghandle->lgh_hdr_lock);
-       if (!ext2_clear_bit(index, llh->llh_bitmap)) {
-               spin_unlock(&loghandle->lgh_hdr_lock);
+       th->th_wait_submit = 1;
+       rc = dt_trans_start_local(env, dt, th);
+       if (rc < 0)
+               GOTO(out_trans, rc);
+
+       down_write(&loghandle->lgh_lock);
+       /* clear bitmap */
+       mutex_lock(&loghandle->lgh_hdr_mutex);
+       if (!ext2_clear_bit(index, LLOG_HDR_BITMAP(llh))) {
                CDEBUG(D_RPCTRACE, "Catalog index %u already clear?\n", index);
-               RETURN(-ENOENT);
+               GOTO(out_unlock, rc);
        }
 
-       llh->llh_count--;
+       loghandle->lgh_hdr->llh_count--;
+       subtract_count = true;
+       /* Pass this index to llog_osd_write_rec(), which will use the index
+        * to only update the necesary bitmap. */
+       lgi->lgi_cookie.lgc_index = index;
+       /* update header */
+       rc = llog_write_rec(env, loghandle, &llh->llh_hdr, &lgi->lgi_cookie,
+                           LLOG_HEADER_IDX, th);
+       if (rc != 0)
+               GOTO(out_unlock, rc);
 
        if ((llh->llh_flags & LLOG_F_ZAP_WHEN_EMPTY) &&
            (llh->llh_count == 1) &&
-           (loghandle->lgh_last_idx == (LLOG_BITMAP_BYTES * 8) - 1)) {
-               spin_unlock(&loghandle->lgh_hdr_lock);
-               rc = llog_destroy(env, loghandle);
+           ((loghandle->lgh_last_idx == LLOG_HDR_BITMAP_SIZE(llh) - 1) ||
+            (loghandle->u.phd.phd_cat_handle != NULL &&
+             loghandle->u.phd.phd_cat_handle->u.chd.chd_current_log !=
+               loghandle))) {
+               /* never try to destroy it again */
+               llh->llh_flags &= ~LLOG_F_ZAP_WHEN_EMPTY;
+               rc = llog_trans_destroy(env, loghandle, th);
                if (rc < 0) {
-                       CERROR("%s: can't destroy empty llog #"DOSTID
-                              "#%08x: rc = %d\n",
+                       /* Sigh, can not destroy the final plain llog, but
+                        * the bitmap has been clearly, so the record can not
+                        * be accessed anymore, let's return 0 for now, and
+                        * the orphan will be handled by LFSCK. */
+                       CERROR("%s: can't destroy empty llog "DFID": rc = %d\n",
                               loghandle->lgh_ctxt->loc_obd->obd_name,
-                              POSTID(&loghandle->lgh_id.lgl_oi),
-                              loghandle->lgh_id.lgl_ogen, rc);
-                       GOTO(out_err, rc);
+                              PFID(&loghandle->lgh_id.lgl_oi.oi_fid), rc);
+                       GOTO(out_unlock, rc = 0);
                }
-               RETURN(1);
+               rc = LLOG_DEL_PLAIN;
        }
-       spin_unlock(&loghandle->lgh_hdr_lock);
 
-       rc = llog_write(env, loghandle, &llh->llh_hdr, NULL, 0, NULL, 0);
-       if (rc < 0) {
-               CERROR("%s: fail to write header for llog #"DOSTID
-                      "#%08x: rc = %d\n",
-                      loghandle->lgh_ctxt->loc_obd->obd_name,
-                      POSTID(&loghandle->lgh_id.lgl_oi),
-                      loghandle->lgh_id.lgl_ogen, rc);
-               GOTO(out_err, rc);
+out_unlock:
+       mutex_unlock(&loghandle->lgh_hdr_mutex);
+       up_write(&loghandle->lgh_lock);
+out_trans:
+       rc1 = dt_trans_stop(env, dt, th);
+       if (rc == 0)
+               rc = rc1;
+       if (rc < 0 && subtract_count) {
+               mutex_lock(&loghandle->lgh_hdr_mutex);
+               loghandle->lgh_hdr->llh_count++;
+               ext2_set_bit(index, LLOG_HDR_BITMAP(llh));
+               mutex_unlock(&loghandle->lgh_hdr_mutex);
        }
-       RETURN(0);
-out_err:
-       spin_lock(&loghandle->lgh_hdr_lock);
-       ext2_set_bit(index, llh->llh_bitmap);
-       llh->llh_count++;
-       spin_unlock(&loghandle->lgh_hdr_lock);
-       return rc;
+       RETURN(rc);
 }
-EXPORT_SYMBOL(llog_cancel_rec);
 
-static int llog_read_header(const struct lu_env *env,
-                           struct llog_handle *handle,
-                           struct obd_uuid *uuid)
+int llog_read_header(const struct lu_env *env, struct llog_handle *handle,
+                    const struct obd_uuid *uuid)
 {
        struct llog_operations *lop;
        int rc;
+       ENTRY;
 
        rc = llog_handle2ops(handle, &lop);
        if (rc)
@@ -187,35 +312,51 @@ static int llog_read_header(const struct lu_env *env,
        if (rc == LLOG_EEMPTY) {
                struct llog_log_hdr *llh = handle->lgh_hdr;
 
+               /* lrh_len should be initialized in llog_init_handle */
                handle->lgh_last_idx = 0; /* header is record with index 0 */
                llh->llh_count = 1;         /* for the header record */
                llh->llh_hdr.lrh_type = LLOG_HDR_MAGIC;
-               llh->llh_hdr.lrh_len = llh->llh_tail.lrt_len = LLOG_CHUNK_SIZE;
-               llh->llh_hdr.lrh_index = llh->llh_tail.lrt_index = 0;
-               llh->llh_timestamp = cfs_time_current_sec();
+               LASSERT(handle->lgh_ctxt->loc_chunk_size >=
+                                               LLOG_MIN_CHUNK_SIZE);
+               llh->llh_hdr.lrh_len = handle->lgh_ctxt->loc_chunk_size;
+               llh->llh_hdr.lrh_index = 0;
+               llh->llh_timestamp = ktime_get_real_seconds();
                if (uuid)
                        memcpy(&llh->llh_tgtuuid, uuid,
                               sizeof(llh->llh_tgtuuid));
                llh->llh_bitmap_offset = offsetof(typeof(*llh), llh_bitmap);
-               ext2_set_bit(0, llh->llh_bitmap);
+               /* Since update llog header might also call this function,
+                * let's reset the bitmap to 0 here */
+               memset(LLOG_HDR_BITMAP(llh), 0, llh->llh_hdr.lrh_len -
+                                               llh->llh_bitmap_offset -
+                                               sizeof(llh->llh_tail));
+               ext2_set_bit(0, LLOG_HDR_BITMAP(llh));
+               LLOG_HDR_TAIL(llh)->lrt_len = llh->llh_hdr.lrh_len;
+               LLOG_HDR_TAIL(llh)->lrt_index = llh->llh_hdr.lrh_index;
                rc = 0;
        }
-       return rc;
+       RETURN(rc);
 }
+EXPORT_SYMBOL(llog_read_header);
 
 int llog_init_handle(const struct lu_env *env, struct llog_handle *handle,
                     int flags, struct obd_uuid *uuid)
 {
        struct llog_log_hdr     *llh;
+       enum llog_flag           fmt = flags & LLOG_F_EXT_MASK;
        int                      rc;
-
+       int                     chunk_size = handle->lgh_ctxt->loc_chunk_size;
        ENTRY;
+
        LASSERT(handle->lgh_hdr == NULL);
 
-       OBD_ALLOC_PTR(llh);
+       LASSERT(chunk_size >= LLOG_MIN_CHUNK_SIZE);
+       OBD_ALLOC_LARGE(llh, chunk_size);
        if (llh == NULL)
                RETURN(-ENOMEM);
+
        handle->lgh_hdr = llh;
+       handle->lgh_hdr_size = chunk_size;
        /* first assign flags to use llog_client_ops */
        llh->llh_flags = flags;
        rc = llog_read_header(env, handle, uuid);
@@ -252,18 +393,20 @@ int llog_init_handle(const struct lu_env *env, struct llog_handle *handle,
                }
        }
        if (flags & LLOG_F_IS_CAT) {
-               LASSERT(cfs_list_empty(&handle->u.chd.chd_head));
-               CFS_INIT_LIST_HEAD(&handle->u.chd.chd_head);
+               LASSERT(list_empty(&handle->u.chd.chd_head));
+               INIT_LIST_HEAD(&handle->u.chd.chd_head);
                llh->llh_size = sizeof(struct llog_logid_rec);
+               llh->llh_flags |= LLOG_F_IS_FIXSIZE;
        } else if (!(flags & LLOG_F_IS_PLAIN)) {
                CERROR("%s: unknown flags: %#x (expected %#x or %#x)\n",
                       handle->lgh_ctxt->loc_obd->obd_name,
                       flags, LLOG_F_IS_CAT, LLOG_F_IS_PLAIN);
                rc = -EINVAL;
        }
+       llh->llh_flags |= fmt;
 out:
        if (rc) {
-               OBD_FREE_PTR(llh);
+               OBD_FREE_LARGE(llh, chunk_size);
                handle->lgh_hdr = NULL;
        }
        RETURN(rc);
@@ -277,140 +420,276 @@ static int llog_process_thread(void *arg)
        struct llog_log_hdr             *llh = loghandle->lgh_hdr;
        struct llog_process_cat_data    *cd  = lpi->lpi_catdata;
        char                            *buf;
-       __u64                            cur_offset = LLOG_CHUNK_SIZE;
-       __u64                            last_offset;
+       size_t                           chunk_size;
+       __u64                            cur_offset;
        int                              rc = 0, index = 1, last_index;
        int                              saved_index = 0;
        int                              last_called_index = 0;
+       bool                             repeated = false;
 
        ENTRY;
 
-        LASSERT(llh);
+       if (llh == NULL)
+               RETURN(-EINVAL);
+
+       cur_offset = chunk_size = llh->llh_hdr.lrh_len;
+       /* expect chunk_size to be power of two */
+       LASSERT(is_power_of_2(chunk_size));
 
-        OBD_ALLOC(buf, LLOG_CHUNK_SIZE);
-        if (!buf) {
-                lpi->lpi_rc = -ENOMEM;
+       OBD_ALLOC_LARGE(buf, chunk_size);
+       if (buf == NULL) {
+               lpi->lpi_rc = -ENOMEM;
                RETURN(0);
-        }
+       }
 
-        if (cd != NULL) {
-                last_called_index = cd->lpcd_first_idx;
-                index = cd->lpcd_first_idx + 1;
-        }
-        if (cd != NULL && cd->lpcd_last_idx)
-                last_index = cd->lpcd_last_idx;
-        else
-                last_index = LLOG_BITMAP_BYTES * 8 - 1;
-
-        while (rc == 0) {
-                struct llog_rec_hdr *rec;
-
-                /* skip records not set in bitmap */
-                while (index <= last_index &&
-                       !ext2_test_bit(index, llh->llh_bitmap))
-                        ++index;
-
-                LASSERT(index <= last_index + 1);
-                if (index == last_index + 1)
-                        break;
-repeat:
-                CDEBUG(D_OTHER, "index: %d last_index %d\n",
-                       index, last_index);
+       if (cd != NULL) {
+               last_called_index = cd->lpcd_first_idx;
+               index = cd->lpcd_first_idx + 1;
+       }
+       if (cd != NULL && cd->lpcd_last_idx)
+               last_index = cd->lpcd_last_idx;
+       else
+               last_index = LLOG_HDR_BITMAP_SIZE(llh) - 1;
+
+       while (rc == 0) {
+               struct llog_rec_hdr *rec;
+               off_t chunk_offset = 0;
+               unsigned int buf_offset = 0;
+               bool partial_chunk;
+               int     lh_last_idx;
+
+               /* skip records not set in bitmap */
+               while (index <= last_index &&
+                      !ext2_test_bit(index, LLOG_HDR_BITMAP(llh)))
+                       ++index;
+
+               /* There are no indices prior the last_index */
+               if (index > last_index)
+                       break;
+
+               CDEBUG(D_OTHER, "index: %d last_index %d\n", index,
+                      last_index);
 
-                /* get the buf with our target record; avoid old garbage */
-                memset(buf, 0, LLOG_CHUNK_SIZE);
-                last_offset = cur_offset;
+repeat:
+               /* get the buf with our target record; avoid old garbage */
+               memset(buf, 0, chunk_size);
+               /* the record index for outdated chunk data */
+               lh_last_idx = loghandle->lgh_last_idx + 1;
                rc = llog_next_block(lpi->lpi_env, loghandle, &saved_index,
-                                    index, &cur_offset, buf, LLOG_CHUNK_SIZE);
-                if (rc)
-                        GOTO(out, rc);
+                                    index, &cur_offset, buf, chunk_size);
+               if (repeated && rc)
+                       CDEBUG(D_OTHER, "cur_offset %llu, chunk_offset %llu,"
+                              " buf_offset %u, rc = %d\n", cur_offset,
+                              (__u64)chunk_offset, buf_offset, rc);
+               /* we`ve tried to reread the chunk, but there is no
+                * new records */
+               if (rc == -EIO && repeated && (chunk_offset + buf_offset) ==
+                   cur_offset)
+                       GOTO(out, rc = 0);
+               if (rc != 0)
+                       GOTO(out, rc);
+
+               /* NB: after llog_next_block() call the cur_offset is the
+                * offset of the next block after read one.
+                * The absolute offset of the current chunk is calculated
+                * from cur_offset value and stored in chunk_offset variable.
+                */
+               if ((cur_offset & (chunk_size - 1)) != 0) {
+                       partial_chunk = true;
+                       chunk_offset = cur_offset & ~(chunk_size - 1);
+               } else {
+                       partial_chunk = false;
+                       chunk_offset = cur_offset - chunk_size;
+               }
 
-                /* NB: when rec->lrh_len is accessed it is already swabbed
-                 * since it is used at the "end" of the loop and the rec
-                 * swabbing is done at the beginning of the loop. */
-                for (rec = (struct llog_rec_hdr *)buf;
-                     (char *)rec < buf + LLOG_CHUNK_SIZE;
-                     rec = (struct llog_rec_hdr *)((char *)rec + rec->lrh_len)){
+               /* NB: when rec->lrh_len is accessed it is already swabbed
+                * since it is used at the "end" of the loop and the rec
+                * swabbing is done at the beginning of the loop. */
+               for (rec = (struct llog_rec_hdr *)(buf + buf_offset);
+                    (char *)rec < buf + chunk_size;
+                    rec = llog_rec_hdr_next(rec)) {
 
-                        CDEBUG(D_OTHER, "processing rec 0x%p type %#x\n",
-                               rec, rec->lrh_type);
+                       CDEBUG(D_OTHER, "processing rec 0x%p type %#x\n",
+                              rec, rec->lrh_type);
 
-                        if (LLOG_REC_HDR_NEEDS_SWABBING(rec))
+                       if (LLOG_REC_HDR_NEEDS_SWABBING(rec))
                                lustre_swab_llog_rec(rec);
 
-                        CDEBUG(D_OTHER, "after swabbing, type=%#x idx=%d\n",
-                               rec->lrh_type, rec->lrh_index);
+                       CDEBUG(D_OTHER, "after swabbing, type=%#x idx=%d\n",
+                              rec->lrh_type, rec->lrh_index);
+
+                       /* the bitmap could be changed during processing
+                        * records from the chunk. For wrapped catalog
+                        * it means we can read deleted record and try to
+                        * process it. Check this case and reread the chunk. */
+
+                       /* for partial chunk the end of it is zeroed, check
+                        * for index 0 to distinguish it. */
+                       if ((partial_chunk && rec->lrh_index == 0) ||
+                            (index == lh_last_idx &&
+                             lh_last_idx != (loghandle->lgh_last_idx + 1))) {
+                               /* concurrent llog_add() might add new records
+                                * while llog_processing, check this is not
+                                * the case and re-read the current chunk
+                                * otherwise. */
+                               int records;
+                               /* lgh_last_idx could be less then index
+                                * for catalog, if catalog is wrapped */
+                               if ((index > loghandle->lgh_last_idx &&
+                                   !(loghandle->lgh_hdr->llh_flags &
+                                     LLOG_F_IS_CAT)) || repeated ||
+                                   (loghandle->lgh_obj != NULL &&
+                                    dt_object_remote(loghandle->lgh_obj)))
+                                       GOTO(out, rc = 0);
+                               /* <2 records means no more records
+                                * if the last record we processed was
+                                * the final one, then the underlying
+                                * object might have been destroyed yet.
+                                * we better don't access that.. */
+                               mutex_lock(&loghandle->lgh_hdr_mutex);
+                               records = loghandle->lgh_hdr->llh_count;
+                               mutex_unlock(&loghandle->lgh_hdr_mutex);
+                               if (records <= 1)
+                                       GOTO(out, rc = 0);
+                               CDEBUG(D_OTHER, "Re-read last llog buffer for "
+                                      "new records, index %u, last %u\n",
+                                      index, loghandle->lgh_last_idx);
+                               /* save offset inside buffer for the re-read */
+                               buf_offset = (char *)rec - (char *)buf;
+                               cur_offset = chunk_offset;
+                               repeated = true;
+                               goto repeat;
+                       }
 
-                       if (rec->lrh_index == 0) {
-                               /* probably another rec just got added? */
-                               if (index <= loghandle->lgh_last_idx)
-                                       GOTO(repeat, rc = 0);
-                               GOTO(out, rc = 0); /* no more records */
+                       repeated = false;
+
+                       if (rec->lrh_len == 0 || rec->lrh_len > chunk_size) {
+                               CWARN("%s: invalid length %d in llog "DFID
+                                     "record for index %d/%d\n",
+                                      loghandle->lgh_ctxt->loc_obd->obd_name,
+                                      rec->lrh_len,
+                                      PFID(&loghandle->lgh_id.lgl_oi.oi_fid),
+                                      rec->lrh_index, index);
+
+                               GOTO(out, rc = -EINVAL);
                        }
-                       if (rec->lrh_len == 0 ||
-                           rec->lrh_len > LLOG_CHUNK_SIZE) {
-                                CWARN("invalid length %d in llog record for "
-                                      "index %d/%d\n", rec->lrh_len,
-                                      rec->lrh_index, index);
-                                GOTO(out, rc = -EINVAL);
-                        }
 
-                        if (rec->lrh_index < index) {
-                                CDEBUG(D_OTHER, "skipping lrh_index %d\n",
-                                       rec->lrh_index);
-                                continue;
-                        }
+                       if (rec->lrh_index < index) {
+                               CDEBUG(D_OTHER, "skipping lrh_index %d\n",
+                                      rec->lrh_index);
+                               continue;
+                       }
+
+                       if (rec->lrh_index != index) {
+                               CERROR("%s: "DFID" Invalid record: index %u"
+                                      " but expected %u\n",
+                                      loghandle->lgh_ctxt->loc_obd->obd_name,
+                                      PFID(&loghandle->lgh_id.lgl_oi.oi_fid),
+                                      rec->lrh_index, index);
+                               GOTO(out, rc = -ERANGE);
+                       }
 
-                        CDEBUG(D_OTHER,
-                               "lrh_index: %d lrh_len: %d (%d remains)\n",
-                               rec->lrh_index, rec->lrh_len,
-                               (int)(buf + LLOG_CHUNK_SIZE - (char *)rec));
+                       CDEBUG(D_OTHER,
+                              "lrh_index: %d lrh_len: %d (%d remains)\n",
+                              rec->lrh_index, rec->lrh_len,
+                              (int)(buf + chunk_size - (char *)rec));
 
-                        loghandle->lgh_cur_idx = rec->lrh_index;
-                        loghandle->lgh_cur_offset = (char *)rec - (char *)buf +
-                                                    last_offset;
+                       loghandle->lgh_cur_idx = rec->lrh_index;
+                       loghandle->lgh_cur_offset = (char *)rec - (char *)buf +
+                                                   chunk_offset;
 
-                        /* if set, process the callback on this record */
-                        if (ext2_test_bit(index, llh->llh_bitmap)) {
+                       /* if set, process the callback on this record */
+                       if (ext2_test_bit(index, LLOG_HDR_BITMAP(llh))) {
                                rc = lpi->lpi_cb(lpi->lpi_env, loghandle, rec,
                                                 lpi->lpi_cbdata);
                                last_called_index = index;
                                if (rc == LLOG_PROC_BREAK) {
                                        GOTO(out, rc);
                                } else if (rc == LLOG_DEL_RECORD) {
-                                       llog_cancel_rec(lpi->lpi_env,
-                                                       loghandle,
-                                                       rec->lrh_index);
-                                        rc = 0;
-                                }
-                                if (rc)
-                                        GOTO(out, rc);
-                        } else {
-                                CDEBUG(D_OTHER, "Skipped index %d\n", index);
-                        }
-
-                        /* next record, still in buffer? */
-                        ++index;
-                        if (index > last_index)
-                                GOTO(out, rc = 0);
-                }
-        }
+                                       rc = llog_cancel_rec(lpi->lpi_env,
+                                                            loghandle,
+                                                            rec->lrh_index);
+                               }
+                               if (rc)
+                                       GOTO(out, rc);
+                               /* some stupid callbacks directly cancel records
+                                * and delete llog. Check it and stop
+                                * processing. */
+                               if (loghandle->lgh_hdr == NULL ||
+                                   loghandle->lgh_hdr->llh_count == 1)
+                                       GOTO(out, rc = 0);
+                       }
+                       /* exit if the last index is reached */
+                       if (index >= last_index)
+                               GOTO(out, rc = 0);
+                       ++index;
+               }
+       }
 
 out:
-        if (cd != NULL)
-                cd->lpcd_last_idx = last_called_index;
+       if (cd != NULL)
+               cd->lpcd_last_idx = last_called_index;
+
+       if (unlikely(rc == -EIO && loghandle->lgh_obj != NULL)) {
+               if (dt_object_remote(loghandle->lgh_obj)) {
+                       /* If it is remote object, then -EIO might means
+                        * disconnection or eviction, let's return -EAGAIN,
+                        * so for update recovery log processing, it will
+                        * retry until the umount or abort recovery, see
+                        * lod_sub_recovery_thread() */
+                       CERROR("%s retry remote llog process\n",
+                              loghandle->lgh_ctxt->loc_obd->obd_name);
+                       rc = -EAGAIN;
+               } else {
+                       /* something bad happened to the processing of a local
+                        * llog file, probably I/O error or the log got
+                        * corrupted to be able to finally release the log we
+                        * discard any remaining bits in the header */
+                       CERROR("%s: Local llog found corrupted #"DOSTID":%x"
+                              " %s index %d count %d\n",
+                              loghandle->lgh_ctxt->loc_obd->obd_name,
+                              POSTID(&loghandle->lgh_id.lgl_oi),
+                              loghandle->lgh_id.lgl_ogen,
+                              ((llh->llh_flags & LLOG_F_IS_CAT) ? "catalog" :
+                               "plain"), index, llh->llh_count);
+
+                       while (index <= last_index) {
+                               if (ext2_test_bit(index,
+                                                 LLOG_HDR_BITMAP(llh)) != 0)
+                                       llog_cancel_rec(lpi->lpi_env, loghandle,
+                                                       index);
+                               index++;
+                       }
+                       rc = 0;
+               }
+       }
 
-       OBD_FREE(buf, LLOG_CHUNK_SIZE);
-        lpi->lpi_rc = rc;
-        return 0;
+       OBD_FREE_LARGE(buf, chunk_size);
+       lpi->lpi_rc = rc;
+       return 0;
 }
 
-#ifdef __KERNEL__
 static int llog_process_thread_daemonize(void *arg)
 {
        struct llog_process_info        *lpi = arg;
        struct lu_env                    env;
        int                              rc;
+       struct nsproxy                  *new_ns, *curr_ns = current->nsproxy;
+
+       task_lock(lpi->lpi_reftask);
+       new_ns = lpi->lpi_reftask->nsproxy;
+       if (curr_ns != new_ns) {
+               get_nsproxy(new_ns);
+
+               current->nsproxy = new_ns;
+               /* XXX: we should call put_nsproxy() instead of
+                * atomic_dec(&ns->count) directly. But put_nsproxy() cannot be
+                * used outside of the kernel itself, because it calls
+                * free_nsproxy() which is not exported by the kernel
+                * (defined in kernel/nsproxy.c) */
+               atomic_dec(&curr_ns->count);
+       }
+       task_unlock(lpi->lpi_reftask);
 
        unshare_fs_struct();
 
@@ -427,7 +706,6 @@ out:
        complete(&lpi->lpi_completion);
        return rc;
 }
-#endif
 
 int llog_process_or_fork(const struct lu_env *env,
                         struct llog_handle *loghandle,
@@ -438,49 +716,54 @@ int llog_process_or_fork(const struct lu_env *env,
 
         ENTRY;
 
-        OBD_ALLOC_PTR(lpi);
-        if (lpi == NULL) {
-                CERROR("cannot alloc pointer\n");
-                RETURN(-ENOMEM);
-        }
-        lpi->lpi_loghandle = loghandle;
-        lpi->lpi_cb        = cb;
-        lpi->lpi_cbdata    = data;
-        lpi->lpi_catdata   = catdata;
+       OBD_ALLOC_PTR(lpi);
+       if (lpi == NULL) {
+               CERROR("cannot alloc pointer\n");
+               RETURN(-ENOMEM);
+       }
+       lpi->lpi_loghandle = loghandle;
+       lpi->lpi_cb        = cb;
+       lpi->lpi_cbdata    = data;
+       lpi->lpi_catdata   = catdata;
 
-#ifdef __KERNEL__
        if (fork) {
+               struct task_struct *task;
+
                /* The new thread can't use parent env,
                 * init the new one in llog_process_thread_daemonize. */
                lpi->lpi_env = NULL;
                init_completion(&lpi->lpi_completion);
-               rc = PTR_ERR(kthread_run(llog_process_thread_daemonize, lpi,
-                                            "llog_process_thread"));
-               if (IS_ERR_VALUE(rc)) {
+               /* take reference to current, so that
+                * llog_process_thread_daemonize() can use it to switch to
+                * namespace associated with current  */
+               lpi->lpi_reftask = current;
+               task = kthread_run(llog_process_thread_daemonize, lpi,
+                                  "llog_process_thread");
+               if (IS_ERR(task)) {
+                       rc = PTR_ERR(task);
                        CERROR("%s: cannot start thread: rc = %d\n",
                               loghandle->lgh_ctxt->loc_obd->obd_name, rc);
-                       OBD_FREE_PTR(lpi);
-                       RETURN(rc);
+                       GOTO(out_lpi, rc);
                }
                wait_for_completion(&lpi->lpi_completion);
        } else {
                lpi->lpi_env = env;
                llog_process_thread(lpi);
        }
-#else
-       lpi->lpi_env = env;
-       llog_process_thread(lpi);
-#endif
-        rc = lpi->lpi_rc;
-        OBD_FREE_PTR(lpi);
-        RETURN(rc);
+       rc = lpi->lpi_rc;
+
+out_lpi:
+       OBD_FREE_PTR(lpi);
+       RETURN(rc);
 }
 EXPORT_SYMBOL(llog_process_or_fork);
 
 int llog_process(const struct lu_env *env, struct llog_handle *loghandle,
                 llog_cb_t cb, void *data, void *catdata)
 {
-       return llog_process_or_fork(env, loghandle, cb, data, catdata, true);
+       int rc;
+       rc = llog_process_or_fork(env, loghandle, cb, data, catdata, true);
+       return rc == LLOG_DEL_PLAIN ? 0 : rc;
 }
 EXPORT_SYMBOL(llog_process);
 
@@ -492,36 +775,36 @@ int llog_reverse_process(const struct lu_env *env,
         struct llog_process_cat_data *cd = catdata;
         void *buf;
         int rc = 0, first_index = 1, index, idx;
+       __u32   chunk_size = llh->llh_hdr.lrh_len;
         ENTRY;
 
-        OBD_ALLOC(buf, LLOG_CHUNK_SIZE);
-        if (!buf)
-                RETURN(-ENOMEM);
+       OBD_ALLOC_LARGE(buf, chunk_size);
+       if (buf == NULL)
+               RETURN(-ENOMEM);
 
-        if (cd != NULL)
-                first_index = cd->lpcd_first_idx + 1;
-        if (cd != NULL && cd->lpcd_last_idx)
-                index = cd->lpcd_last_idx;
-        else
-                index = LLOG_BITMAP_BYTES * 8 - 1;
+       if (cd != NULL)
+               first_index = cd->lpcd_first_idx + 1;
+       if (cd != NULL && cd->lpcd_last_idx)
+               index = cd->lpcd_last_idx;
+       else
+               index = LLOG_HDR_BITMAP_SIZE(llh) - 1;
 
-        while (rc == 0) {
-                struct llog_rec_hdr *rec;
-                struct llog_rec_tail *tail;
+       while (rc == 0) {
+               struct llog_rec_hdr *rec;
+               struct llog_rec_tail *tail;
 
-                /* skip records not set in bitmap */
-                while (index >= first_index &&
-                       !ext2_test_bit(index, llh->llh_bitmap))
-                        --index;
+               /* skip records not set in bitmap */
+               while (index >= first_index &&
+                      !ext2_test_bit(index, LLOG_HDR_BITMAP(llh)))
+                       --index;
 
-                LASSERT(index >= first_index - 1);
-                if (index == first_index - 1)
-                        break;
+               LASSERT(index >= first_index - 1);
+               if (index == first_index - 1)
+                       break;
 
-                /* get the buf with our target record; avoid old garbage */
-                memset(buf, 0, LLOG_CHUNK_SIZE);
-               rc = llog_prev_block(env, loghandle, index, buf,
-                                    LLOG_CHUNK_SIZE);
+               /* get the buf with our target record; avoid old garbage */
+               memset(buf, 0, chunk_size);
+               rc = llog_prev_block(env, loghandle, index, buf, chunk_size);
                if (rc)
                        GOTO(out, rc);
 
@@ -537,13 +820,13 @@ int llog_reverse_process(const struct lu_env *env,
                LASSERT(idx == index);
                tail = (void *)rec + rec->lrh_len - sizeof(*tail);
 
-                /* process records in buffer, starting where we found one */
-                while ((void *)tail > buf) {
+               /* process records in buffer, starting where we found one */
+               while ((void *)tail > buf) {
                        if (tail->lrt_index == 0)
                                GOTO(out, rc = 0); /* no more records */
 
-                        /* if set, process the callback on this record */
-                        if (ext2_test_bit(index, llh->llh_bitmap)) {
+                       /* if set, process the callback on this record */
+                       if (ext2_test_bit(index, LLOG_HDR_BITMAP(llh))) {
                                rec = (void *)tail - tail->lrt_len +
                                      sizeof(*tail);
 
@@ -551,9 +834,8 @@ int llog_reverse_process(const struct lu_env *env,
                                if (rc == LLOG_PROC_BREAK) {
                                        GOTO(out, rc);
                                } else if (rc == LLOG_DEL_RECORD) {
-                                       llog_cancel_rec(env, loghandle,
-                                                       tail->lrt_index);
-                                       rc = 0;
+                                       rc = llog_cancel_rec(env, loghandle,
+                                                            tail->lrt_index);
                                }
                                 if (rc)
                                         GOTO(out, rc);
@@ -568,8 +850,8 @@ int llog_reverse_process(const struct lu_env *env,
         }
 
 out:
-        if (buf)
-                OBD_FREE(buf, LLOG_CHUNK_SIZE);
+       if (buf != NULL)
+               OBD_FREE_LARGE(buf, chunk_size);
         RETURN(rc);
 }
 EXPORT_SYMBOL(llog_reverse_process);
@@ -628,7 +910,6 @@ int llog_declare_create(const struct lu_env *env,
                cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
        RETURN(rc);
 }
-EXPORT_SYMBOL(llog_declare_create);
 
 int llog_create(const struct lu_env *env, struct llog_handle *handle,
                struct thandle *th)
@@ -652,7 +933,6 @@ int llog_create(const struct lu_env *env, struct llog_handle *handle,
                cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
        RETURN(rc);
 }
-EXPORT_SYMBOL(llog_create);
 
 int llog_declare_write_rec(const struct lu_env *env,
                           struct llog_handle *handle,
@@ -679,46 +959,57 @@ int llog_declare_write_rec(const struct lu_env *env,
                cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
        RETURN(rc);
 }
-EXPORT_SYMBOL(llog_declare_write_rec);
 
 int llog_write_rec(const struct lu_env *env, struct llog_handle *handle,
                   struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
-                  int numcookies, void *buf, int idx, struct thandle *th)
+                  int idx, struct thandle *th)
 {
        struct llog_operations  *lop;
        int                      raised, rc, buflen;
 
        ENTRY;
 
+       /* API sanity checks */
+       if (handle == NULL) {
+               CERROR("loghandle is missed\n");
+               RETURN(-EPROTO);
+       } else if (handle->lgh_obj == NULL) {
+               CERROR("loghandle %p with NULL object\n",
+                       handle);
+               RETURN(-EPROTO);
+       } else if (th == NULL) {
+               CERROR("%s: missed transaction handle\n",
+                       handle->lgh_obj->do_lu.lo_dev->ld_obd->obd_name);
+               RETURN(-EPROTO);
+       } else if (handle->lgh_hdr == NULL) {
+               CERROR("%s: loghandle %p with no header\n",
+                       handle->lgh_obj->do_lu.lo_dev->ld_obd->obd_name,
+                       handle);
+               RETURN(-EPROTO);
+       }
+
        rc = llog_handle2ops(handle, &lop);
        if (rc)
                RETURN(rc);
 
-       LASSERT(lop);
        if (lop->lop_write_rec == NULL)
                RETURN(-EOPNOTSUPP);
 
-       if (buf)
-               buflen = rec->lrh_len + sizeof(struct llog_rec_hdr) +
-                        sizeof(struct llog_rec_tail);
-       else
-               buflen = rec->lrh_len;
+       buflen = rec->lrh_len;
        LASSERT(cfs_size_round(buflen) == buflen);
 
        raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
        if (!raised)
                cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
-       rc = lop->lop_write_rec(env, handle, rec, logcookies, numcookies,
-                               buf, idx, th);
+       rc = lop->lop_write_rec(env, handle, rec, logcookies, idx, th);
        if (!raised)
                cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
        RETURN(rc);
 }
-EXPORT_SYMBOL(llog_write_rec);
 
 int llog_add(const struct lu_env *env, struct llog_handle *lgh,
             struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
-            void *buf, struct thandle *th)
+            struct thandle *th)
 {
        int raised, rc;
 
@@ -730,7 +1021,7 @@ int llog_add(const struct lu_env *env, struct llog_handle *lgh,
        raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
        if (!raised)
                cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
-       rc = lgh->lgh_logops->lop_add(env, lgh, rec, logcookies, buf, th);
+       rc = lgh->lgh_logops->lop_add(env, lgh, rec, logcookies, th);
        if (!raised)
                cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
        RETURN(rc);
@@ -786,6 +1077,15 @@ int llog_open_create(const struct lu_env *env, struct llog_ctxt *ctxt,
        if (IS_ERR(th))
                GOTO(out, rc = PTR_ERR(th));
 
+       /* Create update llog object synchronously, which
+        * happens during inialization process see
+        * lod_sub_prep_llog(), to make sure the update
+        * llog object is created before corss-MDT writing
+        * updates into the llog object */
+       if (ctxt->loc_flags & LLOG_CTXT_FLAG_NORMAL_FID)
+               th->th_sync = 1;
+
+       th->th_wait_submit = 1;
        rc = llog_declare_create(env, *res, th);
        if (rc == 0) {
                rc = dt_trans_start_local(env, d, th);
@@ -836,8 +1136,7 @@ EXPORT_SYMBOL(llog_erase);
  * Valid only with local llog.
  */
 int llog_write(const struct lu_env *env, struct llog_handle *loghandle,
-              struct llog_rec_hdr *rec, struct llog_cookie *reccookie,
-              int cookiecount, void *buf, int idx)
+              struct llog_rec_hdr *rec, int idx)
 {
        struct dt_device        *dt;
        struct thandle          *th;
@@ -859,13 +1158,13 @@ int llog_write(const struct lu_env *env, struct llog_handle *loghandle,
        if (rc)
                GOTO(out_trans, rc);
 
+       th->th_wait_submit = 1;
        rc = dt_trans_start_local(env, dt, th);
        if (rc)
                GOTO(out_trans, rc);
 
        down_write(&loghandle->lgh_lock);
-       rc = llog_write_rec(env, loghandle, rec, reccookie,
-                           cookiecount, buf, idx, th);
+       rc = llog_write_rec(env, loghandle, rec, NULL, idx, th);
        up_write(&loghandle->lgh_lock);
 out_trans:
        dt_trans_stop(env, dt, th);
@@ -929,6 +1228,17 @@ out:
 }
 EXPORT_SYMBOL(llog_close);
 
+/**
+ * Helper function to get the llog size in records. It is used by MGS
+ * mostly to check that config llog exists and contains data.
+ *
+ * \param[in] env      execution environment
+ * \param[in] ctxt     llog context
+ * \param[in] name     llog name
+ *
+ * \retval             true if there are records in llog besides a header
+ * \retval             false on error or llog without records
+ */
 int llog_is_empty(const struct lu_env *env, struct llog_ctxt *ctxt,
                  char *name)
 {
@@ -950,7 +1260,8 @@ int llog_is_empty(const struct lu_env *env, struct llog_ctxt *ctxt,
 out_close:
        llog_close(env, llh);
 out:
-       /* header is record 1 */
+       /* The header is record 1, the llog is still considered as empty
+        * if there is only header */
        return (rc <= 1);
 }
 EXPORT_SYMBOL(llog_is_empty);
@@ -961,9 +1272,8 @@ int llog_copy_handler(const struct lu_env *env, struct llog_handle *llh,
        struct llog_handle      *copy_llh = data;
 
        /* Append all records */
-       return llog_write(env, copy_llh, rec, NULL, 0, NULL, -1);
+       return llog_write(env, copy_llh, rec, LLOG_NEXT_IDX);
 }
-EXPORT_SYMBOL(llog_copy_handler);
 
 /* backup plain llog */
 int llog_backup(const struct lu_env *env, struct obd_device *obd,
@@ -1029,3 +1339,22 @@ out_close:
        RETURN(rc);
 }
 EXPORT_SYMBOL(llog_backup);
+
+/* Get size of llog */
+__u64 llog_size(const struct lu_env *env, struct llog_handle *llh)
+{
+       int rc;
+       struct lu_attr la;
+
+       rc = llh->lgh_obj->do_ops->do_attr_get(env, llh->lgh_obj, &la);
+       if (rc) {
+               CERROR("%s: attr_get failed for "DFID": rc = %d\n",
+                      llh->lgh_ctxt->loc_obd->obd_name,
+                      PFID(&llh->lgh_id.lgl_oi.oi_fid), rc);
+               return 0;
+       }
+
+       return la.la_size;
+}
+EXPORT_SYMBOL(llog_size);
+