Whamcloud - gitweb
LU-3470 llog: fix return value of llog_alloc_handle
[fs/lustre-release.git] / lustre / obdclass / llog.c
index fec344f..a690233 100644 (file)
@@ -26,6 +26,8 @@
 /*
  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
+ *
+ * Copyright (c) 2012, 2013, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
  *   if an OST or MDS fails it need only look at log(s) relevant to itself
  *
  * Author: Andreas Dilger <adilger@clusterfs.com>
+ * Author: Alex Zhuravlev <bzzz@whamcloud.com>
+ * Author: Mikhail Pershin <tappro@whamcloud.com>
  */
 
 #define DEBUG_SUBSYSTEM S_LOG
 
-#ifndef EXPORT_SYMTAB
-#define EXPORT_SYMTAB
-#endif
-
 #ifndef __KERNEL__
 #include <liblustre.h>
 #endif
 
 #include <obd_class.h>
 #include <lustre_log.h>
-#include <libcfs/list.h>
 #include "llog_internal.h"
 
-/* Allocate a new log or catalog handle */
+/*
+ * Allocate a new log or catalog handle
+ * Used inside llog_open().
+ */
 struct llog_handle *llog_alloc_handle(void)
 {
-        struct llog_handle *loghandle;
-        ENTRY;
+       struct llog_handle *loghandle;
 
-        OBD_ALLOC(loghandle, sizeof(*loghandle));
-        if (loghandle == NULL)
-                RETURN(ERR_PTR(-ENOMEM));
+       OBD_ALLOC_PTR(loghandle);
+       if (loghandle == NULL)
+               return NULL;
 
-        cfs_init_rwsem(&loghandle->lgh_lock);
+       init_rwsem(&loghandle->lgh_lock);
+       spin_lock_init(&loghandle->lgh_hdr_lock);
+       CFS_INIT_LIST_HEAD(&loghandle->u.phd.phd_entry);
+       cfs_atomic_set(&loghandle->lgh_refcount, 1);
 
-        RETURN(loghandle);
+       return loghandle;
 }
-EXPORT_SYMBOL(llog_alloc_handle);
-
 
+/*
+ * Free llog handle and header data if exists. Used in llog_close() only
+ */
 void llog_free_handle(struct llog_handle *loghandle)
 {
-        if (!loghandle)
-                return;
-
-        if (!loghandle->lgh_hdr)
-                goto out;
-        if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_PLAIN)
-                cfs_list_del_init(&loghandle->u.phd.phd_entry);
-        if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_CAT)
-                LASSERT(cfs_list_empty(&loghandle->u.chd.chd_head));
-        OBD_FREE(loghandle->lgh_hdr, LLOG_CHUNK_SIZE);
-
- out:
-        OBD_FREE(loghandle, sizeof(*loghandle));
+       LASSERT(loghandle != NULL);
+
+       /* failed llog_init_handle */
+       if (!loghandle->lgh_hdr)
+               goto out;
+
+       if (loghandle->lgh_hdr->llh_flags & LLOG_F_IS_PLAIN)
+               LASSERT(cfs_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);
+out:
+       OBD_FREE_PTR(loghandle);
+}
+
+void llog_handle_get(struct llog_handle *loghandle)
+{
+       cfs_atomic_inc(&loghandle->lgh_refcount);
+}
+
+void llog_handle_put(struct llog_handle *loghandle)
+{
+       LASSERT(cfs_atomic_read(&loghandle->lgh_refcount) > 0);
+       if (cfs_atomic_dec_and_test(&loghandle->lgh_refcount))
+               llog_free_handle(loghandle);
 }
-EXPORT_SYMBOL(llog_free_handle);
 
 /* returns negative on error; 0 if success; 1 if success & log destroyed */
-int llog_cancel_rec(struct llog_handle *loghandle, int index)
+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;
 
-        CDEBUG(D_RPCTRACE, "Canceling %d in log "LPX64"\n",
-               index, loghandle->lgh_id.lgl_oid);
+        CDEBUG(D_RPCTRACE, "Canceling %d in log "DOSTID"\n",
+               index, POSTID(&loghandle->lgh_id.lgl_oi));
 
         if (index == 0) {
                 CERROR("Can't cancel index 0 which is header\n");
                 RETURN(-EINVAL);
         }
 
-        if (!ext2_clear_bit(index, llh->llh_bitmap)) {
-                CDEBUG(D_RPCTRACE, "Catalog index %u already clear?\n", index);
-                RETURN(-ENOENT);
-        }
-
-        llh->llh_count--;
-
-        if ((llh->llh_flags & LLOG_F_ZAP_WHEN_EMPTY) &&
-            (llh->llh_count == 1) &&
-            (loghandle->lgh_last_idx == (LLOG_BITMAP_BYTES * 8) - 1)) {
-                rc = llog_destroy(loghandle);
-                if (rc) {
-                        CERROR("Failure destroying log after last cancel: %d\n",
-                               rc);
-                        ext2_set_bit(index, llh->llh_bitmap);
-                        llh->llh_count++;
-                } else {
-                        rc = 1;
-                }
-                RETURN(rc);
-        }
-
-        rc = llog_write_rec(loghandle, &llh->llh_hdr, NULL, 0, NULL, 0);
-        if (rc) {
-                CERROR("Failure re-writing header %d\n", rc);
-                ext2_set_bit(index, llh->llh_bitmap);
-                llh->llh_count++;
-        }
-        RETURN(rc);
+       spin_lock(&loghandle->lgh_hdr_lock);
+       if (!ext2_clear_bit(index, llh->llh_bitmap)) {
+               spin_unlock(&loghandle->lgh_hdr_lock);
+               CDEBUG(D_RPCTRACE, "Catalog index %u already clear?\n", index);
+               RETURN(-ENOENT);
+       }
+
+       llh->llh_count--;
+
+       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);
+               if (rc < 0) {
+                       CERROR("%s: can't destroy empty 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);
+               }
+               RETURN(1);
+       }
+       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);
+       }
+       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;
 }
 EXPORT_SYMBOL(llog_cancel_rec);
 
-int llog_init_handle(struct llog_handle *handle, int flags,
-                     struct obd_uuid *uuid)
+static int llog_read_header(const struct lu_env *env,
+                           struct llog_handle *handle,
+                           struct obd_uuid *uuid)
 {
-        int rc;
-        struct llog_log_hdr *llh;
-        ENTRY;
-        LASSERT(handle->lgh_hdr == NULL);
-
-        OBD_ALLOC(llh, sizeof(*llh));
-        if (llh == NULL)
-                RETURN(-ENOMEM);
-        handle->lgh_hdr = llh;
-        /* first assign flags to use llog_client_ops */
-        llh->llh_flags = flags;
-        rc = llog_read_header(handle);
-        if (rc == 0) {
-                flags = llh->llh_flags;
-                if (uuid && !obd_uuid_equals(uuid, &llh->llh_tgtuuid)) {
-                        CERROR("uuid mismatch: %s/%s\n", (char *)uuid->uuid,
-                               (char *)llh->llh_tgtuuid.uuid);
-                        rc = -EEXIST;
-                }
-                GOTO(out, rc);
-        } else if (rc != LLOG_EEMPTY || !flags) {
-                /* set a pesudo flag for initialization */
-                flags = LLOG_F_IS_CAT;
-                GOTO(out, rc);
-        }
-        rc = 0;
-
-        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();
-        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);
-
-out:
-        if (flags & LLOG_F_IS_CAT) {
-                CFS_INIT_LIST_HEAD(&handle->u.chd.chd_head);
-                llh->llh_size = sizeof(struct llog_logid_rec);
-        } else if (flags & LLOG_F_IS_PLAIN) {
-                CFS_INIT_LIST_HEAD(&handle->u.phd.phd_entry);
-        } else {
-                CERROR("Unknown flags: %#x (Expected %#x or %#x\n",
-                       flags, LLOG_F_IS_CAT, LLOG_F_IS_PLAIN);
-                LBUG();
-        }
-
-        if (rc) {
-                OBD_FREE(llh, sizeof(*llh));
-                handle->lgh_hdr = NULL;
-        }
-        RETURN(rc);
+       struct llog_operations *lop;
+       int rc;
+
+       rc = llog_handle2ops(handle, &lop);
+       if (rc)
+               RETURN(rc);
+
+       if (lop->lop_read_header == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       rc = lop->lop_read_header(env, handle);
+       if (rc == LLOG_EEMPTY) {
+               struct llog_log_hdr *llh = handle->lgh_hdr;
+
+               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();
+               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);
+               rc = 0;
+       }
+       return rc;
 }
-EXPORT_SYMBOL(llog_init_handle);
 
-int llog_close(struct llog_handle *loghandle)
+int llog_init_handle(const struct lu_env *env, struct llog_handle *handle,
+                    int flags, struct obd_uuid *uuid)
 {
-        struct llog_operations *lop;
-        int rc;
-        ENTRY;
-
-        rc = llog_handle2ops(loghandle, &lop);
-        if (rc)
-                GOTO(out, rc);
-        if (lop->lop_close == NULL)
-                GOTO(out, -EOPNOTSUPP);
-        rc = lop->lop_close(loghandle);
- out:
-        llog_free_handle(loghandle);
-        RETURN(rc);
+       struct llog_log_hdr     *llh;
+       int                      rc;
+
+       ENTRY;
+       LASSERT(handle->lgh_hdr == NULL);
+
+       OBD_ALLOC_PTR(llh);
+       if (llh == NULL)
+               RETURN(-ENOMEM);
+       handle->lgh_hdr = llh;
+       /* first assign flags to use llog_client_ops */
+       llh->llh_flags = flags;
+       rc = llog_read_header(env, handle, uuid);
+       if (rc == 0) {
+               if (unlikely((llh->llh_flags & LLOG_F_IS_PLAIN &&
+                             flags & LLOG_F_IS_CAT) ||
+                            (llh->llh_flags & LLOG_F_IS_CAT &&
+                             flags & LLOG_F_IS_PLAIN))) {
+                       CERROR("%s: llog type is %s but initializing %s\n",
+                              handle->lgh_ctxt->loc_obd->obd_name,
+                              llh->llh_flags & LLOG_F_IS_CAT ?
+                              "catalog" : "plain",
+                              flags & LLOG_F_IS_CAT ? "catalog" : "plain");
+                       GOTO(out, rc = -EINVAL);
+               } else if (llh->llh_flags &
+                          (LLOG_F_IS_PLAIN | LLOG_F_IS_CAT)) {
+                       /*
+                        * it is possible to open llog without specifying llog
+                        * type so it is taken from llh_flags
+                        */
+                       flags = llh->llh_flags;
+               } else {
+                       /* for some reason the llh_flags has no type set */
+                       CERROR("llog type is not specified!\n");
+                       GOTO(out, rc = -EINVAL);
+               }
+               if (unlikely(uuid &&
+                            !obd_uuid_equals(uuid, &llh->llh_tgtuuid))) {
+                       CERROR("%s: llog uuid mismatch: %s/%s\n",
+                              handle->lgh_ctxt->loc_obd->obd_name,
+                              (char *)uuid->uuid,
+                              (char *)llh->llh_tgtuuid.uuid);
+                       GOTO(out, rc = -EEXIST);
+               }
+       }
+       if (flags & LLOG_F_IS_CAT) {
+               LASSERT(cfs_list_empty(&handle->u.chd.chd_head));
+               CFS_INIT_LIST_HEAD(&handle->u.chd.chd_head);
+               llh->llh_size = sizeof(struct llog_logid_rec);
+       } 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;
+       }
+out:
+       if (rc) {
+               OBD_FREE_PTR(llh);
+               handle->lgh_hdr = NULL;
+       }
+       RETURN(rc);
 }
-EXPORT_SYMBOL(llog_close);
+EXPORT_SYMBOL(llog_init_handle);
 
 static int llog_process_thread(void *arg)
 {
-        struct llog_process_info     *lpi = (struct llog_process_info *)arg;
-        struct llog_handle           *loghandle = lpi->lpi_loghandle;
-        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;
-        int                           rc = 0, index = 1, last_index;
-        int                           saved_index = 0, last_called_index = 0;
+       struct llog_process_info        *lpi = arg;
+       struct llog_handle              *loghandle = lpi->lpi_loghandle;
+       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;
+       int                              rc = 0, index = 1, last_index;
+       int                              saved_index = 0;
+       int                              last_called_index = 0;
+
+       ENTRY;
 
         LASSERT(llh);
 
         OBD_ALLOC(buf, LLOG_CHUNK_SIZE);
         if (!buf) {
                 lpi->lpi_rc = -ENOMEM;
-#ifdef __KERNEL__
-                cfs_complete(&lpi->lpi_completion);
-#endif
-                return 0;
+               RETURN(0);
         }
 
-        if (!(lpi->lpi_flags & LLOG_FLAG_NODEAMON))
-                cfs_daemonize_ctxt("llog_process_thread");
-
         if (cd != NULL) {
                 last_called_index = cd->lpcd_first_idx;
                 index = cd->lpcd_first_idx + 1;
@@ -263,15 +313,15 @@ static int llog_process_thread(void *arg)
                 LASSERT(index <= last_index + 1);
                 if (index == last_index + 1)
                         break;
-
+repeat:
                 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;
-                rc = llog_next_block(loghandle, &saved_index, index,
-                                     &cur_offset, buf, LLOG_CHUNK_SIZE);
+               rc = llog_next_block(lpi->lpi_env, loghandle, &saved_index,
+                                    index, &cur_offset, buf, LLOG_CHUNK_SIZE);
                 if (rc)
                         GOTO(out, rc);
 
@@ -286,15 +336,19 @@ static int llog_process_thread(void *arg)
                                rec, rec->lrh_type);
 
                         if (LLOG_REC_HDR_NEEDS_SWABBING(rec))
-                                lustre_swab_llog_rec(rec, NULL);
+                               lustre_swab_llog_rec(rec);
 
                         CDEBUG(D_OTHER, "after swabbing, type=%#x idx=%d\n",
                                rec->lrh_type, rec->lrh_index);
 
-                        if (rec->lrh_index == 0)
-                                GOTO(out, 0); /* no more records */
-
-                        if (rec->lrh_len == 0 || rec->lrh_len >LLOG_CHUNK_SIZE){
+                       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 */
+                       }
+                       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);
@@ -318,14 +372,15 @@ static int llog_process_thread(void *arg)
 
                         /* if set, process the callback on this record */
                         if (ext2_test_bit(index, llh->llh_bitmap)) {
-                                rc = lpi->lpi_cb(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(loghandle,
-                                                        rec->lrh_index);
+                               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)
@@ -341,23 +396,46 @@ static int llog_process_thread(void *arg)
                 }
         }
 
- out:
+out:
         if (cd != NULL)
                 cd->lpcd_last_idx = last_called_index;
-        if (buf)
-                OBD_FREE(buf, LLOG_CHUNK_SIZE);
+
+       OBD_FREE(buf, LLOG_CHUNK_SIZE);
         lpi->lpi_rc = rc;
-#ifdef __KERNEL__
-        cfs_complete(&lpi->lpi_completion);
-#endif
         return 0;
 }
 
-int llog_process_flags(struct llog_handle *loghandle, llog_cb_t cb,
-                       void *data, void *catdata, int flags)
+#ifdef __KERNEL__
+static int llog_process_thread_daemonize(void *arg)
+{
+       struct llog_process_info        *lpi = arg;
+       struct lu_env                    env;
+       int                              rc;
+
+       unshare_fs_struct();
+
+       /* client env has no keys, tags is just 0 */
+       rc = lu_env_init(&env, LCT_LOCAL | LCT_MG_THREAD);
+       if (rc)
+               goto out;
+       lpi->lpi_env = &env;
+
+       rc = llog_process_thread(arg);
+
+       lu_env_fini(&env);
+out:
+       complete(&lpi->lpi_completion);
+       return rc;
+}
+#endif
+
+int llog_process_or_fork(const struct lu_env *env,
+                        struct llog_handle *loghandle,
+                        llog_cb_t cb, void *data, void *catdata, bool fork)
 {
         struct llog_process_info *lpi;
         int                      rc;
+
         ENTRY;
 
         OBD_ALLOC_PTR(lpi);
@@ -369,43 +447,46 @@ int llog_process_flags(struct llog_handle *loghandle, llog_cb_t cb,
         lpi->lpi_cb        = cb;
         lpi->lpi_cbdata    = data;
         lpi->lpi_catdata   = catdata;
-        lpi->lpi_flags     = flags;
 
 #ifdef __KERNEL__
-        cfs_init_completion(&lpi->lpi_completion);
-        rc = cfs_create_thread(llog_process_thread, lpi, CFS_DAEMON_FLAGS);
-        if (rc < 0) {
-                CERROR("cannot start thread: %d\n", rc);
-                OBD_FREE_PTR(lpi);
-                RETURN(rc);
-        }
-        cfs_wait_for_completion(&lpi->lpi_completion);
+       if (fork) {
+               /* 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)) {
+                       CERROR("%s: cannot start thread: rc = %d\n",
+                              loghandle->lgh_ctxt->loc_obd->obd_name, rc);
+                       OBD_FREE_PTR(lpi);
+                       RETURN(rc);
+               }
+               wait_for_completion(&lpi->lpi_completion);
+       } else {
+               lpi->lpi_env = env;
+               llog_process_thread(lpi);
+       }
 #else
-        llog_process_thread(lpi);
+       lpi->lpi_env = env;
+       llog_process_thread(lpi);
 #endif
         rc = lpi->lpi_rc;
         OBD_FREE_PTR(lpi);
         RETURN(rc);
 }
-EXPORT_SYMBOL(llog_process_flags);
+EXPORT_SYMBOL(llog_process_or_fork);
 
-int llog_process(struct llog_handle *loghandle, llog_cb_t cb,
-                 void *data, void *catdata)
+int llog_process(const struct lu_env *env, struct llog_handle *loghandle,
+                llog_cb_t cb, void *data, void *catdata)
 {
-        return llog_process_flags(loghandle, cb, data, catdata, 0);
+       return llog_process_or_fork(env, loghandle, cb, data, catdata, true);
 }
 EXPORT_SYMBOL(llog_process);
 
-inline int llog_get_size(struct llog_handle *loghandle)
-{
-        if (loghandle && loghandle->lgh_hdr)
-                return loghandle->lgh_hdr->llh_count;
-        return 0;
-}
-EXPORT_SYMBOL(llog_get_size);
-
-int llog_reverse_process(struct llog_handle *loghandle, llog_cb_t cb,
-                         void *data, void *catdata)
+int llog_reverse_process(const struct lu_env *env,
+                        struct llog_handle *loghandle, llog_cb_t cb,
+                        void *data, void *catdata)
 {
         struct llog_log_hdr *llh = loghandle->lgh_hdr;
         struct llog_process_cat_data *cd = catdata;
@@ -439,34 +520,41 @@ int llog_reverse_process(struct llog_handle *loghandle, llog_cb_t cb,
 
                 /* get the buf with our target record; avoid old garbage */
                 memset(buf, 0, LLOG_CHUNK_SIZE);
-                rc = llog_prev_block(loghandle, index, buf, LLOG_CHUNK_SIZE);
-                if (rc)
-                        GOTO(out, rc);
-
-                rec = buf;
-                idx = le32_to_cpu(rec->lrh_index);
-                if (idx < index)
-                        CDEBUG(D_RPCTRACE, "index %u : idx %u\n", index, idx);
+               rc = llog_prev_block(env, loghandle, index, buf,
+                                    LLOG_CHUNK_SIZE);
+               if (rc)
+                       GOTO(out, rc);
+
+               rec = buf;
+               idx = rec->lrh_index;
+               CDEBUG(D_RPCTRACE, "index %u : idx %u\n", index, idx);
                 while (idx < index) {
-                        rec = ((void *)rec + le32_to_cpu(rec->lrh_len));
+                       rec = (void *)rec + rec->lrh_len;
+                       if (LLOG_REC_HDR_NEEDS_SWABBING(rec))
+                               lustre_swab_llog_rec(rec);
                         idx ++;
                 }
-                tail = (void *)rec + le32_to_cpu(rec->lrh_len) - sizeof(*tail);
+               LASSERT(idx == index);
+               tail = (void *)rec + rec->lrh_len - sizeof(*tail);
 
                 /* process records in buffer, starting where we found one */
                 while ((void *)tail > buf) {
-                        rec = (void *)tail - le32_to_cpu(tail->lrt_len) +
-                                sizeof(*tail);
-
-                        if (rec->lrh_index == 0)
-                                GOTO(out, 0); /* no more records */
+                       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)) {
-                                rc = cb(loghandle, rec, data);
-                                if (rc == LLOG_PROC_BREAK) {
-                                        GOTO(out, rc);
-                                }
+                               rec = (void *)tail - tail->lrt_len +
+                                     sizeof(*tail);
+
+                               rc = cb(env, loghandle, rec, data);
+                               if (rc == LLOG_PROC_BREAK) {
+                                       GOTO(out, rc);
+                               } else if (rc == LLOG_DEL_RECORD) {
+                                       llog_cancel_rec(env, loghandle,
+                                                       tail->lrt_index);
+                                       rc = 0;
+                               }
                                 if (rc)
                                         GOTO(out, rc);
                         }
@@ -475,7 +563,7 @@ int llog_reverse_process(struct llog_handle *loghandle, llog_cb_t cb,
                         --index;
                         if (index < first_index)
                                 GOTO(out, rc = 0);
-                        tail = (void *)rec - sizeof(*tail);
+                       tail = (void *)tail - tail->lrt_len;
                 }
         }
 
@@ -485,3 +573,459 @@ out:
         RETURN(rc);
 }
 EXPORT_SYMBOL(llog_reverse_process);
+
+/**
+ * new llog API
+ *
+ * API functions:
+ *      llog_open - open llog, may not exist
+ *      llog_exist - check if llog exists
+ *      llog_close - close opened llog, pair for open, frees llog_handle
+ *      llog_declare_create - declare llog creation
+ *      llog_create - create new llog on disk, need transaction handle
+ *      llog_declare_write_rec - declaration of llog write
+ *      llog_write_rec - write llog record on disk, need transaction handle
+ *      llog_declare_add - declare llog catalog record addition
+ *      llog_add - add llog record in catalog, need transaction handle
+ */
+int llog_exist(struct llog_handle *loghandle)
+{
+       struct llog_operations  *lop;
+       int                      rc;
+
+       ENTRY;
+
+       rc = llog_handle2ops(loghandle, &lop);
+       if (rc)
+               RETURN(rc);
+       if (lop->lop_exist == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       rc = lop->lop_exist(loghandle);
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_exist);
+
+int llog_declare_create(const struct lu_env *env,
+                       struct llog_handle *loghandle, struct thandle *th)
+{
+       struct llog_operations  *lop;
+       int                      raised, rc;
+
+       ENTRY;
+
+       rc = llog_handle2ops(loghandle, &lop);
+       if (rc)
+               RETURN(rc);
+       if (lop->lop_declare_create == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+       if (!raised)
+               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       rc = lop->lop_declare_create(env, loghandle, th);
+       if (!raised)
+               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)
+{
+       struct llog_operations  *lop;
+       int                      raised, rc;
+
+       ENTRY;
+
+       rc = llog_handle2ops(handle, &lop);
+       if (rc)
+               RETURN(rc);
+       if (lop->lop_create == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+       if (!raised)
+               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       rc = lop->lop_create(env, handle, th);
+       if (!raised)
+               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,
+                          struct llog_rec_hdr *rec, int idx,
+                          struct thandle *th)
+{
+       struct llog_operations  *lop;
+       int                      raised, rc;
+
+       ENTRY;
+
+       rc = llog_handle2ops(handle, &lop);
+       if (rc)
+               RETURN(rc);
+       LASSERT(lop);
+       if (lop->lop_declare_write_rec == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+       if (!raised)
+               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       rc = lop->lop_declare_write_rec(env, handle, rec, idx, th);
+       if (!raised)
+               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)
+{
+       struct llog_operations  *lop;
+       int                      raised, rc, buflen;
+
+       ENTRY;
+
+       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;
+       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);
+       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)
+{
+       int raised, rc;
+
+       ENTRY;
+
+       if (lgh->lgh_logops->lop_add == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       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);
+       if (!raised)
+               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_add);
+
+int llog_declare_add(const struct lu_env *env, struct llog_handle *lgh,
+                    struct llog_rec_hdr *rec, struct thandle *th)
+{
+       int raised, rc;
+
+       ENTRY;
+
+       if (lgh->lgh_logops->lop_declare_add == NULL)
+               RETURN(-EOPNOTSUPP);
+
+       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+       if (!raised)
+               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       rc = lgh->lgh_logops->lop_declare_add(env, lgh, rec, th);
+       if (!raised)
+               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_declare_add);
+
+/**
+ * Helper function to open llog or create it if doesn't exist.
+ * It hides all transaction handling from caller.
+ */
+int llog_open_create(const struct lu_env *env, struct llog_ctxt *ctxt,
+                    struct llog_handle **res, struct llog_logid *logid,
+                    char *name)
+{
+       struct dt_device        *d;
+       struct thandle          *th;
+       int                      rc;
+
+       ENTRY;
+
+       rc = llog_open(env, ctxt, res, logid, name, LLOG_OPEN_NEW);
+       if (rc)
+               RETURN(rc);
+
+       if (llog_exist(*res))
+               RETURN(0);
+
+       LASSERT((*res)->lgh_obj != NULL);
+
+       d = lu2dt_dev((*res)->lgh_obj->do_lu.lo_dev);
+
+       th = dt_trans_create(env, d);
+       if (IS_ERR(th))
+               GOTO(out, rc = PTR_ERR(th));
+
+       rc = llog_declare_create(env, *res, th);
+       if (rc == 0) {
+               rc = dt_trans_start_local(env, d, th);
+               if (rc == 0)
+                       rc = llog_create(env, *res, th);
+       }
+       dt_trans_stop(env, d, th);
+out:
+       if (rc)
+               llog_close(env, *res);
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_open_create);
+
+/**
+ * Helper function to delete existent llog.
+ */
+int llog_erase(const struct lu_env *env, struct llog_ctxt *ctxt,
+              struct llog_logid *logid, char *name)
+{
+       struct llog_handle      *handle;
+       int                      rc = 0, rc2;
+
+       ENTRY;
+
+       /* nothing to erase */
+       if (name == NULL && logid == NULL)
+               RETURN(0);
+
+       rc = llog_open(env, ctxt, &handle, logid, name, LLOG_OPEN_EXISTS);
+       if (rc < 0)
+               RETURN(rc);
+
+       rc = llog_init_handle(env, handle, LLOG_F_IS_PLAIN, NULL);
+       if (rc == 0)
+               rc = llog_destroy(env, handle);
+
+       rc2 = llog_close(env, handle);
+       if (rc == 0)
+               rc = rc2;
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_erase);
+
+/*
+ * Helper function for write record in llog.
+ * It hides all transaction handling from caller.
+ * 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 dt_device        *dt;
+       struct thandle          *th;
+       int                      rc;
+
+       ENTRY;
+
+       LASSERT(loghandle);
+       LASSERT(loghandle->lgh_ctxt);
+       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, rec, idx, th);
+       if (rc)
+               GOTO(out_trans, rc);
+
+       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);
+       up_write(&loghandle->lgh_lock);
+out_trans:
+       dt_trans_stop(env, dt, th);
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_write);
+
+int llog_open(const struct lu_env *env, struct llog_ctxt *ctxt,
+             struct llog_handle **lgh, struct llog_logid *logid,
+             char *name, enum llog_open_param open_param)
+{
+       int      raised;
+       int      rc;
+
+       ENTRY;
+
+       LASSERT(ctxt);
+       LASSERT(ctxt->loc_logops);
+
+       if (ctxt->loc_logops->lop_open == NULL) {
+               *lgh = NULL;
+               RETURN(-EOPNOTSUPP);
+       }
+
+       *lgh = llog_alloc_handle();
+       if (*lgh == NULL)
+               RETURN(-ENOMEM);
+       (*lgh)->lgh_ctxt = ctxt;
+       (*lgh)->lgh_logops = ctxt->loc_logops;
+
+       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
+       if (!raised)
+               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       rc = ctxt->loc_logops->lop_open(env, *lgh, logid, name, open_param);
+       if (!raised)
+               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       if (rc) {
+               llog_free_handle(*lgh);
+               *lgh = NULL;
+       }
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_open);
+
+int llog_close(const struct lu_env *env, struct llog_handle *loghandle)
+{
+       struct llog_operations  *lop;
+       int                      rc;
+
+       ENTRY;
+
+       rc = llog_handle2ops(loghandle, &lop);
+       if (rc)
+               GOTO(out, rc);
+       if (lop->lop_close == NULL)
+               GOTO(out, rc = -EOPNOTSUPP);
+       rc = lop->lop_close(env, loghandle);
+out:
+       llog_handle_put(loghandle);
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_close);
+
+int llog_is_empty(const struct lu_env *env, struct llog_ctxt *ctxt,
+                 char *name)
+{
+       struct llog_handle      *llh;
+       int                      rc = 0;
+
+       rc = llog_open(env, ctxt, &llh, NULL, name, LLOG_OPEN_EXISTS);
+       if (rc < 0) {
+               if (likely(rc == -ENOENT))
+                       rc = 0;
+               GOTO(out, rc);
+       }
+
+       rc = llog_init_handle(env, llh, LLOG_F_IS_PLAIN, NULL);
+       if (rc)
+               GOTO(out_close, rc);
+       rc = llog_get_size(llh);
+
+out_close:
+       llog_close(env, llh);
+out:
+       /* header is record 1 */
+       return (rc <= 1);
+}
+EXPORT_SYMBOL(llog_is_empty);
+
+int llog_copy_handler(const struct lu_env *env, struct llog_handle *llh,
+                     struct llog_rec_hdr *rec, void *data)
+{
+       struct llog_handle      *copy_llh = data;
+
+       /* Append all records */
+       return llog_write(env, copy_llh, rec, NULL, 0, NULL, -1);
+}
+EXPORT_SYMBOL(llog_copy_handler);
+
+/* backup plain llog */
+int llog_backup(const struct lu_env *env, struct obd_device *obd,
+               struct llog_ctxt *ctxt, struct llog_ctxt *bctxt,
+               char *name, char *backup)
+{
+       struct llog_handle      *llh, *bllh;
+       int                      rc;
+
+       ENTRY;
+
+       /* open original log */
+       rc = llog_open(env, ctxt, &llh, NULL, name, LLOG_OPEN_EXISTS);
+       if (rc < 0) {
+               /* the -ENOENT case is also reported to the caller
+                * but silently so it should handle that if needed.
+                */
+               if (rc != -ENOENT)
+                       CERROR("%s: failed to open log %s: rc = %d\n",
+                              obd->obd_name, name, rc);
+               RETURN(rc);
+       }
+
+       rc = llog_init_handle(env, llh, LLOG_F_IS_PLAIN, NULL);
+       if (rc)
+               GOTO(out_close, rc);
+
+       /* Make sure there's no old backup log */
+       rc = llog_erase(env, bctxt, NULL, backup);
+       if (rc < 0 && rc != -ENOENT)
+               GOTO(out_close, rc);
+
+       /* open backup log */
+       rc = llog_open_create(env, bctxt, &bllh, NULL, backup);
+       if (rc) {
+               CERROR("%s: failed to open backup logfile %s: rc = %d\n",
+                      obd->obd_name, backup, rc);
+               GOTO(out_close, rc);
+       }
+
+       /* check that backup llog is not the same object as original one */
+       if (llh->lgh_obj == bllh->lgh_obj) {
+               CERROR("%s: backup llog %s to itself (%s), objects %p/%p\n",
+                      obd->obd_name, name, backup, llh->lgh_obj,
+                      bllh->lgh_obj);
+               GOTO(out_backup, rc = -EEXIST);
+       }
+
+       rc = llog_init_handle(env, bllh, LLOG_F_IS_PLAIN, NULL);
+       if (rc)
+               GOTO(out_backup, rc);
+
+       /* Copy log record by record */
+       rc = llog_process_or_fork(env, llh, llog_copy_handler, (void *)bllh,
+                                 NULL, false);
+       if (rc)
+               CERROR("%s: failed to backup log %s: rc = %d\n",
+                      obd->obd_name, name, rc);
+out_backup:
+       llog_close(env, bllh);
+out_close:
+       llog_close(env, llh);
+       RETURN(rc);
+}
+EXPORT_SYMBOL(llog_backup);