kernel - Fix excessive mbuf use in nfs_realign()

[dragonfly.git] / sys / vfs / hammer / hammer_pfs.c

diff --git a/sys/vfs/hammer/hammer_pfs.c b/sys/vfs/hammer/hammer_pfs.c
index 49e8465..6699a53 100644 (file)
--- a/sys/vfs/hammer/hammer_pfs.c
+++ b/sys/vfs/hammer/hammer_pfs.c
@@ -74,7 +74,7 @@ hammer_ioc_get_pseudofs(hammer_transaction_t trans, hammer_inode_t ip,
 
        /*
         * If the PFS is a master the sync tid is set by normal operation
-        * rather then the mirroring code, and will always track the
+        * rather than the mirroring code, and will always track the
         * real HAMMER filesystem.
         *
         * We use flush_tid1, which is the highest fully committed TID.
@@ -125,9 +125,14 @@ hammer_ioc_set_pseudofs(hammer_transaction_t trans, hammer_inode_t ip,
                /*
                 * Save it back, create a root inode if we are in master
                 * mode and no root exists.
+                *
+                * We do not create root inodes for slaves, the root inode
+                * must be mirrored from the master.
                 */
-               if (error == 0)
+               if (error == 0 &&
+                   (pfsm->pfsd.mirror_flags & HAMMER_PFSD_SLAVE) == 0) {
                        error = hammer_mkroot_pseudofs(trans, cred, pfsm);
+               }
                if (error == 0)
                        error = hammer_save_pseudofs(trans, pfsm);
 
@@ -188,14 +193,12 @@ hammer_ioc_upgrade_pseudofs(hammer_transaction_t trans, hammer_inode_t ip,
 /*
  * Downgrade a master to a slave
  *
- * This is really easy to do, just set the SLAVE flag.
+ * This is really easy to do, just set the SLAVE flag and update sync_end_tid.
  *
- * We also leave sync_end_tid intact... the field is not used in master
- * mode (vol0_next_tid overrides it), but if someone switches to master
- * mode accidently and then back to slave mode we don't want it to change.  
- * Eventually it will be used as the cross-synchronization TID in
- * multi-master mode, and we don't want to mess with it for that feature
- * either.
+ * We previously did not update sync_end_tid in consideration for a slave
+ * upgraded to a master and then downgraded again, but this completely breaks
+ * the case where one starts with a master and then downgrades to a slave,
+ * then upgrades again.
  *
  * NOTE: The ip used for ioctl is not necessarily related to the PFS
  */
@@ -203,6 +206,7 @@ int
 hammer_ioc_downgrade_pseudofs(hammer_transaction_t trans, hammer_inode_t ip,
                        struct hammer_ioc_pseudofs_rw *pfs)
 {
+       hammer_mount_t hmp = trans->hmp;
        hammer_pseudofs_inmem_t pfsm;
        u_int32_t localization;
        int error;
@@ -217,6 +221,8 @@ hammer_ioc_downgrade_pseudofs(hammer_transaction_t trans, hammer_inode_t ip,
        if (error == 0) {
                if ((pfsm->pfsd.mirror_flags & HAMMER_PFSD_SLAVE) == 0) {
                        pfsm->pfsd.mirror_flags |= HAMMER_PFSD_SLAVE;
+                       if (pfsm->pfsd.sync_end_tid < hmp->flush_tid1)
+                               pfsm->pfsd.sync_end_tid = hmp->flush_tid1;
                        error = hammer_save_pseudofs(trans, pfsm);
                }
        }
@@ -402,6 +408,8 @@ retry:
                 * We only care about leafs.  Internal nodes can be returned
                 * in mirror-filtered mode (they are used to generate SKIP
                 * mrecords), but we don't need them for this code.
+                *
+                * WARNING: See warnings in hammer_unlock_cursor() function.
                 */
                cursor.flags |= HAMMER_CURSOR_ATEDISK;
                if (cursor.node->ondisk->type == HAMMER_BTREE_TYPE_LEAF) {