FreeBSD/Linux Kernel Cross Reference
sys/ufs/ffs/softdep.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright 1998, 2000 Marshall Kirk McKusick. All Rights Reserved.
      *
      * The soft updates code is derived from the appendix of a University
      * of Michigan technical report (Gregory R. Ganger and Yale N. Patt,
      * "Soft Updates: A Solution to the Metadata Update Problem in File
      * Systems", CSE-TR-254-95, August 1995).
     *
     * Further information about soft updates can be obtained from:
     *
     *      Marshall Kirk McKusick          http://www.mckusick.com/softdep/
     *      1614 Oxford Street              mckusick@mckusick.com
     *      Berkeley, CA 94709-1608         +1-510-843-9542
     *      USA
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     *
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``AS IS'' AND ANY
     * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     * DISCLAIMED.  IN NO EVENT SHALL MARSHALL KIRK MCKUSICK BE LIABLE FOR
     * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)softdep.h   9.7 (McKusick) 6/21/00
     * $FreeBSD$
     */
    
    #include <sys/queue.h>
    
    /*
     * Allocation dependencies are handled with undo/redo on the in-memory
     * copy of the data. A particular data dependency is eliminated when
     * it is ALLCOMPLETE: that is ATTACHED, DEPCOMPLETE, and COMPLETE.
     * 
     * The ATTACHED flag means that the data is not currently being written
     * to disk.
     * 
     * The UNDONE flag means that the data has been rolled back to a safe
     * state for writing to the disk. When the I/O completes, the data is
     * restored to its current form and the state reverts to ATTACHED.
     * The data must be locked throughout the rollback, I/O, and roll
     * forward so that the rolled back information is never visible to
     * user processes.
     *
     * The COMPLETE flag indicates that the item has been written. For example,
     * a dependency that requires that an inode be written will be marked
     * COMPLETE after the inode has been written to disk.
     * 
     * The DEPCOMPLETE flag indicates the completion of any other
     * dependencies such as the writing of a cylinder group map has been
     * completed. A dependency structure may be freed only when both it
     * and its dependencies have completed and any rollbacks that are in
     * progress have finished as indicated by the set of ALLCOMPLETE flags
     * all being set.
     * 
     * The two MKDIR flags indicate additional dependencies that must be done
     * when creating a new directory. MKDIR_BODY is cleared when the directory
     * data block containing the "." and ".." entries has been written.
     * MKDIR_PARENT is cleared when the parent inode with the increased link
     * count for ".." has been written. When both MKDIR flags have been
     * cleared, the DEPCOMPLETE flag is set to indicate that the directory
     * dependencies have been completed. The writing of the directory inode
     * itself sets the COMPLETE flag which then allows the directory entry for
     * the new directory to be written to disk. The RMDIR flag marks a dirrem
     * structure as representing the removal of a directory rather than a
     * file. When the removal dependencies are completed, additional work needs
     * to be done* (an additional decrement of the associated inode, and a
     * decrement of the parent inode).
     *
     * The DIRCHG flag marks a diradd structure as representing the changing
     * of an existing entry rather than the addition of a new one. When
     * the update is complete the dirrem associated with the inode for
     * the old name must be added to the worklist to do the necessary
     * reference count decrement.
     * 
     * The GOINGAWAY flag indicates that the data structure is frozen from
     * further change until its dependencies have been completed and its
     * resources freed after which it will be discarded.
     *
     * The IOSTARTED flag prevents multiple calls to the I/O start routine from
     * doing multiple rollbacks.
     *
     * The NEWBLOCK flag marks pagedep structures that have just been allocated,
    * so must be claimed by the inode before all dependencies are complete.
    *
    * The INPROGRESS flag marks worklist structures that are still on the
    * worklist, but are being considered for action by some process.
    *
    * The UFS1FMT flag indicates that the inode being processed is a ufs1 format.
    *
    * The EXTDATA flag indicates that the allocdirect describes an
    * extended-attributes dependency.
    *
    * The ONWORKLIST flag shows whether the structure is currently linked
    * onto a worklist.
    *
    * The UNLINK* flags track the progress of updating the on-disk linked
    * list of active but unlinked inodes. When an inode is first unlinked
    * it is marked as UNLINKED. When its on-disk di_freelink has been
    * written its UNLINKNEXT flags is set. When its predecessor in the
    * list has its di_freelink pointing at us its UNLINKPREV is set.
    * When the on-disk list can reach it from the superblock, its
    * UNLINKONLIST flag is set. Once all of these flags are set, it
    * is safe to let its last name be removed.
    */
   #define ATTACHED        0x000001
   #define UNDONE          0x000002
   #define COMPLETE        0x000004
   #define DEPCOMPLETE     0x000008
   #define MKDIR_PARENT    0x000010 /* diradd, mkdir, jaddref, jsegdep only */
   #define MKDIR_BODY      0x000020 /* diradd, mkdir, jaddref only */
   #define RMDIR           0x000040 /* dirrem only */
   #define DIRCHG          0x000080 /* diradd, dirrem only */
   #define GOINGAWAY       0x000100 /* indirdep, jremref only */
   #define IOSTARTED       0x000200 /* inodedep, pagedep, bmsafemap only */
   #define DELAYEDFREE     0x000400 /* allocindirect free delayed. */
   #define NEWBLOCK        0x000800 /* pagedep, jaddref only */
   #define INPROGRESS      0x001000 /* dirrem, freeblks, freefrag, freefile only */
   #define UFS1FMT         0x002000 /* indirdep only */
   #define EXTDATA         0x004000 /* allocdirect only */
   #define ONWORKLIST      0x008000
   #define IOWAITING       0x010000 /* Thread is waiting for IO to complete. */
   #define ONDEPLIST       0x020000 /* Structure is on a dependency list. */
   #define UNLINKED        0x040000 /* inodedep has been unlinked. */
   #define UNLINKNEXT      0x080000 /* inodedep has valid di_freelink */
   #define UNLINKPREV      0x100000 /* inodedep is pointed at in the unlink list */
   #define UNLINKONLIST    0x200000 /* inodedep is in the unlinked list on disk */
   #define UNLINKLINKS     (UNLINKNEXT | UNLINKPREV)
   #define WRITESUCCEEDED  0x400000 /* the disk write completed successfully */
   
   #define ALLCOMPLETE     (ATTACHED | COMPLETE | DEPCOMPLETE)
   
   #define PRINT_SOFTDEP_FLAGS "\2\27writesucceeded\26unlinkonlist" \
           "\25unlinkprev\24unlinknext\23unlinked\22ondeplist\21iowaiting" \
           "\20onworklist\17extdata\16ufs1fmt\15inprogress\14newblock" \
           "\13delayedfree\12iostarted\11goingaway\10dirchg\7rmdir\6mkdir_body" \
           "\5mkdir_parent\4depcomplete\3complete\2undone\1attached"
   
   /*
    * Values for each of the soft dependency types.
    */
   #define D_UNUSED        0
   #define D_FIRST         D_PAGEDEP
   #define D_PAGEDEP       1
   #define D_INODEDEP      2
   #define D_BMSAFEMAP     3
   #define D_NEWBLK        4
   #define D_ALLOCDIRECT   5
   #define D_INDIRDEP      6
   #define D_ALLOCINDIR    7
   #define D_FREEFRAG      8
   #define D_FREEBLKS      9
   #define D_FREEFILE      10
   #define D_DIRADD        11
   #define D_MKDIR         12
   #define D_DIRREM        13
   #define D_NEWDIRBLK     14
   #define D_FREEWORK      15
   #define D_FREEDEP       16
   #define D_JADDREF       17
   #define D_JREMREF       18
   #define D_JMVREF        19
   #define D_JNEWBLK       20
   #define D_JFREEBLK      21
   #define D_JFREEFRAG     22
   #define D_JSEG          23
   #define D_JSEGDEP       24
   #define D_SBDEP         25
   #define D_JTRUNC        26
   #define D_JFSYNC        27
   #define D_SENTINEL      28
   #define D_LAST          D_SENTINEL
   
   /*
    * The workitem queue.
    * 
    * It is sometimes useful and/or necessary to clean up certain dependencies
    * in the background rather than during execution of an application process
    * or interrupt service routine. To realize this, we append dependency
    * structures corresponding to such tasks to a "workitem" queue. In a soft
    * updates implementation, most pending workitems should not wait for more
    * than a couple of seconds, so the filesystem syncer process awakens once
    * per second to process the items on the queue.
    */
   
   /* LIST_HEAD(workhead, worklist);       -- declared in buf.h */
   
   /*
    * Each request can be linked onto a work queue through its worklist structure.
    * To avoid the need for a pointer to the structure itself, this structure
    * MUST be declared FIRST in each type in which it appears! If more than one
    * worklist is needed in the structure, then a wk_data field must be added
    * and the macros below changed to use it.
    */
   struct worklist {
           LIST_ENTRY(worklist)    wk_list;        /* list of work requests */
           struct mount            *wk_mp;         /* Mount we live in */
           unsigned int            wk_type:8,      /* type of request */
                                   wk_state:24;    /* state flags */
           LIST_ENTRY(worklist)    wk_all;         /* list of deps of this type */
   #ifdef INVARIANTS
           const char              *wk_func;       /* func where added / removed */
           int                     wk_line;        /* line where added / removed */
   #endif
   };
   #define WK_DATA(wk) ((void *)(wk))
   #define WK_PAGEDEP(wk) ((struct pagedep *)(wk))
   #define WK_INODEDEP(wk) ((struct inodedep *)(wk))
   #define WK_BMSAFEMAP(wk) ((struct bmsafemap *)(wk))
   #define WK_NEWBLK(wk)  ((struct newblk *)(wk))
   #define WK_ALLOCDIRECT(wk) ((struct allocdirect *)(wk))
   #define WK_INDIRDEP(wk) ((struct indirdep *)(wk))
   #define WK_ALLOCINDIR(wk) ((struct allocindir *)(wk))
   #define WK_FREEFRAG(wk) ((struct freefrag *)(wk))
   #define WK_FREEBLKS(wk) ((struct freeblks *)(wk))
   #define WK_FREEWORK(wk) ((struct freework *)(wk))
   #define WK_FREEFILE(wk) ((struct freefile *)(wk))
   #define WK_DIRADD(wk) ((struct diradd *)(wk))
   #define WK_MKDIR(wk) ((struct mkdir *)(wk))
   #define WK_DIRREM(wk) ((struct dirrem *)(wk))
   #define WK_NEWDIRBLK(wk) ((struct newdirblk *)(wk))
   #define WK_JADDREF(wk) ((struct jaddref *)(wk))
   #define WK_JREMREF(wk) ((struct jremref *)(wk))
   #define WK_JMVREF(wk) ((struct jmvref *)(wk))
   #define WK_JSEGDEP(wk) ((struct jsegdep *)(wk))
   #define WK_JSEG(wk) ((struct jseg *)(wk))
   #define WK_JNEWBLK(wk) ((struct jnewblk *)(wk))
   #define WK_JFREEBLK(wk) ((struct jfreeblk *)(wk))
   #define WK_FREEDEP(wk) ((struct freedep *)(wk))
   #define WK_JFREEFRAG(wk) ((struct jfreefrag *)(wk))
   #define WK_SBDEP(wk) ((struct sbdep *)(wk))
   #define WK_JTRUNC(wk) ((struct jtrunc *)(wk))
   #define WK_JFSYNC(wk) ((struct jfsync *)(wk))
   
   /*
    * Various types of lists
    */
   LIST_HEAD(dirremhd, dirrem);
   LIST_HEAD(diraddhd, diradd);
   LIST_HEAD(newblkhd, newblk);
   LIST_HEAD(inodedephd, inodedep);
   LIST_HEAD(allocindirhd, allocindir);
   LIST_HEAD(allocdirecthd, allocdirect);
   TAILQ_HEAD(allocdirectlst, allocdirect);
   LIST_HEAD(indirdephd, indirdep);
   LIST_HEAD(jaddrefhd, jaddref);
   LIST_HEAD(jremrefhd, jremref);
   LIST_HEAD(jmvrefhd, jmvref);
   LIST_HEAD(jnewblkhd, jnewblk);
   LIST_HEAD(jblkdephd, jblkdep);
   LIST_HEAD(freeworkhd, freework);
   TAILQ_HEAD(freeworklst, freework);
   TAILQ_HEAD(jseglst, jseg);
   TAILQ_HEAD(inoreflst, inoref);
   TAILQ_HEAD(freeblklst, freeblks);
   
   /*
    * The "pagedep" structure tracks the various dependencies related to
    * a particular directory page. If a directory page has any dependencies,
    * it will have a pagedep linked to its associated buffer. The
    * pd_dirremhd list holds the list of dirrem requests which decrement
    * inode reference counts. These requests are processed after the
    * directory page with the corresponding zero'ed entries has been
    * written. The pd_diraddhd list maintains the list of diradd requests
    * which cannot be committed until their corresponding inode has been
    * written to disk. Because a directory may have many new entries
    * being created, several lists are maintained hashed on bits of the
    * offset of the entry into the directory page to keep the lists from
    * getting too long. Once a new directory entry has been cleared to
    * be written, it is moved to the pd_pendinghd list. After the new
    * entry has been written to disk it is removed from the pd_pendinghd
    * list, any removed operations are done, and the dependency structure
    * is freed.
    */
   #define DAHASHSZ 5
   #define DIRADDHASH(offset) (((offset) >> 2) % DAHASHSZ)
   struct pagedep {
           struct  worklist pd_list;       /* page buffer */
   #       define  pd_state pd_list.wk_state /* check for multiple I/O starts */
           LIST_ENTRY(pagedep) pd_hash;    /* hashed lookup */
           ino_t   pd_ino;                 /* associated file */
           ufs_lbn_t pd_lbn;               /* block within file */
           struct  newdirblk *pd_newdirblk; /* associated newdirblk if NEWBLOCK */
           struct  dirremhd pd_dirremhd;   /* dirrem's waiting for page */
           struct  diraddhd pd_diraddhd[DAHASHSZ]; /* diradd dir entry updates */
           struct  diraddhd pd_pendinghd;  /* directory entries awaiting write */
           struct  jmvrefhd pd_jmvrefhd;   /* Dependent journal writes. */
   };
   
   /*
    * The "inodedep" structure tracks the set of dependencies associated
    * with an inode. One task that it must manage is delayed operations
    * (i.e., work requests that must be held until the inodedep's associated
    * inode has been written to disk). Getting an inode from its incore 
    * state to the disk requires two steps to be taken by the filesystem
    * in this order: first the inode must be copied to its disk buffer by
    * the VOP_UPDATE operation; second the inode's buffer must be written
    * to disk. To ensure that both operations have happened in the required
    * order, the inodedep maintains two lists. Delayed operations are
    * placed on the id_inowait list. When the VOP_UPDATE is done, all
    * operations on the id_inowait list are moved to the id_bufwait list.
    * When the buffer is written, the items on the id_bufwait list can be
    * safely moved to the work queue to be processed. A second task of the
    * inodedep structure is to track the status of block allocation within
    * the inode.  Each block that is allocated is represented by an
    * "allocdirect" structure (see below). It is linked onto the id_newinoupdt
    * list until both its contents and its allocation in the cylinder
    * group map have been written to disk. Once these dependencies have been
    * satisfied, it is removed from the id_newinoupdt list and any followup
    * actions such as releasing the previous block or fragment are placed
    * on the id_inowait list. When an inode is updated (a VOP_UPDATE is
    * done), the "inodedep" structure is linked onto the buffer through
    * its worklist. Thus, it will be notified when the buffer is about
    * to be written and when it is done. At the update time, all the
    * elements on the id_newinoupdt list are moved to the id_inoupdt list
    * since those changes are now relevant to the copy of the inode in the
    * buffer. Also at update time, the tasks on the id_inowait list are
    * moved to the id_bufwait list so that they will be executed when
    * the updated inode has been written to disk. When the buffer containing
    * the inode is written to disk, any updates listed on the id_inoupdt
    * list are rolled back as they are not yet safe. Following the write,
    * the changes are once again rolled forward and any actions on the
    * id_bufwait list are processed (since those actions are now safe).
    * The entries on the id_inoupdt and id_newinoupdt lists must be kept
    * sorted by logical block number to speed the calculation of the size
    * of the rolled back inode (see explanation in initiate_write_inodeblock).
    * When a directory entry is created, it is represented by a diradd.
    * The diradd is added to the id_inowait list as it cannot be safely
    * written to disk until the inode that it represents is on disk. After
    * the inode is written, the id_bufwait list is processed and the diradd
    * entries are moved to the id_pendinghd list where they remain until
    * the directory block containing the name has been written to disk.
    * The purpose of keeping the entries on the id_pendinghd list is so that
    * the softdep_fsync function can find and push the inode's directory
    * name(s) as part of the fsync operation for that file.
    */
   struct inodedep {
           struct  worklist id_list;       /* buffer holding inode block */
   #       define  id_state id_list.wk_state /* inode dependency state */
           LIST_ENTRY(inodedep) id_hash;   /* hashed lookup */
           TAILQ_ENTRY(inodedep) id_unlinked;      /* Unlinked but ref'd inodes */
           struct  fs *id_fs;              /* associated filesystem */
           ino_t   id_ino;                 /* dependent inode */
           nlink_t id_nlinkdelta;          /* saved effective link count */
           nlink_t id_nlinkwrote;          /* i_nlink that we wrote to disk */
           nlink_t id_savednlink;          /* Link saved during rollback */
           LIST_ENTRY(inodedep) id_deps;   /* bmsafemap's list of inodedep's */
           struct  bmsafemap *id_bmsafemap; /* related bmsafemap (if pending) */
           struct  diradd *id_mkdiradd;    /* diradd for a mkdir. */
           struct  inoreflst id_inoreflst; /* Inode reference adjustments. */
           long    id_savedextsize;        /* ext size saved during rollback */
           off_t   id_savedsize;           /* file size saved during rollback */
           struct  dirremhd id_dirremhd;   /* Removals pending. */
           struct  workhead id_pendinghd;  /* entries awaiting directory write */
           struct  workhead id_bufwait;    /* operations after inode written */
           struct  workhead id_inowait;    /* operations waiting inode update */
           struct  allocdirectlst id_inoupdt; /* updates before inode written */
           struct  allocdirectlst id_newinoupdt; /* updates when inode written */
           struct  allocdirectlst id_extupdt; /* extdata updates pre-inode write */
           struct  allocdirectlst id_newextupdt; /* extdata updates at ino write */
           struct  freeblklst id_freeblklst; /* List of partial truncates. */
           union {
           struct  ufs1_dinode *idu_savedino1; /* saved ufs1_dinode contents */
           struct  ufs2_dinode *idu_savedino2; /* saved ufs2_dinode contents */
           } id_un;
   };
   #define id_savedino1 id_un.idu_savedino1
   #define id_savedino2 id_un.idu_savedino2
   
   /*
    * A "bmsafemap" structure maintains a list of dependency structures
    * that depend on the update of a particular cylinder group map.
    * It has lists for newblks, allocdirects, allocindirs, and inodedeps.
    * It is attached to the buffer of a cylinder group block when any of
    * these things are allocated from the cylinder group. It is freed
    * after the cylinder group map is written and the state of its
    * dependencies are updated with DEPCOMPLETE to indicate that it has
    * been processed.
    */
   struct bmsafemap {
           struct  worklist sm_list;       /* cylgrp buffer */
   #       define  sm_state sm_list.wk_state
           LIST_ENTRY(bmsafemap) sm_hash;  /* Hash links. */
           LIST_ENTRY(bmsafemap) sm_next;  /* Mount list. */
           int     sm_cg;
           struct  buf *sm_buf;            /* associated buffer */
           struct  allocdirecthd sm_allocdirecthd; /* allocdirect deps */
           struct  allocdirecthd sm_allocdirectwr; /* writing allocdirect deps */
           struct  allocindirhd sm_allocindirhd; /* allocindir deps */
           struct  allocindirhd sm_allocindirwr; /* writing allocindir deps */
           struct  inodedephd sm_inodedephd; /* inodedep deps */
           struct  inodedephd sm_inodedepwr; /* writing inodedep deps */
           struct  newblkhd sm_newblkhd;   /* newblk deps */
           struct  newblkhd sm_newblkwr;   /* writing newblk deps */
           struct  jaddrefhd sm_jaddrefhd; /* Pending inode allocations. */
           struct  jnewblkhd sm_jnewblkhd; /* Pending block allocations. */
           struct  workhead sm_freehd;     /* Freedep deps. */
           struct  workhead sm_freewr;     /* Written freedeps. */
   };
   
   /*
    * A "newblk" structure is attached to a bmsafemap structure when a block
    * or fragment is allocated from a cylinder group. Its state is set to
    * DEPCOMPLETE when its cylinder group map is written. It is converted to
    * an allocdirect or allocindir allocation once the allocator calls the
    * appropriate setup function. It will initially be linked onto a bmsafemap
    * list. Once converted it can be linked onto the lists described for
    * allocdirect or allocindir as described below.
    */ 
   struct newblk {
           struct  worklist nb_list;       /* See comment above. */
   #       define  nb_state nb_list.wk_state
           LIST_ENTRY(newblk) nb_hash;     /* Hashed lookup. */
           LIST_ENTRY(newblk) nb_deps;     /* Bmsafemap's list of newblks. */
           struct  jnewblk *nb_jnewblk;    /* New block journal entry. */
           struct  bmsafemap *nb_bmsafemap;/* Cylgrp dep (if pending). */
           struct  freefrag *nb_freefrag;  /* Fragment to be freed (if any). */
           struct  indirdephd nb_indirdeps; /* Children indirect blocks. */
           struct  workhead nb_newdirblk;  /* Dir block to notify when written. */
           struct  workhead nb_jwork;      /* Journal work pending. */
           ufs2_daddr_t    nb_newblkno;    /* New value of block pointer. */
   };
   
   /*
    * An "allocdirect" structure is attached to an "inodedep" when a new block
    * or fragment is allocated and pointed to by the inode described by
    * "inodedep". The worklist is linked to the buffer that holds the block.
    * When the block is first allocated, it is linked to the bmsafemap
    * structure associated with the buffer holding the cylinder group map
    * from which it was allocated. When the cylinder group map is written
    * to disk, ad_state has the DEPCOMPLETE flag set. When the block itself
    * is written, the COMPLETE flag is set. Once both the cylinder group map
    * and the data itself have been written, it is safe to write the inode
    * that claims the block. If there was a previous fragment that had been
    * allocated before the file was increased in size, the old fragment may
    * be freed once the inode claiming the new block is written to disk.
    * This ad_fragfree request is attached to the id_inowait list of the
    * associated inodedep (pointed to by ad_inodedep) for processing after
    * the inode is written. When a block is allocated to a directory, an
    * fsync of a file whose name is within that block must ensure not only
    * that the block containing the file name has been written, but also
    * that the on-disk inode references that block. When a new directory
    * block is created, we allocate a newdirblk structure which is linked
    * to the associated allocdirect (on its ad_newdirblk list). When the
    * allocdirect has been satisfied, the newdirblk structure is moved to
    * the inodedep id_bufwait list of its directory to await the inode
    * being written. When the inode is written, the directory entries are
    * fully committed and can be deleted from their pagedep->id_pendinghd
    * and inodedep->id_pendinghd lists.
    */
   struct allocdirect {
           struct  newblk ad_block;        /* Common block logic */
   #       define  ad_list ad_block.nb_list /* block pointer worklist */
   #       define  ad_state ad_list.wk_state /* block pointer state */
           TAILQ_ENTRY(allocdirect) ad_next; /* inodedep's list of allocdirect's */
           struct  inodedep *ad_inodedep;  /* associated inodedep */
           ufs2_daddr_t    ad_oldblkno;    /* old value of block pointer */
           int             ad_offset;      /* Pointer offset in parent. */
           long            ad_newsize;     /* size of new block */
           long            ad_oldsize;     /* size of old block */
   };
   #define ad_newblkno     ad_block.nb_newblkno
   #define ad_freefrag     ad_block.nb_freefrag
   #define ad_newdirblk    ad_block.nb_newdirblk
   
   /*
    * A single "indirdep" structure manages all allocation dependencies for
    * pointers in an indirect block. The up-to-date state of the indirect
    * block is stored in ir_savedata. The set of pointers that may be safely
    * written to the disk is stored in ir_savebp. The state field is used
    * only to track whether the buffer is currently being written (in which
    * case it is not safe to update ir_savebp). Ir_deplisthd contains the
    * list of allocindir structures, one for each block that needs to be
    * written to disk. Once the block and its bitmap allocation have been
    * written the safecopy can be updated to reflect the allocation and the
    * allocindir structure freed. If ir_state indicates that an I/O on the
    * indirect block is in progress when ir_savebp is to be updated, the
    * update is deferred by placing the allocindir on the ir_donehd list.
    * When the I/O on the indirect block completes, the entries on the
    * ir_donehd list are processed by updating their corresponding ir_savebp
    * pointers and then freeing the allocindir structure.
    */
   struct indirdep {
           struct  worklist ir_list;       /* buffer holding indirect block */
   #       define  ir_state ir_list.wk_state /* indirect block pointer state */
           LIST_ENTRY(indirdep) ir_next;   /* alloc{direct,indir} list */
           TAILQ_HEAD(, freework) ir_trunc;        /* List of truncations. */
           caddr_t ir_saveddata;           /* buffer cache contents */
           struct  buf *ir_savebp;         /* buffer holding safe copy */
           struct  buf *ir_bp;             /* buffer holding live copy */
           struct  allocindirhd ir_completehd; /* waiting for indirdep complete */
           struct  allocindirhd ir_writehd; /* Waiting for the pointer write. */
           struct  allocindirhd ir_donehd; /* done waiting to update safecopy */
           struct  allocindirhd ir_deplisthd; /* allocindir deps for this block */
           struct  freeblks *ir_freeblks;  /* Freeblks that frees this indir. */
   };
   
   /*
    * An "allocindir" structure is attached to an "indirdep" when a new block
    * is allocated and pointed to by the indirect block described by the
    * "indirdep". The worklist is linked to the buffer that holds the new block.
    * When the block is first allocated, it is linked to the bmsafemap
    * structure associated with the buffer holding the cylinder group map
    * from which it was allocated. When the cylinder group map is written
    * to disk, ai_state has the DEPCOMPLETE flag set. When the block itself
    * is written, the COMPLETE flag is set. Once both the cylinder group map
    * and the data itself have been written, it is safe to write the entry in
    * the indirect block that claims the block; the "allocindir" dependency 
    * can then be freed as it is no longer applicable.
    */
   struct allocindir {
           struct  newblk ai_block;        /* Common block area */
   #       define  ai_state ai_block.nb_list.wk_state /* indirect pointer state */
           LIST_ENTRY(allocindir) ai_next; /* indirdep's list of allocindir's */
           struct  indirdep *ai_indirdep;  /* address of associated indirdep */
           ufs2_daddr_t    ai_oldblkno;    /* old value of block pointer */
           ufs_lbn_t       ai_lbn;         /* Logical block number. */
           int             ai_offset;      /* Pointer offset in parent. */
   };
   #define ai_newblkno     ai_block.nb_newblkno
   #define ai_freefrag     ai_block.nb_freefrag
   #define ai_newdirblk    ai_block.nb_newdirblk
   
   /*
    * The allblk union is used to size the newblk structure on allocation so
    * that it may be any one of three types.
    */
   union allblk {
           struct  allocindir ab_allocindir;
           struct  allocdirect ab_allocdirect;
           struct  newblk  ab_newblk;
   };
   
   /*
    * A "freefrag" structure is attached to an "inodedep" when a previously
    * allocated fragment is replaced with a larger fragment, rather than extended.
    * The "freefrag" structure is constructed and attached when the replacement
    * block is first allocated. It is processed after the inode claiming the
    * bigger block that replaces it has been written to disk.
    */
   struct freefrag {
           struct  worklist ff_list;       /* id_inowait or delayed worklist */
   #       define  ff_state ff_list.wk_state
           struct  worklist *ff_jdep;      /* Associated journal entry. */
           struct  workhead ff_jwork;      /* Journal work pending. */
           ufs2_daddr_t ff_blkno;          /* fragment physical block number */
           long    ff_fragsize;            /* size of fragment being deleted */
           ino_t   ff_inum;                /* owning inode number */
           enum    vtype ff_vtype;         /* owning inode's file type */
           int     ff_key;                 /* trim key when deleted */
   };
   
   /*
    * A "freeblks" structure is attached to an "inodedep" when the
    * corresponding file's length is reduced to zero. It records all
    * the information needed to free the blocks of a file after its
    * zero'ed inode has been written to disk.  The actual work is done
    * by child freework structures which are responsible for individual
    * inode pointers while freeblks is responsible for retiring the
    * entire operation when it is complete and holding common members.
    */
   struct freeblks {
           struct  worklist fb_list;       /* id_inowait or delayed worklist */
   #       define  fb_state fb_list.wk_state /* inode and dirty block state */
           TAILQ_ENTRY(freeblks) fb_next;  /* List of inode truncates. */
           struct  jblkdephd fb_jblkdephd; /* Journal entries pending */
           struct  workhead fb_freeworkhd; /* Work items pending */
           struct  workhead fb_jwork;      /* Journal work pending */
           struct  vnode *fb_devvp;        /* filesystem device vnode */
   #ifdef QUOTA
           struct  dquot *fb_quota[MAXQUOTAS]; /* quotas to be adjusted */
   #endif
           uint64_t fb_modrev;             /* Inode revision at start of trunc. */
           off_t   fb_len;                 /* Length we're truncating to. */
           ufs2_daddr_t fb_chkcnt;         /* Blocks released. */
           ino_t   fb_inum;                /* inode owner of blocks */
           enum    vtype fb_vtype;         /* inode owner's file type */
           uid_t   fb_uid;                 /* uid of previous owner of blocks */
           int     fb_ref;                 /* Children outstanding. */
           int     fb_cgwait;              /* cg writes outstanding. */
   };
   
   /*
    * A "freework" structure handles the release of a tree of blocks or a single
    * block.  Each indirect block in a tree is allocated its own freework
    * structure so that the indirect block may be freed only when all of its
    * children are freed.  In this way we enforce the rule that an allocated
    * block must have a valid path to a root that is journaled.  Each child
    * block acquires a reference and when the ref hits zero the parent ref
    * is decremented.  If there is no parent the freeblks ref is decremented.
    */
   struct freework {
           struct  worklist fw_list;               /* Delayed worklist. */
   #       define  fw_state fw_list.wk_state
           LIST_ENTRY(freework) fw_segs;           /* Seg list. */
           TAILQ_ENTRY(freework) fw_next;          /* Hash/Trunc list. */
           struct  jnewblk  *fw_jnewblk;           /* Journal entry to cancel. */
           struct  freeblks *fw_freeblks;          /* Root of operation. */
           struct  freework *fw_parent;            /* Parent indirect. */
           struct  indirdep *fw_indir;             /* indirect block. */
           ufs2_daddr_t     fw_blkno;              /* Our block #. */
           ufs_lbn_t        fw_lbn;                /* Original lbn before free. */
           uint16_t         fw_frags;              /* Number of frags. */
           uint16_t         fw_ref;                /* Number of children out. */
           uint16_t         fw_off;                /* Current working position. */
           uint16_t         fw_start;              /* Start of partial truncate. */
   };
   
   /*
    * A "freedep" structure is allocated to track the completion of a bitmap
    * write for a freework.  One freedep may cover many freed blocks so long
    * as they reside in the same cylinder group.  When the cg is written
    * the freedep decrements the ref on the freework which may permit it
    * to be freed as well.
    */
   struct freedep {
           struct  worklist fd_list;       /* Delayed worklist. */
           struct  freework *fd_freework;  /* Parent freework. */
   };
   
   /*
    * A "freefile" structure is attached to an inode when its
    * link count is reduced to zero. It marks the inode as free in
    * the cylinder group map after the zero'ed inode has been written
    * to disk and any associated blocks and fragments have been freed.
    */
   struct freefile {
           struct  worklist fx_list;       /* id_inowait or delayed worklist */
           mode_t  fx_mode;                /* mode of inode */
           ino_t   fx_oldinum;             /* inum of the unlinked file */
           struct  vnode *fx_devvp;        /* filesystem device vnode */
           struct  workhead fx_jwork;      /* journal work pending. */
   };
   
   /*
    * A "diradd" structure is linked to an "inodedep" id_inowait list when a
    * new directory entry is allocated that references the inode described
    * by "inodedep". When the inode itself is written (either the initial
    * allocation for new inodes or with the increased link count for
    * existing inodes), the COMPLETE flag is set in da_state. If the entry
    * is for a newly allocated inode, the "inodedep" structure is associated
    * with a bmsafemap which prevents the inode from being written to disk
    * until the cylinder group has been updated. Thus the da_state COMPLETE
    * flag cannot be set until the inode bitmap dependency has been removed.
    * When creating a new file, it is safe to write the directory entry that
    * claims the inode once the referenced inode has been written. Since
    * writing the inode clears the bitmap dependencies, the DEPCOMPLETE flag
    * in the diradd can be set unconditionally when creating a file. When
    * creating a directory, there are two additional dependencies described by
    * mkdir structures (see their description below). When these dependencies
    * are resolved the DEPCOMPLETE flag is set in the diradd structure.
    * If there are multiple links created to the same inode, there will be
    * a separate diradd structure created for each link. The diradd is
    * linked onto the pg_diraddhd list of the pagedep for the directory
    * page that contains the entry. When a directory page is written,
    * the pg_diraddhd list is traversed to rollback any entries that are
    * not yet ready to be written to disk. If a directory entry is being
    * changed (by rename) rather than added, the DIRCHG flag is set and
    * the da_previous entry points to the entry that will be "removed"
    * once the new entry has been committed. During rollback, entries
    * with da_previous are replaced with the previous inode number rather
    * than zero.
    *
    * The overlaying of da_pagedep and da_previous is done to keep the
    * structure down. If a da_previous entry is present, the pointer to its
    * pagedep is available in the associated dirrem entry. If the DIRCHG flag
    * is set, the da_previous entry is valid; if not set the da_pagedep entry
    * is valid. The DIRCHG flag never changes; it is set when the structure
    * is created if appropriate and is never cleared.
    */
   struct diradd {
           struct  worklist da_list;       /* id_inowait or id_pendinghd list */
   #       define  da_state da_list.wk_state /* state of the new directory entry */
           LIST_ENTRY(diradd) da_pdlist;   /* pagedep holding directory block */
           doff_t  da_offset;              /* offset of new dir entry in dir blk */
           ino_t   da_newinum;             /* inode number for the new dir entry */
           union {
           struct  dirrem *dau_previous;   /* entry being replaced in dir change */
           struct  pagedep *dau_pagedep;   /* pagedep dependency for addition */
           } da_un;
           struct workhead da_jwork;       /* Journal work awaiting completion. */
   };
   #define da_previous da_un.dau_previous
   #define da_pagedep da_un.dau_pagedep
   
   /*
    * Two "mkdir" structures are needed to track the additional dependencies
    * associated with creating a new directory entry. Normally a directory
    * addition can be committed as soon as the newly referenced inode has been
    * written to disk with its increased link count. When a directory is
    * created there are two additional dependencies: writing the directory
    * data block containing the "." and ".." entries (MKDIR_BODY) and writing
    * the parent inode with the increased link count for ".." (MKDIR_PARENT).
    * These additional dependencies are tracked by two mkdir structures that
    * reference the associated "diradd" structure. When they have completed,
    * they set the DEPCOMPLETE flag on the diradd so that it knows that its
    * extra dependencies have been completed. The md_state field is used only
    * to identify which type of dependency the mkdir structure is tracking.
    * It is not used in the mainline code for any purpose other than consistency
    * checking. All the mkdir structures in the system are linked together on
    * a list. This list is needed so that a diradd can find its associated
    * mkdir structures and deallocate them if it is prematurely freed (as for
    * example if a mkdir is immediately followed by a rmdir of the same directory).
    * Here, the free of the diradd must traverse the list to find the associated
    * mkdir structures that reference it. The deletion would be faster if the
    * diradd structure were simply augmented to have two pointers that referenced
    * the associated mkdir's. However, this would increase the size of the diradd
    * structure to speed a very infrequent operation.
    */
   struct mkdir {
           struct  worklist md_list;       /* id_inowait or buffer holding dir */
   #       define  md_state md_list.wk_state /* type: MKDIR_PARENT or MKDIR_BODY */
           struct  diradd *md_diradd;      /* associated diradd */
           struct  jaddref *md_jaddref;    /* dependent jaddref. */
           struct  buf *md_buf;            /* MKDIR_BODY: buffer holding dir */
           LIST_ENTRY(mkdir) md_mkdirs;    /* list of all mkdirs */
   };
   
   /*
    * A "dirrem" structure describes an operation to decrement the link
    * count on an inode. The dirrem structure is attached to the pg_dirremhd
    * list of the pagedep for the directory page that contains the entry.
    * It is processed after the directory page with the deleted entry has
    * been written to disk.
    */
   struct dirrem {
           struct  worklist dm_list;       /* delayed worklist */
   #       define  dm_state dm_list.wk_state /* state of the old directory entry */
           LIST_ENTRY(dirrem) dm_next;     /* pagedep's list of dirrem's */
           LIST_ENTRY(dirrem) dm_inonext;  /* inodedep's list of dirrem's */
           struct  jremrefhd dm_jremrefhd; /* Pending remove reference deps. */
           ino_t   dm_oldinum;             /* inum of the removed dir entry */
           doff_t  dm_offset;              /* offset of removed dir entry in blk */
           union {
           struct  pagedep *dmu_pagedep;   /* pagedep dependency for remove */
           ino_t   dmu_dirinum;            /* parent inode number (for rmdir) */
           } dm_un;
           struct workhead dm_jwork;       /* Journal work awaiting completion. */
   };
   #define dm_pagedep dm_un.dmu_pagedep
   #define dm_dirinum dm_un.dmu_dirinum
   
   /*
    * A "newdirblk" structure tracks the progress of a newly allocated
    * directory block from its creation until it is claimed by its on-disk
    * inode. When a block is allocated to a directory, an fsync of a file
    * whose name is within that block must ensure not only that the block
    * containing the file name has been written, but also that the on-disk
    * inode references that block. When a new directory block is created,
    * we allocate a newdirblk structure which is linked to the associated
    * allocdirect (on its ad_newdirblk list). When the allocdirect has been
    * satisfied, the newdirblk structure is moved to the inodedep id_bufwait
    * list of its directory to await the inode being written. When the inode
    * is written, the directory entries are fully committed and can be
    * deleted from their pagedep->id_pendinghd and inodedep->id_pendinghd
    * lists. Note that we could track directory blocks allocated to indirect
    * blocks using a similar scheme with the allocindir structures. Rather
    * than adding this level of complexity, we simply write those newly 
    * allocated indirect blocks synchronously as such allocations are rare.
    * In the case of a new directory the . and .. links are tracked with
    * a mkdir rather than a pagedep.  In this case we track the mkdir
    * so it can be released when it is written.  A workhead is used
    * to simplify canceling a mkdir that is removed by a subsequent dirrem.
    */
   struct newdirblk {
           struct  worklist db_list;       /* id_inowait or pg_newdirblk */
   #       define  db_state db_list.wk_state
           struct  pagedep *db_pagedep;    /* associated pagedep */
           struct  workhead db_mkdir;
   };
   
   /*
    * The inoref structure holds the elements common to jaddref and jremref
    * so they may easily be queued in-order on the inodedep.
    */
   struct inoref {
           struct  worklist if_list;       /* Journal pending or jseg entries. */
   #       define  if_state if_list.wk_state
           TAILQ_ENTRY(inoref) if_deps;    /* Links for inodedep. */
           struct  jsegdep *if_jsegdep;    /* Will track our journal record. */
           off_t           if_diroff;      /* Directory offset. */
           ino_t           if_ino;         /* Inode number. */
           ino_t           if_parent;      /* Parent inode number. */
           nlink_t         if_nlink;       /* nlink before addition. */
           uint16_t        if_mode;        /* File mode, needed for IFMT. */
   };
   
   /*
    * A "jaddref" structure tracks a new reference (link count) on an inode
    * and prevents the link count increase and bitmap allocation until a
    * journal entry can be written.  Once the journal entry is written,
    * the inode is put on the pendinghd of the bmsafemap and a diradd or
    * mkdir entry is placed on the bufwait list of the inode.  The DEPCOMPLETE
    * flag is used to indicate that all of the required information for writing
    * the journal entry is present.  MKDIR_BODY and MKDIR_PARENT are used to
    * differentiate . and .. links from regular file names.  NEWBLOCK indicates
    * a bitmap is still pending.  If a new reference is canceled by a delete
    * prior to writing the journal the jaddref write is canceled and the
    * structure persists to prevent any disk-visible changes until it is
    * ultimately released when the file is freed or the link is dropped again.
    */
   struct jaddref {
           struct  inoref  ja_ref;         /* see inoref above. */
   #       define  ja_list ja_ref.if_list  /* Jrnl pending, id_inowait, dm_jwork.*/
   #       define  ja_state ja_ref.if_list.wk_state
           LIST_ENTRY(jaddref) ja_bmdeps;  /* Links for bmsafemap. */
           union {
                   struct  diradd  *jau_diradd;    /* Pending diradd. */
                   struct  mkdir   *jau_mkdir;     /* MKDIR_{PARENT,BODY} */
           } ja_un;
   };
   #define ja_diradd       ja_un.jau_diradd
   #define ja_mkdir        ja_un.jau_mkdir
   #define ja_diroff       ja_ref.if_diroff
   #define ja_ino          ja_ref.if_ino
   #define ja_parent       ja_ref.if_parent
   #define ja_mode         ja_ref.if_mode
   
   /*
    * A "jremref" structure tracks a removed reference (unlink) on an
    * inode and prevents the directory remove from proceeding until the
    * journal entry is written.  Once the journal has been written the remove
    * may proceed as normal. 
    */
   struct jremref {
           struct  inoref  jr_ref;         /* see inoref above. */
   #       define  jr_list jr_ref.if_list  /* Linked to softdep_journal_pending. */
   #       define  jr_state jr_ref.if_list.wk_state
           LIST_ENTRY(jremref) jr_deps;    /* Links for dirrem. */
           struct  dirrem  *jr_dirrem;     /* Back pointer to dirrem. */
   };
   
   /*
    * A "jmvref" structure tracks a name relocations within the same
    * directory block that occur as a result of directory compaction.
    * It prevents the updated directory entry from being written to disk
    * until the journal entry is written. Once the journal has been
    * written the compacted directory may be written to disk.
    */
   struct jmvref {
           struct  worklist jm_list;       /* Linked to softdep_journal_pending. */
           LIST_ENTRY(jmvref) jm_deps;     /* Jmvref on pagedep. */
           struct pagedep  *jm_pagedep;    /* Back pointer to pagedep. */
           ino_t           jm_parent;      /* Containing directory inode number. */
           ino_t           jm_ino;         /* Inode number of our entry. */
           off_t           jm_oldoff;      /* Our old offset in directory. */
           off_t           jm_newoff;      /* Our new offset in directory. */
   };
   
   /*
    * A "jnewblk" structure tracks a newly allocated block or fragment and
    * prevents the direct or indirect block pointer as well as the cg bitmap
    * from being written until it is logged.  After it is logged the jsegdep
    * is attached to the allocdirect or allocindir until the operation is
    * completed or reverted.  If the operation is reverted prior to the journal
    * write the jnewblk structure is maintained to prevent the bitmaps from
    * reaching the disk.  Ultimately the jnewblk structure will be passed
    * to the free routine as the in memory cg is modified back to the free
    * state at which time it can be released. It may be held on any of the
    * fx_jwork, fw_jwork, fb_jwork, ff_jwork, nb_jwork, or ir_jwork lists.
    */
   struct jnewblk {
           struct  worklist jn_list;       /* See lists above. */
   #       define  jn_state jn_list.wk_state
           struct  jsegdep *jn_jsegdep;    /* Will track our journal record. */
           LIST_ENTRY(jnewblk) jn_deps;    /* Jnewblks on sm_jnewblkhd. */
           struct  worklist *jn_dep;       /* Dependency to ref completed seg. */
           ufs_lbn_t       jn_lbn;         /* Lbn to which allocated. */
           ufs2_daddr_t    jn_blkno;       /* Blkno allocated */
           ino_t           jn_ino;         /* Ino to which allocated. */
           int             jn_oldfrags;    /* Previous fragments when extended. */
           int             jn_frags;       /* Number of fragments. */
   };
   
   /*
    * A "jblkdep" structure tracks jfreeblk and jtrunc records attached to a
    * freeblks structure.
    */
   struct jblkdep {
           struct  worklist jb_list;       /* For softdep journal pending. */
           struct  jsegdep *jb_jsegdep;    /* Reference to the jseg. */
           struct  freeblks *jb_freeblks;  /* Back pointer to freeblks. */
           LIST_ENTRY(jblkdep) jb_deps;    /* Dep list on freeblks. */
   
   };
   
   /*
    * A "jfreeblk" structure tracks the journal write for freeing a block
    * or tree of blocks.  The block pointer must not be cleared in the inode
    * or indirect prior to the jfreeblk being written to the journal.
    */
   struct jfreeblk {
           struct  jblkdep jf_dep;         /* freeblks linkage. */
           ufs_lbn_t       jf_lbn;         /* Lbn from which blocks freed. */
           ufs2_daddr_t    jf_blkno;       /* Blkno being freed. */
           ino_t           jf_ino;         /* Ino from which blocks freed. */
           int             jf_frags;       /* Number of frags being freed. */
   };
   
   /*
    * A "jfreefrag" tracks the freeing of a single block when a fragment is
    * extended or an indirect page is replaced.  It is not part of a larger
    * freeblks operation.
    */
   struct jfreefrag {
           struct  worklist fr_list;       /* Linked to softdep_journal_pending. */
   #       define  fr_state fr_list.wk_state
           struct  jsegdep *fr_jsegdep;    /* Will track our journal record. */
           struct freefrag *fr_freefrag;   /* Back pointer to freefrag. */
           ufs_lbn_t       fr_lbn;         /* Lbn from which frag freed. */
           ufs2_daddr_t    fr_blkno;       /* Blkno being freed. */
           ino_t           fr_ino;         /* Ino from which frag freed. */
           int             fr_frags;       /* Size of frag being freed. */
   };
   
   /*
    * A "jtrunc" journals the intent to truncate an inode's data or extent area.
    */
   struct jtrunc {
           struct  jblkdep jt_dep;         /* freeblks linkage. */
           off_t           jt_size;        /* Final file size. */
           int             jt_extsize;     /* Final extent size. */
           ino_t           jt_ino;         /* Ino being truncated. */
   };
   
   /*
    * A "jfsync" journals the completion of an fsync which invalidates earlier
    * jtrunc records in the journal.
    */
   struct jfsync {
           struct worklist jfs_list;       /* For softdep journal pending. */
           off_t           jfs_size;       /* Sync file size. */
           int             jfs_extsize;    /* Sync extent size. */
           ino_t           jfs_ino;        /* ino being synced. */
   };
   
   /*
    * A "jsegdep" structure tracks a single reference to a written journal
    * segment so the journal space can be reclaimed when all dependencies
    * have been written. It can hang off of id_inowait, dm_jwork, da_jwork,
    * nb_jwork, ff_jwork, or fb_jwork lists.
    */
   struct jsegdep {
           struct  worklist jd_list;       /* See above for lists. */
   #       define  jd_state jd_list.wk_state
           struct  jseg    *jd_seg;        /* Our journal record. */
   };
   
   /*
    * A "jseg" structure contains all of the journal records written in a
    * single disk write.  The jaddref and jremref structures are linked into
    * js_entries so thay may be completed when the write completes.  The
    * js_entries also include the write dependency structures: jmvref,
    * jnewblk, jfreeblk, jfreefrag, and jtrunc.  The js_refs field counts
    * the number of entries on the js_entries list. Thus there is a single
    * jseg entry to describe each journal write.
    */
   struct jseg {
           struct  worklist js_list;       /* b_deps link for journal */
   #       define  js_state js_list.wk_state
           struct  workhead js_entries;    /* Entries awaiting write */
           LIST_HEAD(, freework) js_indirs;/* List of indirects in this seg. */
           TAILQ_ENTRY(jseg) js_next;      /* List of all unfinished segments. */
           struct  jblocks *js_jblocks;    /* Back pointer to block/seg list */
           struct  buf *js_buf;            /* Buffer while unwritten */
           uint64_t js_seq;                /* Journal record sequence number. */
           uint64_t js_oldseq;             /* Oldest valid sequence number. */
           int     js_size;                /* Size of journal record in bytes. */
           int     js_cnt;                 /* Total items allocated. */
           int     js_refs;                /* Count of js_entries items. */
   };
   
   /*
    * A 'sbdep' structure tracks the head of the free inode list and
    * superblock writes.  This makes sure the superblock is always pointing at
    * the first possible unlinked inode for the suj recovery process.  If a
    * block write completes and we discover a new head is available the buf
    * is dirtied and the dep is kept. See the description of the UNLINK*
    * flags above for more details.
    */
   struct sbdep {
           struct  worklist sb_list;       /* b_dep linkage */
           struct  fs      *sb_fs;         /* Filesystem pointer within buf. */
          struct  ufsmount *sb_ump;       /* Our mount structure */
  };
  
  /*
   * Private journaling structures.
   */
  struct jblocks {
          struct jseglst  jb_segs;        /* TAILQ of current segments. */
          struct jseg     *jb_writeseg;   /* Next write to complete. */
          struct jseg     *jb_oldestseg;  /* Oldest segment with valid entries. */
          struct jextent  *jb_extent;     /* Extent array. */
          uint64_t        jb_nextseq;     /* Next sequence number. */
          uint64_t        jb_oldestwrseq; /* Oldest written sequence number. */
          uint8_t         jb_needseg;     /* Need a forced segment. */
          uint8_t         jb_suspended;   /* Did journal suspend writes? */
          int             jb_avail;       /* Available extents. */
          int             jb_used;        /* Last used extent. */
          int             jb_head;        /* Allocator head. */
          int             jb_off;         /* Allocator extent offset. */
          int             jb_blocks;      /* Total disk blocks covered. */
          int             jb_free;        /* Total disk blocks free. */
          int             jb_min;         /* Minimum free space. */
          int             jb_low;         /* Low on space. */
          int             jb_age;         /* Insertion time of oldest rec. */
  };
  
  struct jextent {
          ufs2_daddr_t    je_daddr;       /* Disk block address. */
          int             je_blocks;      /* Disk block count. */
  };
  
  /*
   * Hash table declarations.
   */
  LIST_HEAD(mkdirlist, mkdir);
  LIST_HEAD(pagedep_hashhead, pagedep);
  LIST_HEAD(inodedep_hashhead, inodedep);
  LIST_HEAD(newblk_hashhead, newblk);
  LIST_HEAD(bmsafemap_hashhead, bmsafemap);
  TAILQ_HEAD(indir_hashhead, freework);
  
  /*
   * Per-filesystem soft dependency data.
   * Allocated at mount and freed at unmount.
   */
  struct mount_softdeps {
          struct  rwlock sd_fslock;               /* softdep lock */
          struct  workhead sd_workitem_pending;   /* softdep work queue */
          struct  worklist *sd_worklist_tail;     /* Tail pointer for above */
          struct  workhead sd_journal_pending;    /* journal work queue */
          struct  worklist *sd_journal_tail;      /* Tail pointer for above */
          struct  jblocks *sd_jblocks;            /* Journal block information */
          struct  inodedeplst sd_unlinked;        /* Unlinked inodes */
          struct  bmsafemaphd sd_dirtycg;         /* Dirty CGs */
          struct  mkdirlist sd_mkdirlisthd;       /* Track mkdirs */
          struct  pagedep_hashhead *sd_pdhash;    /* pagedep hash table */
          u_long  sd_pdhashsize;                  /* pagedep hash table size-1 */
          long    sd_pdnextclean;                 /* next hash bucket to clean */
          struct  inodedep_hashhead *sd_idhash;   /* inodedep hash table */
          u_long  sd_idhashsize;                  /* inodedep hash table size-1 */
          long    sd_idnextclean;                 /* next hash bucket to clean */
          struct  newblk_hashhead *sd_newblkhash; /* newblk hash table */
          u_long  sd_newblkhashsize;              /* newblk hash table size-1 */
          struct  bmsafemap_hashhead *sd_bmhash;  /* bmsafemap hash table */
          u_long  sd_bmhashsize;                  /* bmsafemap hash table size-1*/
          struct  indir_hashhead *sd_indirhash;   /* indir hash table */
          u_long  sd_indirhashsize;               /* indir hash table size-1 */
          int     sd_on_journal;                  /* Items on the journal list */
          int     sd_on_worklist;                 /* Items on the worklist */
          int     sd_deps;                        /* Total dependency count */
          int     sd_accdeps;                     /* accumulated dep count */
          int     sd_req;                         /* Wakeup when deps hits 0. */
          int     sd_flags;                       /* comm with flushing thread */
          int     sd_cleanups;                    /* Calls to cleanup */
          struct  thread *sd_flushtd;             /* thread handling flushing */
          TAILQ_ENTRY(mount_softdeps) sd_next;    /* List of softdep filesystem */
          struct  ufsmount *sd_ump;               /* our ufsmount structure */
          u_long  sd_curdeps[D_LAST + 1];         /* count of current deps */
          struct  workhead sd_alldeps[D_LAST + 1];/* Lists of all deps */
  };
  /*
   * Flags for communicating with the syncer thread.
   */
  #define FLUSH_EXIT      0x0001  /* time to exit */
  #define FLUSH_CLEANUP   0x0002  /* need to clear out softdep structures */
  #define FLUSH_STARTING  0x0004  /* flush thread not yet started */
  #define FLUSH_RC_ACTIVE 0x0008  /* a thread is flushing the mount point */
  #define FLUSH_DI_ACTIVE 0x0010  /* a thread is processing delayed
                                     inactivations */
  
  /*
   * Keep the old names from when these were in the ufsmount structure.
   */
  #define softdep_workitem_pending        um_softdep->sd_workitem_pending
  #define softdep_worklist_tail           um_softdep->sd_worklist_tail
  #define softdep_journal_pending         um_softdep->sd_journal_pending
  #define softdep_journal_tail            um_softdep->sd_journal_tail
  #define softdep_jblocks                 um_softdep->sd_jblocks
  #define softdep_unlinked                um_softdep->sd_unlinked
  #define softdep_dirtycg                 um_softdep->sd_dirtycg
  #define softdep_mkdirlisthd             um_softdep->sd_mkdirlisthd
  #define pagedep_hashtbl                 um_softdep->sd_pdhash
  #define pagedep_hash_size               um_softdep->sd_pdhashsize
  #define pagedep_nextclean               um_softdep->sd_pdnextclean
  #define inodedep_hashtbl                um_softdep->sd_idhash
  #define inodedep_hash_size              um_softdep->sd_idhashsize
  #define inodedep_nextclean              um_softdep->sd_idnextclean
  #define newblk_hashtbl                  um_softdep->sd_newblkhash
  #define newblk_hash_size                um_softdep->sd_newblkhashsize
  #define bmsafemap_hashtbl               um_softdep->sd_bmhash
  #define bmsafemap_hash_size             um_softdep->sd_bmhashsize
  #define indir_hashtbl                   um_softdep->sd_indirhash
  #define indir_hash_size                 um_softdep->sd_indirhashsize
  #define softdep_on_journal              um_softdep->sd_on_journal
  #define softdep_on_worklist             um_softdep->sd_on_worklist
  #define softdep_deps                    um_softdep->sd_deps
  #define softdep_accdeps                 um_softdep->sd_accdeps
  #define softdep_req                     um_softdep->sd_req
  #define softdep_flags                   um_softdep->sd_flags
  #define softdep_flushtd                 um_softdep->sd_flushtd
  #define softdep_curdeps                 um_softdep->sd_curdeps
  #define softdep_alldeps                 um_softdep->sd_alldeps

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