Annotation of sys/ufs/ffs/softdep.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: softdep.h,v 1.14 2007/06/01 20:23:26 pedro Exp $ */
2:
3: /*
4: * Copyright 1998, 2000 Marshall Kirk McKusick. All Rights Reserved.
5: *
6: * The soft updates code is derived from the appendix of a University
7: * of Michigan technical report (Gregory R. Ganger and Yale N. Patt,
8: * "Soft Updates: A Solution to the Metadata Update Problem in File
9: * Systems", CSE-TR-254-95, August 1995).
10: *
11: * Further information about soft updates can be obtained from:
12: *
13: * Marshall Kirk McKusick http://www.mckusick.com/softdep/
14: * 1614 Oxford Street mckusick@mckusick.com
15: * Berkeley, CA 94709-1608 +1-510-843-9542
16: * USA
17: *
18: * Redistribution and use in source and binary forms, with or without
19: * modification, are permitted provided that the following conditions
20: * are met:
21: *
22: * 1. Redistributions of source code must retain the above copyright
23: * notice, this list of conditions and the following disclaimer.
24: * 2. Redistributions in binary form must reproduce the above copyright
25: * notice, this list of conditions and the following disclaimer in the
26: * documentation and/or other materials provided with the distribution.
27: *
28: * THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``AS IS'' AND ANY
29: * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
30: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
31: * DISCLAIMED. IN NO EVENT SHALL MARSHALL KIRK MCKUSICK BE LIABLE FOR
32: * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38: * SUCH DAMAGE.
39: *
40: * @(#)softdep.h 9.7 (McKusick) 6/21/00
41: * $FreeBSD: src/sys/ufs/ffs/softdep.h,v 1.10 2000/06/22 00:29:53 mckusick Exp $
42: */
43:
44: #include <sys/queue.h>
45:
46: /*
47: * Allocation dependencies are handled with undo/redo on the in-memory
48: * copy of the data. A particular data dependency is eliminated when
49: * it is ALLCOMPLETE: that is ATTACHED, DEPCOMPLETE, and COMPLETE.
50: *
51: * ATTACHED means that the data is not currently being written to
52: * disk. UNDONE means that the data has been rolled back to a safe
53: * state for writing to the disk. When the I/O completes, the data is
54: * restored to its current form and the state reverts to ATTACHED.
55: * The data must be locked throughout the rollback, I/O, and roll
56: * forward so that the rolled back information is never visible to
57: * user processes. The COMPLETE flag indicates that the item has been
58: * written. For example, a dependency that requires that an inode be
59: * written will be marked COMPLETE after the inode has been written
60: * to disk. The DEPCOMPLETE flag indicates the completion of any other
61: * dependencies such as the writing of a cylinder group map has been
62: * completed. A dependency structure may be freed only when both it
63: * and its dependencies have completed and any rollbacks that are in
64: * progress have finished as indicated by the set of ALLCOMPLETE flags
65: * all being set. The two MKDIR flags indicate additional dependencies
66: * that must be done when creating a new directory. MKDIR_BODY is
67: * cleared when the directory data block containing the "." and ".."
68: * entries has been written. MKDIR_PARENT is cleared when the parent
69: * inode with the increased link count for ".." has been written. When
70: * both MKDIR flags have been cleared, the DEPCOMPLETE flag is set to
71: * indicate that the directory dependencies have been completed. The
72: * writing of the directory inode itself sets the COMPLETE flag which
73: * then allows the directory entry for the new directory to be written
74: * to disk. The RMDIR flag marks a dirrem structure as representing
75: * the removal of a directory rather than a file. When the removal
76: * dependencies are completed, additional work needs to be done
77: * (truncation of the "." and ".." entries, an additional decrement
78: * of the associated inode, and a decrement of the parent inode). The
79: * DIRCHG flag marks a diradd structure as representing the changing
80: * of an existing entry rather than the addition of a new one. When
81: * the update is complete the dirrem associated with the inode for
82: * the old name must be added to the worklist to do the necessary
83: * reference count decrement. The GOINGAWAY flag indicates that the
84: * data structure is frozen from further change until its dependencies
85: * have been completed and its resources freed after which it will be
86: * discarded. The IOSTARTED flag prevents multiple calls to the I/O
87: * start routine from doing multiple rollbacks. The SPACECOUNTED flag
88: * says that the files space has been accounted to the pending free
89: * space count. The NEWBLOCK flag marks pagedep structures that have
90: * just been allocated, so must be claimed by the inode before all
91: * dependencies are complete. The ONWORKLIST flag shows whether the
92: * structure is currently linked onto a worklist.
93: *
94: */
95: #define ATTACHED 0x0001
96: #define UNDONE 0x0002
97: #define COMPLETE 0x0004
98: #define DEPCOMPLETE 0x0008
99: #define MKDIR_PARENT 0x0010 /* diradd & mkdir only */
100: #define MKDIR_BODY 0x0020 /* diradd & mkdir only */
101: #define RMDIR 0x0040 /* dirrem only */
102: #define DIRCHG 0x0080 /* diradd & dirrem only */
103: #define GOINGAWAY 0x0100 /* indirdep only */
104: #define IOSTARTED 0x0200 /* inodedep & pagedep only */
105: #define SPACECOUNTED 0x0400 /* inodedep only */
106: #define NEWBLOCK 0x0800 /* pagedep only */
107: #define UFS1FMT 0x2000 /* indirdep only */
108: #define ONWORKLIST 0x8000
109:
110: #define ALLCOMPLETE (ATTACHED | COMPLETE | DEPCOMPLETE)
111:
112: #define DEP_BITS "\020\01ATTACHED\02UNDONE\03COMPLETE\04DEPCOMPLETE" \
113: "\05MKDIR_PARENT\06MKDIR_BODY\07RMDIR\010DIRCHG\011GOINGAWAY" \
114: "\012IOSTARTED\013SPACECOUNTED\014NEWBLOCK\016UFS1FMT\020ONWORKLIST"
115:
116: /*
117: * The workitem queue.
118: *
119: * It is sometimes useful and/or necessary to clean up certain dependencies
120: * in the background rather than during execution of an application process
121: * or interrupt service routine. To realize this, we append dependency
122: * structures corresponding to such tasks to a "workitem" queue. In a soft
123: * updates implementation, most pending workitems should not wait for more
124: * than a couple of seconds, so the filesystem syncer process awakens once
125: * per second to process the items on the queue.
126: */
127:
128: /* LIST_HEAD(workhead, worklist); -- declared in buf.h */
129:
130: /*
131: * Each request can be linked onto a work queue through its worklist structure.
132: * To avoid the need for a pointer to the structure itself, this structure
133: * MUST be declared FIRST in each type in which it appears! If more than one
134: * worklist is needed in the structure, then a wk_data field must be added
135: * and the macros below changed to use it.
136: */
137: struct worklist {
138: LIST_ENTRY(worklist) wk_list; /* list of work requests */
139: unsigned short wk_type; /* type of request */
140: unsigned short wk_state; /* state flags */
141: };
142: #define WK_DATA(wk) ((void *)(wk))
143: #define WK_PAGEDEP(wk) ((struct pagedep *)(wk))
144: #define WK_INODEDEP(wk) ((struct inodedep *)(wk))
145: #define WK_NEWBLK(wk) ((struct newblk *)(wk))
146: #define WK_BMSAFEMAP(wk) ((struct bmsafemap *)(wk))
147: #define WK_ALLOCDIRECT(wk) ((struct allocdirect *)(wk))
148: #define WK_INDIRDEP(wk) ((struct indirdep *)(wk))
149: #define WK_ALLOCINDIR(wk) ((struct allocindir *)(wk))
150: #define WK_FREEFRAG(wk) ((struct freefrag *)(wk))
151: #define WK_FREEBLKS(wk) ((struct freeblks *)(wk))
152: #define WK_FREEFILE(wk) ((struct freefile *)(wk))
153: #define WK_DIRADD(wk) ((struct diradd *)(wk))
154: #define WK_MKDIR(wk) ((struct mkdir *)(wk))
155: #define WK_DIRREM(wk) ((struct dirrem *)(wk))
156: #define WK_NEWDIRBLK(wk) ((struct newdirblk *)(wk))
157:
158: /*
159: * Various types of lists
160: */
161: LIST_HEAD(dirremhd, dirrem);
162: LIST_HEAD(diraddhd, diradd);
163: LIST_HEAD(newblkhd, newblk);
164: LIST_HEAD(inodedephd, inodedep);
165: LIST_HEAD(allocindirhd, allocindir);
166: LIST_HEAD(allocdirecthd, allocdirect);
167: TAILQ_HEAD(allocdirectlst, allocdirect);
168:
169: /*
170: * The "pagedep" structure tracks the various dependencies related to
171: * a particular directory page. If a directory page has any dependencies,
172: * it will have a pagedep linked to its associated buffer. The
173: * pd_dirremhd list holds the list of dirrem requests which decrement
174: * inode reference counts. These requests are processed after the
175: * directory page with the corresponding zero'ed entries has been
176: * written. The pd_diraddhd list maintains the list of diradd requests
177: * which cannot be committed until their corresponding inode has been
178: * written to disk. Because a directory may have many new entries
179: * being created, several lists are maintained hashed on bits of the
180: * offset of the entry into the directory page to keep the lists from
181: * getting too long. Once a new directory entry has been cleared to
182: * be written, it is moved to the pd_pendinghd list. After the new
183: * entry has been written to disk it is removed from the pd_pendinghd
184: * list, any removed operations are done, and the dependency structure
185: * is freed.
186: */
187: #define DAHASHSZ 6
188: #define DIRADDHASH(offset) (((offset) >> 2) % DAHASHSZ)
189: struct pagedep {
190: struct worklist pd_list; /* page buffer */
191: # define pd_state pd_list.wk_state /* check for multiple I/O starts */
192: LIST_ENTRY(pagedep) pd_hash; /* hashed lookup */
193: struct mount *pd_mnt; /* associated mount point */
194: ino_t pd_ino; /* associated file */
195: daddr64_t pd_lbn; /* block within file */
196: struct dirremhd pd_dirremhd; /* dirrem's waiting for page */
197: struct diraddhd pd_diraddhd[DAHASHSZ]; /* diradd dir entry updates */
198: struct diraddhd pd_pendinghd; /* directory entries awaiting write */
199: };
200:
201: /*
202: * The "inodedep" structure tracks the set of dependencies associated
203: * with an inode. One task that it must manage is delayed operations
204: * (i.e., work requests that must be held until the inodedep's associated
205: * inode has been written to disk). Getting an inode from its incore
206: * state to the disk requires two steps to be taken by the filesystem
207: * in this order: first the inode must be copied to its disk buffer by
208: * the VOP_UPDATE operation; second the inode's buffer must be written
209: * to disk. To ensure that both operations have happened in the required
210: * order, the inodedep maintains two lists. Delayed operations are
211: * placed on the id_inowait list. When the VOP_UPDATE is done, all
212: * operations on the id_inowait list are moved to the id_bufwait list.
213: * When the buffer is written, the items on the id_bufwait list can be
214: * safely moved to the work queue to be processed. A second task of the
215: * inodedep structure is to track the status of block allocation within
216: * the inode. Each block that is allocated is represented by an
217: * "allocdirect" structure (see below). It is linked onto the id_newinoupdt
218: * list until both its contents and its allocation in the cylinder
219: * group map have been written to disk. Once these dependencies have been
220: * satisfied, it is removed from the id_newinoupdt list and any followup
221: * actions such as releasing the previous block or fragment are placed
222: * on the id_inowait list. When an inode is updated (a VOP_UPDATE is
223: * done), the "inodedep" structure is linked onto the buffer through
224: * its worklist. Thus, it will be notified when the buffer is about
225: * to be written and when it is done. At the update time, all the
226: * elements on the id_newinoupdt list are moved to the id_inoupdt list
227: * since those changes are now relevant to the copy of the inode in the
228: * buffer. Also at update time, the tasks on the id_inowait list are
229: * moved to the id_bufwait list so that they will be executed when
230: * the updated inode has been written to disk. When the buffer containing
231: * the inode is written to disk, any updates listed on the id_inoupdt
232: * list are rolled back as they are not yet safe. Following the write,
233: * the changes are once again rolled forward and any actions on the
234: * id_bufwait list are processed (since those actions are now safe).
235: * The entries on the id_inoupdt and id_newinoupdt lists must be kept
236: * sorted by logical block number to speed the calculation of the size
237: * of the rolled back inode (see explanation in initiate_write_inodeblock).
238: * When a directory entry is created, it is represented by a diradd.
239: * The diradd is added to the id_inowait list as it cannot be safely
240: * written to disk until the inode that it represents is on disk. After
241: * the inode is written, the id_bufwait list is processed and the diradd
242: * entries are moved to the id_pendinghd list where they remain until
243: * the directory block containing the name has been written to disk.
244: * The purpose of keeping the entries on the id_pendinghd list is so that
245: * the softdep_fsync function can find and push the inode's directory
246: * name(s) as part of the fsync operation for that file.
247: */
248: struct inodedep {
249: struct worklist id_list; /* buffer holding inode block */
250: # define id_state id_list.wk_state /* inode dependency state */
251: LIST_ENTRY(inodedep) id_hash; /* hashed lookup */
252: struct fs *id_fs; /* associated filesystem */
253: ino_t id_ino; /* dependent inode */
254: nlink_t id_nlinkdelta; /* saved effective link count */
255: union { /* Saved UFS1/UFS2 dinode contents */
256: struct ufs1_dinode *idu_savedino1;
257: struct ufs2_dinode *idu_savedino2;
258: } id_un;
259: LIST_ENTRY(inodedep) id_deps; /* bmsafemap's list of inodedep's */
260: struct buf *id_buf; /* related bmsafemap (if pending) */
261: off_t id_savedsize; /* file size saved during rollback */
262: struct workhead id_pendinghd; /* entries awaiting directory write */
263: struct workhead id_bufwait; /* operations after inode written */
264: struct workhead id_inowait; /* operations waiting inode update */
265: struct allocdirectlst id_inoupdt; /* updates before inode written */
266: struct allocdirectlst id_newinoupdt; /* updates when inode written */
267: };
268:
269: #define id_savedino1 id_un.idu_savedino1
270: #define id_savedino2 id_un.idu_savedino2
271:
272: /*
273: * A "newblk" structure is attached to a bmsafemap structure when a block
274: * or fragment is allocated from a cylinder group. Its state is set to
275: * DEPCOMPLETE when its cylinder group map is written. It is consumed by
276: * an associated allocdirect or allocindir allocation which will attach
277: * themselves to the bmsafemap structure if the newblk's DEPCOMPLETE flag
278: * is not set (i.e., its cylinder group map has not been written).
279: */
280: struct newblk {
281: LIST_ENTRY(newblk) nb_hash; /* hashed lookup */
282: struct fs *nb_fs; /* associated filesystem */
283: daddr_t nb_newblkno; /* allocated block number */
284: int nb_state; /* state of bitmap dependency */
285: LIST_ENTRY(newblk) nb_deps; /* bmsafemap's list of newblk's */
286: struct bmsafemap *nb_bmsafemap; /* associated bmsafemap */
287: };
288:
289: /*
290: * A "bmsafemap" structure maintains a list of dependency structures
291: * that depend on the update of a particular cylinder group map.
292: * It has lists for newblks, allocdirects, allocindirs, and inodedeps.
293: * It is attached to the buffer of a cylinder group block when any of
294: * these things are allocated from the cylinder group. It is freed
295: * after the cylinder group map is written and the state of its
296: * dependencies are updated with DEPCOMPLETE to indicate that it has
297: * been processed.
298: */
299: struct bmsafemap {
300: struct worklist sm_list; /* cylgrp buffer */
301: struct buf *sm_buf; /* associated buffer */
302: struct allocdirecthd sm_allocdirecthd; /* allocdirect deps */
303: struct allocindirhd sm_allocindirhd; /* allocindir deps */
304: struct inodedephd sm_inodedephd; /* inodedep deps */
305: struct newblkhd sm_newblkhd; /* newblk deps */
306: };
307:
308: /*
309: * An "allocdirect" structure is attached to an "inodedep" when a new block
310: * or fragment is allocated and pointed to by the inode described by
311: * "inodedep". The worklist is linked to the buffer that holds the block.
312: * When the block is first allocated, it is linked to the bmsafemap
313: * structure associated with the buffer holding the cylinder group map
314: * from which it was allocated. When the cylinder group map is written
315: * to disk, ad_state has the DEPCOMPLETE flag set. When the block itself
316: * is written, the COMPLETE flag is set. Once both the cylinder group map
317: * and the data itself have been written, it is safe to write the inode
318: * that claims the block. If there was a previous fragment that had been
319: * allocated before the file was increased in size, the old fragment may
320: * be freed once the inode claiming the new block is written to disk.
321: * This ad_fragfree request is attached to the id_inowait list of the
322: * associated inodedep (pointed to by ad_inodedep) for processing after
323: * the inode is written. When a block is allocated to a directory, an
324: * fsync of a file whose name is within that block must ensure not only
325: * that the block containing the file name has been written, but also
326: * that the on-disk inode references that block. When a new directory
327: * block is created, we allocate a newdirblk structure which is linked
328: * to the associated allocdirect (on its ad_newdirblk list). When the
329: * allocdirect has been satisfied, the newdirblk structure is moved to
330: * the inodedep id_bufwait list of its directory to await the inode
331: * being written. When the inode is written, the directory entries are
332: * fully committed and can be deleted from their pagedep->id_pendinghd
333: * and inodedep->id_pendinghd lists.
334: */
335: struct allocdirect {
336: struct worklist ad_list; /* buffer holding block */
337: # define ad_state ad_list.wk_state /* block pointer state */
338: TAILQ_ENTRY(allocdirect) ad_next; /* inodedep's list of allocdirect's */
339: daddr64_t ad_lbn; /* block within file */
340: daddr_t ad_newblkno; /* new value of block pointer */
341: daddr_t ad_oldblkno; /* old value of block pointer */
342: long ad_newsize; /* size of new block */
343: long ad_oldsize; /* size of old block */
344: LIST_ENTRY(allocdirect) ad_deps; /* bmsafemap's list of allocdirect's */
345: struct buf *ad_buf; /* cylgrp buffer (if pending) */
346: struct inodedep *ad_inodedep; /* associated inodedep */
347: struct freefrag *ad_freefrag; /* fragment to be freed (if any) */
348: struct workhead ad_newdirblk; /* dir block to notify when written */
349: };
350:
351: /*
352: * A single "indirdep" structure manages all allocation dependencies for
353: * pointers in an indirect block. The up-to-date state of the indirect
354: * block is stored in ir_savedata. The set of pointers that may be safely
355: * written to the disk is stored in ir_safecopy. The state field is used
356: * only to track whether the buffer is currently being written (in which
357: * case it is not safe to update ir_safecopy). Ir_deplisthd contains the
358: * list of allocindir structures, one for each block that needs to be
359: * written to disk. Once the block and its bitmap allocation have been
360: * written the safecopy can be updated to reflect the allocation and the
361: * allocindir structure freed. If ir_state indicates that an I/O on the
362: * indirect block is in progress when ir_safecopy is to be updated, the
363: * update is deferred by placing the allocindir on the ir_donehd list.
364: * When the I/O on the indirect block completes, the entries on the
365: * ir_donehd list are processed by updating their corresponding ir_safecopy
366: * pointers and then freeing the allocindir structure.
367: */
368: struct indirdep {
369: struct worklist ir_list; /* buffer holding indirect block */
370: # define ir_state ir_list.wk_state /* indirect block pointer state */
371: caddr_t ir_saveddata; /* buffer cache contents */
372: struct buf *ir_savebp; /* buffer holding safe copy */
373: struct allocindirhd ir_donehd; /* done waiting to update safecopy */
374: struct allocindirhd ir_deplisthd; /* allocindir deps for this block */
375: };
376:
377: /*
378: * An "allocindir" structure is attached to an "indirdep" when a new block
379: * is allocated and pointed to by the indirect block described by the
380: * "indirdep". The worklist is linked to the buffer that holds the new block.
381: * When the block is first allocated, it is linked to the bmsafemap
382: * structure associated with the buffer holding the cylinder group map
383: * from which it was allocated. When the cylinder group map is written
384: * to disk, ai_state has the DEPCOMPLETE flag set. When the block itself
385: * is written, the COMPLETE flag is set. Once both the cylinder group map
386: * and the data itself have been written, it is safe to write the entry in
387: * the indirect block that claims the block; the "allocindir" dependency
388: * can then be freed as it is no longer applicable.
389: */
390: struct allocindir {
391: struct worklist ai_list; /* buffer holding indirect block */
392: # define ai_state ai_list.wk_state /* indirect block pointer state */
393: LIST_ENTRY(allocindir) ai_next; /* indirdep's list of allocindir's */
394: int ai_offset; /* pointer offset in indirect block */
395: daddr_t ai_newblkno; /* new block pointer value */
396: daddr_t ai_oldblkno; /* old block pointer value */
397: struct freefrag *ai_freefrag; /* block to be freed when complete */
398: struct indirdep *ai_indirdep; /* address of associated indirdep */
399: LIST_ENTRY(allocindir) ai_deps; /* bmsafemap's list of allocindir's */
400: struct buf *ai_buf; /* cylgrp buffer (if pending) */
401: };
402:
403: /*
404: * A "freefrag" structure is attached to an "inodedep" when a previously
405: * allocated fragment is replaced with a larger fragment, rather than extended.
406: * The "freefrag" structure is constructed and attached when the replacement
407: * block is first allocated. It is processed after the inode claiming the
408: * bigger block that replaces it has been written to disk. Note that the
409: * ff_state field is used to store the uid, so may lose data. However,
410: * the uid is used only in printing an error message, so is not critical.
411: * Keeping it in a short keeps the data structure down to 32 bytes.
412: */
413: struct freefrag {
414: struct worklist ff_list; /* id_inowait or delayed worklist */
415: # define ff_state ff_list.wk_state /* owning user; should be uid_t */
416: struct vnode *ff_devvp; /* filesystem device vnode */
417: struct mount *ff_mnt; /* associated mount point */
418: daddr_t ff_blkno; /* fragment physical block number */
419: long ff_fragsize; /* size of fragment being deleted */
420: ino_t ff_inum; /* owning inode number */
421: };
422:
423: /*
424: * A "freeblks" structure is attached to an "inodedep" when the
425: * corresponding file's length is reduced to zero. It records all
426: * the information needed to free the blocks of a file after its
427: * zero'ed inode has been written to disk.
428: */
429: struct freeblks {
430: struct worklist fb_list; /* id_inowait or delayed worklist */
431: # define fb_state fb_list.wk_state /* inode and dirty block state */
432: ino_t fb_previousinum; /* inode of previous owner of blocks */
433: struct vnode *fb_devvp; /* filesystem device vnode */
434: struct mount *fb_mnt; /* associated mount point */
435: off_t fb_oldsize; /* previous file size */
436: off_t fb_newsize; /* new file size */
437: int fb_chkcnt; /* used to check cnt of blks released */
438: uid_t fb_uid; /* uid of previous owner of blocks */
439: daddr_t fb_dblks[NDADDR]; /* direct blk ptrs to deallocate */
440: daddr_t fb_iblks[NIADDR]; /* indirect blk ptrs to deallocate */
441: };
442:
443: /*
444: * A "freefile" structure is attached to an inode when its
445: * link count is reduced to zero. It marks the inode as free in
446: * the cylinder group map after the zero'ed inode has been written
447: * to disk and any associated blocks and fragments have been freed.
448: */
449: struct freefile {
450: struct worklist fx_list; /* id_inowait or delayed worklist */
451: mode_t fx_mode; /* mode of inode */
452: ino_t fx_oldinum; /* inum of the unlinked file */
453: struct vnode *fx_devvp; /* filesystem device vnode */
454: struct mount *fx_mnt; /* associated mount point */
455: };
456:
457: /*
458: * A "diradd" structure is linked to an "inodedep" id_inowait list when a
459: * new directory entry is allocated that references the inode described
460: * by "inodedep". When the inode itself is written (either the initial
461: * allocation for new inodes or with the increased link count for
462: * existing inodes), the COMPLETE flag is set in da_state. If the entry
463: * is for a newly allocated inode, the "inodedep" structure is associated
464: * with a bmsafemap which prevents the inode from being written to disk
465: * until the cylinder group has been updated. Thus the da_state COMPLETE
466: * flag cannot be set until the inode bitmap dependency has been removed.
467: * When creating a new file, it is safe to write the directory entry that
468: * claims the inode once the referenced inode has been written. Since
469: * writing the inode clears the bitmap dependencies, the DEPCOMPLETE flag
470: * in the diradd can be set unconditionally when creating a file. When
471: * creating a directory, there are two additional dependencies described by
472: * mkdir structures (see their description below). When these dependencies
473: * are resolved the DEPCOMPLETE flag is set in the diradd structure.
474: * If there are multiple links created to the same inode, there will be
475: * a separate diradd structure created for each link. The diradd is
476: * linked onto the pg_diraddhd list of the pagedep for the directory
477: * page that contains the entry. When a directory page is written,
478: * the pg_diraddhd list is traversed to rollback any entries that are
479: * not yet ready to be written to disk. If a directory entry is being
480: * changed (by rename) rather than added, the DIRCHG flag is set and
481: * the da_previous entry points to the entry that will be "removed"
482: * once the new entry has been committed. During rollback, entries
483: * with da_previous are replaced with the previous inode number rather
484: * than zero.
485: *
486: * The overlaying of da_pagedep and da_previous is done to keep the
487: * structure down to 32 bytes in size on a 32-bit machine. If a
488: * da_previous entry is present, the pointer to its pagedep is available
489: * in the associated dirrem entry. If the DIRCHG flag is set, the
490: * da_previous entry is valid; if not set the da_pagedep entry is valid.
491: * The DIRCHG flag never changes; it is set when the structure is created
492: * if appropriate and is never cleared.
493: */
494: struct diradd {
495: struct worklist da_list; /* id_inowait or id_pendinghd list */
496: # define da_state da_list.wk_state /* state of the new directory entry */
497: LIST_ENTRY(diradd) da_pdlist; /* pagedep holding directory block */
498: doff_t da_offset; /* offset of new dir entry in dir blk */
499: ino_t da_newinum; /* inode number for the new dir entry */
500: union {
501: struct dirrem *dau_previous; /* entry being replaced in dir change */
502: struct pagedep *dau_pagedep; /* pagedep dependency for addition */
503: } da_un;
504: };
505: #define da_previous da_un.dau_previous
506: #define da_pagedep da_un.dau_pagedep
507:
508: /*
509: * Two "mkdir" structures are needed to track the additional dependencies
510: * associated with creating a new directory entry. Normally a directory
511: * addition can be committed as soon as the newly referenced inode has been
512: * written to disk with its increased link count. When a directory is
513: * created there are two additional dependencies: writing the directory
514: * data block containing the "." and ".." entries (MKDIR_BODY) and writing
515: * the parent inode with the increased link count for ".." (MKDIR_PARENT).
516: * These additional dependencies are tracked by two mkdir structures that
517: * reference the associated "diradd" structure. When they have completed,
518: * they set the DEPCOMPLETE flag on the diradd so that it knows that its
519: * extra dependencies have been completed. The md_state field is used only
520: * to identify which type of dependency the mkdir structure is tracking.
521: * It is not used in the mainline code for any purpose other than consistency
522: * checking. All the mkdir structures in the system are linked together on
523: * a list. This list is needed so that a diradd can find its associated
524: * mkdir structures and deallocate them if it is prematurely freed (as for
525: * example if a mkdir is immediately followed by a rmdir of the same directory).
526: * Here, the free of the diradd must traverse the list to find the associated
527: * mkdir structures that reference it. The deletion would be faster if the
528: * diradd structure were simply augmented to have two pointers that referenced
529: * the associated mkdir's. However, this would increase the size of the diradd
530: * structure from 32 to 64-bits to speed a very infrequent operation.
531: */
532: struct mkdir {
533: struct worklist md_list; /* id_inowait or buffer holding dir */
534: # define md_state md_list.wk_state /* type: MKDIR_PARENT or MKDIR_BODY */
535: struct diradd *md_diradd; /* associated diradd */
536: struct buf *md_buf; /* MKDIR_BODY: buffer holding dir */
537: LIST_ENTRY(mkdir) md_mkdirs; /* list of all mkdirs */
538: };
539: LIST_HEAD(mkdirlist, mkdir) mkdirlisthd;
540:
541: /*
542: * A "dirrem" structure describes an operation to decrement the link
543: * count on an inode. The dirrem structure is attached to the pg_dirremhd
544: * list of the pagedep for the directory page that contains the entry.
545: * It is processed after the directory page with the deleted entry has
546: * been written to disk.
547: *
548: * The overlaying of dm_pagedep and dm_dirinum is done to keep the
549: * structure down to 32 bytes in size on a 32-bit machine. It works
550: * because they are never used concurrently.
551: */
552: struct dirrem {
553: struct worklist dm_list; /* delayed worklist */
554: # define dm_state dm_list.wk_state /* state of the old directory entry */
555: LIST_ENTRY(dirrem) dm_next; /* pagedep's list of dirrem's */
556: struct mount *dm_mnt; /* associated mount point */
557: ino_t dm_oldinum; /* inum of the removed dir entry */
558: union {
559: struct pagedep *dmu_pagedep; /* pagedep dependency for remove */
560: ino_t dmu_dirinum; /* parent inode number (for rmdir) */
561: } dm_un;
562: };
563: #define dm_pagedep dm_un.dmu_pagedep
564: #define dm_dirinum dm_un.dmu_dirinum
565:
566:
567: /*
568: * A "newdirblk" structure tracks the progress of a newly allocated
569: * directory block from its creation until it is claimed by its on-disk
570: * inode. When a block is allocated to a directory, an fsync of a file
571: * whose name is within that block must ensure not only that the block
572: * containing the file name has been written, but also that the on-disk
573: * inode references that block. When a new directory block is created,
574: * we allocate a newdirblk structure which is linked to the associated
575: * allocdirect (on its ad_newdirblk list). When the allocdirect has been
576: * satisfied, the newdirblk structure is moved to the inodedep id_bufwait
577: * list of its directory to await the inode being written. When the inode
578: * is written, the directory entries are fully committed and can be
579: * deleted from their pagedep->id_pendinghd and inodedep->id_pendinghd
580: * lists. Note that we could track directory blocks allocated to indirect
581: * blocks using a similar scheme with the allocindir structures. Rather
582: * than adding this level of complexity, we simply write those newly
583: * allocated indirect blocks synchronously as such allocations are rare.
584: */
585: struct newdirblk {
586: struct worklist db_list;/* id_inowait or pg_newdirblk */
587: # define db_state db_list.wk_state /* unused */
588: struct pagedep *db_pagedep;/* associated pagedep */
589: };
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