freebsd-dev/sys/ufs/ffs/softdep.h
Kirk McKusick 7aca6291e3 Add support to UFS2 to provide storage for extended attributes.
As this code is not actually used by any of the existing
interfaces, it seems unlikely to break anything (famous
last words).

The internal kernel interface to manipulate these attributes
is invoked using two new IO_ flags: IO_NORMAL and IO_EXT.
These flags may be specified in the ioflags word of VOP_READ,
VOP_WRITE, and VOP_TRUNCATE. Specifying IO_NORMAL means that
you want to do I/O to the normal data part of the file and
IO_EXT means that you want to do I/O to the extended attributes
part of the file. IO_NORMAL and IO_EXT are mutually exclusive
for VOP_READ and VOP_WRITE, but may be specified individually
or together in the case of VOP_TRUNCATE. For example, when
removing a file, VOP_TRUNCATE is called with both IO_NORMAL
and IO_EXT set. For backward compatibility, if neither IO_NORMAL
nor IO_EXT is set, then IO_NORMAL is assumed.

Note that the BA_ and IO_ flags have been `merged' so that they
may both be used in the same flags word. This merger is possible
by assigning the IO_ flags to the low sixteen bits and the BA_
flags the high sixteen bits. This works because the high sixteen
bits of the IO_ word is reserved for read-ahead and help with
write clustering so will never be used for flags. This merge
lets us get away from code of the form:

        if (ioflags & IO_SYNC)
                flags |= BA_SYNC;

For the future, I have considered adding a new field to the
vattr structure, va_extsize. This addition could then be
exported through the stat structure to allow applications to
find out the size of the extended attribute storage and also
would provide a more standard interface for truncating them
(via VOP_SETATTR rather than VOP_TRUNCATE).

I am also contemplating adding a pathconf parameter (for
concreteness, lets call it _PC_MAX_EXTSIZE) which would
let an application determine the maximum size of the extended
atribute storage.

Sponsored by:	DARPA & NAI Labs.
2002-07-19 07:29:39 +00:00

590 lines
30 KiB
C

/*
* 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.
*
* ATTACHED means that the data is not currently being written to
* disk. UNDONE 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
* (truncation of the "." and ".." entries, 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 SPACECOUNTED flag
* says that the files space has been accounted to the pending free
* space count. 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.
*/
#define ATTACHED 0x0001
#define UNDONE 0x0002
#define COMPLETE 0x0004
#define DEPCOMPLETE 0x0008
#define MKDIR_PARENT 0x0010 /* diradd & mkdir only */
#define MKDIR_BODY 0x0020 /* diradd & mkdir only */
#define RMDIR 0x0040 /* dirrem only */
#define DIRCHG 0x0080 /* diradd & dirrem only */
#define GOINGAWAY 0x0100 /* indirdep only */
#define IOSTARTED 0x0200 /* inodedep & pagedep only */
#define SPACECOUNTED 0x0400 /* inodedep only */
#define NEWBLOCK 0x0800 /* pagedep only */
#define INPROGRESS 0x1000 /* dirrem, freeblks, freefrag, freefile only */
#define UFS1FMT 0x2000 /* indirdep only */
#define EXTDATA 0x4000 /* allocdirect only */
#define ONWORKLIST 0x8000
#define ALLCOMPLETE (ATTACHED | COMPLETE | DEPCOMPLETE)
/*
* 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 */
unsigned short wk_type; /* type of request */
unsigned short wk_state; /* state flags */
};
#define WK_DATA(wk) ((void *)(wk))
#define WK_PAGEDEP(wk) ((struct pagedep *)(wk))
#define WK_INODEDEP(wk) ((struct inodedep *)(wk))
#define WK_NEWBLK(wk) ((struct newblk *)(wk))
#define WK_BMSAFEMAP(wk) ((struct bmsafemap *)(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_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))
/*
* 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);
/*
* 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 */
struct mount *pd_mnt; /* associated mount point */
ino_t pd_ino; /* associated file */
ufs_lbn_t pd_lbn; /* block within file */
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 */
};
/*
* 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 */
struct fs *id_fs; /* associated filesystem */
ino_t id_ino; /* dependent inode */
nlink_t id_nlinkdelta; /* saved effective link count */
LIST_ENTRY(inodedep) id_deps; /* bmsafemap's list of inodedep's */
struct buf *id_buf; /* related bmsafemap (if pending) */
long id_savedextsize; /* ext size saved during rollback */
off_t id_savedsize; /* file size saved during rollback */
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 */
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 "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 consumed by
* an associated allocdirect or allocindir allocation which will attach
* themselves to the bmsafemap structure if the newblk's DEPCOMPLETE flag
* is not set (i.e., its cylinder group map has not been written).
*/
struct newblk {
LIST_ENTRY(newblk) nb_hash; /* hashed lookup */
struct fs *nb_fs; /* associated filesystem */
int nb_state; /* state of bitmap dependency */
ufs2_daddr_t nb_newblkno; /* allocated block number */
LIST_ENTRY(newblk) nb_deps; /* bmsafemap's list of newblk's */
struct bmsafemap *nb_bmsafemap; /* associated bmsafemap */
};
/*
* 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 */
struct buf *sm_buf; /* associated buffer */
struct allocdirecthd sm_allocdirecthd; /* allocdirect deps */
struct allocindirhd sm_allocindirhd; /* allocindir deps */
struct inodedephd sm_inodedephd; /* inodedep deps */
struct newblkhd sm_newblkhd; /* newblk deps */
};
/*
* 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 worklist ad_list; /* buffer holding block */
# define ad_state ad_list.wk_state /* block pointer state */
TAILQ_ENTRY(allocdirect) ad_next; /* inodedep's list of allocdirect's */
ufs_lbn_t ad_lbn; /* block within file */
ufs2_daddr_t ad_newblkno; /* new value of block pointer */
ufs2_daddr_t ad_oldblkno; /* old value of block pointer */
long ad_newsize; /* size of new block */
long ad_oldsize; /* size of old block */
LIST_ENTRY(allocdirect) ad_deps; /* bmsafemap's list of allocdirect's */
struct buf *ad_buf; /* cylgrp buffer (if pending) */
struct inodedep *ad_inodedep; /* associated inodedep */
struct freefrag *ad_freefrag; /* fragment to be freed (if any) */
struct workhead ad_newdirblk; /* dir block to notify when written */
};
/*
* 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_safecopy. 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_safecopy). 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_safecopy 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_safecopy
* 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 */
caddr_t ir_saveddata; /* buffer cache contents */
struct buf *ir_savebp; /* buffer holding safe copy */
struct allocindirhd ir_donehd; /* done waiting to update safecopy */
struct allocindirhd ir_deplisthd; /* allocindir deps for this block */
};
/*
* 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 worklist ai_list; /* buffer holding indirect block */
# define ai_state ai_list.wk_state /* indirect block pointer state */
LIST_ENTRY(allocindir) ai_next; /* indirdep's list of allocindir's */
int ai_offset; /* pointer offset in indirect block */
ufs2_daddr_t ai_newblkno; /* new block pointer value */
ufs2_daddr_t ai_oldblkno; /* old block pointer value */
struct freefrag *ai_freefrag; /* block to be freed when complete */
struct indirdep *ai_indirdep; /* address of associated indirdep */
LIST_ENTRY(allocindir) ai_deps; /* bmsafemap's list of allocindir's */
struct buf *ai_buf; /* cylgrp buffer (if pending) */
};
/*
* 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. Note that the
* ff_state field is is used to store the uid, so may lose data. However,
* the uid is used only in printing an error message, so is not critical.
* Keeping it in a short keeps the data structure down to 32 bytes.
*/
struct freefrag {
struct worklist ff_list; /* id_inowait or delayed worklist */
# define ff_state ff_list.wk_state /* owning user; should be uid_t */
struct mount *ff_mnt; /* associated mount point */
ufs2_daddr_t ff_blkno; /* fragment physical block number */
long ff_fragsize; /* size of fragment being deleted */
ino_t ff_inum; /* owning inode number */
};
/*
* 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.
*/
struct freeblks {
struct worklist fb_list; /* id_inowait or delayed worklist */
ino_t fb_previousinum; /* inode of previous owner of blocks */
uid_t fb_uid; /* uid of previous owner of blocks */
struct vnode *fb_devvp; /* filesystem device vnode */
struct mount *fb_mnt; /* associated mount point */
long fb_oldextsize; /* previous ext data size */
off_t fb_oldsize; /* previous file size */
ufs2_daddr_t fb_chkcnt; /* used to check cnt of blks released */
ufs2_daddr_t fb_dblks[NDADDR]; /* direct blk ptrs to deallocate */
ufs2_daddr_t fb_iblks[NIADDR]; /* indirect blk ptrs to deallocate */
ufs2_daddr_t fb_eblks[NXADDR]; /* indirect blk ptrs to deallocate */
};
/*
* 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 mount *fx_mnt; /* associated mount point */
};
/*
* 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 to 32 bytes in size on a 32-bit machine. 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;
};
#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 from 32 to 64-bits 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 buf *md_buf; /* MKDIR_BODY: buffer holding dir */
LIST_ENTRY(mkdir) md_mkdirs; /* list of all mkdirs */
};
LIST_HEAD(mkdirlist, mkdir) mkdirlisthd;
/*
* 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.
*
* The overlaying of dm_pagedep and dm_dirinum is done to keep the
* structure down to 32 bytes in size on a 32-bit machine. It works
* because they are never used concurrently.
*/
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 */
struct mount *dm_mnt; /* associated mount point */
ino_t dm_oldinum; /* inum of the removed dir entry */
union {
struct pagedep *dmu_pagedep; /* pagedep dependency for remove */
ino_t dmu_dirinum; /* parent inode number (for rmdir) */
} dm_un;
};
#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.
*/
struct newdirblk {
struct worklist db_list; /* id_inowait or pg_newdirblk */
# define db_state db_list.wk_state /* unused */
struct pagedep *db_pagedep; /* associated pagedep */
};