* Copyright (c) 1989 The Regents of the University of California.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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
* @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91
struct nchstats nchstats
;
* Convert a component of a pathname into a pointer to a locked inode.
* This is a very central and rather complicated routine.
* If the file system is not maintained in a strict tree hierarchy,
* this can result in a deadlock situation (see comments in code below).
* The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
* whether the name is to be looked up, created, renamed, or deleted.
* When CREATE, RENAME, or DELETE is specified, information usable in
* creating, renaming, or deleting a directory entry may be calculated.
* If flag has LOCKPARENT or'ed into it and the target of the pathname
* exists, lookup returns both the target and its parent directory locked.
* When creating or renaming and LOCKPARENT is specified, the target may
* not be ".". When deleting and LOCKPARENT is specified, the target may
* be "."., but the caller must check to ensure it does an vrele and iput
* Overall outline of ufs_lookup:
* check accessibility of directory
* look for name in cache, if found, then if at end of path
* and deleting or creating, drop it, else return name
* search for name in directory, to found or notfound
* if creating, return locked directory, leaving info on available slots
* if at end of path and deleting, return information to allow delete
* if at end of path and rewriting (RENAME and LOCKPARENT), lock target
* inode and return info to allow rewrite
* if not at end, add name to cache; if at end and neither creating
* nor deleting, add name to cache
* NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
isofs_lookup(vdp
, ndp
, p
)
register struct vnode
*vdp
;
register struct nameidata
*ndp
;
register struct iso_node
*dp
; /* the directory we are searching */
register struct iso_mnt
*imp
; /* file system that directory is in */
struct buf
*bp
= 0; /* a buffer of directory entries */
register struct iso_directory_record
*ep
;
/* the current directory entry */
int entryoffsetinblock
; /* offset of ep in bp's buffer */
enum {NONE
, COMPACT
, FOUND
} slotstatus
;
int slotoffset
= -1; /* offset of area with free space */
int slotsize
; /* size of area at slotoffset */
int slotfreespace
; /* amount of space free in slot */
int slotneeded
; /* size of the entry we're seeking */
int numdirpasses
; /* strategy for directory search */
int endsearch
; /* offset to end directory search */
struct iso_node
*pdp
; /* saved dp during symlink work */
struct iso_node
*tdp
; /* returned by iget */
int flag
; /* LOOKUP, CREATE, RENAME, or DELETE */
int lockparent
; /* 1 => lockparent flag is set */
int wantparent
; /* 1 => wantparent or lockparent flag */
lockparent
= ndp
->ni_nameiop
& LOCKPARENT
;
flag
= ndp
->ni_nameiop
& OPMASK
;
wantparent
= ndp
->ni_nameiop
& (LOCKPARENT
|WANTPARENT
);
* Check accessiblity of directory.
if ((dp
->iso_flags
& 2) == 0)
* We now have a segment name to search for, and a directory to search.
* Before tediously performing a linear scan of the directory,
* check the name cache to see if the directory/name pair
* we are looking for is known already.
if (error
= cache_lookup(ndp
)) {
int vpid
; /* capability number of vnode */
if (vdp
== ndp
->ni_rdir
&& ndp
->ni_isdotdot
)
panic("ufs_lookup: .. through root");
* Get the next vnode in the path.
* See comment below starting `Step through' for
* an explaination of the locking protocol.
} else if (ndp
->ni_isdotdot
) {
if (!error
&& lockparent
&& *ndp
->ni_next
== '\0')
if (!lockparent
|| error
|| *ndp
->ni_next
!= '\0')
* Check that the capability number did not change
* while we were waiting for the lock.
if (lockparent
&& pdp
!= dp
&& *ndp
->ni_next
== '\0')
* If there is cached information on a previous search of
* this directory, pick up where we last left off.
* We cache only lookups as these are the most common
* and have the greatest payoff. Caching CREATE has little
* benefit as it usually must search the entire directory
* to determine that the entry does not exist. Caching the
* location of the last DELETE or RENAME has not reduced
* profiling time and hence has been removed in the interest
if (flag
!= LOOKUP
|| dp
->i_diroff
== 0 || dp
->i_diroff
> dp
->i_size
) {
ndp
->ni_ufs
.ufs_offset
= 0;
ndp
->ni_ufs
.ufs_offset
= dp
->i_diroff
;
entryoffsetinblock
= iso_blkoff(imp
, ndp
->ni_ufs
.ufs_offset
);
if (entryoffsetinblock
!= 0) {
if (error
= iso_blkatoff(dp
, ndp
->ni_ufs
.ufs_offset
,
endsearch
= roundup(dp
->i_size
, imp
->logical_block_size
);
while (ndp
->ni_ufs
.ufs_offset
< endsearch
) {
* If offset is on a block boundary,
* read the next directory block.
* Release previous if it exists.
if (iso_blkoff(imp
, ndp
->ni_ufs
.ufs_offset
) == 0) {
if (error
= iso_blkatoff(dp
, ndp
->ni_ufs
.ufs_offset
,
* Get pointer to next entry.
ep
= (struct iso_directory_record
*)
(bp
->b_un
.b_addr
+ entryoffsetinblock
);
reclen
= isonum_711 (ep
->length
);
/* skip to next block, if any */
roundup (ndp
->ni_ufs
.ufs_offset
,
imp
->logical_block_size
);
if (reclen
< sizeof (struct iso_directory_record
))
/* illegal entry, stop */
if (entryoffsetinblock
+ reclen
>= imp
->logical_block_size
)
/* entries are not allowed to cross boundaries */
* Check for a name match.
namelen
= isonum_711 (ep
->name_len
);
if (reclen
< sizeof (struct iso_directory_record
) + namelen
)
/* illegal entry, stop */
&& ((ndp
->ni_namelen
== 1
|| (ndp
->ni_isdotdot
&& ep
->name
[0] == 1)))
|| (namelen
>= ndp
->ni_namelen
&& isofncmp(ndp
->ni_ptr
, ndp
->ni_namelen
, ep
->name
,
* Save directory entry's inode number and
* reclen in ndp->ni_ufs area, and release
ndp
->ni_ufs
.ufs_ino
= isonum_733 (ep
->extent
);
ndp
->ni_ufs
.ufs_offset
+= reclen
;
entryoffsetinblock
+= reclen
;
* If we started in the middle of the directory and failed
* to find our target, we must check the beginning as well.
ndp
->ni_ufs
.ufs_offset
= 0;
endsearch
= dp
->i_diroff
;
* Insert name into cache (as non-existent) if appropriate.
* Found component in pathname.
* If the final component of path name, save information
* in the cache as to where the entry was found.
if (*ndp
->ni_next
== '\0' && flag
== LOOKUP
)
dp
->i_diroff
= ndp
->ni_ufs
.ufs_offset
&~ (imp
->logical_block_size
- 1);
* Step through the translation in the name. We do not `iput' the
* directory because we may need it again if a symbolic link
* is relative to the current directory. Instead we save it
* unlocked as "pdp". We must get the target inode before unlocking
* the directory to insure that the inode will not be removed
* before we get it. We prevent deadlock by always fetching
* inodes from the root, moving down the directory tree. Thus
* when following backward pointers ".." we must unlock the
* parent directory before getting the requested directory.
* There is a potential race condition here if both the current
* and parent directories are removed before the `iget' for the
* inode associated with ".." returns. We hope that this occurs
* infrequently since we cannot avoid this race condition without
* implementing a sophisticated deadlock detection algorithm.
* Note also that this simple deadlock detection scheme will not
* work if the file system has any hard links other than ".."
* that point backwards in the directory structure.
ISO_IUNLOCK(pdp
); /* race to get the inode */
if (error
= iso_iget(dp
, ndp
->ni_ufs
.ufs_ino
, &tdp
, ep
)) {
if (lockparent
&& *ndp
->ni_next
== '\0')
} else if (dp
->i_number
== ndp
->ni_ufs
.ufs_ino
) {
VREF(vdp
); /* we want ourself, ie "." */
if (error
= iso_iget(dp
, ndp
->ni_ufs
.ufs_ino
, &tdp
, ep
))
if (!lockparent
|| *ndp
->ni_next
!= '\0')
* Insert name into cache if appropriate.
* Return buffer with contents of block "offset"
* from the beginning of directory "ip". If "res"
* is non-zero, fill it in with a pointer to the
* remaining space in the directory.
iso_blkatoff(ip
, offset
, res
, bpp
)
register struct iso_mnt
*imp
= ip
->i_mnt
;
daddr_t lbn
= iso_lblkno (imp
, offset
);
int bsize
= iso_blksize (imp
, ip
, lbn
);
if (error
= bread(ITOV(ip
), lbn
, bsize
, NOCRED
, &bp
)) {
*res
= bp
->b_un
.b_addr
+ iso_blkoff(imp
, offset
);