jfs_dtree.c

jfs-2.4-1.1.7.tar.gz jfs 2.4－1.1.7 源码

	}

	memcpy(dirtab_slot, slot, sizeof(struct dir_table_slot));

	if (mp)
		release_metapage(mp);

	return 0;
}

/*
 *	dtSearch()
 *
 * function:
 *	Search for the entry with specified key
 *
 * parameter:
 *
 * return: 0 - search result on stack, leaf page pinned;
 *	   errno - I/O error
 */
int dtSearch(struct inode *ip, struct component_name * key, ino_t * data,
	     struct btstack * btstack, int flag)
{
	int rc = 0;
	int cmp = 1;		/* init for empty page */
	s64 bn;
	struct metapage *mp;
	dtpage_t *p;
	s8 *stbl;
	int base, index, lim;
	struct btframe *btsp;
	pxd_t *pxd;
	int psize = 288;	/* initial in-line directory */
	ino_t inumber;
	struct component_name ciKey;
	struct super_block *sb = ip->i_sb;

	ciKey.name =
	    (wchar_t *) kmalloc((JFS_NAME_MAX + 1) * sizeof(wchar_t),
				GFP_NOFS);
	if (ciKey.name == 0) {
		rc = -ENOMEM;
		goto dtSearch_Exit2;
	}


	/* uppercase search key for c-i directory */
	UniStrcpy(ciKey.name, key->name);
	ciKey.namlen = key->namlen;

	/* only uppercase if case-insensitive support is on */
	if ((JFS_SBI(sb)->mntflag & JFS_OS2) == JFS_OS2) {
		ciToUpper(&ciKey);
	}
	BT_CLR(btstack);	/* reset stack */

	/* init level count for max pages to split */
	btstack->nsplit = 1;

	/*
	 *      search down tree from root:
	 *
	 * between two consecutive entries of <Ki, Pi> and <Kj, Pj> of
	 * internal page, child page Pi contains entry with k, Ki <= K < Kj.
	 *
	 * if entry with search key K is not found
	 * internal page search find the entry with largest key Ki
	 * less than K which point to the child page to search;
	 * leaf page search find the entry with smallest key Kj
	 * greater than K so that the returned index is the position of
	 * the entry to be shifted right for insertion of new entry.
	 * for empty tree, search key is greater than any key of the tree.
	 *
	 * by convention, root bn = 0.
	 */
	for (bn = 0;;) {
		/* get/pin the page to search */
		DT_GETPAGE(ip, bn, mp, psize, p, rc);
		if (rc)
			goto dtSearch_Exit1;

		/* get sorted entry table of the page */
		stbl = DT_GETSTBL(p);

		/*
		 * binary search with search key K on the current page.
		 */
		for (base = 0, lim = p->header.nextindex; lim; lim >>= 1) {
			index = base + (lim >> 1);

			if (p->header.flag & BT_LEAF) {
				/* uppercase leaf name to compare */
				cmp =
				    ciCompare(&ciKey, p, stbl[index],
					      JFS_SBI(sb)->mntflag);
			} else {
				/* router key is in uppercase */

				cmp = dtCompare(&ciKey, p, stbl[index]);


			}
			if (cmp == 0) {
				/*
				 *      search hit
				 */
				/* search hit - leaf page:
				 * return the entry found
				 */
				if (p->header.flag & BT_LEAF) {
					inumber = le32_to_cpu(
			((struct ldtentry *) & p->slot[stbl[index]])->inumber);

					/*
					 * search for JFS_LOOKUP
					 */
					if (flag == JFS_LOOKUP) {
						*data = inumber;
						rc = 0;
						goto out;
					}

					/*
					 * search for JFS_CREATE
					 */
					if (flag == JFS_CREATE) {
						*data = inumber;
						rc = -EEXIST;
						goto out;
					}

					/*
					 * search for JFS_REMOVE or JFS_RENAME
					 */
					if ((flag == JFS_REMOVE ||
					     flag == JFS_RENAME) &&
					    *data != inumber) {
						rc = -ESTALE;
						goto out;
					}

					/*
					 * JFS_REMOVE|JFS_FINDDIR|JFS_RENAME
					 */
					/* save search result */
					*data = inumber;
					btsp = btstack->top;
					btsp->bn = bn;
					btsp->index = index;
					btsp->mp = mp;

					rc = 0;
					goto dtSearch_Exit1;
				}

				/* search hit - internal page:
				 * descend/search its child page
				 */
				goto getChild;
			}

			if (cmp > 0) {
				base = index + 1;
				--lim;
			}
		}

		/*
		 *      search miss
		 *
		 * base is the smallest index with key (Kj) greater than
		 * search key (K) and may be zero or (maxindex + 1) index.
		 */
		/*
		 * search miss - leaf page
		 *
		 * return location of entry (base) where new entry with
		 * search key K is to be inserted.
		 */
		if (p->header.flag & BT_LEAF) {
			/*
			 * search for JFS_LOOKUP, JFS_REMOVE, or JFS_RENAME
			 */
			if (flag == JFS_LOOKUP || flag == JFS_REMOVE ||
			    flag == JFS_RENAME) {
				rc = -ENOENT;
				goto out;
			}

			/*
			 * search for JFS_CREATE|JFS_FINDDIR:
			 *
			 * save search result
			 */
			*data = 0;
			btsp = btstack->top;
			btsp->bn = bn;
			btsp->index = base;
			btsp->mp = mp;

			rc = 0;
			goto dtSearch_Exit1;
		}

		/*
		 * search miss - internal page
		 *
		 * if base is non-zero, decrement base by one to get the parent
		 * entry of the child page to search.
		 */
		index = base ? base - 1 : base;

		/*
		 * go down to child page
		 */
	      getChild:
		/* update max. number of pages to split */
		if (BT_STACK_FULL(btstack)) {
			/* Something's corrupted, mark filesytem dirty so
			 * chkdsk will fix it.
			 */
			jfs_error(sb, "stack overrun in dtSearch!");
			BT_STACK_DUMP(btstack);
			rc = -EIO;
			goto out;
		}
		btstack->nsplit++;

		/* push (bn, index) of the parent page/entry */
		BT_PUSH(btstack, bn, index);

		/* get the child page block number */
		pxd = (pxd_t *) & p->slot[stbl[index]];
		bn = addressPXD(pxd);
		psize = lengthPXD(pxd) << JFS_SBI(ip->i_sb)->l2bsize;

		/* unpin the parent page */
		DT_PUTPAGE(mp);
	}

      out:
	DT_PUTPAGE(mp);

      dtSearch_Exit1:

	kfree(ciKey.name);

      dtSearch_Exit2:

	return rc;
}


/*
 *	dtInsert()
 *
 * function: insert an entry to directory tree
 *
 * parameter:
 *
 * return: 0 - success;
 *	   errno - failure;
 */
int dtInsert(tid_t tid, struct inode *ip,
	 struct component_name * name, ino_t * fsn, struct btstack * btstack)
{
	int rc = 0;
	struct metapage *mp;	/* meta-page buffer */
	dtpage_t *p;		/* base B+-tree index page */
	s64 bn;
	int index;
	struct dtsplit split;	/* split information */
	ddata_t data;
	struct dt_lock *dtlck;
	int n;
	struct tlock *tlck;
	struct lv *lv;

	/*
	 *      retrieve search result
	 *
	 * dtSearch() returns (leaf page pinned, index at which to insert).
	 * n.b. dtSearch() may return index of (maxindex + 1) of
	 * the full page.
	 */
	DT_GETSEARCH(ip, btstack->top, bn, mp, p, index);

	/*
	 *      insert entry for new key
	 */
	if (DO_INDEX(ip)) {
		if (JFS_IP(ip)->next_index == DIREND) {
			DT_PUTPAGE(mp);
			return -EMLINK;
		}
		n = NDTLEAF(name->namlen);
		data.leaf.tid = tid;
		data.leaf.ip = ip;
	} else {
		n = NDTLEAF_LEGACY(name->namlen);
		data.leaf.ip = 0;	/* signifies legacy directory format */
	}
	data.leaf.ino = cpu_to_le32(*fsn);

	/*
	 *      leaf page does not have enough room for new entry:
	 *
	 *      extend/split the leaf page;
	 *
	 * dtSplitUp() will insert the entry and unpin the leaf page.
	 */
	if (n > p->header.freecnt) {
		split.mp = mp;
		split.index = index;
		split.nslot = n;
		split.key = name;
		split.data = &data;
		rc = dtSplitUp(tid, ip, &split, btstack);
		return rc;
	}

	/*
	 *      leaf page does have enough room for new entry:
	 *
	 *      insert the new data entry into the leaf page;
	 */
	BT_MARK_DIRTY(mp, ip);
	/*
	 * acquire a transaction lock on the leaf page
	 */
	tlck = txLock(tid, ip, mp, tlckDTREE | tlckENTRY);
	dtlck = (struct dt_lock *) & tlck->lock;
	ASSERT(dtlck->index == 0);
	lv = & dtlck->lv[0];

	/* linelock header */
	lv->offset = 0;
	lv->length = 1;
	dtlck->index++;

	dtInsertEntry(p, index, name, &data, &dtlck);

	/* linelock stbl of non-root leaf page */
	if (!(p->header.flag & BT_ROOT)) {
		if (dtlck->index >= dtlck->maxcnt)
			dtlck = (struct dt_lock *) txLinelock(dtlck);
		lv = & dtlck->lv[dtlck->index];
		n = index >> L2DTSLOTSIZE;
		lv->offset = p->header.stblindex + n;
		lv->length =
		    ((p->header.nextindex - 1) >> L2DTSLOTSIZE) - n + 1;
		dtlck->index++;
	}

	/* unpin the leaf page */
	DT_PUTPAGE(mp);

	return 0;
}


/*
 *	dtSplitUp()
 *
 * function: propagate insertion bottom up;
 *
 * parameter:
 *
 * return: 0 - success;
 *	   errno - failure;
 * 	leaf page unpinned;
 */
static int dtSplitUp(tid_t tid,
	  struct inode *ip, struct dtsplit * split, struct btstack * btstack)
{
	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
	int rc = 0;
	struct metapage *smp;
	dtpage_t *sp;		/* split page */
	struct metapage *rmp;
	dtpage_t *rp;		/* new right page split from sp */
	pxd_t rpxd;		/* new right page extent descriptor */
	struct metapage *lmp;
	dtpage_t *lp;		/* left child page */
	int skip;		/* index of entry of insertion */
	struct btframe *parent;	/* parent page entry on traverse stack */
	s64 xaddr, nxaddr;
	int xlen, xsize;
	struct pxdlist pxdlist;
	pxd_t *pxd;
	struct component_name key = { 0, 0 };
	ddata_t *data = split->data;
	int n;
	struct dt_lock *dtlck;
	struct tlock *tlck;
	struct lv *lv;

	/* get split page */
	smp = split->mp;
	sp = DT_PAGE(ip, smp);

	key.name =
	    (wchar_t *) kmalloc((JFS_NAME_MAX + 2) * sizeof(wchar_t),
				GFP_NOFS);
	if (key.name == 0) {
		DT_PUTPAGE(smp);
		rc = -ENOMEM;
		goto dtSplitUp_Exit;
	}

	/*
	 *      split leaf page
	 *
	 * The split routines insert the new entry, and
	 * acquire txLock as appropriate.
	 */
	/*
	 *      split root leaf page:
	 */
	if (sp->header.flag & BT_ROOT) {
		/*
		 * allocate a single extent child page
		 */
		xlen = 1;
		n = sbi->bsize >> L2DTSLOTSIZE;
		n -= (n + 31) >> L2DTSLOTSIZE;	/* stbl size */
		n -= DTROOTMAXSLOT - sp->header.freecnt; /* header + entries */
		if (n <= split->nslot)
			xlen++;
		if ((rc = dbAlloc(ip, 0, (s64) xlen, &xaddr))) {
			DT_PUTPAGE(smp);
			goto freeKeyName;
		}

		pxdlist.maxnpxd = 1;
		pxdlist.npxd = 0;
		pxd = &pxdlist.pxd[0];
		PXDaddress(pxd, xaddr);
		PXDlength(pxd, xlen);
		split->pxdlist = &pxdlist;
		rc = dtSplitRoot(tid, ip, split, &rmp);

		if (!rc)
			DT_PUTPAGE(rmp);

		DT_PUTPAGE(smp);

		goto freeKeyName;
	}

	/*
	 *      extend first leaf page
	 *
	 * extend the 1st extent if less than buffer page size
	 * (dtExtendPage() reurns leaf page unpinned)
	 */
	pxd = &sp->header.self;
	xlen = lengthPXD(pxd);
	xsize = xlen << sbi->l2bsize;
	if (xsize < PSIZE) {
		xaddr = addressPXD(pxd);
		n = xsize >> L2DTSLOTSIZE;
		n -= (n + 31) >> L2DTSLOTSIZE;	/* stbl size */
		if ((n + sp->header.freecnt) <= split->nslot)
			n = xlen + (xlen << 1);
		else
			n = xlen;
		if ((rc = dbReAlloc(sbi->ipbmap, xaddr, (s64) xlen,
				    (s64) n, &nxaddr)))
			goto extendOut;

		pxdlist.maxnpxd = 1;
		pxdlist.npxd = 0;
		pxd = &pxdlist.pxd[0];
		PXDaddress(pxd, nxaddr)
		    PXDlength(pxd, xlen + n);
		split->pxdlist = &pxdlist;
		if ((rc = dtExtendPage(tid, ip, split, btstack))) {
			nxaddr = addressPXD(pxd);
			if (xaddr != nxaddr) {
				/* free relocated extent */
				xlen = lengthPXD(pxd);
				dbFree(ip, nxaddr, (s64) xlen);
			} else {
				/* free extended delta */
				xlen = lengthPXD(pxd) - n;
				xaddr = addressPXD(pxd) + xlen;
				dbFree(ip, xaddr, (s64) n);
			}
		}

	      extendOut:
		DT_PUTPAGE(smp);
		goto freeKeyName;
	}

	/*
	 *      split leaf page <sp> into <sp> and a new right page <rp>.
	 *
	 * return <rp> pinned and its extent descriptor <rpxd>
	 */
	/*
	 * allocate new directory page extent and
	 * new index page(s) to cover page split(s)
	 *
	 * allocation hint: ?
	 */
	n = btstack->nsplit;
	pxdlist.maxnpxd = pxdlist.npxd = 0;
	xlen = sbi->nbperpage;
	for (pxd = pxdlist.pxd; n > 0; n--, pxd++) {
		if ((rc = dbAlloc(ip, 0, (s64) xlen, &xaddr)) == 0) {
			PXDaddress(pxd, xaddr);
			PXDlength(pxd, xlen);
			pxdlist.maxnpxd++;
			continue;
		}

		DT_PUTPAGE(smp);

		/* undo allocation */
		goto splitOut;
	}

	split->pxdlist = &pxdlist;
	if ((rc = dtSplitPage(tid, ip, split, &rmp, &rp, &rpxd))) {
		DT_PUTPAGE(smp);

		/* undo allocation */
		goto splitOut;
	}

	/*
	 * propagate up the router entry for the leaf page just split
	 *
	 * insert a router entry for the new page into the parent page,
	 * propagate the insert/split up the tree by walking back the stack
	 * of (bn of parent page, index of child page entry in parent page)
	 * that were traversed during the search for the page that split.
	 *
	 * the propagation of insert/split up the tree stops if the root
	 * splits or the page inserted into doesn't have to split to hold
	 * the new entry.
	 *
	 * the parent entry for the split page remains the same, and
	 * a new entry is inserted at its right with the first key and
	 * block number of the new right page.
	 *
	 * There are a maximum of 4 pages pinned at any time:
	 * two children, left parent and right parent (when the parent splits).