namei.c

jfs-2.4-1.1.7.tar.gz jfs 2.4－1.1.7 源码

	 *      commit zero link count object
	 */
	if (ip->i_nlink == 0) {
		assert(!test_cflag(COMMIT_Nolink, ip));
		/* free block resources */
		if ((new_size = commitZeroLink(tid, ip)) < 0) {
			txAbort(tid, 1);	/* Marks FS Dirty */
			txEnd(tid);
			up(&JFS_IP(dip)->commit_sem);
			up(&JFS_IP(ip)->commit_sem);
			IWRITE_UNLOCK(ip);
			rc = new_size;
			goto out1;
		}
		tblk = tid_to_tblock(tid);
		tblk->xflag |= COMMIT_DELETE;
		tblk->ip = ip;
	}

	/*
	 * Incomplete truncate of file data can
	 * result in timing problems unless we synchronously commit the
	 * transaction.
	 */
	if (new_size)
		commit_flag = COMMIT_SYNC;
	else
		commit_flag = 0;

	/*
	 * If xtTruncate was incomplete, commit synchronously to avoid
	 * timing complications
	 */
	rc = txCommit(tid, 2, &iplist[0], commit_flag);

	txEnd(tid);

	up(&JFS_IP(dip)->commit_sem);
	up(&JFS_IP(ip)->commit_sem);


	while (new_size && (rc == 0)) {
		tid = txBegin(dip->i_sb, 0);
		down(&JFS_IP(ip)->commit_sem);
		new_size = xtTruncate_pmap(tid, ip, new_size);
		if (new_size < 0) {
			txAbort(tid, 1);	/* Marks FS Dirty */
			rc = new_size;
		} else
			rc = txCommit(tid, 2, &iplist[0], COMMIT_SYNC);
		txEnd(tid);
		up(&JFS_IP(ip)->commit_sem);
	}

	if (ip->i_nlink == 0)
		set_cflag(COMMIT_Nolink, ip);

	IWRITE_UNLOCK(ip);

	/*
	 * Truncating the directory index table is not guaranteed.  It
	 * may need to be done iteratively
	 */
	if (test_cflag(COMMIT_Stale, dip)) {
		if (dip->i_size > 1)
			jfs_truncate_nolock(dip, 0);

		clear_cflag(COMMIT_Stale, dip);
	}

      out1:
	free_UCSname(&dname);
      out:
	jfs_info("jfs_unlink: rc:%d", rc);
	return rc;
}

/*
 * NAME:	commitZeroLink()
 *
 * FUNCTION:    for non-directory, called by jfs_remove(),
 *		truncate a regular file, directory or symbolic
 *		link to zero length. return 0 if type is not 
 *		one of these.
 *
 *		if the file is currently associated with a VM segment
 *		only permanent disk and inode map resources are freed,
 *		and neither the inode nor indirect blocks are modified
 *		so that the resources can be later freed in the work
 *		map by ctrunc1.
 *		if there is no VM segment on entry, the resources are
 *		freed in both work and permanent map.
 *		(? for temporary file - memory object is cached even 
 *		after no reference:
 *		reference count > 0 -   )
 *
 * PARAMETERS:	cd	- pointer to commit data structure.
 *			  current inode is the one to truncate.
 *
 * RETURN:	Errors from subroutines
 */
static s64 commitZeroLink(tid_t tid, struct inode *ip)
{
	int filetype;
	struct tblock *tblk;

	jfs_info("commitZeroLink: tid = %d, ip = 0x%p", tid, ip);

	filetype = ip->i_mode & S_IFMT;
	switch (filetype) {
	case S_IFREG:
		break;
	case S_IFLNK:
		/* fast symbolic link */
		if (ip->i_size < IDATASIZE) {
			ip->i_size = 0;
			return 0;
		}
		break;
	default:
		assert(filetype != S_IFDIR);
		return 0;
	}

	set_cflag(COMMIT_Freewmap, ip);

	/* mark transaction of block map update type */
	tblk = tid_to_tblock(tid);
	tblk->xflag |= COMMIT_PMAP;

	/*
	 * free EA
	 */
	if (JFS_IP(ip)->ea.flag & DXD_EXTENT)
		/* acquire maplock on EA to be freed from block map */
		txEA(tid, ip, &JFS_IP(ip)->ea, NULL);

	/*
	 * free ACL
	 */
	if (JFS_IP(ip)->acl.flag & DXD_EXTENT)
		/* acquire maplock on EA to be freed from block map */
		txEA(tid, ip, &JFS_IP(ip)->acl, NULL);

	/*
	 * free xtree/data (truncate to zero length):
	 * free xtree/data pages from cache if COMMIT_PWMAP, 
	 * free xtree/data blocks from persistent block map, and
	 * free xtree/data blocks from working block map if COMMIT_PWMAP;
	 */
	if (ip->i_size)
		return xtTruncate_pmap(tid, ip, 0);

	return 0;
}


/*
 * NAME:	freeZeroLink()
 *
 * FUNCTION:    for non-directory, called by iClose(),
 *		free resources of a file from cache and WORKING map 
 *		for a file previously committed with zero link count
 *		while associated with a pager object,
 *
 * PARAMETER:	ip	- pointer to inode of file.
 *
 * RETURN:	0 -ok
 */
int freeZeroLink(struct inode *ip)
{
	int rc = 0;
	int type;

	jfs_info("freeZeroLink: ip = 0x%p", ip);

	/* return if not reg or symbolic link or if size is
	 * already ok.
	 */
	type = ip->i_mode & S_IFMT;

	switch (type) {
	case S_IFREG:
		break;
	case S_IFLNK:
		/* if its contained in inode nothing to do */
		if (ip->i_size < IDATASIZE)
			return 0;
		break;
	default:
		return 0;
	}

	/*
	 * free EA
	 */
	if (JFS_IP(ip)->ea.flag & DXD_EXTENT) {
		s64 xaddr = addressDXD(&JFS_IP(ip)->ea);
		int xlen = lengthDXD(&JFS_IP(ip)->ea);
		struct maplock maplock;	/* maplock for COMMIT_WMAP */
		struct pxd_lock *pxdlock;	/* maplock for COMMIT_WMAP */

		/* free EA pages from cache */
		invalidate_dxd_metapages(ip, JFS_IP(ip)->ea);

		/* free EA extent from working block map */
		maplock.index = 1;
		pxdlock = (struct pxd_lock *) & maplock;
		pxdlock->flag = mlckFREEPXD;
		PXDaddress(&pxdlock->pxd, xaddr);
		PXDlength(&pxdlock->pxd, xlen);
		txFreeMap(ip, pxdlock, 0, COMMIT_WMAP);
	}

	/*
	 * free ACL
	 */
	if (JFS_IP(ip)->acl.flag & DXD_EXTENT) {
		s64 xaddr = addressDXD(&JFS_IP(ip)->acl);
		int xlen = lengthDXD(&JFS_IP(ip)->acl);
		struct maplock maplock;	/* maplock for COMMIT_WMAP */
		struct pxd_lock *pxdlock;	/* maplock for COMMIT_WMAP */

		invalidate_dxd_metapages(ip, JFS_IP(ip)->acl);

		/* free ACL extent from working block map */
		maplock.index = 1;
		pxdlock = (struct pxd_lock *) & maplock;
		pxdlock->flag = mlckFREEPXD;
		PXDaddress(&pxdlock->pxd, xaddr);
		PXDlength(&pxdlock->pxd, xlen);
		txFreeMap(ip, pxdlock, 0, COMMIT_WMAP);
	}

	/*
	 * free xtree/data (truncate to zero length):
	 * free xtree/data pages from cache, and
	 * free xtree/data blocks from working block map;
	 */
	if (ip->i_size)
		rc = xtTruncate(0, ip, 0, COMMIT_WMAP);

	return rc;
}

/*
 * NAME:	jfs_link(vp, dvp, name, crp)
 *
 * FUNCTION:	create a link to <vp> by the name = <name>
 *		in the parent directory <dvp>
 *
 * PARAMETER:	vp 	- target object
 *		dvp	- parent directory of new link
 *		name	- name of new link to target object
 *		crp	- credential
 *
 * RETURN:	Errors from subroutines
 *
 * note:
 * JFS does NOT support link() on directories (to prevent circular
 * path in the directory hierarchy);
 * EPERM: the target object is a directory, and either the caller
 * does not have appropriate privileges or the implementation prohibits
 * using link() on directories [XPG4.2].
 *
 * JFS does NOT support links between file systems:
 * EXDEV: target object and new link are on different file systems and
 * implementation does not support links between file systems [XPG4.2].
 */
static int jfs_link(struct dentry *old_dentry,
	     struct inode *dir, struct dentry *dentry)
{
	int rc;
	tid_t tid;
	struct inode *ip = old_dentry->d_inode;
	ino_t ino;
	struct component_name dname;
	struct btstack btstack;
	struct inode *iplist[2];

	jfs_info("jfs_link: %s %s", old_dentry->d_name.name,
		 dentry->d_name.name);

	/* JFS does NOT support link() on directories */
	if (S_ISDIR(ip->i_mode))
		return -EPERM;

	tid = txBegin(ip->i_sb, 0);

	down(&JFS_IP(dir)->commit_sem);
	down(&JFS_IP(ip)->commit_sem);

	if (ip->i_nlink == JFS_LINK_MAX) {
		rc = -EMLINK;
		goto out;
	}

	if (ip->i_nlink == 0) {
		rc = -ENOENT;
		goto out;
	}

	/*
	 * scan parent directory for entry/freespace
	 */
	if ((rc = get_UCSname(&dname, dentry, JFS_SBI(ip->i_sb)->nls_tab)))
		goto out;

	if ((rc = dtSearch(dir, &dname, &ino, &btstack, JFS_CREATE)))
		goto free_dname;

	/*
	 * create entry for new link in parent directory
	 */
	ino = ip->i_ino;
	if ((rc = dtInsert(tid, dir, &dname, &ino, &btstack)))
		goto free_dname;

	/* update object inode */
	ip->i_nlink++;		/* for new link */
	ip->i_ctime = CURRENT_TIME;
	mark_inode_dirty(dir);
	atomic_inc(&ip->i_count);

	iplist[0] = ip;
	iplist[1] = dir;
	rc = txCommit(tid, 2, &iplist[0], 0);

	if (!rc)
		d_instantiate(dentry, ip);
      free_dname:
	free_UCSname(&dname);

      out:
	txEnd(tid);

	up(&JFS_IP(dir)->commit_sem);
	up(&JFS_IP(ip)->commit_sem);

	jfs_info("jfs_link: rc:%d", rc);
	return rc;
}

/*
 * NAME:	jfs_symlink(dip, dentry, name)
 *
 * FUNCTION:	creates a symbolic link to <symlink> by name <name>
 *		        in directory <dip>
 *
 * PARAMETER:	dip	    - parent directory vnode
 *		        dentry 	- dentry of symbolic link
 *		        name    - the path name of the existing object 
 *			              that will be the source of the link
 *
 * RETURN:	errors from subroutines
 *
 * note:
 * ENAMETOOLONG: pathname resolution of a symbolic link produced
 * an intermediate result whose length exceeds PATH_MAX [XPG4.2]
*/

static int jfs_symlink(struct inode *dip, struct dentry *dentry,
		const char *name)
{
	int rc;
	tid_t tid;
	ino_t ino = 0;
	struct component_name dname;
	int ssize;		/* source pathname size */
	struct btstack btstack;
	struct inode *ip = dentry->d_inode;
	unchar *i_fastsymlink;
	s64 xlen = 0;
	int bmask = 0, xsize;
	s64 extent = 0, xaddr;
	struct metapage *mp;
	struct super_block *sb;
	struct tblock *tblk;

	struct inode *iplist[2];

	jfs_info("jfs_symlink: dip:0x%p name:%s", dip, name);

	ssize = strlen(name) + 1;

	/*
	 * search parent directory for entry/freespace
	 * (dtSearch() returns parent directory page pinned)
	 */

	if ((rc = get_UCSname(&dname, dentry, JFS_SBI(dip->i_sb)->nls_tab)))
		goto out1;

	/*
	 * allocate on-disk/in-memory inode for symbolic link:
	 * (iAlloc() returns new, locked inode)
	 */
	ip = ialloc(dip, S_IFLNK | 0777);
	if (ip == NULL) {
		rc = -ENOSPC;
		goto out2;
	}

	tid = txBegin(dip->i_sb, 0);

	down(&JFS_IP(dip)->commit_sem);
	down(&JFS_IP(ip)->commit_sem);

	tblk = tid_to_tblock(tid);
	tblk->xflag |= COMMIT_CREATE;
	tblk->ip = ip;

	/* fix symlink access permission
	 * (dir_create() ANDs in the u.u_cmask, 
	 * but symlinks really need to be 777 access)
	 */
	ip->i_mode |= 0777;

	/*
	 * write symbolic link target path name
	 */
	xtInitRoot(tid, ip);

	/*
	 * write source path name inline in on-disk inode (fast symbolic link)
	 */

	if (ssize <= IDATASIZE) {
		ip->i_op = &jfs_symlink_inode_operations;

		i_fastsymlink = JFS_IP(ip)->i_inline;
		memcpy(i_fastsymlink, name, ssize);
		ip->i_size = ssize - 1;

		/*
		 * if symlink is > 128 bytes, we don't have the space to
		 * store inline extended attributes
		 */
		if (ssize > sizeof (JFS_IP(ip)->i_inline))
			JFS_IP(ip)->mode2 &= ~INLINEEA;

		jfs_info("jfs_symlink: fast symlink added  ssize:%d name:%s ",
			 ssize, name);
	}
	/*
	 * write source path name in a single extent
	 */
	else {
		jfs_info("jfs_symlink: allocate extent ip:0x%p", ip);

		ip->i_op = &page_symlink_inode_operations;
		ip->i_mapping->a_ops = &jfs_aops;

		/*
		 * even though the data of symlink object (source 
		 * path name) is treated as non-journaled user data,
		 * it is read/written thru buffer cache for performance.
		 */
		sb = ip->i_sb;
		bmask = JFS_SBI(sb)->bsize - 1;
		xsize = (ssize + bmask) & ~bmask;
		xaddr = 0;
		xlen = xsize >> JFS_SBI(sb)->l2bsize;
		if ((rc = xtInsert(tid, ip, 0, 0, xlen, &xaddr, 0))) {
			txAbort(tid, 0);
			rc = -ENOSPC;
			goto out3;
		}
		extent = xaddr;
		ip->i_size = ssize - 1;
		while (ssize) {
			/* This is kind of silly since PATH_MAX == 4K */
			int copy_size = min(ssize, PSIZE);

			mp = get_metapage(ip, xaddr, PSIZE, 1);

			if (mp == NULL) {
				dbFree(ip, extent, xlen);