jfs_imap.c

linux 内核源代码

				 * extent, so allocate it.
				 */
				rc = diAllocBit(imap, iagp, ino);
				IREAD_UNLOCK(ipimap);
				if (rc) {
					assert(rc == -EIO);
				} else {
					/* set the results of the allocation
					 * and write the iag.
					 */
					diInitInode(ip, iagno, ino, extno,
						    iagp);
					mark_metapage_dirty(mp);
				}
				release_metapage(mp);

				/* free the AG lock and return.
				 */
				AG_UNLOCK(imap, agno);
				return (rc);
			}

			if (!addext)
				extno =
				    (extno ==
				     EXTSPERIAG - 1) ? 0 : extno + 1;
		}

		/*
		 * no free inodes within the extent containing the hint.
		 *
		 * try to allocate from the backed extents following
		 * hint or, if appropriate (i.e. addext is true), allocate
		 * an extent of free inodes at or following the extent
		 * containing the hint.
		 *
		 * the free inode and free extent summary maps are used
		 * here, so determine the starting summary map position
		 * and the number of words we'll have to examine.  again,
		 * the approach is to allocate following the hint, so we
		 * might have to initially ignore prior bits of the summary
		 * map that represent extents prior to the extent containing
		 * the hint and later revisit these bits.
		 */
		bitno = extno & (EXTSPERSUM - 1);
		nwords = (bitno == 0) ? SMAPSZ : SMAPSZ + 1;
		sword = extno >> L2EXTSPERSUM;

		/* mask any prior bits for the starting words of the
		 * summary map.
		 */
		mask = ONES << (EXTSPERSUM - bitno);
		inosmap = le32_to_cpu(iagp->inosmap[sword]) | mask;
		extsmap = le32_to_cpu(iagp->extsmap[sword]) | mask;

		/* scan the free inode and free extent summary maps for
		 * free resources.
		 */
		for (i = 0; i < nwords; i++) {
			/* check if this word of the free inode summary
			 * map describes an extent with free inodes.
			 */
			if (~inosmap) {
				/* an extent with free inodes has been
				 * found. determine the extent number
				 * and the inode number within the extent.
				 */
				rem = diFindFree(inosmap, 0);
				extno = (sword << L2EXTSPERSUM) + rem;
				rem = diFindFree(le32_to_cpu(iagp->wmap[extno]),
						 0);
				if (rem >= INOSPEREXT) {
					IREAD_UNLOCK(ipimap);
					release_metapage(mp);
					AG_UNLOCK(imap, agno);
					jfs_error(ip->i_sb,
						  "diAlloc: can't find free bit "
						  "in wmap");
					return EIO;
				}

				/* determine the inode number within the
				 * iag and allocate the inode from the
				 * map.
				 */
				ino = (extno << L2INOSPEREXT) + rem;
				rc = diAllocBit(imap, iagp, ino);
				IREAD_UNLOCK(ipimap);
				if (rc)
					assert(rc == -EIO);
				else {
					/* set the results of the allocation
					 * and write the iag.
					 */
					diInitInode(ip, iagno, ino, extno,
						    iagp);
					mark_metapage_dirty(mp);
				}
				release_metapage(mp);

				/* free the AG lock and return.
				 */
				AG_UNLOCK(imap, agno);
				return (rc);

			}

			/* check if we may allocate an extent of free
			 * inodes and whether this word of the free
			 * extents summary map describes a free extent.
			 */
			if (addext && ~extsmap) {
				/* a free extent has been found.  determine
				 * the extent number.
				 */
				rem = diFindFree(extsmap, 0);
				extno = (sword << L2EXTSPERSUM) + rem;

				/* allocate an extent of free inodes.
				 */
				if ((rc = diNewExt(imap, iagp, extno))) {
					/* if there is no disk space for a
					 * new extent, try to allocate the
					 * disk inode from somewhere else.
					 */
					if (rc == -ENOSPC)
						break;

					assert(rc == -EIO);
				} else {
					/* set the results of the allocation
					 * and write the iag.
					 */
					diInitInode(ip, iagno,
						    extno << L2INOSPEREXT,
						    extno, iagp);
					mark_metapage_dirty(mp);
				}
				release_metapage(mp);
				/* free the imap inode & the AG lock & return.
				 */
				IREAD_UNLOCK(ipimap);
				AG_UNLOCK(imap, agno);
				return (rc);
			}

			/* move on to the next set of summary map words.
			 */
			sword = (sword == SMAPSZ - 1) ? 0 : sword + 1;
			inosmap = le32_to_cpu(iagp->inosmap[sword]);
			extsmap = le32_to_cpu(iagp->extsmap[sword]);
		}
	}
	/* unlock imap inode */
	IREAD_UNLOCK(ipimap);

	/* nothing doing in this iag, so release it. */
	release_metapage(mp);

      tryag:
	/*
	 * try to allocate anywhere within the same AG as the parent inode.
	 */
	rc = diAllocAG(imap, agno, dir, ip);

	AG_UNLOCK(imap, agno);

	if (rc != -ENOSPC)
		return (rc);

	/*
	 * try to allocate in any AG.
	 */
	return (diAllocAny(imap, agno, dir, ip));
}


/*
 * NAME:	diAllocAG(imap,agno,dir,ip)
 *
 * FUNCTION:	allocate a disk inode from the allocation group.
 *
 *		this routine first determines if a new extent of free
 *		inodes should be added for the allocation group, with
 *		the current request satisfied from this extent. if this
 *		is the case, an attempt will be made to do just that.  if
 *		this attempt fails or it has been determined that a new
 *		extent should not be added, an attempt is made to satisfy
 *		the request by allocating an existing (backed) free inode
 *		from the allocation group.
 *
 * PRE CONDITION: Already have the AG lock for this AG.
 *
 * PARAMETERS:
 *	imap	- pointer to inode map control structure.
 *	agno	- allocation group to allocate from.
 *	dir	- 'true' if the new disk inode is for a directory.
 *	ip	- pointer to the new inode to be filled in on successful return
 *		  with the disk inode number allocated, its extent address
 *		  and the start of the ag.
 *
 * RETURN VALUES:
 *	0	- success.
 *	-ENOSPC	- insufficient disk resources.
 *	-EIO	- i/o error.
 */
static int
diAllocAG(struct inomap * imap, int agno, bool dir, struct inode *ip)
{
	int rc, addext, numfree, numinos;

	/* get the number of free and the number of backed disk
	 * inodes currently within the ag.
	 */
	numfree = imap->im_agctl[agno].numfree;
	numinos = imap->im_agctl[agno].numinos;

	if (numfree > numinos) {
		jfs_error(ip->i_sb, "diAllocAG: numfree > numinos");
		return -EIO;
	}

	/* determine if we should allocate a new extent of free inodes
	 * within the ag: for directory inodes, add a new extent
	 * if there are a small number of free inodes or number of free
	 * inodes is a small percentage of the number of backed inodes.
	 */
	if (dir)
		addext = (numfree < 64 ||
			  (numfree < 256
			   && ((numfree * 100) / numinos) <= 20));
	else
		addext = (numfree == 0);

	/*
	 * try to allocate a new extent of free inodes.
	 */
	if (addext) {
		/* if free space is not avaliable for this new extent, try
		 * below to allocate a free and existing (already backed)
		 * inode from the ag.
		 */
		if ((rc = diAllocExt(imap, agno, ip)) != -ENOSPC)
			return (rc);
	}

	/*
	 * try to allocate an existing free inode from the ag.
	 */
	return (diAllocIno(imap, agno, ip));
}


/*
 * NAME:	diAllocAny(imap,agno,dir,iap)
 *
 * FUNCTION:	allocate a disk inode from any other allocation group.
 *
 *		this routine is called when an allocation attempt within
 *		the primary allocation group has failed. if attempts to
 *		allocate an inode from any allocation group other than the
 *		specified primary group.
 *
 * PARAMETERS:
 *	imap	- pointer to inode map control structure.
 *	agno	- primary allocation group (to avoid).
 *	dir	- 'true' if the new disk inode is for a directory.
 *	ip	- pointer to a new inode to be filled in on successful return
 *		  with the disk inode number allocated, its extent address
 *		  and the start of the ag.
 *
 * RETURN VALUES:
 *	0	- success.
 *	-ENOSPC	- insufficient disk resources.
 *	-EIO	- i/o error.
 */
static int
diAllocAny(struct inomap * imap, int agno, bool dir, struct inode *ip)
{
	int ag, rc;
	int maxag = JFS_SBI(imap->im_ipimap->i_sb)->bmap->db_maxag;


	/* try to allocate from the ags following agno up to
	 * the maximum ag number.
	 */
	for (ag = agno + 1; ag <= maxag; ag++) {
		AG_LOCK(imap, ag);

		rc = diAllocAG(imap, ag, dir, ip);

		AG_UNLOCK(imap, ag);

		if (rc != -ENOSPC)
			return (rc);
	}

	/* try to allocate from the ags in front of agno.
	 */
	for (ag = 0; ag < agno; ag++) {
		AG_LOCK(imap, ag);

		rc = diAllocAG(imap, ag, dir, ip);

		AG_UNLOCK(imap, ag);

		if (rc != -ENOSPC)
			return (rc);
	}

	/* no free disk inodes.
	 */
	return -ENOSPC;
}


/*
 * NAME:	diAllocIno(imap,agno,ip)
 *
 * FUNCTION:	allocate a disk inode from the allocation group's free
 *		inode list, returning an error if this free list is
 *		empty (i.e. no iags on the list).
 *
 *		allocation occurs from the first iag on the list using
 *		the iag's free inode summary map to find the leftmost
 *		free inode in the iag.
 *
 * PRE CONDITION: Already have AG lock for this AG.
 *
 * PARAMETERS:
 *	imap	- pointer to inode map control structure.
 *	agno	- allocation group.
 *	ip	- pointer to new inode to be filled in on successful return
 *		  with the disk inode number allocated, its extent address
 *		  and the start of the ag.
 *
 * RETURN VALUES:
 *	0	- success.
 *	-ENOSPC	- insufficient disk resources.
 *	-EIO	- i/o error.
 */
static int diAllocIno(struct inomap * imap, int agno, struct inode *ip)
{
	int iagno, ino, rc, rem, extno, sword;
	struct metapage *mp;
	struct iag *iagp;

	/* check if there are iags on the ag's free inode list.
	 */
	if ((iagno = imap->im_agctl[agno].inofree) < 0)
		return -ENOSPC;

	/* obtain read lock on imap inode */
	IREAD_LOCK(imap->im_ipimap, RDWRLOCK_IMAP);

	/* read the iag at the head of the list.
	 */
	if ((rc = diIAGRead(imap, iagno, &mp))) {
		IREAD_UNLOCK(imap->im_ipimap);
		return (rc);
	}
	iagp = (struct iag *) mp->data;

	/* better be free inodes in this iag if it is on the
	 * list.
	 */
	if (!iagp->nfreeinos) {
		IREAD_UNLOCK(imap->im_ipimap);
		release_metapage(mp);
		jfs_error(ip->i_sb,
			  "diAllocIno: nfreeinos = 0, but iag on freelist");
		return -EIO;
	}

	/* scan the free inode summary map to find an extent
	 * with free inodes.
	 */
	for (sword = 0;; sword++) {
		if (sword >= SMAPSZ) {
			IREAD_UNLOCK(imap->im_ipimap);
			release_metapage(mp);
			jfs_error(ip->i_sb,
				  "diAllocIno: free inode not found in summary map");
			return -EIO;
		}

		if (~iagp->inosmap[sword])
			break;
	}

	/* found a extent with free inodes. determine
	 * the extent number.
	 */
	rem = diFindFree(le32_to_cpu(iagp->inosmap[sword]), 0);
	if (rem >= EXTSPERSUM) {
		IREAD_UNLOCK(imap->im_ipimap);
		release_metapage(mp);
		jfs_error(ip->i_sb, "diAllocIno: no free extent found");
		return -EIO;
	}
	extno = (sword << L2EXTSPERSUM) + rem;

	/* find the first free inode in the extent.
	 */
	rem = diFindFree(le32_to_cpu(iagp->wmap[extno]), 0);
	if (rem >= INOSPEREXT) {
		IREAD_UNLOCK(imap->im_ipimap);
		release_metapage(mp);
		jfs_error(ip->i_sb, "diAllocIno: free inode not found");
		return -EIO;
	}

	/* compute the inode number within the iag.
	 */
	ino = (extno << L2INOSPEREXT) + rem;

	/* allocate the inode.
	 */
	rc = diAllocBit(imap, iagp, ino);
	IREAD_UNLOCK(imap->im_ipimap);
	if (rc) {
		release_metapage(mp);
		return (rc);
	}

	/* set the results of the allocation and write the iag.
	 */
	diInitInode(ip, iagno, ino, extno, iagp);
	write_metapage(mp);

	return (0);
}


/*
 * NAME:	diAllocExt(imap,agno,ip)
 *
 * FUNCTION:	add a new extent of free inodes to an iag, allocating
 *		an inode from this extent to satisfy the current allocation
 *		request.
 *
 *		this routine first tries to find an existing iag with free
 *		extents through the ag free extent list.  if list is not
 *		empty, the head of the list will be selected as the home
 *		of the new extent of free inodes.  otherwise (the list is
 *		empty), a new iag will be allocated for the ag to contain
 *		the extent.
 *
 *		once an iag has been selected, the free extent summary map
 *		is used to locate a free extent within the iag and diNewExt()
 *		is called to initialize the extent, with initialization
 *		including the allocation of the first inode of the extent
 *		for the purpose of satisfying this request.
 *
 * PARAMETERS:
 *	imap	- pointer to inode map control structure.
 *	agno	- allocation group number.
 *	ip	- pointer to new inode to be filled in on successful return
 *		  with the disk inode number allocated, its extent address
 *		  and the start of the ag.
 *
 * RETURN VALUES:
 *	0	- success.
 *	-ENOSPC	- insufficient disk resources.
 *	-EIO	- i/o error.
 */
static int diAllocExt(struct inomap * imap, int agno, struct inode *ip)
{
	int rem, iagno, sword, extno, rc;
	struct metapage *mp;
	struct iag *iagp;

	/* check if the ag has any iags with free extents.  if not,
	 * allocate a new iag for the ag.
	 */
	if ((iagno = imap->im_agctl[agno].extfree) < 0) {
		/* If successful, diNewIAG will obtain the read lock on the
		 * imap inode.
		 */
		if ((rc = diNewIAG(imap, &iagno, agno, &mp))) {
			return (rc);
		}