jfs_extent.c

jfs-2.4-1.1.7.tar.gz jfs 2.4－1.1.7 源码

	XADoffset(xp, xoff);
	xp->flag = xflag;

	mark_inode_dirty(ip);
exit:
	up(&JFS_IP(ip)->commit_sem);
	return (rc);
}
#endif			/* _NOTYET */


/*
 * NAME:        extHint()
 *
 * FUNCTION:    produce an extent allocation hint for a file offset.
 *
 * PARAMETERS:
 *	ip	- the inode of the file.
 *	offset  - file offset for which the hint is needed.
 *	xp	- pointer to the xad that is to be filled in with
 *		  the hint.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO	- i/o error.
 */
int extHint(struct inode *ip, s64 offset, xad_t * xp)
{
	struct super_block *sb = ip->i_sb;
	struct xadlist xadl;
	struct lxdlist lxdl;
	lxd_t lxd;
	s64 prev;
	int rc, nbperpage = JFS_SBI(sb)->nbperpage;

	/* init the hint as "no hint provided" */
	XADaddress(xp, 0);

	/* determine the starting extent offset of the page previous
	 * to the page containing the offset.
	 */
	prev = ((offset & ~POFFSET) >> JFS_SBI(sb)->l2bsize) - nbperpage;

	/* if the offsets in the first page of the file,
	 * no hint provided.
	 */
	if (prev < 0)
		return (0);

	/* prepare to lookup the previous page's extent info */
	lxdl.maxnlxd = 1;
	lxdl.nlxd = 1;
	lxdl.lxd = &lxd;
	LXDoffset(&lxd, prev)
	    LXDlength(&lxd, nbperpage);

	xadl.maxnxad = 1;
	xadl.nxad = 0;
	xadl.xad = xp;

	/* perform the lookup */
	if ((rc = xtLookupList(ip, &lxdl, &xadl, 0)))
		return (rc);

	/* check if not extent exists for the previous page.  
	 * this is possible for sparse files.
	 */
	if (xadl.nxad == 0) {
//              assert(ISSPARSE(ip));
		return (0);
	}

	/* only preserve the abnr flag within the xad flags
	 * of the returned hint.
	 */
	xp->flag &= XAD_NOTRECORDED;

        if(xadl.nxad != 1 || lengthXAD(xp) != nbperpage) {          
		jfs_error(ip->i_sb, "extHint: corrupt xtree");
		return -EIO;
        }

	return (0);
}


/*
 * NAME:        extRecord()
 *
 * FUNCTION:    change a page with a file from not recorded to recorded.
 *
 * PARAMETERS:
 *	ip	- inode of the file.
 *	cp	- cbuf of the file page.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO	- i/o error.
 *      -ENOSPC	- insufficient disk resources.
 */
int extRecord(struct inode *ip, xad_t * xp)
{
	int rc;

	txBeginAnon(ip->i_sb);

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

	/* update the extent */
	rc = xtUpdate(0, ip, xp);

	up(&JFS_IP(ip)->commit_sem);
	return rc;
}


#ifdef _NOTYET
/*
 * NAME:        extFill()
 *
 * FUNCTION:    allocate disk space for a file page that represents
 *		a file hole.
 *
 * PARAMETERS:
 *	ip	- the inode of the file.
 *	cp	- cbuf of the file page represent the hole.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO	- i/o error.
 *      -ENOSPC	- insufficient disk resources.
 */
int extFill(struct inode *ip, xad_t * xp)
{
	int rc, nbperpage = JFS_SBI(ip->i_sb)->nbperpage;
	s64 blkno = offsetXAD(xp) >> ip->i_blksize;

//      assert(ISSPARSE(ip));

	/* initialize the extent allocation hint */
	XADaddress(xp, 0);

	/* allocate an extent to fill the hole */
	if ((rc = extAlloc(ip, nbperpage, blkno, xp, FALSE)))
		return (rc);

	assert(lengthPXD(xp) == nbperpage);

	return (0);
}
#endif			/* _NOTYET */


/*
 * NAME:	extBalloc()
 *
 * FUNCTION:    allocate disk blocks to form an extent.
 *
 *		initially, we will try to allocate disk blocks for the
 *		requested size (nblocks).  if this fails (nblocks 
 *		contigious free blocks not avaliable), we'll try to allocate
 *		a smaller number of blocks (producing a smaller extent), with
 *		this smaller number of blocks consisting of the requested
 *		number of blocks rounded down to the next smaller power of 2
 *		number (i.e. 16 -> 8).  we'll continue to round down and
 *		retry the allocation until the number of blocks to allocate
 *		is smaller than the number of blocks per page.
 *		
 * PARAMETERS:
 *	ip	 - the inode of the file.
 *	hint	 - disk block number to be used as an allocation hint.
 *	*nblocks - pointer to an s64 value.  on entry, this value specifies
 *		   the desired number of block to be allocated. on successful
 *		   exit, this value is set to the number of blocks actually
 *		   allocated.
 *	blkno	 - pointer to a block address that is filled in on successful
 *		   return with the starting block number of the newly 
 *		   allocated block range.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO	- i/o error.
 *      -ENOSPC	- insufficient disk resources.
 */
static int
extBalloc(struct inode *ip, s64 hint, s64 * nblocks, s64 * blkno)
{
	struct jfs_inode_info *ji = JFS_IP(ip);
	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
	s64 nb, nblks, daddr, max;
	int rc, nbperpage = sbi->nbperpage;
	struct bmap *bmp = sbi->bmap;
	int ag;

	/* get the number of blocks to initially attempt to allocate.
	 * we'll first try the number of blocks requested unless this
	 * number is greater than the maximum number of contigious free
	 * blocks in the map. in that case, we'll start off with the 
	 * maximum free.
	 */
	max = (s64) 1 << bmp->db_maxfreebud;
	if (*nblocks >= max && *nblocks > nbperpage)
		nb = nblks = (max > nbperpage) ? max : nbperpage;
	else
		nb = nblks = *nblocks;

	/* try to allocate blocks */
	while ((rc = dbAlloc(ip, hint, nb, &daddr))) {
		/* if something other than an out of space error,
		 * stop and return this error.
		 */
		if (rc != -ENOSPC)
			return (rc);

		/* decrease the allocation request size */
		nb = min(nblks, extRoundDown(nb));

		/* give up if we cannot cover a page */
		if (nb < nbperpage)
			return (rc);
	}

	*nblocks = nb;
	*blkno = daddr;

	if (S_ISREG(ip->i_mode) && (ji->fileset == FILESYSTEM_I)) {
		ag = BLKTOAG(daddr, sbi);
		spin_lock_irq(&ji->ag_lock);
		if (ji->active_ag == -1) {
			atomic_inc(&bmp->db_active[ag]);
			ji->active_ag = ag;
		} else if (ji->active_ag != ag) {
			atomic_dec(&bmp->db_active[ji->active_ag]);
			atomic_inc(&bmp->db_active[ag]);
			ji->active_ag = ag;
		}
		spin_unlock_irq(&ji->ag_lock);
	}

	return (0);
}


#ifdef _NOTYET
/*
 * NAME:	extBrealloc()
 *
 * FUNCTION:    attempt to extend an extent's allocation.
 *
 *		initially, we will try to extend the extent's allocation
 *		in place.  if this fails, we'll try to move the extent
 *		to a new set of blocks. if moving the extent, we initially
 *		will try to allocate disk blocks for the requested size
 *		(nnew).  if this fails 	(nnew contigious free blocks not
 *		avaliable), we'll try  to allocate a smaller number of
 *		blocks (producing a smaller extent), with this smaller
 *		number of blocks consisting of the requested number of
 *		blocks rounded down to the next smaller power of 2
 *		number (i.e. 16 -> 8).  we'll continue to round down and
 *		retry the allocation until the number of blocks to allocate
 *		is smaller than the number of blocks per page.
 *		
 * PARAMETERS:
 *	ip	 - the inode of the file.
 *	blkno    - starting block number of the extents current allocation.
 *	nblks    - number of blocks within the extents current allocation.
 *	newnblks - pointer to a s64 value.  on entry, this value is the
 *		   the new desired extent size (number of blocks).  on
 *		   successful exit, this value is set to the extent's actual
 *		   new size (new number of blocks).
 *	newblkno - the starting block number of the extents new allocation.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO	- i/o error.
 *      -ENOSPC	- insufficient disk resources.
 */
static int
extBrealloc(struct inode *ip,
	    s64 blkno, s64 nblks, s64 * newnblks, s64 * newblkno)
{
	int rc;

	/* try to extend in place */
	if ((rc = dbExtend(ip, blkno, nblks, *newnblks - nblks)) == 0) {
		*newblkno = blkno;
		return (0);
	} else {
		if (rc != -ENOSPC)
			return (rc);
	}

	/* in place extension not possible.  
	 * try to move the extent to a new set of blocks.
	 */
	return (extBalloc(ip, blkno, newnblks, newblkno));
}
#endif			/* _NOTYET */


/*
 * NAME:        extRoundDown()
 *
 * FUNCTION:    round down a specified number of blocks to the next
 *		smallest power of 2 number.
 *
 * PARAMETERS:
 *	nb	- the inode of the file.
 *
 * RETURN VALUES:
 *      next smallest power of 2 number.
 */
static s64 extRoundDown(s64 nb)
{
	int i;
	u64 m, k;

	for (i = 0, m = (u64) 1 << 63; i < 64; i++, m >>= 1) {
		if (m & nb)
			break;
	}

	i = 63 - i;
	k = (u64) 1 << i;
	k = ((k - 1) & nb) ? k : k >> 1;

	return (k);
}