xfs_rtalloc.c

linux 内核源代码

			if (i >= 0) {
				/*
				 * Try to allocate an extent starting in
				 * this block.
				 */
				error = xfs_rtallocate_extent_block(mp, tp,
					bbno + i, minlen, maxlen, len, &n, rbpp,
					rsb, prod, &r);
				if (error) {
					return error;
				}
				/*
				 * If it worked, return it.
				 */
				if (r != NULLRTBLOCK) {
					*rtblock = r;
					return 0;
				}
			}
			/*
			 * On the negative side of the starting location.
			 */
			else {		/* i < 0 */
				/*
				 * Loop backwards through the bitmap blocks from
				 * the starting point-1 up to where we are now.
				 * There should be an extent which ends in this
				 * bitmap block and is long enough.
				 */
				for (j = -1; j > i; j--) {
					/*
					 * Grab the summary information for
					 * this bitmap block.
					 */
					error = xfs_rtany_summary(mp, tp,
						log2len, mp->m_rsumlevels - 1,
						bbno + j, rbpp, rsb, &any);
					if (error) {
						return error;
					}
					/*
					 * If there's no extent given in the
					 * summary that means the extent we
					 * found must carry over from an
					 * earlier block.  If there is an
					 * extent given, we've already tried
					 * that allocation, don't do it again.
					 */
					if (any)
						continue;
					error = xfs_rtallocate_extent_block(mp,
						tp, bbno + j, minlen, maxlen,
						len, &n, rbpp, rsb, prod, &r);
					if (error) {
						return error;
					}
					/*
					 * If it works, return the extent.
					 */
					if (r != NULLRTBLOCK) {
						*rtblock = r;
						return 0;
					}
				}
				/*
				 * There weren't intervening bitmap blocks
				 * with a long enough extent, or the
				 * allocation didn't work for some reason
				 * (i.e. it's a little * too short).
				 * Try to allocate from the summary block
				 * that we found.
				 */
				error = xfs_rtallocate_extent_block(mp, tp,
					bbno + i, minlen, maxlen, len, &n, rbpp,
					rsb, prod, &r);
				if (error) {
					return error;
				}
				/*
				 * If it works, return the extent.
				 */
				if (r != NULLRTBLOCK) {
					*rtblock = r;
					return 0;
				}
			}
		}
		/*
		 * Loop control.  If we were on the positive side, and there's
		 * still more blocks on the negative side, go there.
		 */
		if (i > 0 && (int)bbno - i >= 0)
			i = -i;
		/*
		 * If positive, and no more negative, but there are more
		 * positive, go there.
		 */
		else if (i > 0 && (int)bbno + i < mp->m_sb.sb_rbmblocks - 1)
			i++;
		/*
		 * If negative or 0 (just started), and there are positive
		 * blocks to go, go there.  The 0 case moves to block 1.
		 */
		else if (i <= 0 && (int)bbno - i < mp->m_sb.sb_rbmblocks - 1)
			i = 1 - i;
		/*
		 * If negative or 0 and there are more negative blocks,
		 * go there.
		 */
		else if (i <= 0 && (int)bbno + i > 0)
			i--;
		/*
		 * Must be done.  Return failure.
		 */
		else
			break;
	}
	*rtblock = NULLRTBLOCK;
	return 0;
}

/*
 * Allocate an extent of length minlen<=len<=maxlen, with no position
 * specified.  If we don't get maxlen then use prod to trim
 * the length, if given.  The lengths are all in rtextents.
 */
STATIC int				/* error */
xfs_rtallocate_extent_size(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_extlen_t	minlen,		/* minimum length to allocate */
	xfs_extlen_t	maxlen,		/* maximum length to allocate */
	xfs_extlen_t	*len,		/* out: actual length allocated */
	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	xfs_extlen_t	prod,		/* extent product factor */
	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
{
	int		error;		/* error value */
	int		i;		/* bitmap block number */
	int		l;		/* level number (loop control) */
	xfs_rtblock_t	n;		/* next block to be tried */
	xfs_rtblock_t	r;		/* result block number */
	xfs_suminfo_t	sum;		/* summary information for extents */

	ASSERT(minlen % prod == 0 && maxlen % prod == 0);
	/*
	 * Loop over all the levels starting with maxlen.
	 * At each level, look at all the bitmap blocks, to see if there
	 * are extents starting there that are long enough (>= maxlen).
	 * Note, only on the initial level can the allocation fail if
	 * the summary says there's an extent.
	 */
	for (l = xfs_highbit32(maxlen); l < mp->m_rsumlevels; l++) {
		/*
		 * Loop over all the bitmap blocks.
		 */
		for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
			/*
			 * Get the summary for this level/block.
			 */
			error = xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
				&sum);
			if (error) {
				return error;
			}
			/*
			 * Nothing there, on to the next block.
			 */
			if (!sum)
				continue;
			/*
			 * Try allocating the extent.
			 */
			error = xfs_rtallocate_extent_block(mp, tp, i, maxlen,
				maxlen, len, &n, rbpp, rsb, prod, &r);
			if (error) {
				return error;
			}
			/*
			 * If it worked, return that.
			 */
			if (r != NULLRTBLOCK) {
				*rtblock = r;
				return 0;
			}
			/*
			 * If the "next block to try" returned from the
			 * allocator is beyond the next bitmap block,
			 * skip to that bitmap block.
			 */
			if (XFS_BITTOBLOCK(mp, n) > i + 1)
				i = XFS_BITTOBLOCK(mp, n) - 1;
		}
	}
	/*
	 * Didn't find any maxlen blocks.  Try smaller ones, unless
	 * we're asking for a fixed size extent.
	 */
	if (minlen > --maxlen) {
		*rtblock = NULLRTBLOCK;
		return 0;
	}
	/*
	 * Loop over sizes, from maxlen down to minlen.
	 * This time, when we do the allocations, allow smaller ones
	 * to succeed.
	 */
	for (l = xfs_highbit32(maxlen); l >= xfs_highbit32(minlen); l--) {
		/*
		 * Loop over all the bitmap blocks, try an allocation
		 * starting in that block.
		 */
		for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
			/*
			 * Get the summary information for this level/block.
			 */
			error =	xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
						  &sum);
			if (error) {
				return error;
			}
			/*
			 * If nothing there, go on to next.
			 */
			if (!sum)
				continue;
			/*
			 * Try the allocation.  Make sure the specified
			 * minlen/maxlen are in the possible range for
			 * this summary level.
			 */
			error = xfs_rtallocate_extent_block(mp, tp, i,
					XFS_RTMAX(minlen, 1 << l),
					XFS_RTMIN(maxlen, (1 << (l + 1)) - 1),
					len, &n, rbpp, rsb, prod, &r);
			if (error) {
				return error;
			}
			/*
			 * If it worked, return that extent.
			 */
			if (r != NULLRTBLOCK) {
				*rtblock = r;
				return 0;
			}
			/*
			 * If the "next block to try" returned from the
			 * allocator is beyond the next bitmap block,
			 * skip to that bitmap block.
			 */
			if (XFS_BITTOBLOCK(mp, n) > i + 1)
				i = XFS_BITTOBLOCK(mp, n) - 1;
		}
	}
	/*
	 * Got nothing, return failure.
	 */
	*rtblock = NULLRTBLOCK;
	return 0;
}

/*
 * Mark an extent specified by start and len allocated.
 * Updates all the summary information as well as the bitmap.
 */
STATIC int				/* error */
xfs_rtallocate_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* start block to allocate */
	xfs_extlen_t	len,		/* length to allocate */
	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb)		/* in/out: summary block number */
{
	xfs_rtblock_t	end;		/* end of the allocated extent */
	int		error;		/* error value */
	xfs_rtblock_t	postblock;	/* first block allocated > end */
	xfs_rtblock_t	preblock;	/* first block allocated < start */

	end = start + len - 1;
	/*
	 * Assume we're allocating out of the middle of a free extent.
	 * We need to find the beginning and end of the extent so we can
	 * properly update the summary.
	 */
	error = xfs_rtfind_back(mp, tp, start, 0, &preblock);
	if (error) {
		return error;
	}
	/*
	 * Find the next allocated block (end of free extent).
	 */
	error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
		&postblock);
	if (error) {
		return error;
	}
	/*
	 * Decrement the summary information corresponding to the entire
	 * (old) free extent.
	 */
	error = xfs_rtmodify_summary(mp, tp,
		XFS_RTBLOCKLOG(postblock + 1 - preblock),
		XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
	if (error) {
		return error;
	}
	/*
	 * If there are blocks not being allocated at the front of the
	 * old extent, add summary data for them to be free.
	 */
	if (preblock < start) {
		error = xfs_rtmodify_summary(mp, tp,
			XFS_RTBLOCKLOG(start - preblock),
			XFS_BITTOBLOCK(mp, preblock), 1, rbpp, rsb);
		if (error) {
			return error;
		}
	}
	/*
	 * If there are blocks not being allocated at the end of the
	 * old extent, add summary data for them to be free.
	 */
	if (postblock > end) {
		error = xfs_rtmodify_summary(mp, tp,
			XFS_RTBLOCKLOG(postblock - end),
			XFS_BITTOBLOCK(mp, end + 1), 1, rbpp, rsb);
		if (error) {
			return error;
		}
	}
	/*
	 * Modify the bitmap to mark this extent allocated.
	 */
	error = xfs_rtmodify_range(mp, tp, start, len, 0);
	return error;
}

/*
 * Return whether there are any free extents in the size range given
 * by low and high, for the bitmap block bbno.
 */
STATIC int				/* error */
xfs_rtany_summary(
	xfs_mount_t	*mp,		/* file system mount structure */
	xfs_trans_t	*tp,		/* transaction pointer */
	int		low,		/* low log2 extent size */
	int		high,		/* high log2 extent size */
	xfs_rtblock_t	bbno,		/* bitmap block number */
	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	int		*stat)		/* out: any good extents here? */
{
	int		error;		/* error value */
	int		log;		/* loop counter, log2 of ext. size */
	xfs_suminfo_t	sum;		/* summary data */

	/*
	 * Loop over logs of extent sizes.  Order is irrelevant.
	 */
	for (log = low; log <= high; log++) {
		/*
		 * Get one summary datum.
		 */
		error = xfs_rtget_summary(mp, tp, log, bbno, rbpp, rsb, &sum);
		if (error) {
			return error;
		}
		/*
		 * If there are any, return success.
		 */
		if (sum) {
			*stat = 1;
			return 0;
		}
	}
	/*
	 * Found nothing, return failure.
	 */
	*stat = 0;
	return 0;
}

/*
 * Get a buffer for the bitmap or summary file block specified.
 * The buffer is returned read and locked.
 */
STATIC int				/* error */
xfs_rtbuf_get(
	xfs_mount_t	*mp,		/* file system mount structure */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	block,		/* block number in bitmap or summary */
	int		issum,		/* is summary not bitmap */
	xfs_buf_t	**bpp)		/* output: buffer for the block */
{
	xfs_buf_t	*bp;		/* block buffer, result */
	xfs_daddr_t	d;		/* disk addr of block */
	int		error;		/* error value */
	xfs_fsblock_t	fsb;		/* fs block number for block */
	xfs_inode_t	*ip;		/* bitmap or summary inode */

	ip = issum ? mp->m_rsumip : mp->m_rbmip;
	/*
	 * Map from the file offset (block) and inode number to the
	 * file system block.
	 */
	error = xfs_bmapi_single(tp, ip, XFS_DATA_FORK, &fsb, block);
	if (error) {
		return error;
	}
	ASSERT(fsb != NULLFSBLOCK);
	/*
	 * Convert to disk address for buffer cache.
	 */
	d = XFS_FSB_TO_DADDR(mp, fsb);
	/*
	 * Read the buffer.
	 */
	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
				   mp->m_bsize, 0, &bp);
	if (error) {
		return error;
	}
	ASSERT(bp && !XFS_BUF_GETERROR(bp));
	*bpp = bp;
	return 0;
}

#ifdef DEBUG
/*
 * Check that the given extent (block range) is allocated already.
 */
STATIC int				/* error */
xfs_rtcheck_alloc_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	bno,		/* starting block number of extent */
	xfs_extlen_t	len,		/* length of extent */
	int		*stat)		/* out: 1 for allocated, 0 for not */
{
	xfs_rtblock_t	new;		/* dummy for xfs_rtcheck_range */

	return xfs_rtcheck_range(mp, tp, bno, len, 0, &new, stat);
}
#endif

/*
 * Check that the given range is either all allocated (val = 0) or
 * all free (val = 1).
 */
STATIC int				/* error */
xfs_rtcheck_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* starting block number of extent */
	xfs_extlen_t	len,		/* length of extent */
	int		val,		/* 1 for free, 0 for allocated */
	xfs_rtblock_t	*new,		/* out: first block not matching */
	int		*stat)		/* out: 1 for matches, 0 for not */
{
	xfs_rtword_t	*b;		/* current word in buffer */
	int		bit;		/* bit number in the word */
	xfs_rtblock_t	block;		/* bitmap block number */
	xfs_buf_t	*bp;		/* buf for the block */
	xfs_rtword_t	*bufp;		/* starting word in buffer */
	int		error;		/* error value */
	xfs_rtblock_t	i;		/* current bit number rel. to start */