コード例 #1
0
ファイル: xfs_ialloc.c プロジェクト: xf739645524/kernel-rhel5
/*
 * Select an allocation group to look for a free inode in, based on the parent
 * inode and then mode.  Return the allocation group buffer.
 */
STATIC xfs_buf_t *			/* allocation group buffer */
xfs_ialloc_ag_select(
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_ino_t	parent,		/* parent directory inode number */
	mode_t		mode,		/* bits set to indicate file type */
	int		okalloc)	/* ok to allocate more space */
{
	xfs_buf_t	*agbp;		/* allocation group header buffer */
	xfs_agnumber_t	agcount;	/* number of ag's in the filesystem */
	xfs_agnumber_t	agno;		/* current ag number */
	int		flags;		/* alloc buffer locking flags */
	xfs_extlen_t	ineed;		/* blocks needed for inode allocation */
	xfs_extlen_t	longest = 0;	/* longest extent available */
	xfs_mount_t	*mp;		/* mount point structure */
	int		needspace;	/* file mode implies space allocated */
	xfs_perag_t	*pag;		/* per allocation group data */
	xfs_agnumber_t	pagno;		/* parent (starting) ag number */

	/*
	 * Files of these types need at least one block if length > 0
	 * (and they won't fit in the inode, but that's hard to figure out).
	 */
	needspace = S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode);
	mp = tp->t_mountp;
	agcount = mp->m_maxagi;
	if (S_ISDIR(mode))
		pagno = xfs_ialloc_next_ag(mp);
	else {
		pagno = XFS_INO_TO_AGNO(mp, parent);
		if (pagno >= agcount)
			pagno = 0;
	}
	ASSERT(pagno < agcount);
	/*
	 * Loop through allocation groups, looking for one with a little
	 * free space in it.  Note we don't look for free inodes, exactly.
	 * Instead, we include whether there is a need to allocate inodes
	 * to mean that blocks must be allocated for them,
	 * if none are currently free.
	 */
	agno = pagno;
	flags = XFS_ALLOC_FLAG_TRYLOCK;
	down_read(&mp->m_peraglock);
	for (;;) {
		pag = &mp->m_perag[agno];
		if (!pag->pagi_init) {
			if (xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
				agbp = NULL;
				goto nextag;
			}
		} else
			agbp = NULL;

		if (!pag->pagi_inodeok) {
			xfs_ialloc_next_ag(mp);
			goto unlock_nextag;
		}

		/*
		 * Is there enough free space for the file plus a block
		 * of inodes (if we need to allocate some)?
		 */
		ineed = pag->pagi_freecount ? 0 : XFS_IALLOC_BLOCKS(mp);
		if (ineed && !pag->pagf_init) {
			if (agbp == NULL &&
			    xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
				agbp = NULL;
				goto nextag;
			}
			(void)xfs_alloc_pagf_init(mp, tp, agno, flags);
		}
		if (!ineed || pag->pagf_init) {
			if (ineed && !(longest = pag->pagf_longest))
				longest = pag->pagf_flcount > 0;
			if (!ineed ||
			    (pag->pagf_freeblks >= needspace + ineed &&
			     longest >= ineed &&
			     okalloc)) {
				if (agbp == NULL &&
				    xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
					agbp = NULL;
					goto nextag;
				}
				up_read(&mp->m_peraglock);
				return agbp;
			}
		}
unlock_nextag:
		if (agbp)
			xfs_trans_brelse(tp, agbp);
nextag:
		/*
		 * No point in iterating over the rest, if we're shutting
		 * down.
		 */
		if (XFS_FORCED_SHUTDOWN(mp)) {
			up_read(&mp->m_peraglock);
			return NULL;
		}
		agno++;
		if (agno >= agcount)
			agno = 0;
		if (agno == pagno) {
			if (flags == 0) {
				up_read(&mp->m_peraglock);
				return NULL;
			}
			flags = 0;
		}
	}
}
コード例 #2
0
ファイル: xfs_ialloc.c プロジェクト: Cool-Joe/imx23-audio
/*
 * Allocate an inode on disk.
 *
 * Mode is used to tell whether the new inode will need space, and whether it
 * is a directory.
 *
 * This function is designed to be called twice if it has to do an allocation
 * to make more free inodes.  On the first call, *IO_agbp should be set to NULL.
 * If an inode is available without having to performn an allocation, an inode
 * number is returned.  In this case, *IO_agbp is set to NULL.  If an allocation
 * needs to be done, xfs_dialloc returns the current AGI buffer in *IO_agbp.
 * The caller should then commit the current transaction, allocate a
 * new transaction, and call xfs_dialloc() again, passing in the previous value
 * of *IO_agbp.  IO_agbp should be held across the transactions. Since the AGI
 * buffer is locked across the two calls, the second call is guaranteed to have
 * a free inode available.
 *
 * Once we successfully pick an inode its number is returned and the on-disk
 * data structures are updated.  The inode itself is not read in, since doing so
 * would break ordering constraints with xfs_reclaim.
 */
int
xfs_dialloc(
	struct xfs_trans	*tp,
	xfs_ino_t		parent,
	umode_t			mode,
	int			okalloc,
	struct xfs_buf		**IO_agbp,
	xfs_ino_t		*inop)
{
	struct xfs_mount	*mp = tp->t_mountp;
	struct xfs_buf		*agbp;
	xfs_agnumber_t		agno;
	int			error;
	int			ialloced;
	int			noroom = 0;
	xfs_agnumber_t		start_agno;
	struct xfs_perag	*pag;

	if (*IO_agbp) {
		/*
		 * If the caller passes in a pointer to the AGI buffer,
		 * continue where we left off before.  In this case, we
		 * know that the allocation group has free inodes.
		 */
		agbp = *IO_agbp;
		goto out_alloc;
	}

	/*
	 * We do not have an agbp, so select an initial allocation
	 * group for inode allocation.
	 */
	start_agno = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
	if (start_agno == NULLAGNUMBER) {
		*inop = NULLFSINO;
		return 0;
	}

	/*
	 * If we have already hit the ceiling of inode blocks then clear
	 * okalloc so we scan all available agi structures for a free
	 * inode.
	 */
	if (mp->m_maxicount &&
	    mp->m_sb.sb_icount + XFS_IALLOC_INODES(mp) > mp->m_maxicount) {
		noroom = 1;
		okalloc = 0;
	}

	/*
	 * Loop until we find an allocation group that either has free inodes
	 * or in which we can allocate some inodes.  Iterate through the
	 * allocation groups upward, wrapping at the end.
	 */
	agno = start_agno;
	for (;;) {
		pag = xfs_perag_get(mp, agno);
		if (!pag->pagi_inodeok) {
			xfs_ialloc_next_ag(mp);
			goto nextag;
		}

		if (!pag->pagi_init) {
			error = xfs_ialloc_pagi_init(mp, tp, agno);
			if (error)
				goto out_error;
		}

		/*
		 * Do a first racy fast path check if this AG is usable.
		 */
		if (!pag->pagi_freecount && !okalloc)
			goto nextag;

		/*
		 * Then read in the AGI buffer and recheck with the AGI buffer
		 * lock held.
		 */
		error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
		if (error)
			goto out_error;

		if (pag->pagi_freecount) {
			xfs_perag_put(pag);
			goto out_alloc;
		}

		if (!okalloc)
			goto nextag_relse_buffer;


		error = xfs_ialloc_ag_alloc(tp, agbp, &ialloced);
		if (error) {
			xfs_trans_brelse(tp, agbp);

			if (error != ENOSPC)
				goto out_error;

			xfs_perag_put(pag);
			*inop = NULLFSINO;
			return 0;
		}

		if (ialloced) {
			/*
			 * We successfully allocated some inodes, return
			 * the current context to the caller so that it
			 * can commit the current transaction and call
			 * us again where we left off.
			 */
			ASSERT(pag->pagi_freecount > 0);
			xfs_perag_put(pag);

			*IO_agbp = agbp;
			*inop = NULLFSINO;
			return 0;
		}

nextag_relse_buffer:
		xfs_trans_brelse(tp, agbp);
nextag:
		xfs_perag_put(pag);
		if (++agno == mp->m_sb.sb_agcount)
			agno = 0;
		if (agno == start_agno) {
			*inop = NULLFSINO;
			return noroom ? ENOSPC : 0;
		}
	}

out_alloc:
	*IO_agbp = NULL;
	return xfs_dialloc_ag(tp, agbp, parent, inop);
out_error:
	xfs_perag_put(pag);
	return XFS_ERROR(error);
}