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Commit 7b2e2a31 authored by David Chinner's avatar David Chinner Committed by Lachlan McIlroy
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[XFS] Allow 64 bit machines to avoid the AIL lock during flushes 



When copying lsn's from the log item to the inode or dquot flush lsn, we
currently grab the AIL lock. We do this because the LSN is a 64 bit
quantity and it needs to be read atomically. The lock is used to guarantee
atomicity for 32 bit platforms.

Make the LSN copying a small function, and make the function used
conditional on BITS_PER_LONG so that 64 bit machines don't need to take
the AIL lock in these places.

SGI-PV: 988143

SGI-Modid: xfs-linux-melb:xfs-kern:32349a

Signed-off-by: default avatarDavid Chinner <david@fromorbit.com>
Signed-off-by: default avatarLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: default avatarChristoph Hellwig <hch@infradead.org>
parent 5b00f14f

fs/xfs/quota/xfs_dquot.c

+2 −4
Original line number Diff line number Diff line
@@ -1272,10 +1272,8 @@ xfs_qm_dqflush( 
	dqp->dq_flags &= ~(XFS_DQ_DIRTY);

	mp = dqp->q_mount;



	/* lsn is 64 bits */

	spin_lock(&mp->m_ail_lock);

	dqp->q_logitem.qli_flush_lsn = dqp->q_logitem.qli_item.li_lsn;

	spin_unlock(&mp->m_ail_lock);

	xfs_trans_ail_copy_lsn(mp->m_ail, &dqp->q_logitem.qli_flush_lsn,

					&dqp->q_logitem.qli_item.li_lsn);



	/*

	 * Attach an iodone routine so that we can remove this dquot from the

fs/xfs/xfs_inode.c

+7 −10
Original line number Diff line number Diff line
@@ -2214,9 +2214,9 @@ xfs_ifree_cluster( 
				iip = (xfs_inode_log_item_t *)lip;

				ASSERT(iip->ili_logged == 1);

				lip->li_cb = (void(*)(xfs_buf_t*,xfs_log_item_t*)) xfs_istale_done;

				spin_lock(&mp->m_ail_lock);

				iip->ili_flush_lsn = iip->ili_item.li_lsn;

				spin_unlock(&mp->m_ail_lock);

				xfs_trans_ail_copy_lsn(mp->m_ail,

							&iip->ili_flush_lsn,

							&iip->ili_item.li_lsn);

				xfs_iflags_set(iip->ili_inode, XFS_ISTALE);

				pre_flushed++;

			}
@@ -2237,9 +2237,8 @@ xfs_ifree_cluster( 
			iip->ili_last_fields = iip->ili_format.ilf_fields;

			iip->ili_format.ilf_fields = 0;

			iip->ili_logged = 1;

			spin_lock(&mp->m_ail_lock);

			iip->ili_flush_lsn = iip->ili_item.li_lsn;

			spin_unlock(&mp->m_ail_lock);

			xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,

						&iip->ili_item.li_lsn);



			xfs_buf_attach_iodone(bp,

				(void(*)(xfs_buf_t*,xfs_log_item_t*))
@@ -3476,10 +3475,8 @@ xfs_iflush_int( 
		iip->ili_format.ilf_fields = 0;

		iip->ili_logged = 1;



		ASSERT(sizeof(xfs_lsn_t) == 8);	/* don't lock if it shrinks */

		spin_lock(&mp->m_ail_lock);

		iip->ili_flush_lsn = iip->ili_item.li_lsn;

		spin_unlock(&mp->m_ail_lock);

		xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,

					&iip->ili_item.li_lsn);



		/*

		 * Attach the function xfs_iflush_done to the inode's

fs/xfs/xfs_trans_priv.h

+23 −0
Original line number Diff line number Diff line
@@ -106,4 +106,27 @@ void xfsaild_wakeup(struct xfs_ail *, xfs_lsn_t); 
int	xfsaild_start(struct xfs_ail *);

void	xfsaild_stop(struct xfs_ail *);



#if BITS_PER_LONG != 64

static inline void

xfs_trans_ail_copy_lsn(

	struct xfs_ail	*ailp,

	xfs_lsn_t	*dst,

	xfs_lsn_t	*src)

{

	ASSERT(sizeof(xfs_lsn_t) == 8);	/* don't lock if it shrinks */

	spin_lock(&ailp->xa_mount->m_ail_lock);

	*dst = *src;

	spin_unlock(&ailp->xa_mount->m_ail_lock);

}

#else

static inline void

xfs_trans_ail_copy_lsn(

	struct xfs_ail	*ailp,

	xfs_lsn_t	*dst,

	xfs_lsn_t	*src)

{

	ASSERT(sizeof(xfs_lsn_t) == 8);

	*dst = *src;

}

#endif

#endif	/* __XFS_TRANS_PRIV_H__ */