Commit 90c60e16 authored by Dave Chinner's avatar Dave Chinner Committed by Darrick J. Wong
Browse files

xfs: xfs_iflush() is no longer necessary 



Now we have a cached buffer on inode log items, we don't need
to do buffer lookups when flushing inodes anymore - all we need
to do is lock the buffer and we are ready to go.

This largely gets rid of the need for xfs_iflush(), which is
essentially just a mechanism to look up the buffer and flush the
inode to it. Instead, we can just call xfs_iflush_cluster() with a
few modifications to ensure it also flushes the inode we already
hold locked.

This allows the AIL inode item pushing to be almost entirely
non-blocking in XFS - we won't block unless memory allocation
for the cluster inode lookup blocks or the block device queues are
full.

Writeback during inode reclaim becomes a little more complex because
we now have to lock the buffer ourselves, but otherwise this change
is largely a functional no-op that removes a whole lot of code.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 48d55e2a

fs/xfs/xfs_inode.c

+14 −93
Original line number Diff line number Diff line
@@ -3450,7 +3450,18 @@ xfs_rename( 
	return error;

}



STATIC int

/*

 * Non-blocking flush of dirty inode metadata into the backing buffer.

 *

 * The caller must have a reference to the inode and hold the cluster buffer

 * locked. The function will walk across all the inodes on the cluster buffer it

 * can find and lock without blocking, and flush them to the cluster buffer.

 *

 * On success, the caller must write out the buffer returned in *bp and

 * release it. On failure, the filesystem will be shut down, the buffer will

 * have been unlocked and released, and EFSCORRUPTED will be returned.

 */

int

xfs_iflush_cluster(

	struct xfs_inode	*ip,

	struct xfs_buf		*bp)
@@ -3485,8 +3496,6 @@ xfs_iflush_cluster( 


	for (i = 0; i < nr_found; i++) {

		cip = cilist[i];

		if (cip == ip)

			continue;



		/*

		 * because this is an RCU protected lookup, we could find a
@@ -3577,99 +3586,11 @@ xfs_iflush_cluster( 
	kmem_free(cilist);

out_put:

	xfs_perag_put(pag);

	return error;

}



/*

 * Flush dirty inode metadata into the backing buffer.

 *

 * The caller must have the inode lock and the inode flush lock held.  The

 * inode lock will still be held upon return to the caller, and the inode

 * flush lock will be released after the inode has reached the disk.

 *

 * The caller must write out the buffer returned in *bpp and release it.

 */

int

xfs_iflush(

	struct xfs_inode	*ip,

	struct xfs_buf		**bpp)

{

	struct xfs_mount	*mp = ip->i_mount;

	struct xfs_buf		*bp = NULL;

	struct xfs_dinode	*dip;

	int			error;



	XFS_STATS_INC(mp, xs_iflush_count);



	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));

	ASSERT(xfs_isiflocked(ip));

	ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||

	       ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));



	*bpp = NULL;



	xfs_iunpin_wait(ip);



	/*

	 * For stale inodes we cannot rely on the backing buffer remaining

	 * stale in cache for the remaining life of the stale inode and so

	 * xfs_imap_to_bp() below may give us a buffer that no longer contains

	 * inodes below. We have to check this after ensuring the inode is

	 * unpinned so that it is safe to reclaim the stale inode after the

	 * flush call.

	 */

	if (xfs_iflags_test(ip, XFS_ISTALE)) {

		xfs_ifunlock(ip);

		return 0;

	}



	/*

	 * Get the buffer containing the on-disk inode. We are doing a try-lock

	 * operation here, so we may get an EAGAIN error. In that case, return

	 * leaving the inode dirty.

	 *

	 * If we get any other error, we effectively have a corruption situation

	 * and we cannot flush the inode. Abort the flush and shut down.

	 */

	error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK);

	if (error == -EAGAIN) {

		xfs_ifunlock(ip);

		return error;

	}

	if (error)

		goto abort;



	/*

	 * If the buffer is pinned then push on the log now so we won't

	 * get stuck waiting in the write for too long.

	 */

	if (xfs_buf_ispinned(bp))

		xfs_log_force(mp, 0);



	/*

	 * Flush the provided inode then attempt to gather others from the

	 * cluster into the write.

	 *

	 * Note: Once we attempt to flush an inode, we must run buffer

	 * completion callbacks on any failure. If this fails, simulate an I/O

	 * failure on the buffer and shut down.

	 */

	error = xfs_iflush_int(ip, bp);

	if (!error)

		error = xfs_iflush_cluster(ip, bp);

	if (error) {

		bp->b_flags |= XBF_ASYNC;

		xfs_buf_ioend_fail(bp);

		goto shutdown;

	}



	*bpp = bp;

	return 0;



abort:

	xfs_iflush_abort(ip);

shutdown:

		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);

	}

	return error;

}
@@ -3687,7 +3608,7 @@ xfs_iflush_int( 
	ASSERT(xfs_isiflocked(ip));

	ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||

	       ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));

	ASSERT(iip != NULL && iip->ili_fields != 0);

	ASSERT(iip->ili_item.li_buf == bp);



	dip = xfs_buf_offset(bp, ip->i_imap.im_boffset);

fs/xfs/xfs_inode.h

+1 −1
Original line number Diff line number Diff line
@@ -426,7 +426,7 @@ int xfs_log_force_inode(struct xfs_inode *ip); 
void		xfs_iunpin_wait(xfs_inode_t *);

#define xfs_ipincount(ip)	((unsigned int) atomic_read(&ip->i_pincount))



int		xfs_iflush(struct xfs_inode *, struct xfs_buf **);

int		xfs_iflush_cluster(struct xfs_inode *, struct xfs_buf *);

void		xfs_lock_two_inodes(struct xfs_inode *ip0, uint ip0_mode,

				struct xfs_inode *ip1, uint ip1_mode);

fs/xfs/xfs_inode_item.c

+18 −33
Original line number Diff line number Diff line
@@ -485,53 +485,38 @@ xfs_inode_item_push( 
	uint			rval = XFS_ITEM_SUCCESS;

	int			error;



	if (xfs_ipincount(ip) > 0)

	ASSERT(iip->ili_item.li_buf);



	if (xfs_ipincount(ip) > 0 || xfs_buf_ispinned(bp) ||

	    (ip->i_flags & XFS_ISTALE))

		return XFS_ITEM_PINNED;



	if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED))

		return XFS_ITEM_LOCKED;

	/* If the inode is already flush locked, we're already flushing. */

	if (xfs_isiflocked(ip))

		return XFS_ITEM_FLUSHING;



	/*

	 * Re-check the pincount now that we stabilized the value by

	 * taking the ilock.

	 */

	if (xfs_ipincount(ip) > 0) {

		rval = XFS_ITEM_PINNED;

		goto out_unlock;

	}

	if (!xfs_buf_trylock(bp))

		return XFS_ITEM_LOCKED;



	/*

	 * Stale inode items should force out the iclog.

	 */

	if (ip->i_flags & XFS_ISTALE) {

		rval = XFS_ITEM_PINNED;

		goto out_unlock;

	}

	spin_unlock(&lip->li_ailp->ail_lock);



	/*

	 * Someone else is already flushing the inode.  Nothing we can do

	 * here but wait for the flush to finish and remove the item from

	 * the AIL.

	 * We need to hold a reference for flushing the cluster buffer as it may

	 * fail the buffer without IO submission. In which case, we better get a

	 * reference for that completion because otherwise we don't get a

	 * reference for IO until we queue the buffer for delwri submission.

	 */

	if (!xfs_iflock_nowait(ip)) {

		rval = XFS_ITEM_FLUSHING;

		goto out_unlock;

	}



	ASSERT(iip->ili_fields != 0 || XFS_FORCED_SHUTDOWN(ip->i_mount));

	spin_unlock(&lip->li_ailp->ail_lock);



	error = xfs_iflush(ip, &bp);

	xfs_buf_hold(bp);

	error = xfs_iflush_cluster(ip, bp);

	if (!error) {

		if (!xfs_buf_delwri_queue(bp, buffer_list))

			rval = XFS_ITEM_FLUSHING;

		xfs_buf_relse(bp);

	} else if (error == -EAGAIN)

	} else {

		rval = XFS_ITEM_LOCKED;

	}



	spin_lock(&lip->li_ailp->ail_lock);

out_unlock:

	xfs_iunlock(ip, XFS_ILOCK_SHARED);

	return rval;

}