Commit 1214f1cf authored by Brian Foster's avatar Brian Foster Committed by Darrick J. Wong
Browse files

xfs: replace dop_low with transaction flag 



The dop_low field enables the low free space allocation mode when a
previous allocation has detected difficulty allocating blocks. It
has historically been part of the xfs_defer_ops structure, which
means if enabled, it remains enabled across a set of transactions
until the deferred operations have completed and the dfops is reset.

Now that the dfops is embedded in the transaction, we can save a bit
more space by using a transaction flag rather than a standalone
boolean. Drop the ->dop_low field and replace it with a transaction
flag that is set at the same points, carried across rolling
transactions and cleared on completion of deferred operations. This
essentially emulates the behavior of ->dop_low and so should not
change behavior.

Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent ce356d64

fs/xfs/libxfs/xfs_bmap.c

+4 −4
Original line number Diff line number Diff line
@@ -700,7 +700,7 @@ xfs_bmap_extents_to_btree( 
	if (tp->t_firstblock == NULLFSBLOCK) {

		args.type = XFS_ALLOCTYPE_START_BNO;

		args.fsbno = XFS_INO_TO_FSB(mp, ip->i_ino);

	} else if (tp->t_dfops->dop_low) {

	} else if (tp->t_flags & XFS_TRANS_LOWMODE) {

		args.type = XFS_ALLOCTYPE_START_BNO;

		args.fsbno = tp->t_firstblock;

	} else {
@@ -3449,7 +3449,7 @@ xfs_bmap_btalloc( 
			error = xfs_bmap_btalloc_nullfb(ap, &args, &blen);

		if (error)

			return error;

	} else if (ap->tp->t_dfops->dop_low) {

	} else if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {

		if (xfs_inode_is_filestream(ap->ip))

			args.type = XFS_ALLOCTYPE_FIRST_AG;

		else
@@ -3484,7 +3484,7 @@ xfs_bmap_btalloc( 
	 * is >= the stripe unit and the allocation offset is

	 * at the end of file.

	 */

	if (!ap->tp->t_dfops->dop_low && ap->aeof) {

	if (!(ap->tp->t_flags & XFS_TRANS_LOWMODE) && ap->aeof) {

		if (!ap->offset) {

			args.alignment = stripe_align;

			atype = args.type;
@@ -3576,7 +3576,7 @@ xfs_bmap_btalloc( 
		args.total = ap->minlen;

		if ((error = xfs_alloc_vextent(&args)))

			return error;

		ap->tp->t_dfops->dop_low = true;

		ap->tp->t_flags |= XFS_TRANS_LOWMODE;

	}

	if (args.fsbno != NULLFSBLOCK) {

		/*

fs/xfs/libxfs/xfs_bmap_btree.c

+2 −2
Original line number Diff line number Diff line
@@ -226,7 +226,7 @@ xfs_bmbt_alloc_block( 
		 * block allocation here and corrupt the filesystem.

		 */

		args.minleft = args.tp->t_blk_res;

	} else if (cur->bc_tp->t_dfops->dop_low) {

	} else if (cur->bc_tp->t_flags & XFS_TRANS_LOWMODE) {

		args.type = XFS_ALLOCTYPE_START_BNO;

	} else {

		args.type = XFS_ALLOCTYPE_NEAR_BNO;
@@ -253,7 +253,7 @@ xfs_bmbt_alloc_block( 
		error = xfs_alloc_vextent(&args);

		if (error)

			goto error0;

		cur->bc_tp->t_dfops->dop_low = true;

		cur->bc_tp->t_flags |= XFS_TRANS_LOWMODE;

	}

	if (WARN_ON_ONCE(args.fsbno == NULLFSBLOCK)) {

		*stat = 0;

fs/xfs/libxfs/xfs_defer.c

+14 −2
Original line number Diff line number Diff line
@@ -330,9 +330,14 @@ xfs_defer_reset( 


	ASSERT(!xfs_defer_has_unfinished_work(dop));



	dop->dop_low = false;

	memset(dop->dop_inodes, 0, sizeof(dop->dop_inodes));

	memset(dop->dop_bufs, 0, sizeof(dop->dop_bufs));



	/*

	 * Low mode state transfers across transaction rolls to mirror dfops

	 * lifetime. Clear it now that dfops is reset.

	 */

	tp->t_flags &= ~XFS_TRANS_LOWMODE;

}



/*
@@ -590,7 +595,14 @@ xfs_defer_move( 


	memcpy(dst->dop_inodes, src->dop_inodes, sizeof(dst->dop_inodes));

	memcpy(dst->dop_bufs, src->dop_bufs, sizeof(dst->dop_bufs));

	dst->dop_low = src->dop_low;



	/*

	 * Low free space mode was historically controlled by a dfops field.

	 * This meant that low mode state potentially carried across multiple

	 * transaction rolls. Transfer low mode on a dfops move to preserve

	 * that behavior.

	 */

	dtp->t_flags |= (stp->t_flags & XFS_TRANS_LOWMODE);



	xfs_defer_reset(stp);

}

fs/xfs/libxfs/xfs_defer.h

+0 −11
Original line number Diff line number Diff line
@@ -25,17 +25,6 @@ struct xfs_defer_pending { 


/*

 * Header for deferred operation list.

 *

 * dop_low is used by the allocator to activate the lowspace algorithm -

 * when free space is running low the extent allocator may choose to

 * allocate an extent from an AG without leaving sufficient space for

 * a btree split when inserting the new extent.  In this case the allocator

 * will enable the lowspace algorithm which is supposed to allow further

 * allocations (such as btree splits and newroots) to allocate from

 * sequential AGs.  In order to avoid locking AGs out of order the lowspace

 * algorithm will start searching for free space from AG 0.  If the correct

 * transaction reservations have been made then this algorithm will eventually

 * find all the space it needs.

 */

enum xfs_defer_ops_type {

	XFS_DEFER_OPS_TYPE_BMAP,

fs/xfs/libxfs/xfs_shared.h

+12 −0
Original line number Diff line number Diff line
@@ -64,6 +64,18 @@ void xfs_log_get_max_trans_res(struct xfs_mount *mp, 
#define XFS_TRANS_RESERVE	0x20    /* OK to use reserved data blocks */

#define XFS_TRANS_NO_WRITECOUNT 0x40	/* do not elevate SB writecount */

#define XFS_TRANS_NOFS		0x80	/* pass KM_NOFS to kmem_alloc */

/*

 * LOWMODE is used by the allocator to activate the lowspace algorithm - when

 * free space is running low the extent allocator may choose to allocate an

 * extent from an AG without leaving sufficient space for a btree split when

 * inserting the new extent. In this case the allocator will enable the

 * lowspace algorithm which is supposed to allow further allocations (such as

 * btree splits and newroots) to allocate from sequential AGs. In order to

 * avoid locking AGs out of order the lowspace algorithm will start searching

 * for free space from AG 0. If the correct transaction reservations have been

 * made then this algorithm will eventually find all the space it needs.

 */

#define XFS_TRANS_LOWMODE	0x100	/* allocate in low space mode */



/*

 * Field values for xfs_trans_mod_sb.

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