Commit 3070451e authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Alex Elder
Browse files

xfs: reduce stack usage in xfs_iomap 



xfs_iomap passes a xfs_bmbt_irec pointer to xfs_iomap_write_direct and
xfs_iomap_write_allocate to give them the results of our read-only
xfs_bmapi query.  Instead of allocating a new xfs_bmbt_irec on stack
for the next call to xfs_bmapi re use the one we got passed as it's not
used after this point.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
parent 7a36c8a9

fs/xfs/xfs_iomap.c

+28 −24
Original line number Diff line number Diff line
@@ -242,7 +242,7 @@ xfs_iomap_write_direct( 
	xfs_off_t	offset,

	size_t		count,

	int		flags,

	xfs_bmbt_irec_t *ret_imap,

	xfs_bmbt_irec_t *imap,

	int		*nmaps)

{

	xfs_mount_t	*mp = ip->i_mount;
@@ -256,7 +256,6 @@ xfs_iomap_write_direct( 
	int		quota_flag;

	int		rt;

	xfs_trans_t	*tp;

	xfs_bmbt_irec_t imap;

	xfs_bmap_free_t free_list;

	uint		qblocks, resblks, resrtextents;

	int		committed;
@@ -280,10 +279,10 @@ xfs_iomap_write_direct( 
		if (error)

			goto error_out;

	} else {

		if (*nmaps && (ret_imap->br_startblock == HOLESTARTBLOCK))

		if (*nmaps && (imap->br_startblock == HOLESTARTBLOCK))

			last_fsb = MIN(last_fsb, (xfs_fileoff_t)

					ret_imap->br_blockcount +

					ret_imap->br_startoff);

					imap->br_blockcount +

					imap->br_startoff);

	}

	count_fsb = last_fsb - offset_fsb;

	ASSERT(count_fsb > 0);
@@ -336,12 +335,15 @@ xfs_iomap_write_direct( 
		bmapi_flag |= XFS_BMAPI_PREALLOC;



	/*

	 * Issue the xfs_bmapi() call to allocate the blocks

	 * Issue the xfs_bmapi() call to allocate the blocks.

	 *

	 * From this point onwards we overwrite the imap pointer that the

	 * caller gave to us.

	 */

	xfs_bmap_init(&free_list, &firstfsb);

	nimaps = 1;

	error = xfs_bmapi(tp, ip, offset_fsb, count_fsb, bmapi_flag,

		&firstfsb, 0, &imap, &nimaps, &free_list);

		&firstfsb, 0, imap, &nimaps, &free_list);

	if (error)

		goto error0;
@@ -363,12 +365,11 @@ xfs_iomap_write_direct( 
		goto error_out;

	}



	if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip))) {

		error = xfs_cmn_err_fsblock_zero(ip, &imap);

	if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) {

		error = xfs_cmn_err_fsblock_zero(ip, imap);

		goto error_out;

	}



	*ret_imap = imap;

	*nmaps = 1;

	return 0;
@@ -542,7 +543,7 @@ xfs_iomap_write_allocate( 
	xfs_inode_t	*ip,

	xfs_off_t	offset,

	size_t		count,

	xfs_bmbt_irec_t *map,

	xfs_bmbt_irec_t *imap,

	int		*retmap)

{

	xfs_mount_t	*mp = ip->i_mount;
@@ -551,7 +552,6 @@ xfs_iomap_write_allocate( 
	xfs_fsblock_t	first_block;

	xfs_bmap_free_t	free_list;

	xfs_filblks_t	count_fsb;

	xfs_bmbt_irec_t	imap;

	xfs_trans_t	*tp;

	int		nimaps, committed;

	int		error = 0;
@@ -567,8 +567,8 @@ xfs_iomap_write_allocate( 
		return XFS_ERROR(error);



	offset_fsb = XFS_B_TO_FSBT(mp, offset);

	count_fsb = map->br_blockcount;

	map_start_fsb = map->br_startoff;

	count_fsb = imap->br_blockcount;

	map_start_fsb = imap->br_startoff;



	XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
@@ -647,10 +647,15 @@ xfs_iomap_write_allocate( 
				}

			}



			/* Go get the actual blocks */

			/*

			 * Go get the actual blocks.

	 	 	 *

			 * From this point onwards we overwrite the imap

			 * pointer that the caller gave to us.

			 */

			error = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,

					XFS_BMAPI_WRITE, &first_block, 1,

					&imap, &nimaps, &free_list);

					imap, &nimaps, &free_list);

			if (error)

				goto trans_cancel;
@@ -669,13 +674,12 @@ xfs_iomap_write_allocate( 
		 * See if we were able to allocate an extent that

		 * covers at least part of the callers request

		 */

		if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))

			return xfs_cmn_err_fsblock_zero(ip, &imap);

		if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))

			return xfs_cmn_err_fsblock_zero(ip, imap);



		if ((offset_fsb >= imap.br_startoff) &&

		    (offset_fsb < (imap.br_startoff +

				   imap.br_blockcount))) {

			*map = imap;

		if ((offset_fsb >= imap->br_startoff) &&

		    (offset_fsb < (imap->br_startoff +

				   imap->br_blockcount))) {

			*retmap = 1;

			XFS_STATS_INC(xs_xstrat_quick);

			return 0;
@@ -685,8 +689,8 @@ xfs_iomap_write_allocate( 
		 * So far we have not mapped the requested part of the

		 * file, just surrounding data, try again.

		 */

		count_fsb -= imap.br_blockcount;

		map_start_fsb = imap.br_startoff + imap.br_blockcount;

		count_fsb -= imap->br_blockcount;

		map_start_fsb = imap->br_startoff + imap->br_blockcount;

	}



trans_cancel:

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