Commit 35dc55b9 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Chandan Babu R
Browse files

xfs: handle nimaps=0 from xfs_bmapi_write in xfs_alloc_file_space 



If xfs_bmapi_write finds a delalloc extent at the requested range, it
tries to convert the entire delalloc extent to a real allocation.

But if the allocator cannot find a single free extent large enough to
cover the start block of the requested range, xfs_bmapi_write will
return 0 but leave *nimaps set to 0.

In that case we simply need to keep looping with the same startoffset_fsb
so that one of the following allocations will eventually reach the
requested range.

Note that this could affect any caller of xfs_bmapi_write that covers
an existing delayed allocation.  As far as I can tell we do not have
any other such caller, though - the regular writeback path uses
xfs_bmapi_convert_delalloc to convert delayed allocations to real ones,
and direct I/O invalidates the page cache first.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatar"Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: default avatarChandan Babu R <chandanbabu@kernel.org>
parent 2b99e410

fs/xfs/xfs_bmap_util.c

+13 −11
Original line number Diff line number Diff line
@@ -774,12 +774,10 @@ xfs_alloc_file_space( 
{

	xfs_mount_t		*mp = ip->i_mount;

	xfs_off_t		count;

	xfs_filblks_t		allocated_fsb;

	xfs_filblks_t		allocatesize_fsb;

	xfs_extlen_t		extsz, temp;

	xfs_fileoff_t		startoffset_fsb;

	xfs_fileoff_t		endoffset_fsb;

	int			nimaps;

	int			rt;

	xfs_trans_t		*tp;

	xfs_bmbt_irec_t		imaps[1], *imapp;
@@ -802,7 +800,6 @@ xfs_alloc_file_space( 


	count = len;

	imapp = &imaps[0];

	nimaps = 1;

	startoffset_fsb	= XFS_B_TO_FSBT(mp, offset);

	endoffset_fsb = XFS_B_TO_FSB(mp, offset + count);

	allocatesize_fsb = endoffset_fsb - startoffset_fsb;
@@ -813,6 +810,7 @@ xfs_alloc_file_space( 
	while (allocatesize_fsb && !error) {

		xfs_fileoff_t	s, e;

		unsigned int	dblocks, rblocks, resblks;

		int		nimaps = 1;



		/*

		 * Determine space reservations for data/realtime.
@@ -878,15 +876,19 @@ xfs_alloc_file_space( 
		if (error)

			break;



		allocated_fsb = imapp->br_blockcount;



		if (nimaps == 0) {

			error = -ENOSPC;

			break;

		/*

		 * If the allocator cannot find a single free extent large

		 * enough to cover the start block of the requested range,

		 * xfs_bmapi_write will return 0 but leave *nimaps set to 0.

		 *

		 * In that case we simply need to keep looping with the same

		 * startoffset_fsb so that one of the following allocations

		 * will eventually reach the requested range.

		 */

		if (nimaps) {

			startoffset_fsb += imapp->br_blockcount;

			allocatesize_fsb -= imapp->br_blockcount;

		}



		startoffset_fsb += allocated_fsb;

		allocatesize_fsb -= allocated_fsb;

	}



	return error;