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Commit 0cc6eee1 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Felix Blyakher
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xfs: avoid memory allocation under m_peraglock in growfs code 



Allocate the memory for the larger m_perag array before taking the
per-AG lock as the per-AG lock can be taken under the i_lock which
can be taken from reclaim context.

Reported by the new reclaim context tracing in lockdep.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarFelix Blyakher <felixb@sgi.com>
Signed-off-by: default avatarFelix Blyakher <felixb@sgi.com>
parent c8a4051c

fs/xfs/xfs_fsops.c

+14 −6
Original line number Diff line number Diff line
@@ -167,17 +167,25 @@ xfs_growfs_data_private( 
	new = nb - mp->m_sb.sb_dblocks;

	oagcount = mp->m_sb.sb_agcount;

	if (nagcount > oagcount) {

		void *new_perag, *old_perag;



		xfs_filestream_flush(mp);



		new_perag = kmem_zalloc(sizeof(xfs_perag_t) * nagcount,

					KM_MAYFAIL);

		if (!new_perag)

			return XFS_ERROR(ENOMEM);



		down_write(&mp->m_peraglock);

		mp->m_perag = kmem_realloc(mp->m_perag,

			sizeof(xfs_perag_t) * nagcount,

			sizeof(xfs_perag_t) * oagcount,

			KM_SLEEP);

		memset(&mp->m_perag[oagcount], 0,

			(nagcount - oagcount) * sizeof(xfs_perag_t));

		memcpy(new_perag, mp->m_perag, sizeof(xfs_perag_t) * oagcount);

		old_perag = mp->m_perag;

		mp->m_perag = new_perag;



		mp->m_flags |= XFS_MOUNT_32BITINODES;

		nagimax = xfs_initialize_perag(mp, nagcount);

		up_write(&mp->m_peraglock);



		kmem_free(old_perag);

	}

	tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);

	tp->t_flags |= XFS_TRANS_RESERVE;