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Commit f0c6bcba authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Dave Chinner
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xfs: reorder zeroing and flushing sequence in truncate 



Currently zeroing out blocks and waiting for writeout is a bit of a mess in
truncate.  This patch gives it a clear order in preparation for the iomap
path:

 (1) we first wait for any direct I/O to complete to prevent any races
     for it
 (2) we then perform the actual zeroing, and only use the truncate_page
     helpers for truncating down.  The truncate up case already is
     handled by the separate call to xfs_zero_eof.
 (3) only then we write back dirty data, as zeroing block may cause
     dirty pages when using either xfs_zero_eof or the new iomap
     infrastructure.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBob Peterson <rpeterso@redhat.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent 3b3dce05

fs/xfs/xfs_iops.c

+19 −14
Original line number Diff line number Diff line
@@ -800,20 +800,35 @@ xfs_setattr_size( 
	if (error)

		return error;



	/*

	 * Wait for all direct I/O to complete.

	 */

	inode_dio_wait(inode);



	/*

	 * File data changes must be complete before we start the transaction to

	 * modify the inode.  This needs to be done before joining the inode to

	 * the transaction because the inode cannot be unlocked once it is a

	 * part of the transaction.

	 *

	 * Start with zeroing any data block beyond EOF that we may expose on

	 * file extension.

	 * Start with zeroing any data beyond EOF that we may expose on file

	 * extension, or zeroing out the rest of the block on a downward

	 * truncate.

	 */

	if (newsize > oldsize) {

		error = xfs_zero_eof(ip, newsize, oldsize, &did_zeroing);

	} else {

		if (IS_DAX(inode)) {

			error = dax_truncate_page(inode, newsize,

					xfs_get_blocks_direct);

		} else {

			error = block_truncate_page(inode->i_mapping, newsize,

					xfs_get_blocks);

		}

	}



	if (error)

		return error;

	}



	/*

	 * We are going to log the inode size change in this transaction so
@@ -831,9 +846,6 @@ xfs_setattr_size( 
			return error;

	}



	/* Now wait for all direct I/O to complete. */

	inode_dio_wait(inode);



	/*

	 * We've already locked out new page faults, so now we can safely remove

	 * pages from the page cache knowing they won't get refaulted until we
@@ -851,13 +863,6 @@ xfs_setattr_size( 
	 * to hope that the caller sees ENOMEM and retries the truncate

	 * operation.

	 */

	if (IS_DAX(inode))

		error = dax_truncate_page(inode, newsize, xfs_get_blocks_direct);

	else

		error = block_truncate_page(inode->i_mapping, newsize,

					    xfs_get_blocks);

	if (error)

		return error;

	truncate_setsize(inode, newsize);



	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);