From f0c6bcba74ac51cb77aadb33ad35cb2dc1ad1506 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 21 Jun 2016 09:52:47 +1000 Subject: [PATCH] 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: Christoph Hellwig Reviewed-by: Bob Peterson Signed-off-by: Dave Chinner --- fs/xfs/xfs_iops.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index c5d4eba6972e..1a5ca4b4a866 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -800,21 +800,36 @@ 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); - if (error) - return error; + } 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 * any previous writes that are beyond the on disk EOF and the new @@ -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); -- 2.20.1