[PATCH 02/12] xfs: set IOMAP_F_NEW more carefully

Christoph Hellwig
2019-10-15T15:44:06Z

Don't set IOMAP_F_NEW if we COW over and existing allocated range, as
these aren't strictly new allocations. This is required to be able to
use IOMAP_F_NEW to zero newly allocated blocks, which is required for
the iomap code to fully support file systems that don't do delayed
allocations or use unwritten extents.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/xfs_iomap.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 54c9ec7ad337..c0a492353826 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -707,9 +707,12 @@ xfs_file_iomap_begin_delay(
* Flag newly allocated delalloc blocks with IOMAP_F_NEW so we punch
* them out if the write happens to fail.
*/
- iomap_flags |= IOMAP_F_NEW;
- trace_xfs_iomap_alloc(ip, offset, count, whichfork,
- whichfork == XFS_DATA_FORK ? &imap : &cmap);
+ if (whichfork == XFS_DATA_FORK) {
+ iomap_flags |= IOMAP_F_NEW;
+ trace_xfs_iomap_alloc(ip, offset, count, whichfork, &imap);
+ } else {
+ trace_xfs_iomap_alloc(ip, offset, count, whichfork, &cmap);
+ }
done:
if (whichfork == XFS_COW_FORK) {
if (imap.br_startoff > offset_fsb) {
--
2.20.1