diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c488ae26b23d0..2542f15496488 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -777,9 +777,10 @@ xfs_file_buffered_write(
ssize_t ret;
bool cleared_space = false;
unsigned int iolock;
+ bool atomic_write = iocb->ki_flags & IOCB_ATOMIC;
write_retry:
- iolock = XFS_IOLOCK_EXCL;
+ iolock = atomic_write ? XFS_IOLOCK_SHARED : XFS_IOLOCK_EXCL;
ret = xfs_ilock_iocb(iocb, iolock);
--
xfs_file_write_checks() afterwards already takes care of promoting
XFS_IOLOCK_SHARED to XFS_IOLOCK_EXCL for extending writes.
It is possible that XFS_IOLOCK_EXCL could be immediately demoted
back to XFS_IOLOCK_SHARED for atomic_writes as done in
xfs_file_dio_write_aligned().
TBH, I am not sure which blockdevs support 4K atomic writes that could
be used to test this.
John, can you share your test setup instructions for atomic writes?
Please note that IOCB_ATOMIC is not supported for buffered IO, so we
can't do this - we only support direct IO today.
And supporting buffered IO has its challenges; how to handle overlapping
atomic writes of differing sizes sitting in the page cache is the main
issue which comes to mind.
Thanks,
John
