Only bail out once we know that a COW allocation is actually required,
similar to how we handle normal data fork allocations.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/xfs_iomap.c | 23 +++++------------------
1 file changed, 5 insertions(+), 18 deletions(-)
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index e4e79aa5b695..9e1b4b94acac 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -693,15 +693,8 @@ xfs_ilock_for_iomap(
* COW writes may allocate delalloc space or convert unwritten COW
* extents, so we need to make sure to take the lock exclusively here.
*/
- if (xfs_is_cow_inode(ip) && is_write) {
- /*
- * FIXME: It could still overwrite on unshared extents and not
- * need allocation.
- */
- if (flags & IOMAP_NOWAIT)
- return -EAGAIN;
+ if (xfs_is_cow_inode(ip) && is_write)
mode = XFS_ILOCK_EXCL;
- }
/*
* Extents not yet cached requires exclusive access, don't block. This
@@ -760,12 +753,6 @@ xfs_direct_write_iomap_begin(
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
- /*
- * Lock the inode in the manner required for the specified operation and
- * check for as many conditions that would result in blocking as
- * possible. This removes most of the non-blocking checks from the
- * mapping code below.
- */
error = xfs_ilock_for_iomap(ip, flags, &lockmode);
if (error)
return error;
@@ -775,11 +762,11 @@ xfs_direct_write_iomap_begin(
if (error)
goto out_unlock;
- /*
- * Break shared extents if necessary. Checks for non-blocking IO have
- * been done up front, so we don't need to do them here.
- */
if (imap_needs_cow(ip, &imap, flags, nimaps)) {
+ error = -EAGAIN;
+ if (flags & IOMAP_NOWAIT)
+ goto out_unlock;
+
/* may drop and re-acquire the ilock */
error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
&lockmode, flags & IOMAP_DIRECT);
--
2.20.1
