On 2021/8/20 上午11:01, Dan Williams wrote:
On Sun, Aug 15, 2021 at 11:05 PM Shiyang Ruan <[email protected]> wrote:
After writing data, reflink requires end operations to remap those new
allocated extents. The current ->iomap_end() ignores the error code
returned from ->actor(), so we introduce this dax_iomap_ops and change
the dax_iomap_*() interfaces to do this job.
- the dax_iomap_ops contains the original struct iomap_ops and fsdax
specific ->actor_end(), which is for the end operations of reflink
- also introduce dax specific zero_range, truncate_page
- create new dax_iomap_ops for ext2 and ext4
Signed-off-by: Shiyang Ruan <[email protected]>
---
fs/dax.c | 68 +++++++++++++++++++++++++++++++++++++-----
fs/ext2/ext2.h | 3 ++
fs/ext2/file.c | 6 ++--
fs/ext2/inode.c | 11 +++++--
fs/ext4/ext4.h | 3 ++
fs/ext4/file.c | 6 ++--
fs/ext4/inode.c | 13 ++++++--
fs/iomap/buffered-io.c | 3 +-
fs/xfs/xfs_bmap_util.c | 3 +-
fs/xfs/xfs_file.c | 8 ++---
fs/xfs/xfs_iomap.c | 36 +++++++++++++++++++++-
fs/xfs/xfs_iomap.h | 33 ++++++++++++++++++++
fs/xfs/xfs_iops.c | 7 ++---
fs/xfs/xfs_reflink.c | 3 +-
include/linux/dax.h | 21 ++++++++++---
include/linux/iomap.h | 1 +
16 files changed, 189 insertions(+), 36 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 74dd918cff1f..0e0536765a7e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1348,11 +1348,30 @@ static loff_t dax_iomap_iter(const struct iomap_iter
*iomi,
return done ? done : ret;
}
+static inline int
+__dax_iomap_iter(struct iomap_iter *iter, const struct dax_iomap_ops *ops)
+{
+ int ret;
+
+ /*
+ * Call dax_iomap_ops->actor_end() before iomap_ops->iomap_end() in
+ * each iteration.
+ */
+ if (iter->iomap.length && ops->actor_end) {
+ ret = ops->actor_end(iter->inode, iter->pos, iter->len,
+ iter->processed);
+ if (ret < 0)
+ return ret;
+ }
+
+ return iomap_iter(iter, &ops->iomap_ops);
This reorganization looks needlessly noisy. Why not require the
iomap_end operation to perform the actor_end work. I.e. why can't
xfs_dax_write_iomap_actor_end() just be the passed in iomap_end? I am
not seeing where the ->iomap_end() result is ignored?
The V6 patch[1] was did in this way.
[1]https://lore.kernel.org/linux-xfs/20210526005159.GF202144@locust/T/#m79a66a928da2d089e2458c1a97c0516dbfde2f7f
But Darrick reminded me that ->iomap_end() will always take zero or
positive 'written' because iomap_apply() handles this argument.
```
if (ops->iomap_end) {
ret = ops->iomap_end(inode, pos, length,
written > 0 ? written : 0,
flags, &iomap);
}
```
So, we cannot get actual return code from CoW in ->actor(), and as a
result, we cannot handle the xfs end_cow correctly in ->iomap_end().
That's where the result of CoW was ignored.
--
Thanks,
Ruan.
