On 4/21/22 9:19 PM, Gregory Farnum wrote:
On Thu, Apr 21, 2022 at 1:37 AM Xiubo Li <xiubli@xxxxxxxxxx> wrote:
Since we have held the Fr capibility it's safe to skip reading from
Rados if the ki_pos is larger than or euqals to the file size.
I'm not sure this is correct, based on the patch description. If
you're in a mixed mode where there are writers and readers, they can
all have Frw and extend the file size by issuing rados writes up to
the max_size without updating each other. The client needs to have Fs
before it can rely on knowing the file size, so we should check that
before skipping a read, right?
There still need some other fixes in kclient, that is fixing the
__ceph_should_report_size() to report the size to the MDS when the
i_size changed and dirty the Fw caps before check_caps() for each
write. Then the MDS Locker code will issue new caps to all the clients.
While I think there still has a gap with this fixing. Because the
readers may need a little time to get the notification and to update the
new file size.
For now I will drop this change.
-- Xiubo
-Greg
Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
---
fs/ceph/file.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 6c9e837aa1d3..330e42b3afec 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1614,7 +1614,9 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
return ret;
}
- if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
+ if (unlikely(iocb->ki_pos >= i_size_read(inode))) {
+ ret = 0;
+ } else if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
(iocb->ki_flags & IOCB_DIRECT) ||
(fi->flags & CEPH_F_SYNC)) {
--
2.36.0.rc1
