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authorXiubo Li <xiubli@redhat.com>2020-02-03 21:28:25 -0500
committerIlya Dryomov <idryomov@gmail.com>2020-02-11 17:04:04 +0100
commit8e4473bb50a1796c9c32b244e5dbc5ee24ead937 (patch)
tree7de41d8d856fcca65497e08059ea660f682295d9 /fs/ceph
parentbb6d3fb354c5ee8d6bde2d576eb7220ea09862b9 (diff)
ceph: do not execute direct write in parallel if O_APPEND is specified
In O_APPEND & O_DIRECT mode, the data from different writers will be possibly overlapping each other since they take the shared lock. For example, both Writer1 and Writer2 are in O_APPEND and O_DIRECT mode: Writer1 Writer2 shared_lock() shared_lock() getattr(CAP_SIZE) getattr(CAP_SIZE) iocb->ki_pos = EOF iocb->ki_pos = EOF write(data1) write(data2) shared_unlock() shared_unlock() The data2 will overlap the data1 from the same file offset, the old EOF. Switch to exclusive lock instead when O_APPEND is specified. Signed-off-by: Xiubo Li <xiubli@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph')
-rw-r--r--fs/ceph/file.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index c3b8e8e0bf17..7e0190b1f821 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1418,6 +1418,7 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
struct ceph_cap_flush *prealloc_cf;
ssize_t count, written = 0;
int err, want, got;
+ bool direct_lock = false;
loff_t pos;
loff_t limit = max(i_size_read(inode), fsc->max_file_size);
@@ -1428,8 +1429,11 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
if (!prealloc_cf)
return -ENOMEM;
+ if ((iocb->ki_flags & (IOCB_DIRECT | IOCB_APPEND)) == IOCB_DIRECT)
+ direct_lock = true;
+
retry_snap:
- if (iocb->ki_flags & IOCB_DIRECT)
+ if (direct_lock)
ceph_start_io_direct(inode);
else
ceph_start_io_write(inode);
@@ -1519,14 +1523,15 @@ retry_snap:
/* we might need to revert back to that point */
data = *from;
- if (iocb->ki_flags & IOCB_DIRECT) {
+ if (iocb->ki_flags & IOCB_DIRECT)
written = ceph_direct_read_write(iocb, &data, snapc,
&prealloc_cf);
- ceph_end_io_direct(inode);
- } else {
+ else
written = ceph_sync_write(iocb, &data, pos, snapc);
+ if (direct_lock)
+ ceph_end_io_direct(inode);
+ else
ceph_end_io_write(inode);
- }
if (written > 0)
iov_iter_advance(from, written);
ceph_put_snap_context(snapc);
@@ -1577,7 +1582,7 @@ retry_snap:
goto out_unlocked;
out:
- if (iocb->ki_flags & IOCB_DIRECT)
+ if (direct_lock)
ceph_end_io_direct(inode);
else
ceph_end_io_write(inode);