zonefs: fix IOCB_NOWAIT handling

IOCB_NOWAIT can't just be ignored as it breaks applications expecting
it not to block.  Just refuse the operation as applications must handle
that (e.g. by falling back to a thread pool).

Fixes: 8dcc1a9d90c1 ("fs: New zonefs file system")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index 8bc6ef82d693e06f0dc0da790db63cda8364f989..69aee3dfb6607814cb24d14ea2cdd08642a4c56a 100644 (file)
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -601,13 +601,13 @@ static ssize_t zonefs_file_dio_write(struct kiocb *iocb, struct iov_iter *from)
        ssize_t ret;
 
        /*
-        * For async direct IOs to sequential zone files, ignore IOCB_NOWAIT
+        * For async direct IOs to sequential zone files, refuse IOCB_NOWAIT
         * as this can cause write reordering (e.g. the first aio gets EAGAIN
         * on the inode lock but the second goes through but is now unaligned).
         */
-       if (zi->i_ztype == ZONEFS_ZTYPE_SEQ && !is_sync_kiocb(iocb)
-           && (iocb->ki_flags & IOCB_NOWAIT))
-               iocb->ki_flags &= ~IOCB_NOWAIT;
+       if (zi->i_ztype == ZONEFS_ZTYPE_SEQ && !is_sync_kiocb(iocb) &&
+           (iocb->ki_flags & IOCB_NOWAIT))
+               return -EOPNOTSUPP;
 
        if (iocb->ki_flags & IOCB_NOWAIT) {
                if (!inode_trylock(inode))