LU-17525 llite: soft fail unaligned dio

Skip unaligned DIO and pass io as buffered I/O rather than
hard fail unaligned DIO.

Test-Parameters: testlist=sanity serverversion=2.14 env=SANITY_EXCEPT="65n 211 413"
Fixes: ff018bb77a ("LU-18284 llite: disallow udio exceptions")
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: I638f62ec96abc3032da5fbcf895cd835022fd759
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56775
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Patrick Farrell <patrick.farrell@oracle.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/llite/rw26.c b/lustre/llite/rw26.c
index c3986e9..110af3c 100644 (file)
--- a/lustre/llite/rw26.c
+++ b/lustre/llite/rw26.c
@@ -529,23 +529,6 @@ ll_direct_IO_impl(struct kiocb *iocb, struct iov_iter *iter, int rw)
        if (rw == READ && file_offset >= i_size_read(inode))
                RETURN(0);
 
-       /* unaligned DIO support can be turned off, so is it on? */
-       if (unaligned && !ll_sbi_has_unaligned_dio(ll_i2sbi(inode)))
-               RETURN(-EINVAL);
-
-       /* the requirement to not return EIOCBQUEUED for pipes (see bottom of
-        * this function) plays havoc with the unaligned I/O lifecycle, so
-        * don't allow unaligned I/O on pipes
-        */
-       if (unaligned && iov_iter_is_pipe(iter))
-               RETURN(0);
-
-       /* Unpatched older servers which cannot safely support unaligned DIO
-        * should abort here
-        */
-       if (unaligned && !cl_io_top(io)->ci_allow_unaligned_dio)
-               RETURN(-EINVAL);
-
        /* if one part of an I/O is unaligned, just handle all of it that way -
         * otherwise we create significant complexities with managing the iovec
         * in different ways, etc, all for very marginal benefits
@@ -559,10 +542,31 @@ ll_direct_IO_impl(struct kiocb *iocb, struct iov_iter *iter, int rw)
        LASSERT(ll_dio_aio);
        LASSERT(ll_dio_aio->cda_iocb == iocb);
 
+       /* unaligned DIO support can be turned off, so is it on? */
+       if (unaligned && !ll_sbi_has_unaligned_dio(ll_i2sbi(inode)))
+               RETURN(-EINVAL);
+
        /* unaligned AIO is not supported - see LU-18032 */
        if (unaligned && ll_dio_aio->cda_is_aio)
                RETURN(-EINVAL);
 
+       /* the requirement to not return EIOCBQUEUED for pipes (see bottom of
+        * this function) plays havoc with the unaligned I/O lifecycle, so
+        * don't allow unaligned I/O on pipes
+        */
+       if (unaligned && iov_iter_is_pipe(iter))
+               RETURN(0);
+
+       /* returning 0 here forces the remaining I/O through buffered I/O
+        * while returning -EINVAL stops the I/O from continuing
+        */
+
+       /* Unpatched older servers which cannot safely support unaligned DIO
+        * should abort here
+        */
+       if (unaligned && !cl_io_top(io)->ci_allow_unaligned_dio)
+               RETURN(0);
+
        /* We cannot do parallel submission of sub-I/Os - for AIO or regular
         * DIO - unless lockless because it causes us to release the lock
         * early.