LU-14043 llite: allow DIO with unaligned IO count

DIO only require user buffer page aligned and
IO offset page aligned, it is ok that io count is
not page aligned, remove this unnecessary limit
so that we could use DIO with file not aligned
with PAGE SIZE.

Change-Id: Iaf1e224b3f180f91d1b54016c6e6b7adaf674bf8
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-on: https://review.whamcloud.com/40392
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/llite/rw26.c b/lustre/llite/rw26.c
index 1415d79..1da442e 100644 (file)
--- a/lustre/llite/rw26.c
+++ b/lustre/llite/rw26.c
@@ -250,12 +250,12 @@ static ssize_t ll_get_user_pages(int rw, struct iov_iter *iter,
 
 /* iov_iter_alignment() is introduced in 3.16 similar to HAVE_DIO_ITER */
 #if defined(HAVE_DIO_ITER)
-static unsigned long ll_iov_iter_alignment(const struct iov_iter *i)
+static unsigned long iov_iter_alignment_vfs(const struct iov_iter *i)
 {
        return iov_iter_alignment(i);
 }
 #else /* copied from alignment_iovec() */
-static unsigned long ll_iov_iter_alignment(const struct iov_iter *i)
+static unsigned long iov_iter_alignment_vfs(const struct iov_iter *i)
 {
        const struct iovec *iov = i->iov;
        unsigned long res;
@@ -282,6 +282,35 @@ static unsigned long ll_iov_iter_alignment(const struct iov_iter *i)
 }
 #endif
 
+/*
+ * Lustre could relax a bit for alignment, io count is not
+ * necessary page alignment.
+ */
+static unsigned long ll_iov_iter_alignment(struct iov_iter *i)
+{
+       size_t orig_size = i->count;
+       size_t count = orig_size & ~PAGE_MASK;
+       unsigned long res;
+
+       if (!count)
+               return iov_iter_alignment_vfs(i);
+
+       if (orig_size > PAGE_SIZE) {
+               iov_iter_truncate(i, orig_size - count);
+               res = iov_iter_alignment_vfs(i);
+               iov_iter_reexpand(i, orig_size);
+
+               return res;
+       }
+
+       res = iov_iter_alignment_vfs(i);
+       /* start address is page aligned */
+       if ((res & ~PAGE_MASK) == orig_size)
+               return PAGE_SIZE;
+
+       return res;
+}
+
 /** direct IO pages */
 struct ll_dio_pages {
        struct cl_dio_aio       *ldp_aio;
@@ -433,8 +462,8 @@ ll_direct_IO_impl(struct kiocb *iocb, struct iov_iter *iter, int rw)
                return 0;
 
        /* FIXME: io smaller than PAGE_SIZE is broken on ia64 ??? */
-       if ((file_offset & ~PAGE_MASK) || (count & ~PAGE_MASK))
-               return -EINVAL;
+       if (file_offset & ~PAGE_MASK)
+               RETURN(-EINVAL);
 
        CDEBUG(D_VFSTRACE, "VFS Op:inode="DFID"(%p), size=%zd (max %lu), "
               "offset=%lld=%llx, pages %zd (max %lu)\n",
@@ -444,7 +473,7 @@ ll_direct_IO_impl(struct kiocb *iocb, struct iov_iter *iter, int rw)
 
        /* Check that all user buffers are aligned as well */
        if (ll_iov_iter_alignment(iter) & ~PAGE_MASK)
-               return -EINVAL;
+               RETURN(-EINVAL);
 
        lcc = ll_cl_find(file);
        if (lcc == NULL)