LU-14043 llite: allow DIO with unaligned IO count

[fs/lustre-release.git] / lustre / llite / rw26.c

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)