[DO NOT MERGE] ceph: switch DIO code to use iov_iter_get_pages_alloc

xfstest generic/095 triggers soft lockups in kcephfs. It uses fio to
drive some I/O via vmsplice ane splice. Ceph then ends up trying to
access an ITER_BVEC type iov_iter as a ITER_IOVEC one. That causes it to
pick up a wrong offset and get stuck in an infinite loop while trying to
populate the page array. dio_get_pagev_size has a similar problem.

Now that iov_iter_get_pages_alloc doesn't stop after the first vector in
the array, we can just call it instead and dump the old code that tried
to do the same thing.

Signed-off-by: Jeff Layton <jlayton@redhat.com>

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index f85040d73e3dcaa0214196ca0c242eadd0db475d..a6964eb6d8207797065c9d8865b1d4916cb2935e 100644 (file)
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -69,72 +69,6 @@ static __le32 ceph_flags_sys2wire(u32 flags)
  * need to wait for MDS acknowledgement.
  */
 
-/*
- * Calculate the length sum of direct io vectors that can
- * be combined into one page vector.
- */
-static size_t dio_get_pagev_size(const struct iov_iter *it)
-{
-    const struct iovec *iov = it->iov;
-    const struct iovec *iovend = iov + it->nr_segs;
-    size_t size;
-
-    size = iov->iov_len - it->iov_offset;
-    /*
-     * An iov can be page vectored when both the current tail
-     * and the next base are page aligned.
-     */
-    while (PAGE_ALIGNED((iov->iov_base + iov->iov_len)) &&
-           (++iov < iovend && PAGE_ALIGNED((iov->iov_base)))) {
-        size += iov->iov_len;
-    }
-    dout("dio_get_pagevlen len = %zu\n", size);
-    return size;
-}
-
-/*
- * Allocate a page vector based on (@it, @nbytes).
- * The return value is the tuple describing a page vector,
- * that is (@pages, @page_align, @num_pages).
- */
-static struct page **
-dio_get_pages_alloc(const struct iov_iter *it, size_t nbytes,
-                   size_t *page_align, int *num_pages)
-{
-       struct iov_iter tmp_it = *it;
-       size_t align;
-       struct page **pages;
-       int ret = 0, idx, npages;
-
-       align = (unsigned long)(it->iov->iov_base + it->iov_offset) &
-               (PAGE_SIZE - 1);
-       npages = calc_pages_for(align, nbytes);
-       pages = kvmalloc(sizeof(*pages) * npages, GFP_KERNEL);
-       if (!pages)
-               return ERR_PTR(-ENOMEM);
-
-       for (idx = 0; idx < npages; ) {
-               size_t start;
-               ret = iov_iter_get_pages(&tmp_it, pages + idx, nbytes,
-                                        npages - idx, &start);
-               if (ret < 0)
-                       goto fail;
-
-               iov_iter_advance(&tmp_it, ret);
-               nbytes -= ret;
-               idx += (ret + start + PAGE_SIZE - 1) / PAGE_SIZE;
-       }
-
-       BUG_ON(nbytes != 0);
-       *num_pages = npages;
-       *page_align = align;
-       dout("dio_get_pages_alloc: got %d pages align %zu\n", npages, align);
-       return pages;
-fail:
-       ceph_put_page_vector(pages, idx, false);
-       return ERR_PTR(ret);
-}
-
 /*
  * Prepare an open request.  Preallocate ceph_cap to avoid an
  * inopportune ENOMEM later.
@@ -914,7 +848,7 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter,
        }
 
        while (iov_iter_count(iter) > 0) {
-               u64 size = dio_get_pagev_size(iter);
+               u64 size = iov_iter_count(iter);
                size_t start = 0;
                ssize_t len;
 
@@ -938,13 +872,13 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter,
                else
                        size = min_t(u64, size, fsc->mount_options->rsize);
 
-               len = size;
-               pages = dio_get_pages_alloc(iter, len, &start, &num_pages);
-               if (IS_ERR(pages)) {
+               len = iov_iter_get_pages_alloc(iter, &pages, size, &start);
+               if (len < 0) {
                        ceph_osdc_put_request(req);
-                       ret = PTR_ERR(pages);
+                       ret = len;
                        break;
                }
+               num_pages = DIV_ROUND_UP(len + start, PAGE_SIZE);
 
                /*
                 * To simplify error handling, allow AIO when IO within i_size