pnfsblock: fix partial page buffer wirte

If applications use flock to protect its write range, generic NFS
will not do read-modify-write cycle at page cache level. Therefore
LD should know how to handle non-sector aligned writes. Otherwise
there will be data corruption.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 165 insertions, 12 deletions

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 3c61514599a5..a9fe644a12d1 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -162,25 +162,39 @@ static struct bio *bl_alloc_init_bio(int npg, sector_t isect,
         return bio;
 }
 
-static struct bio *bl_add_page_to_bio(struct bio *bio, int npg, int rw,
+static struct bio *do_add_page_to_bio(struct bio *bio, int npg, int rw,
                                       sector_t isect, struct page *page,
                                       struct pnfs_block_extent *be,
                                       void (*end_io)(struct bio *, int err),
-                                      struct parallel_io *par)
+                                      struct parallel_io *par,
+                                      unsigned int offset, int len)
 {
+        isect = isect + (offset >> SECTOR_SHIFT);
+        dprintk("%s: npg %d rw %d isect %llu offset %u len %d\n", __func__,
+                npg, rw, (unsigned long long)isect, offset, len);
 retry:
         if (!bio) {
                 bio = bl_alloc_init_bio(npg, isect, be, end_io, par);
                 if (!bio)
                         return ERR_PTR(-ENOMEM);
         }
-        if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
+        if (bio_add_page(bio, page, len, offset) < len) {
                 bio = bl_submit_bio(rw, bio);
                 goto retry;
         }
         return bio;
 }
 
+static struct bio *bl_add_page_to_bio(struct bio *bio, int npg, int rw,
+                                      sector_t isect, struct page *page,
+                                      struct pnfs_block_extent *be,
+                                      void (*end_io)(struct bio *, int err),
+                                      struct parallel_io *par)
+{
+        return do_add_page_to_bio(bio, npg, rw, isect, page, be,
+                                  end_io, par, 0, PAGE_CACHE_SIZE);
+}
+
 /* This is basically copied from mpage_end_io_read */
 static void bl_end_io_read(struct bio *bio, int err)
 {
@@ -450,6 +464,106 @@ map_block(struct buffer_head *bh, sector_t isect, struct pnfs_block_extent *be)
         return;
 }
 
+static void
+bl_read_single_end_io(struct bio *bio, int error)
+{
+        struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+        struct page *page = bvec->bv_page;
+
+        /* Only one page in bvec */
+        unlock_page(page);
+}
+
+static int
+bl_do_readpage_sync(struct page *page, struct pnfs_block_extent *be,
+                    unsigned int offset, unsigned int len)
+{
+        struct bio *bio;
+        struct page *shadow_page;
+        sector_t isect;
+        char *kaddr, *kshadow_addr;
+        int ret = 0;
+
+        dprintk("%s: offset %u len %u\n", __func__, offset, len);
+
+        shadow_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+        if (shadow_page == NULL)
+                return -ENOMEM;
+
+        bio = bio_alloc(GFP_NOIO, 1);
+        if (bio == NULL)
+                return -ENOMEM;
+
+        isect = (page->index << PAGE_CACHE_SECTOR_SHIFT) +
+                (offset / SECTOR_SIZE);
+
+        bio->bi_sector = isect - be->be_f_offset + be->be_v_offset;
+        bio->bi_bdev = be->be_mdev;
+        bio->bi_end_io = bl_read_single_end_io;
+
+        lock_page(shadow_page);
+        if (bio_add_page(bio, shadow_page,
+                         SECTOR_SIZE, round_down(offset, SECTOR_SIZE)) == 0) {
+                unlock_page(shadow_page);
+                bio_put(bio);
+                return -EIO;
+        }
+
+        submit_bio(READ, bio);
+        wait_on_page_locked(shadow_page);
+        if (unlikely(!test_bit(BIO_UPTODATE, &bio->bi_flags))) {
+                ret = -EIO;
+        } else {
+                kaddr = kmap_atomic(page);
+                kshadow_addr = kmap_atomic(shadow_page);
+                memcpy(kaddr + offset, kshadow_addr + offset, len);
+                kunmap_atomic(kshadow_addr);
+                kunmap_atomic(kaddr);
+        }
+        __free_page(shadow_page);
+        bio_put(bio);
+
+        return ret;
+}
+
+static int
+bl_read_partial_page_sync(struct page *page, struct pnfs_block_extent *be,
+                          unsigned int dirty_offset, unsigned int dirty_len,
+                          bool full_page)
+{
+        int ret = 0;
+        unsigned int start, end;
+
+        if (full_page) {
+                start = 0;
+                end = PAGE_CACHE_SIZE;
+        } else {
+                start = round_down(dirty_offset, SECTOR_SIZE);
+                end = round_up(dirty_offset + dirty_len, SECTOR_SIZE);
+        }
+
+        dprintk("%s: offset %u len %d\n", __func__, dirty_offset, dirty_len);
+        if (!be) {
+                zero_user_segments(page, start, dirty_offset,
+                                   dirty_offset + dirty_len, end);
+                if (start == 0 && end == PAGE_CACHE_SIZE &&
+                    trylock_page(page)) {
+                        SetPageUptodate(page);
+                        unlock_page(page);
+                }
+                return ret;
+        }
+
+        if (start != dirty_offset)
+                ret = bl_do_readpage_sync(page, be, start, dirty_offset - start);
+
+        if (!ret && (dirty_offset + dirty_len < end))
+                ret = bl_do_readpage_sync(page, be, dirty_offset + dirty_len,
+                                          end - dirty_offset - dirty_len);
+
+        return ret;
+}
+
 /* Given an unmapped page, zero it or read in page for COW, page is locked
  * by caller.
  */
@@ -483,7 +597,6 @@ init_page_for_write(struct page *page, struct pnfs_block_extent *cow_read)
         SetPageUptodate(page);
 
 cleanup:
-        bl_put_extent(cow_read);
         if (bh)
                 free_buffer_head(bh);
         if (ret) {
@@ -555,6 +668,7 @@ bl_write_pagelist(struct nfs_write_data *wdata, int sync)
         struct parallel_io *par;
         loff_t offset = wdata->args.offset;
         size_t count = wdata->args.count;
+        unsigned int pg_offset, pg_len, saved_len;
         struct page **pages = wdata->args.pages;
         struct page *page;
         pgoff_t index;
@@ -659,10 +773,11 @@ next_page:
                 if (!extent_length) {
                         /* We've used up the previous extent */
                         bl_put_extent(be);
+                        bl_put_extent(cow_read);
                         bio = bl_submit_bio(WRITE, bio);
                         /* Get the next one */
                         be = bl_find_get_extent(BLK_LSEG2EXT(header->lseg),
-                                             isect, NULL);
+                                             isect, &cow_read);
                         if (!be || !is_writable(be, isect)) {
                                 header->pnfs_error = -EINVAL;
                                 goto out;
@@ -679,7 +794,26 @@ next_page:
                         extent_length = be->be_length -
                             (isect - be->be_f_offset);
                 }
-                if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
+
+                dprintk("%s offset %lld count %Zu\n", __func__, offset, count);
+                pg_offset = offset & ~PAGE_CACHE_MASK;
+                if (pg_offset + count > PAGE_CACHE_SIZE)
+                        pg_len = PAGE_CACHE_SIZE - pg_offset;
+                else
+                        pg_len = count;
+
+                saved_len = pg_len;
+                if (be->be_state == PNFS_BLOCK_INVALID_DATA &&
+                    !bl_is_sector_init(be->be_inval, isect)) {
+                        ret = bl_read_partial_page_sync(pages[i], cow_read,
+                                                        pg_offset, pg_len, true);
+                        if (ret) {
+                                dprintk("%s bl_read_partial_page_sync fail %d\n",
+                                        __func__, ret);
+                                header->pnfs_error = ret;
+                                goto out;
+                        }
+
                         ret = bl_mark_sectors_init(be->be_inval, isect,
                                                        PAGE_CACHE_SECTORS);
                         if (unlikely(ret)) {
@@ -688,15 +822,35 @@ next_page:
                                 header->pnfs_error = ret;
                                 goto out;
                         }
+
+                        /* Expand to full page write */
+                        pg_offset = 0;
+                        pg_len = PAGE_CACHE_SIZE;
+                } else if  ((pg_offset & (SECTOR_SIZE - 1)) ||
+                            (pg_len & (SECTOR_SIZE - 1))){
+                        /* ahh, nasty case. We have to do sync full sector
+                         * read-modify-write cycles.
+                         */
+                        unsigned int saved_offset = pg_offset;
+                        ret = bl_read_partial_page_sync(pages[i], be, pg_offset,
+                                                        pg_len, false);
+                        pg_offset = round_down(pg_offset, SECTOR_SIZE);
+                        pg_len = round_up(saved_offset + pg_len, SECTOR_SIZE)
+                                 - pg_offset;
                 }
-                bio = bl_add_page_to_bio(bio, wdata->pages.npages - i, WRITE,
+
+
+                bio = do_add_page_to_bio(bio, wdata->pages.npages - i, WRITE,
                                          isect, pages[i], be,
-                                         bl_end_io_write, par);
+                                         bl_end_io_write, par,
+                                         pg_offset, pg_len);
                 if (IS_ERR(bio)) {
                         header->pnfs_error = PTR_ERR(bio);
                         bio = NULL;
                         goto out;
                 }
+                offset += saved_len;
+                count -= saved_len;
                 isect += PAGE_CACHE_SECTORS;
                 last_isect = isect;
                 extent_length -= PAGE_CACHE_SECTORS;
@@ -714,17 +868,16 @@ next_page:
         }
 
 write_done:
-        wdata->res.count = (last_isect << SECTOR_SHIFT) - (offset);
-        if (count < wdata->res.count) {
-                wdata->res.count = count;
-        }
+        wdata->res.count = wdata->args.count;
 out:
         bl_put_extent(be);
+        bl_put_extent(cow_read);
         bl_submit_bio(WRITE, bio);
         put_parallel(par);
         return PNFS_ATTEMPTED;
 out_mds:
         bl_put_extent(be);
+        bl_put_extent(cow_read);
         kfree(par);
         return PNFS_NOT_ATTEMPTED;
 }