pnfsblock: bail out partial page IO

Current block layout driver read/write code assumes page
aligned IO in many places. Add a checker to validate the assumption.
Otherwise there would be data corruption like when application does
open(O_WRONLY) and page unaliged write.

Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 36 insertions, 3 deletions

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 7ae8a608956f..dd392ed5f2e2 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -228,6 +228,14 @@ bl_end_par_io_read(void *data, int unused)
         schedule_work(&rdata->task.u.tk_work);
 }
 
+static bool
+bl_check_alignment(u64 offset, u32 len, unsigned long blkmask)
+{
+        if ((offset & blkmask) || (len & blkmask))
+                return false;
+        return true;
+}
+
 static enum pnfs_try_status
 bl_read_pagelist(struct nfs_read_data *rdata)
 {
@@ -244,6 +252,9 @@ bl_read_pagelist(struct nfs_read_data *rdata)
         dprintk("%s enter nr_pages %u offset %lld count %u\n", __func__,
                rdata->pages.npages, f_offset, (unsigned int)rdata->args.count);
 
+        if (!bl_check_alignment(f_offset, rdata->args.count, PAGE_CACHE_MASK))
+                goto use_mds;
+
         par = alloc_parallel(rdata);
         if (!par)
                 goto use_mds;
@@ -552,7 +563,7 @@ bl_write_pagelist(struct nfs_write_data *wdata, int sync)
         struct bio *bio = NULL;
         struct pnfs_block_extent *be = NULL, *cow_read = NULL;
         sector_t isect, last_isect = 0, extent_length = 0;
-        struct parallel_io *par;
+        struct parallel_io *par = NULL;
         loff_t offset = wdata->args.offset;
         size_t count = wdata->args.count;
         struct page **pages = wdata->args.pages;
@@ -563,6 +574,10 @@ bl_write_pagelist(struct nfs_write_data *wdata, int sync)
             NFS_SERVER(header->inode)->pnfs_blksize >> PAGE_CACHE_SHIFT;
 
         dprintk("%s enter, %Zu@%lld\n", __func__, count, offset);
+        /* Check for alignment first */
+        if (!bl_check_alignment(offset, count, PAGE_CACHE_MASK))
+                goto out_mds;
+
         /* At this point, wdata->pages is a (sequential) list of nfs_pages.
          * We want to write each, and if there is an error set pnfs_error
          * to have it redone using nfs.
@@ -996,14 +1011,32 @@ bl_clear_layoutdriver(struct nfs_server *server)
         return 0;
 }
 
+static void
+bl_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
+{
+        if (!bl_check_alignment(req->wb_offset, req->wb_bytes, PAGE_CACHE_MASK))
+                nfs_pageio_reset_read_mds(pgio);
+        else
+                pnfs_generic_pg_init_read(pgio, req);
+}
+
+static void
+bl_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
+{
+        if (!bl_check_alignment(req->wb_offset, req->wb_bytes, PAGE_CACHE_MASK))
+                nfs_pageio_reset_write_mds(pgio);
+        else
+                pnfs_generic_pg_init_write(pgio, req);
+}
+
 static const struct nfs_pageio_ops bl_pg_read_ops = {
-        .pg_init = pnfs_generic_pg_init_read,
+        .pg_init = bl_pg_init_read,
         .pg_test = pnfs_generic_pg_test,
         .pg_doio = pnfs_generic_pg_readpages,
 };
 
 static const struct nfs_pageio_ops bl_pg_write_ops = {
-        .pg_init = pnfs_generic_pg_init_write,
+        .pg_init = bl_pg_init_write,
         .pg_test = pnfs_generic_pg_test,
         .pg_doio = pnfs_generic_pg_writepages,
 };