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>

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 7ae8a608956f60d7343fdfa9e77be7532b2db17d..dd392ed5f2e28ef48a85b37d0dc2ade6ab903d80 100644 (file)
--- 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,
 };