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Commit f742dc4a authored by Peng Tao's avatar Peng Tao Committed by Trond Myklebust
Browse files

pnfsblock: fix non-aligned DIO read 



For DIO read, if it is not sector aligned, we should reject it
and resend via MDS. Otherwise there might be data corruption.
Also teach bl_read_pagelist to handle partial page reads for DIO.

Cc: stable <stable@vger.kernel.org> [since v3.4]
Signed-off-by: default avatarPeng Tao <tao.peng@emc.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent fe6e1e8d

fs/nfs/blocklayout/blocklayout.c

+56 −8
Original line number Diff line number Diff line
@@ -252,8 +252,11 @@ bl_read_pagelist(struct nfs_read_data *rdata) 
	sector_t isect, extent_length = 0;

	struct parallel_io *par;

	loff_t f_offset = rdata->args.offset;

	size_t bytes_left = rdata->args.count;

	unsigned int pg_offset, pg_len;

	struct page **pages = rdata->args.pages;

	int pg_index = rdata->args.pgbase >> PAGE_CACHE_SHIFT;

	const bool is_dio = (header->dreq != NULL);



	dprintk("%s enter nr_pages %u offset %lld count %u\n", __func__,

	       rdata->pages.npages, f_offset, (unsigned int)rdata->args.count);
@@ -287,36 +290,53 @@ bl_read_pagelist(struct nfs_read_data *rdata) 
				extent_length = min(extent_length, cow_length);

			}

		}



		if (is_dio) {

			pg_offset = f_offset & ~PAGE_CACHE_MASK;

			if (pg_offset + bytes_left > PAGE_CACHE_SIZE)

				pg_len = PAGE_CACHE_SIZE - pg_offset;

			else

				pg_len = bytes_left;



			f_offset += pg_len;

			bytes_left -= pg_len;

			isect += (pg_offset >> SECTOR_SHIFT);

		} else {

			pg_offset = 0;

			pg_len = PAGE_CACHE_SIZE;

		}



		hole = is_hole(be, isect);

		if (hole && !cow_read) {

			bio = bl_submit_bio(READ, bio);

			/* Fill hole w/ zeroes w/o accessing device */

			dprintk("%s Zeroing page for hole\n", __func__);

			zero_user_segment(pages[i], 0, PAGE_CACHE_SIZE);

			zero_user_segment(pages[i], pg_offset, pg_len);

			print_page(pages[i]);

			SetPageUptodate(pages[i]);

		} else {

			struct pnfs_block_extent *be_read;



			be_read = (hole && cow_read) ? cow_read : be;

			bio = bl_add_page_to_bio(bio, rdata->pages.npages - i,

			bio = do_add_page_to_bio(bio, rdata->pages.npages - i,

						 READ,

						 isect, pages[i], be_read,

						 bl_end_io_read, par);

						 bl_end_io_read, par,

						 pg_offset, pg_len);

			if (IS_ERR(bio)) {

				header->pnfs_error = PTR_ERR(bio);

				bio = NULL;

				goto out;

			}

		}

		isect += PAGE_CACHE_SECTORS;

		isect += (pg_len >> SECTOR_SHIFT);

		extent_length -= PAGE_CACHE_SECTORS;

	}

	if ((isect << SECTOR_SHIFT) >= header->inode->i_size) {

		rdata->res.eof = 1;

		rdata->res.count = header->inode->i_size - f_offset;

		rdata->res.count = header->inode->i_size - rdata->args.offset;

	} else {

		rdata->res.count = (isect << SECTOR_SHIFT) - f_offset;

		rdata->res.count = (isect << SECTOR_SHIFT) - rdata->args.offset;

	}

out:

	bl_put_extent(be);
@@ -1149,9 +1169,37 @@ bl_clear_layoutdriver(struct nfs_server *server) 
	return 0;

}



static bool

is_aligned_req(struct nfs_page *req, unsigned int alignment)

{

	return IS_ALIGNED(req->wb_offset, alignment) &&

	       IS_ALIGNED(req->wb_bytes, alignment);

}



static void

bl_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)

{

	if (pgio->pg_dreq != NULL &&

	    !is_aligned_req(req, SECTOR_SIZE))

		nfs_pageio_reset_read_mds(pgio);

	else

		pnfs_generic_pg_init_read(pgio, req);

}



static bool

bl_pg_test_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,

		struct nfs_page *req)

{

	if (pgio->pg_dreq != NULL &&

	    !is_aligned_req(req, SECTOR_SIZE))

		return false;



	return pnfs_generic_pg_test(pgio, prev, req);

}



static const struct nfs_pageio_ops bl_pg_read_ops = {

	.pg_init = pnfs_generic_pg_init_read,

	.pg_test = pnfs_generic_pg_test,

	.pg_init = bl_pg_init_read,

	.pg_test = bl_pg_test_read,

	.pg_doio = pnfs_generic_pg_readpages,

};