+ struct pnfs_block_layout *bl = BLK_LO2EXT(lo);
+ int i, status = -EIO;
+ uint32_t count;
+ struct pnfs_block_extent *be = NULL, *save;
+ struct xdr_stream stream;
+ struct xdr_buf buf;
+ struct page *scratch;
+ __be32 *p;
+ struct layout_verification lv = {
+ .mode = lgr->range.iomode,
+ .start = lgr->range.offset >> SECTOR_SHIFT,
+ .inval = lgr->range.offset >> SECTOR_SHIFT,
+ .cowread = lgr->range.offset >> SECTOR_SHIFT,
+ };
+ LIST_HEAD(extents);
+
+ dprintk("---> %s\n", __func__);
+
+ scratch = alloc_page(gfp_flags);
+ if (!scratch)
+ return -ENOMEM;
+
+ xdr_init_decode_pages(&stream, &buf, lgr->layoutp->pages, lgr->layoutp->len);
+ xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
+
+ p = xdr_inline_decode(&stream, 4);
+ if (unlikely(!p))
+ goto out_err;
+
+ count = be32_to_cpup(p++);
+
+ dprintk("%s enter, number of extents %i\n", __func__, count);
+ p = xdr_inline_decode(&stream, (28 + NFS4_DEVICEID4_SIZE) * count);
+ if (unlikely(!p))
+ goto out_err;
+
+ /* Decode individual extents, putting them in temporary
+ * staging area until whole layout is decoded to make error
+ * recovery easier.
+ */
+ for (i = 0; i < count; i++) {
+ be = bl_alloc_extent();
+ if (!be) {
+ status = -ENOMEM;
+ goto out_err;
+ }
+ memcpy(&be->be_devid, p, NFS4_DEVICEID4_SIZE);
+ p += XDR_QUADLEN(NFS4_DEVICEID4_SIZE);
+ be->be_mdev = translate_devid(lo, &be->be_devid);
+ if (!be->be_mdev)
+ goto out_err;
+
+ /* The next three values are read in as bytes,
+ * but stored as 512-byte sector lengths
+ */
+ if (decode_sector_number(&p, &be->be_f_offset) < 0)
+ goto out_err;
+ if (decode_sector_number(&p, &be->be_length) < 0)
+ goto out_err;
+ if (decode_sector_number(&p, &be->be_v_offset) < 0)
+ goto out_err;
+ be->be_state = be32_to_cpup(p++);
+ if (be->be_state == PNFS_BLOCK_INVALID_DATA)
+ be->be_inval = &bl->bl_inval;
+ if (verify_extent(be, &lv)) {
+ dprintk("%s verify failed\n", __func__);
+ goto out_err;
+ }
+ list_add_tail(&be->be_node, &extents);
+ }
+ if (lgr->range.offset + lgr->range.length !=
+ lv.start << SECTOR_SHIFT) {
+ dprintk("%s Final length mismatch\n", __func__);
+ be = NULL;
+ goto out_err;
+ }
+ if (lv.start < lv.cowread) {
+ dprintk("%s Final uncovered COW extent\n", __func__);
+ be = NULL;
+ goto out_err;
+ }
+ /* Extents decoded properly, now try to merge them in to
+ * existing layout extents.
+ */
+ spin_lock(&bl->bl_ext_lock);
+ list_for_each_entry_safe(be, save, &extents, be_node) {
+ list_del(&be->be_node);
+ status = bl_add_merge_extent(bl, be);
+ if (status) {
+ spin_unlock(&bl->bl_ext_lock);
+ /* This is a fairly catastrophic error, as the
+ * entire layout extent lists are now corrupted.
+ * We should have some way to distinguish this.
+ */
+ be = NULL;
+ goto out_err;
+ }
+ }
+ spin_unlock(&bl->bl_ext_lock);
+ status = 0;
+ out:
+ __free_page(scratch);
+ dprintk("%s returns %i\n", __func__, status);
+ return status;
+
+ out_err:
+ bl_put_extent(be);
+ while (!list_empty(&extents)) {
+ be = list_first_entry(&extents, struct pnfs_block_extent,
+ be_node);
+ list_del(&be->be_node);
+ bl_put_extent(be);
+ }
+ goto out;