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Commit c8a3292d authored by Peng Tao's avatar Peng Tao Committed by Trond Myklebust
Browse files

pnfs/filelayout: fix race between mark_request_commit and scan_commit_lists 



We need to hold cinfo lock while setting bucket->wlseg and adding req to nwritten
list at the same time. Otherwise there might be a window where nwritten list
is empty yet we set bucket->wlseg, in which case ff_layout_scan_ds_commit_list()
may end up clearing bucket->wlseg incorrectly, casuing client to oops later on.

This was found when testing flexfile layout but filelayout has the same problem.

Signed-off-by: default avatarPeng Tao <tao.peng@primarydata.com>
Signed-off-by: default avatarTom Haynes <Thomas.Haynes@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent f3792d63

fs/nfs/filelayout/filelayout.c

+25 −18
Original line number Diff line number Diff line
@@ -1035,18 +1035,22 @@ filelayout_clear_request_commit(struct nfs_page *req, 
	pnfs_put_lseg(freeme);

}



static struct list_head *

filelayout_choose_commit_list(struct nfs_page *req,

static void

filelayout_mark_request_commit(struct nfs_page *req,

			       struct pnfs_layout_segment *lseg,

			       struct nfs_commit_info *cinfo)



{

	struct nfs4_filelayout_segment *fl = FILELAYOUT_LSEG(lseg);

	u32 i, j;

	struct list_head *list;

	struct pnfs_commit_bucket *buckets;



	if (fl->commit_through_mds)

		return &cinfo->mds->list;

	if (fl->commit_through_mds) {

		list = &cinfo->mds->list;

		spin_lock(cinfo->lock);

		goto mds_commit;

	}



	/* Note that we are calling nfs4_fl_calc_j_index on each page

	 * that ends up being committed to a data server.  An attractive
@@ -1070,19 +1074,22 @@ filelayout_choose_commit_list(struct nfs_page *req, 
	}

	set_bit(PG_COMMIT_TO_DS, &req->wb_flags);

	cinfo->ds->nwritten++;



mds_commit:

	/* nfs_request_add_commit_list(). We need to add req to list without

	 * dropping cinfo lock.

	 */

	set_bit(PG_CLEAN, &(req)->wb_flags);

	nfs_list_add_request(req, list);

	cinfo->mds->ncommit++;

	spin_unlock(cinfo->lock);

	return list;

	if (!cinfo->dreq) {

		inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);

		inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,

			     BDI_RECLAIMABLE);

		__mark_inode_dirty(req->wb_context->dentry->d_inode,

				   I_DIRTY_DATASYNC);

	}



static void

filelayout_mark_request_commit(struct nfs_page *req,

			       struct pnfs_layout_segment *lseg,

			       struct nfs_commit_info *cinfo)

{

	struct list_head *list;



	list = filelayout_choose_commit_list(req, lseg, cinfo);

	nfs_request_add_commit_list(req, list, cinfo);

}



static u32 calc_ds_index_from_commit(struct pnfs_layout_segment *lseg, u32 i)