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Commit 4db72b40 authored by Jeff Layton's avatar Jeff Layton Committed by Trond Myklebust
Browse files

nfs: add memory barriers around NFS_INO_INVALID_DATA and NFS_INO_INVALIDATING 



If the setting of NFS_INO_INVALIDATING gets reordered to before the
clearing of NFS_INO_INVALID_DATA, then another task may hit a race
window where both appear to be clear, even though the inode's pages are
still in need of invalidation. Fix this by adding the appropriate memory
barriers.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 17dfeb91

fs/nfs/dir.c

+11 −3
Original line number Diff line number Diff line
@@ -274,6 +274,15 @@ out_eof: 
	return -EBADCOOKIE;

}



static bool

nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)

{

	if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))

		return false;

	smp_rmb();

	return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);

}



static

int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)

{
@@ -287,9 +296,8 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des 
			struct nfs_open_dir_context *ctx = desc->file->private_data;



			new_pos = desc->current_index + i;

			if (ctx->attr_gencount != nfsi->attr_gencount

			    || (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))

			    || test_bit(NFS_INO_INVALIDATING, &nfsi->flags)) {

			if (ctx->attr_gencount != nfsi->attr_gencount ||

			    !nfs_readdir_inode_mapping_valid(nfsi)) {

				ctx->duped = 0;

				ctx->attr_gencount = nfsi->attr_gencount;

			} else if (new_pos < desc->ctx->pos) {

fs/nfs/inode.c

+1 −0
Original line number Diff line number Diff line
@@ -1050,6 +1050,7 @@ int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping) 
	}



	set_bit(NFS_INO_INVALIDATING, bitlock);

	smp_wmb();

	nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;

	spin_unlock(&inode->i_lock);

	trace_nfs_invalidate_mapping_enter(inode);

fs/nfs/write.c

+1 −0
Original line number Diff line number Diff line
@@ -915,6 +915,7 @@ static bool nfs_write_pageuptodate(struct page *page, struct inode *inode) 
		goto out;

	if (nfsi->cache_validity & (NFS_INO_INVALID_DATA|NFS_INO_REVAL_PAGECACHE))

		return false;

	smp_rmb();

	if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))

		return false;

out: