From: Trond Myklebust Date: Fri, 25 Jan 2008 16:38:17 -0500 NFS: Fix a potential race between umount and nfs_access_cache_shrinker() Thanks to Yawei Niu for spotting the race. Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index e72d427..9f15b09 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1680,13 +1680,19 @@ int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask) restart: spin_lock(&nfs_access_lru_lock); list_for_each_entry(nfsi, &nfs_access_lru_list, access_cache_inode_lru) { + struct rw_semaphore *s_umount; struct inode *inode; if (nr_to_scan-- == 0) break; + s_umount = &nfsi->vfs_inode.i_sb->s_umount; + if (!down_read_trylock(s_umount)) + continue; inode = igrab(&nfsi->vfs_inode); - if (inode == NULL) + if (inode == NULL) { + up_read(s_umount); continue; + } spin_lock(&inode->i_lock); if (list_empty(&nfsi->access_cache_entry_lru)) goto remove_lru_entry; @@ -1705,6 +1711,7 @@ remove_lru_entry: spin_unlock(&inode->i_lock); spin_unlock(&nfs_access_lru_lock); iput(inode); + up_read(s_umount); goto restart; } spin_unlock(&nfs_access_lru_lock);