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Commit 6f23e387 authored by Trond Myklebust's avatar Trond Myklebust
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NFS: Fix a potential race between umount and nfs_access_cache_shrinker() 



Thanks to Yawei Niu for spotting the race.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent e6f81075

fs/nfs/dir.c

+8 −1
Original line number Diff line number Diff line
@@ -1694,13 +1694,19 @@ 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;
@@ -1719,6 +1725,7 @@ int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask) 
		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);