From 17dfeb9113397a6119091a491ef7182649f0c5a9 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 28 Jan 2014 09:37:16 -0500 Subject: [PATCH] NFS: Fix races in nfs_revalidate_mapping Commit d529ef83c355f97027ff85298a9709fe06216a66 (NFS: fix the handling of NFS_INO_INVALID_DATA flag in nfs_revalidate_mapping) introduces a potential race, since it doesn't test the value of nfsi->cache_validity and set the bitlock in nfsi->flags atomically. Signed-off-by: Trond Myklebust Cc: Jeff Layton --- fs/nfs/inode.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 0a972ee9ccc1..e5070aa5f175 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -1038,24 +1038,24 @@ int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping) nfs_wait_bit_killable, TASK_KILLABLE); if (ret) goto out; - if (!(nfsi->cache_validity & NFS_INO_INVALID_DATA)) - goto out; - if (!test_and_set_bit_lock(NFS_INO_INVALIDATING, bitlock)) + spin_lock(&inode->i_lock); + if (test_bit(NFS_INO_INVALIDATING, bitlock)) { + spin_unlock(&inode->i_lock); + continue; + } + if (nfsi->cache_validity & NFS_INO_INVALID_DATA) break; - } - - spin_lock(&inode->i_lock); - if (nfsi->cache_validity & NFS_INO_INVALID_DATA) { - nfsi->cache_validity &= ~NFS_INO_INVALID_DATA; - spin_unlock(&inode->i_lock); - trace_nfs_invalidate_mapping_enter(inode); - ret = nfs_invalidate_mapping(inode, mapping); - trace_nfs_invalidate_mapping_exit(inode, ret); - } else { - /* something raced in and cleared the flag */ spin_unlock(&inode->i_lock); + goto out; } + set_bit(NFS_INO_INVALIDATING, bitlock); + nfsi->cache_validity &= ~NFS_INO_INVALID_DATA; + spin_unlock(&inode->i_lock); + trace_nfs_invalidate_mapping_enter(inode); + ret = nfs_invalidate_mapping(inode, mapping); + trace_nfs_invalidate_mapping_exit(inode, ret); + clear_bit_unlock(NFS_INO_INVALIDATING, bitlock); smp_mb__after_clear_bit(); wake_up_bit(bitlock, NFS_INO_INVALIDATING); -- GitLab