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 <trond.myklebust@xxxxxxxxxxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/nfs/inode.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 0a972ee9ccc1..1ff95ba4fea3 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1038,23 +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))
+ 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)) {
+ spin_unlock(&inode->i_lock);
goto out;
- if (!test_and_set_bit_lock(NFS_INO_INVALIDATING, bitlock))
- break;
+ }
+ set_bit(NFS_INO_INVALIDATING, bitlock);
+ 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);
- }
+ 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();
--
1.8.5.3
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