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NFS: Fix races in nfs_revalidate_mapping 

Commit d529ef83c3 (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@primarydata.com>
Cc: Jeff Layton <jlayton@redhat.com>
This commit is contained in:
Trond Myklebust 2014-01-28 09:37:16 -05:00
parent 0ea9de0ea6
commit 17dfeb9113
1 changed files with 14 additions and 14 deletions
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28
fs/nfs/inode.c
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@ -1038,23 +1038,23 @@ 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_unlock(&inode->i_lock);
goto out;
}
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);
}
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();