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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); nfs_wait_bit_killable, TASK_KILLABLE);
if (ret) if (ret)
goto out; goto out;
if (!(nfsi->cache_validity & NFS_INO_INVALID_DATA)) spin_lock(&inode->i_lock);
goto out; if (test_bit(NFS_INO_INVALIDATING, bitlock)) {
if (!test_and_set_bit_lock(NFS_INO_INVALIDATING, bitlock)) spin_unlock(&inode->i_lock);
continue;
}
if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
break; break;
spin_unlock(&inode->i_lock);
goto out;
} }
spin_lock(&inode->i_lock); set_bit(NFS_INO_INVALIDATING, bitlock);
if (nfsi->cache_validity & NFS_INO_INVALID_DATA) { nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
nfsi->cache_validity &= ~NFS_INO_INVALID_DATA; spin_unlock(&inode->i_lock);
spin_unlock(&inode->i_lock); trace_nfs_invalidate_mapping_enter(inode);
trace_nfs_invalidate_mapping_enter(inode); ret = nfs_invalidate_mapping(inode, mapping);
ret = nfs_invalidate_mapping(inode, mapping); trace_nfs_invalidate_mapping_exit(inode, ret);
trace_nfs_invalidate_mapping_exit(inode, ret);
} else {
/* something raced in and cleared the flag */
spin_unlock(&inode->i_lock);
}
clear_bit_unlock(NFS_INO_INVALIDATING, bitlock); clear_bit_unlock(NFS_INO_INVALIDATING, bitlock);
smp_mb__after_clear_bit(); smp_mb__after_clear_bit();