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NFS/localio: Fix a race in nfs_local_open_fh()

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Once the clp->cl_uuid.lock has been dropped, another CPU could come in
and free the struct nfsd_file that was just added. To prevent that from
happening, take the RCU read lock before dropping the spin lock.

Fixes: 86e0041225 ("nfs: cache all open LOCALIO nfsd_file(s) in client")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Trond Myklebust 2025-04-21 14:43:34 -04:00
parent c367eea504
commit fa7ab64f1e
1 changed files with 1 additions and 1 deletions
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2
fs/nfs/localio.c
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@ -278,6 +278,7 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
new = __nfs_local_open_fh(clp, cred, fh, nfl, mode);
if (IS_ERR(new))
return NULL;
rcu_read_lock();
/* try to swap in the pointer */
spin_lock(&clp->cl_uuid.lock);
nf = rcu_dereference_protected(*pnf, 1);
@ -287,7 +288,6 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
rcu_assign_pointer(*pnf, nf);
}
spin_unlock(&clp->cl_uuid.lock);
rcu_read_lock();
}
nf = nfs_local_file_get(nf);
rcu_read_unlock();