6.15-stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown neil@brown.name
[ Upstream commit 74fc55ab2a6a0c71628fcf3b9783aae7119b5199 ]
nfs_close_local_fh() is called from two different places for quite different use case.
It is called from nfs_uuid_put() when the nfs_uuid is being detached - possibly because the nfs server is not longer serving that filesystem. In this case there will always be an nfs_uuid and so rcu_read_lock() is not needed.
It is also called when the nfs_file_localio is no longer needed. In this case there may not be an active nfs_uuid.
These two can race, and handling the race properly while avoiding excessive locking will require different handling on each side.
This patch prepares the way by opencoding nfs_close_local_fh() into nfs_uuid_put(), then simplifying the code there as befits the context.
Fixes: 86e00412254a ("nfs: cache all open LOCALIO nfsd_file(s) in client") Signed-off-by: NeilBrown neil@brown.name Signed-off-by: Anna Schumaker anna.schumaker@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs_common/nfslocalio.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c index 503f85f64b760..49c59f0c78c62 100644 --- a/fs/nfs_common/nfslocalio.c +++ b/fs/nfs_common/nfslocalio.c @@ -171,7 +171,26 @@ static bool nfs_uuid_put(nfs_uuid_t *nfs_uuid)
/* Walk list of files and ensure their last references dropped */ list_for_each_entry_safe(nfl, tmp, &local_files, list) { - nfs_close_local_fh(nfl); + struct nfsd_file *ro_nf; + struct nfsd_file *rw_nf; + + ro_nf = unrcu_pointer(xchg(&nfl->ro_file, NULL)); + rw_nf = unrcu_pointer(xchg(&nfl->rw_file, NULL)); + + spin_lock(&nfs_uuid->lock); + /* Remove nfl from nfs_uuid->files list */ + list_del_init(&nfl->list); + spin_unlock(&nfs_uuid->lock); + /* Now we can allow racing nfs_close_local_fh() to + * skip the locking. + */ + RCU_INIT_POINTER(nfl->nfs_uuid, NULL); + + if (ro_nf) + nfs_to_nfsd_file_put_local(ro_nf); + if (rw_nf) + nfs_to_nfsd_file_put_local(rw_nf); + cond_resched(); }