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nfs_localio: duplicate nfs_close_local_fh() 

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: 86e0041225 ("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>
This commit is contained in:
NeilBrown 2025-05-09 10:46:41 +10:00 committed by Anna Schumaker
parent e6f7e1487a
commit 74fc55ab2a
1 changed files with 20 additions and 1 deletions
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21
fs/nfs_common/nfslocalio.c
View File

@ -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();
}