This is a note to let you know that I've just added the patch titled
nfsd: rework hashtable handling in nfsd_do_file_acquire
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-rework-hashtable-handling-in-nfsd_do_file_acqui.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4e94bbad46c3f73fa1d45e0897a60e7722359431
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date: Tue Oct 4 15:41:10 2022 -0400
nfsd: rework hashtable handling in nfsd_do_file_acquire
[ Upstream commit 243a5263014a30436c93ed3f1f864c1da845455e ]
nfsd_file is RCU-freed, so we need to hold the rcu_read_lock long enough
to get a reference after finding it in the hash. Take the
rcu_read_lock() and call rhashtable_lookup directly.
Switch to using rhashtable_lookup_insert_key as well, and use the usual
retry mechanism if we hit an -EEXIST. Rename the "retry" bool to
open_retry, and eliminiate the insert_err goto target.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index a0d93e797cdce..0b19eb015c6c8 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -1041,9 +1041,10 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
.need = may_flags & NFSD_FILE_MAY_MASK,
.net = SVC_NET(rqstp),
};
- struct nfsd_file *nf, *new;
- bool retry = true;
+ bool open_retry = true;
+ struct nfsd_file *nf;
__be32 status;
+ int ret;
status = fh_verify(rqstp, fhp, S_IFREG,
may_flags|NFSD_MAY_OWNER_OVERRIDE);
@@ -1053,35 +1054,33 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
key.cred = get_current_cred();
retry:
- /* Avoid allocation if the item is already in cache */
- nf = rhashtable_lookup_fast(&nfsd_file_rhash_tbl, &key,
- nfsd_file_rhash_params);
+ rcu_read_lock();
+ nf = rhashtable_lookup(&nfsd_file_rhash_tbl, &key,
+ nfsd_file_rhash_params);
if (nf)
nf = nfsd_file_get(nf);
+ rcu_read_unlock();
if (nf)
goto wait_for_construction;
- new = nfsd_file_alloc(&key, may_flags);
- if (!new) {
+ nf = nfsd_file_alloc(&key, may_flags);
+ if (!nf) {
status = nfserr_jukebox;
goto out_status;
}
- nf = rhashtable_lookup_get_insert_key(&nfsd_file_rhash_tbl,
- &key, &new->nf_rhash,
- nfsd_file_rhash_params);
- if (!nf) {
- nf = new;
- goto open_file;
- }
- if (IS_ERR(nf))
- goto insert_err;
- nf = nfsd_file_get(nf);
- if (nf == NULL) {
- nf = new;
+ ret = rhashtable_lookup_insert_key(&nfsd_file_rhash_tbl,
+ &key, &nf->nf_rhash,
+ nfsd_file_rhash_params);
+ if (likely(ret == 0))
goto open_file;
- }
- nfsd_file_slab_free(&new->nf_rcu);
+
+ nfsd_file_slab_free(&nf->nf_rcu);
+ if (ret == -EEXIST)
+ goto retry;
+ trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, ret);
+ status = nfserr_jukebox;
+ goto out_status;
wait_for_construction:
wait_on_bit(&nf->nf_flags, NFSD_FILE_PENDING, TASK_UNINTERRUPTIBLE);
@@ -1089,11 +1088,11 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
/* Did construction of this file fail? */
if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
trace_nfsd_file_cons_err(rqstp, key.inode, may_flags, nf);
- if (!retry) {
+ if (!open_retry) {
status = nfserr_jukebox;
goto out;
}
- retry = false;
+ open_retry = false;
nfsd_file_put_noref(nf);
goto retry;
}
@@ -1141,13 +1140,6 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
smp_mb__after_atomic();
wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING);
goto out;
-
-insert_err:
- nfsd_file_slab_free(&new->nf_rcu);
- trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, PTR_ERR(nf));
- nf = NULL;
- status = nfserr_jukebox;
- goto out_status;
}
/**
