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nfsd: rework hashtable handling in nfsd_do_file_acquire

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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@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Jeff Layton 2022-10-04 15:41:10 -04:00 committed by Chuck Lever
parent 8d0d254b15
commit 243a526301
1 changed files with 22 additions and 30 deletions
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52
fs/nfsd/filecache.c
View File

@ -1042,9 +1042,10 @@ 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);
@ -1054,35 +1055,33 @@ 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;
ret = rhashtable_lookup_insert_key(&nfsd_file_rhash_tbl,
&key, &nf->nf_rhash,
nfsd_file_rhash_params);
if (likely(ret == 0))
goto open_file;
}
if (IS_ERR(nf))
goto insert_err;
nf = nfsd_file_get(nf);
if (nf == NULL) {
nf = new;
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);
@ -1090,11 +1089,11 @@ wait_for_construction:
/* 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;
}
@ -1142,13 +1141,6 @@ open_file:
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;
}
/**