[PATCH 6.1 157/215] NFSD: Clean up find_or_add_file()

Greg Kroah-Hartman
2024-03-04T21:49:43Z

From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit 9270fc514ba7d415636b23bcb937573a1ce54f6a ]

Remove the call to find_file_locked() in insert_nfs4_file(). Tracing
shows that over 99% of these calls return NULL. Thus it is not worth
the expense of the extra bucket list traversal. insert_file() already
deals correctly with the case where the item is already in the hash
bucket.

Since nfsd4_file_hash_insert() is now just a wrapper around
insert_file(), move the meat of insert_file() into
nfsd4_file_hash_insert() and get rid of it.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfsd/nfs4state.c | 64 ++++++++++++++++++++++------------------------------
1 file changed, 28 insertions(+), 36 deletions(-)

--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4699,24 +4699,42 @@ find_file_locked(const struct svc_fh *fh
return NULL;
}

-static struct nfs4_file *insert_file(struct nfs4_file *new, struct svc_fh *fh,
- unsigned int hashval)
+static struct nfs4_file * find_file(struct svc_fh *fh)
{
struct nfs4_file *fp;
+ unsigned int hashval = file_hashval(fh);
+
+ rcu_read_lock();
+ fp = find_file_locked(fh, hashval);
+ rcu_read_unlock();
+ return fp;
+}
+
+/*
+ * On hash insertion, identify entries with the same inode but
+ * distinct filehandles. They will all be in the same hash bucket
+ * because nfs4_file's are hashed by the address in the fi_inode
+ * field.
+ */
+static noinline_for_stack struct nfs4_file *
+nfsd4_file_hash_insert(struct nfs4_file *new, const struct svc_fh *fhp)
+{
+ unsigned int hashval = file_hashval(fhp);
struct nfs4_file *ret = NULL;
bool alias_found = false;
+ struct nfs4_file *fi;

spin_lock(&state_lock);
- hlist_for_each_entry_rcu(fp, &file_hashtbl[hashval], fi_hash,
+ hlist_for_each_entry_rcu(fi, &file_hashtbl[hashval], fi_hash,
lockdep_is_held(&state_lock)) {
- if (fh_match(&fp->fi_fhandle, &fh->fh_handle)) {
- if (refcount_inc_not_zero(&fp->fi_ref))
- ret = fp;
- } else if (d_inode(fh->fh_dentry) == fp->fi_inode)
- fp->fi_aliased = alias_found = true;
+ if (fh_match(&fi->fi_fhandle, &fhp->fh_handle)) {
+ if (refcount_inc_not_zero(&fi->fi_ref))
+ ret = fi;
+ } else if (d_inode(fhp->fh_dentry) == fi->fi_inode)
+ fi->fi_aliased = alias_found = true;
}
if (likely(ret == NULL)) {
- nfsd4_file_init(fh, new);
+ nfsd4_file_init(fhp, new);
hlist_add_head_rcu(&new->fi_hash, &file_hashtbl[hashval]);
new->fi_aliased = alias_found;
ret = new;
@@ -4725,32 +4743,6 @@ static struct nfs4_file *insert_file(str
return ret;
}

-static struct nfs4_file * find_file(struct svc_fh *fh)
-{
- struct nfs4_file *fp;
- unsigned int hashval = file_hashval(fh);
-
- rcu_read_lock();
- fp = find_file_locked(fh, hashval);
- rcu_read_unlock();
- return fp;
-}
-
-static struct nfs4_file *
-find_or_add_file(struct nfs4_file *new, struct svc_fh *fh)
-{
- struct nfs4_file *fp;
- unsigned int hashval = file_hashval(fh);
-
- rcu_read_lock();
- fp = find_file_locked(fh, hashval);
- rcu_read_unlock();
- if (fp)
- return fp;
-
- return insert_file(new, fh, hashval);
-}
-
static noinline_for_stack void nfsd4_file_hash_remove(struct nfs4_file *fi)
{
hlist_del_rcu(&fi->fi_hash);
@@ -5661,7 +5653,7 @@ nfsd4_process_open2(struct svc_rqst *rqs
* and check for delegations in the process of being recalled.
* If not found, create the nfs4_file struct
*/
- fp = find_or_add_file(open->op_file, current_fh);
+ fp = nfsd4_file_hash_insert(open->op_file, current_fh);
if (fp != open->op_file) {
status = nfs4_check_deleg(cl, open, &dp);
if (status)