queue-5.15/nfsd-clean-up-find_or_add_file.patch

   1 From 02871b1a7fd36d758517e6687a0c3389991584d4 Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Fri, 28 Oct 2022 10:47:41 -0400
   4 Subject: NFSD: Clean up find_or_add_file()
   5
   6 From: Chuck Lever <chuck.lever@oracle.com>
   7
   8 [ Upstream commit 9270fc514ba7d415636b23bcb937573a1ce54f6a ]
   9
  10 Remove the call to find_file_locked() in insert_nfs4_file(). Tracing
  11 shows that over 99% of these calls return NULL. Thus it is not worth
  12 the expense of the extra bucket list traversal. insert_file() already
  13 deals correctly with the case where the item is already in the hash
  14 bucket.
  15
  16 Since nfsd4_file_hash_insert() is now just a wrapper around
  17 insert_file(), move the meat of insert_file() into
  18 nfsd4_file_hash_insert() and get rid of it.
  19
  20 Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
  21 Reviewed-by: NeilBrown <neilb@suse.de>
  22 Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
  23 ---
  24  fs/nfsd/nfs4state.c | 64 ++++++++++++++++++++-------------------------
  25  1 file changed, 28 insertions(+), 36 deletions(-)
  26
  27 diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
  28 index f723d7d5e1557..192e721525665 100644
  29 --- a/fs/nfsd/nfs4state.c
  30 +++ b/fs/nfsd/nfs4state.c
  31 @@ -4698,24 +4698,42 @@ find_file_locked(const struct svc_fh *fh, unsigned int hashval)
  32         return NULL;
  33  }
  34
  35 -static struct nfs4_file *insert_file(struct nfs4_file *new, struct svc_fh *fh,
  36 -                                    unsigned int hashval)
  37 +static struct nfs4_file * find_file(struct svc_fh *fh)
  38  {
  39         struct nfs4_file *fp;
  40 +       unsigned int hashval = file_hashval(fh);
  41 +
  42 +       rcu_read_lock();
  43 +       fp = find_file_locked(fh, hashval);
  44 +       rcu_read_unlock();
  45 +       return fp;
  46 +}
  47 +
  48 +/*
  49 + * On hash insertion, identify entries with the same inode but
  50 + * distinct filehandles. They will all be in the same hash bucket
  51 + * because nfs4_file's are hashed by the address in the fi_inode
  52 + * field.
  53 + */
  54 +static noinline_for_stack struct nfs4_file *
  55 +nfsd4_file_hash_insert(struct nfs4_file *new, const struct svc_fh *fhp)
  56 +{
  57 +       unsigned int hashval = file_hashval(fhp);
  58         struct nfs4_file *ret = NULL;
  59         bool alias_found = false;
  60 +       struct nfs4_file *fi;
  61
  62         spin_lock(&state_lock);
  63 -       hlist_for_each_entry_rcu(fp, &file_hashtbl[hashval], fi_hash,
  64 +       hlist_for_each_entry_rcu(fi, &file_hashtbl[hashval], fi_hash,
  65                                  lockdep_is_held(&state_lock)) {
  66 -               if (fh_match(&fp->fi_fhandle, &fh->fh_handle)) {
  67 -                       if (refcount_inc_not_zero(&fp->fi_ref))
  68 -                               ret = fp;
  69 -               } else if (d_inode(fh->fh_dentry) == fp->fi_inode)
  70 -                       fp->fi_aliased = alias_found = true;
  71 +               if (fh_match(&fi->fi_fhandle, &fhp->fh_handle)) {
  72 +                       if (refcount_inc_not_zero(&fi->fi_ref))
  73 +                               ret = fi;
  74 +               } else if (d_inode(fhp->fh_dentry) == fi->fi_inode)
  75 +                       fi->fi_aliased = alias_found = true;
  76         }
  77         if (likely(ret == NULL)) {
  78 -               nfsd4_file_init(fh, new);
  79 +               nfsd4_file_init(fhp, new);
  80                 hlist_add_head_rcu(&new->fi_hash, &file_hashtbl[hashval]);
  81                 new->fi_aliased = alias_found;
  82                 ret = new;
  83 @@ -4724,32 +4742,6 @@ static struct nfs4_file *insert_file(struct nfs4_file *new, struct svc_fh *fh,
  84         return ret;
  85  }
  86
  87 -static struct nfs4_file * find_file(struct svc_fh *fh)
  88 -{
  89 -       struct nfs4_file *fp;
  90 -       unsigned int hashval = file_hashval(fh);
  91 -
  92 -       rcu_read_lock();
  93 -       fp = find_file_locked(fh, hashval);
  94 -       rcu_read_unlock();
  95 -       return fp;
  96 -}
  97 -
  98 -static struct nfs4_file *
  99 -find_or_add_file(struct nfs4_file *new, struct svc_fh *fh)
 100 -{
 101 -       struct nfs4_file *fp;
 102 -       unsigned int hashval = file_hashval(fh);
 103 -
 104 -       rcu_read_lock();
 105 -       fp = find_file_locked(fh, hashval);
 106 -       rcu_read_unlock();
 107 -       if (fp)
 108 -               return fp;
 109 -
 110 -       return insert_file(new, fh, hashval);
 111 -}
 112 -
 113  static noinline_for_stack void nfsd4_file_hash_remove(struct nfs4_file *fi)
 114  {
 115         hlist_del_rcu(&fi->fi_hash);
 116 @@ -5641,7 +5633,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
 117          * and check for delegations in the process of being recalled.
 118          * If not found, create the nfs4_file struct
 119          */
 120 -       fp = find_or_add_file(open->op_file, current_fh);
 121 +       fp = nfsd4_file_hash_insert(open->op_file, current_fh);
 122         if (fp != open->op_file) {
 123                 status = nfs4_check_deleg(cl, open, &dp);
 124                 if (status)
 125 --
 126 2.43.0
 127