nfsd: Protect addition to the file_hashtbl
Current code depends on the client_mutex to guarantee a single struct
nfs4_file per inode in the file_hashtbl and make addition atomic with
respect to lookup. Rely instead on the state_Lock, to make it easier to
stop taking the client_mutex here later.
To prevent an i_lock/state_lock inversion, change nfsd4_init_file to
use ihold instead if igrab. That's also more efficient anyway as we
definitely hold a reference to the inode at that point.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c473bd6..29788fd0 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2611,17 +2611,18 @@
{
unsigned int hashval = file_hashval(ino);
+ lockdep_assert_held(&state_lock);
+
atomic_set(&fp->fi_ref, 1);
INIT_LIST_HEAD(&fp->fi_stateids);
INIT_LIST_HEAD(&fp->fi_delegations);
- fp->fi_inode = igrab(ino);
+ ihold(ino);
+ fp->fi_inode = ino;
fp->fi_had_conflict = false;
fp->fi_lease = NULL;
memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
memset(fp->fi_access, 0, sizeof(fp->fi_access));
- spin_lock(&state_lock);
hlist_add_head(&fp->fi_hash, &file_hashtbl[hashval]);
- spin_unlock(&state_lock);
}
void
@@ -2787,23 +2788,49 @@
/* search file_hashtbl[] for file */
static struct nfs4_file *
-find_file(struct inode *ino)
+find_file_locked(struct inode *ino)
{
unsigned int hashval = file_hashval(ino);
struct nfs4_file *fp;
- spin_lock(&state_lock);
+ lockdep_assert_held(&state_lock);
+
hlist_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) {
if (fp->fi_inode == ino) {
get_nfs4_file(fp);
- spin_unlock(&state_lock);
return fp;
}
}
- spin_unlock(&state_lock);
return NULL;
}
+static struct nfs4_file *
+find_file(struct inode *ino)
+{
+ struct nfs4_file *fp;
+
+ spin_lock(&state_lock);
+ fp = find_file_locked(ino);
+ spin_unlock(&state_lock);
+ return fp;
+}
+
+static struct nfs4_file *
+find_or_add_file(struct inode *ino, struct nfs4_file *new)
+{
+ struct nfs4_file *fp;
+
+ spin_lock(&state_lock);
+ fp = find_file_locked(ino);
+ if (fp == NULL) {
+ nfsd4_init_file(new, ino);
+ fp = new;
+ }
+ spin_unlock(&state_lock);
+
+ return fp;
+}
+
/*
* Called to check deny when READ with all zero stateid or
* WRITE with all zero or all one stateid
@@ -3325,21 +3352,19 @@
* and check for delegations in the process of being recalled.
* If not found, create the nfs4_file struct
*/
- fp = find_file(ino);
- if (fp) {
+ fp = find_or_add_file(ino, open->op_file);
+ if (fp != open->op_file) {
if ((status = nfs4_check_open(fp, open, &stp)))
goto out;
status = nfs4_check_deleg(cl, open, &dp);
if (status)
goto out;
} else {
+ open->op_file = NULL;
status = nfserr_bad_stateid;
if (nfsd4_is_deleg_cur(open))
goto out;
status = nfserr_jukebox;
- fp = open->op_file;
- open->op_file = NULL;
- nfsd4_init_file(fp, ino);
}
/*