[PATCH 4/6] cifs: start caching all directories we open and get a lease for

[Ronnie Sahlberg <lsahlber@redhat.com>]

This expands the directory caching to now cache an open handle for all
directories (up to a maximum) and not just the root directory.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/cached_dir.c | 490 ++++++++++++++++++++++++++-----------------
 fs/cifs/cached_dir.h |  20 +-
 fs/cifs/inode.c      |   6 +-
 fs/cifs/smb2ops.c    |   2 +-
 4 files changed, 320 insertions(+), 198 deletions(-)

diff --git a/fs/cifs/cached_dir.c b/fs/cifs/cached_dir.c
index 594ec4385077..8732903aea03 100644
--- a/fs/cifs/cached_dir.c
+++ b/fs/cifs/cached_dir.c
@@ -11,7 +11,107 @@
 #include "smb2proto.h"
 #include "cached_dir.h"
 
-struct cached_fid *init_cached_dir(const char *path);
+static struct cached_fid *init_cached_dir(const char *path);
+static void free_cached_dir(struct cached_fid *cfid);
+
+/*
+ * Locking and reference count for cached directory handles:
+ *
+ * The main function to get a reference to a cached handle is
+ * find_or_create_cached_dir() called from open_cached_dir()
+ * These functions are protected under the cfid_list_lock spin-lock
+ * to make sure we do not race creating new references for cached dirs
+ * with deletion of expired ones.
+ *
+ * An successful open_cached_dir() will take out 2 references to the cfid if
+ * this was the very first and successful call to open the directory and
+ * it acquired a lease from the server.
+ * One reference is for the lease  and the other is for the cfid that we
+ * return. The is lease reference is tracked by cfid->has_lease.
+ * If the directory already has a handle with an active lease, then we just
+ * take out one new reference for the cfid and return it.
+ * It can happen that we have a thread that tries to open a cached directory
+ * where we have a cfid already but we do not, yet, have a working lease. In
+ * this case we will just return NULL, and this the caller will fall back to
+ * the case when no handle was available.
+ *
+ * In this model the total number of references we have on a cfid is
+ * 1 for while the handle is open and we have a lease, and one additional
+ * reference for each open instance of a cfid.
+ *
+ *
+ * Once we get a lease break (cached_dir_lease_break()) we remove the
+ * cfid from the list under the spinlock. This prevents any new threads to
+ * use it, and we also call smb2_cached_lease_break() via the work_queue
+ * in order to drop the reference we got for the lease (we drop it outside
+ * of the spin-lock.)
+ * Anytime a thread calls close_cached_dir() we also drop a reference to the
+ * cfid.
+ * When the last reference to the cfid is released smb2_close_cached_fid()
+ * will be invoked which will drop the reference ot the dentry we held for
+ * this cfid and it will also, if we the handle is open/has a lease
+ * also call SMB2_close() to close the handle on the server.
+ *
+ *
+ * Two events require special handling:
+ * invalidate_all_cached_dirs() this function is called from SMB2_tdis()
+ * and cifs_mark_open_files_invalid().
+ * In both cases the tcon is either gone already or will be shortly so
+ * we do not need to actually close the handles. They will be dropped
+ * server side as part of the tcon dropping.
+ * But we have to be careful about a potential race with a concurrent
+ * lease break so we need to take out additional refences to avoid the
+ * cfid from being freed while we are still referencing it.
+ *
+ * free_cached_dirs() which is called from tconInfoFree().
+ * This is called quite late in the umount process so there should no longer
+ * be any open handles or files and we can just free all the remaining data.
+ */
+
+static struct cached_fid *find_or_create_cached_dir(struct cached_fids *cfids,
+						    const char *path,
+						    bool lookup_only)
+{
+	struct cached_fid *cfid;
+
+	spin_lock(&cfids->cfid_list_lock);
+	list_for_each_entry(cfid, &cfids->entries, entry) {
+		if (!strcmp(cfid->path, path)) {
+			/*
+			 * If it doesn't have a lease it is either not yet
+			 * fully cached or it may be in the process of
+			 * being deleted due to a lease break.
+			 */
+			if (!cfid->has_lease) {
+				spin_unlock(&cfids->cfid_list_lock);
+				return NULL;
+			}
+			kref_get(&cfid->refcount);
+			spin_unlock(&cfids->cfid_list_lock);
+			return cfid;
+		}
+	}
+	if (lookup_only) {
+		spin_unlock(&cfids->cfid_list_lock);
+		return NULL;
+	}
+	if (cfids->num_entries >= MAX_CACHED_FIDS) {
+		spin_unlock(&cfids->cfid_list_lock);
+		return NULL;
+	}
+	cfid = init_cached_dir(path);
+	if (cfid == NULL) {
+		spin_unlock(&cfids->cfid_list_lock);
+		return NULL;
+	}
+	cfid->cfids = cfids;
+	cfids->num_entries++;
+	list_add(&cfid->entry, &cfids->entries);
+	cfid->on_list = true;
+	kref_get(&cfid->refcount);
+	spin_unlock(&cfids->cfid_list_lock);
+	return cfid;
+}
 
 /*
  * Open the and cache a directory handle.
@@ -33,62 +133,65 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 	struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
 	struct kvec qi_iov[1];
 	int rc, flags = 0;
-	__le16 utf16_path = 0; /* Null - since an open of top of share */
+	__le16 *utf16_path = NULL;
 	u8 oplock = SMB2_OPLOCK_LEVEL_II;
 	struct cifs_fid *pfid;
-	struct dentry *dentry;
+	struct dentry *dentry = NULL;
 	struct cached_fid *cfid;
+	struct cached_fids *cfids;
+	  
 
-	if (tcon == NULL || tcon->nohandlecache ||
+	if (tcon == NULL || tcon->cfids == NULL || tcon->nohandlecache ||
 	    is_smb1_server(tcon->ses->server))
-		return -EOPNOTSUPP;
+		return -ENOTSUPP;
 
 	ses = tcon->ses;
 	server = ses->server;
+	cfids = tcon->cfids;
 
+	if (!server->ops->new_lease_key)
+		return -EIO;
+	
 	if (cifs_sb->root == NULL)
 		return -ENOENT;
 
+	/*
+	 * TODO: for better caching we need to find and use the dentry also
+	 * for non-root directories.
+	 */
 	if (!strlen(path))
 		dentry = cifs_sb->root;
 
-	if (strlen(path))
-		return -ENOENT;
+	utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
+	if (!utf16_path)
+		return -ENOMEM;
 
-	cfid = tcon->cfids->cfid;
+	cfid = find_or_create_cached_dir(cfids, path, lookup_only);
 	if (cfid == NULL) {
-		cfid = init_cached_dir(path);
-		tcon->cfids->cfid = cfid;
+		kfree(utf16_path);
+		return -ENOENT;
 	}
-	if (cfid == NULL)
-		return -ENOMEM;
-
-	mutex_lock(&cfid->fid_mutex);
-	if (cfid->is_valid) {
-		cifs_dbg(FYI, "found a cached root file handle\n");
+	/*
+	 * At this point we either have a lease already and we can just
+	 * return it. If not we are guaranteed to be the only thread accessing
+	 * this cfid.
+	 */
+	if (cfid->has_lease) {
 		*ret_cfid = cfid;
-		kref_get(&cfid->refcount);
-		mutex_unlock(&cfid->fid_mutex);
+		kfree(utf16_path);
 		return 0;
 	}
 
 	/*
 	 * We do not hold the lock for the open because in case
-	 * SMB2_open needs to reconnect, it will end up calling
-	 * cifs_mark_open_files_invalid() which takes the lock again
-	 * thus causing a deadlock
+	 * SMB2_open needs to reconnect.
+	 * This is safe because no other thread will be able to get a ref
+	 * to the cfid until we have finished opening the file and (possibly)
+	 * aquired a lease.
 	 */
-	mutex_unlock(&cfid->fid_mutex);
-
-	if (lookup_only)
-		return -ENOENT;
-
 	if (smb3_encryption_required(tcon))
 		flags |= CIFS_TRANSFORM_REQ;
 
-	if (!server->ops->new_lease_key)
-		return -EIO;
-
 	pfid = &cfid->fid;
 	server->ops->new_lease_key(pfid);
 
@@ -109,7 +212,7 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 	oparms.reconnect = false;
 
 	rc = SMB2_open_init(tcon, server,
-			    &rqst[0], &oplock, &oparms, &utf16_path);
+			    &rqst[0], &oplock, &oparms, utf16_path);
 	if (rc)
 		goto oshr_free;
 	smb2_set_next_command(tcon, &rqst[0]);
@@ -132,47 +235,13 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 	rc = compound_send_recv(xid, ses, server,
 				flags, 2, rqst,
 				resp_buftype, rsp_iov);
-	mutex_lock(&cfid->fid_mutex);
-
-	/*
-	 * Now we need to check again as the cached root might have
-	 * been successfully re-opened from a concurrent process
-	 */
-
-	if (cfid->is_valid) {
-		/* work was already done */
-
-		/* stash fids for close() later */
-		struct cifs_fid fid = {
-			.persistent_fid = pfid->persistent_fid,
-			.volatile_fid = pfid->volatile_fid,
-		};
-
-		/*
-		 * caller expects this func to set the fid in cfid to valid
-		 * cached root, so increment the refcount.
-		 */
-		kref_get(&cfid->refcount);
-
-		mutex_unlock(&cfid->fid_mutex);
-
-		if (rc == 0) {
-			/* close extra handle outside of crit sec */
-			SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
-		}
-		rc = 0;
-		goto oshr_free;
-	}
-
-	/* Cached root is still invalid, continue normaly */
-
 	if (rc) {
 		if (rc == -EREMCHG) {
 			tcon->need_reconnect = true;
 			pr_warn_once("server share %s deleted\n",
 				     tcon->treeName);
 		}
-		goto oshr_exit;
+		goto oshr_free;
 	}
 
 	atomic_inc(&tcon->num_remote_opens);
@@ -185,49 +254,56 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 #endif /* CIFS_DEBUG2 */
 
 	cfid->tcon = tcon;
-	cfid->is_valid = true;
-	cfid->dentry = dentry;
-	if (dentry)
+	if (dentry) {
+		cfid->dentry = dentry;
 		dget(dentry);
-	kref_init(&cfid->refcount);
-
+	}
 	/* BB TBD check to see if oplock level check can be removed below */
-	if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE) {
-		/*
-		 * See commit 2f94a3125b87. Increment the refcount when we
-		 * get a lease for root, release it if lease break occurs
-		 */
-		kref_get(&cfid->refcount);
-		cfid->has_lease = true;
-		smb2_parse_contexts(server, o_rsp,
-				&oparms.fid->epoch,
-				    oparms.fid->lease_key, &oplock,
-				    NULL, NULL);
-	} else
-		goto oshr_exit;
+	if (o_rsp->OplockLevel != SMB2_OPLOCK_LEVEL_LEASE) {
+		goto oshr_free;
+	}
 
+	smb2_parse_contexts(server, o_rsp,
+			    &oparms.fid->epoch,
+			    oparms.fid->lease_key, &oplock,
+			    NULL, NULL);
+	
 	qi_rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
 	if (le32_to_cpu(qi_rsp->OutputBufferLength) < sizeof(struct smb2_file_all_info))
-		goto oshr_exit;
+		goto oshr_free;
 	if (!smb2_validate_and_copy_iov(
 				le16_to_cpu(qi_rsp->OutputBufferOffset),
 				sizeof(struct smb2_file_all_info),
 				&rsp_iov[1], sizeof(struct smb2_file_all_info),
 				(char *)&cfid->file_all_info))
 		cfid->file_all_info_is_valid = true;
-
 	cfid->time = jiffies;
+	cfid->is_open = true;
+	cfid->has_lease = true;
 
-oshr_exit:
-	mutex_unlock(&cfid->fid_mutex);
 oshr_free:
+	kfree(utf16_path);
 	SMB2_open_free(&rqst[0]);
 	SMB2_query_info_free(&rqst[1]);
 	free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
 	free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
-	if (rc == 0)
-		*ret_cfid = cfid;
-
+	spin_lock(&cfids->cfid_list_lock);
+	if (!cfid->has_lease) {
+		if (cfid->on_list) {
+			list_del(&cfid->entry);
+			cfid->on_list = false;
+			cfids->num_entries--;
+		}
+		rc = -ENOENT;
+	}
+	spin_unlock(&cfids->cfid_list_lock);
+	if (rc) {
+		free_cached_dir(cfid);
+		cfid = NULL;
+	}
+	if (rc == 0) {
+		*ret_cfid = cfid;	
+	}
 	return rc;
 }
 
@@ -236,20 +312,22 @@ int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
 			      struct cached_fid **ret_cfid)
 {
 	struct cached_fid *cfid;
+	struct cached_fids *cfids = tcon->cfids;
 
-	cfid = tcon->cfids->cfid;
-	if (cfid == NULL)
+	if (cfids == NULL)
 		return -ENOENT;
 
-	mutex_lock(&cfid->fid_mutex);
-	if (cfid->dentry == dentry) {
-		cifs_dbg(FYI, "found a cached root file handle by dentry\n");
-		*ret_cfid = cfid;
-		kref_get(&cfid->refcount);
-		mutex_unlock(&cfid->fid_mutex);
-		return 0;
+	spin_lock(&cfids->cfid_list_lock);
+	list_for_each_entry(cfid, &cfids->entries, entry) {
+		if (dentry && cfid->dentry == dentry) {
+			cifs_dbg(FYI, "found a cached root file handle by dentry\n");
+			kref_get(&cfid->refcount);
+			*ret_cfid = cfid;	
+			spin_unlock(&cfids->cfid_list_lock);
+			return 0;
+		}
 	}
-	mutex_unlock(&cfid->fid_mutex);
+	spin_unlock(&cfids->cfid_list_lock);
 	return -ENOENT;
 }
 
@@ -258,63 +336,29 @@ smb2_close_cached_fid(struct kref *ref)
 {
 	struct cached_fid *cfid = container_of(ref, struct cached_fid,
 					       refcount);
-	struct cached_dirent *dirent, *q;
 
-	if (cfid->is_valid) {
-		cifs_dbg(FYI, "clear cached root file handle\n");
-		SMB2_close(0, cfid->tcon, cfid->fid.persistent_fid,
-			   cfid->fid.volatile_fid);
+	spin_lock(&cfid->cfids->cfid_list_lock);
+	if (cfid->on_list) {
+		list_del(&cfid->entry);
+		cfid->on_list = false;
+		cfid->cfids->num_entries--;
 	}
+	spin_unlock(&cfid->cfids->cfid_list_lock);
 
-	/*
-	 * We only check validity above to send SMB2_close,
-	 * but we still need to invalidate these entries
-	 * when this function is called
-	 */
-	cfid->is_valid = false;
-	cfid->file_all_info_is_valid = false;
-	cfid->has_lease = false;
-	if (cfid->dentry) {
-		dput(cfid->dentry);
-		cfid->dentry = NULL;
-	}
-	/*
-	 * Delete all cached dirent names
-	 */
-	mutex_lock(&cfid->dirents.de_mutex);
-	list_for_each_entry_safe(dirent, q, &cfid->dirents.entries, entry) {
-		list_del(&dirent->entry);
-		kfree(dirent->name);
-		kfree(dirent);
+	dput(cfid->dentry);
+	cfid->dentry = NULL;
+
+	if (cfid->is_open) {
+		SMB2_close(0, cfid->tcon, cfid->fid.persistent_fid,
+			   cfid->fid.volatile_fid);
 	}
-	cfid->dirents.is_valid = 0;
-	cfid->dirents.is_failed = 0;
-	cfid->dirents.ctx = NULL;
-	cfid->dirents.pos = 0;
-	mutex_unlock(&cfid->dirents.de_mutex);
 
+	free_cached_dir(cfid);
 }
 
 void close_cached_dir(struct cached_fid *cfid)
 {
-	mutex_lock(&cfid->fid_mutex);
 	kref_put(&cfid->refcount, smb2_close_cached_fid);
-	mutex_unlock(&cfid->fid_mutex);
-}
-
-void close_cached_dir_lease_locked(struct cached_fid *cfid)
-{
-	if (cfid->has_lease) {
-		cfid->has_lease = false;
-		kref_put(&cfid->refcount, smb2_close_cached_fid);
-	}
-}
-
-void close_cached_dir_lease(struct cached_fid *cfid)
-{
-	mutex_lock(&cfid->fid_mutex);
-	close_cached_dir_lease_locked(cfid);
-	mutex_unlock(&cfid->fid_mutex);
 }
 
 /*
@@ -327,41 +371,62 @@ void close_all_cached_dirs(struct cifs_sb_info *cifs_sb)
 	struct cached_fid *cfid;
 	struct cifs_tcon *tcon;
 	struct tcon_link *tlink;
+	struct cached_fids *cfids;
 
 	for (node = rb_first(root); node; node = rb_next(node)) {
 		tlink = rb_entry(node, struct tcon_link, tl_rbnode);
 		tcon = tlink_tcon(tlink);
 		if (IS_ERR(tcon))
 			continue;
-		cfid = tcon->cfids->cfid;
-		if (cfid == NULL)
+		cfids = tcon->cfids;
+		if (cfids == NULL)
 			continue;
-		mutex_lock(&cfid->fid_mutex);
-		if (cfid->dentry) {
+		list_for_each_entry(cfid, &cfids->entries, entry) {
 			dput(cfid->dentry);
 			cfid->dentry = NULL;
 		}
-		mutex_unlock(&cfid->fid_mutex);
 	}
 }
 
 /*
- * Invalidate and close all cached dirs when a TCON has been reset
+ * Invalidate all cached dirs when a TCON has been reset
  * due to a session loss.
  */
 void invalidate_all_cached_dirs(struct cifs_tcon *tcon)
 {
-	struct cached_fid *cfid = tcon->cfids->cfid;
-
-	if (cfid == NULL)
-		return;
-
-	mutex_lock(&cfid->fid_mutex);
-	cfid->is_valid = false;
-	/* cached handle is not valid, so SMB2_CLOSE won't be sent below */
-	close_cached_dir_lease_locked(cfid);
-	memset(&cfid->fid, 0, sizeof(struct cifs_fid));
-	mutex_unlock(&cfid->fid_mutex);
+	struct cached_fids *cfids = tcon->cfids;
+	struct cached_fid *cfid, *q;
+	struct list_head entry;
+
+	INIT_LIST_HEAD(&entry);
+	spin_lock(&cfids->cfid_list_lock);
+	list_for_each_entry_safe(cfid, q, &cfids->entries, entry) {
+		list_del(&cfid->entry);
+		list_add(&cfid->entry, &entry);
+		cfids->num_entries--;
+		cfid->is_open = false;
+		/* To prevent race with smb2_cached_lease_break() */
+		kref_get(&cfid->refcount);
+	}
+	spin_unlock(&cfids->cfid_list_lock);
+
+	list_for_each_entry_safe(cfid, q, &entry, entry) {
+		cfid->on_list = false;
+		list_del(&cfid->entry);
+		cancel_work_sync(&cfid->lease_break);
+		if (cfid->has_lease) {
+			/*
+			 * We lease was never cancelled from the server so we
+			 * we need to drop the reference.
+			 */
+			spin_lock(&cfids->cfid_list_lock);
+			cfid->has_lease = false;
+			spin_unlock(&cfids->cfid_list_lock);
+			kref_put(&cfid->refcount, smb2_close_cached_fid);
+		}
+		/* Drop the extra reference opened above*/
+		kref_put(&cfid->refcount, smb2_close_cached_fid);
+	}
 }
 
 static void
@@ -370,51 +435,83 @@ smb2_cached_lease_break(struct work_struct *work)
 	struct cached_fid *cfid = container_of(work,
 				struct cached_fid, lease_break);
 
-	close_cached_dir_lease(cfid);
+	spin_lock(&cfid->cfids->cfid_list_lock);
+	cfid->has_lease = false;
+	spin_unlock(&cfid->cfids->cfid_list_lock);
+	kref_put(&cfid->refcount, smb2_close_cached_fid);
 }
 
 int cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16])
 {
-	struct cached_fid *cfid = tcon->cfids->cfid;
+	struct cached_fids *cfids = tcon->cfids;
+	struct cached_fid *cfid;
 
-	if (cfid == NULL)
+	if (cfids == NULL)
 		return false;
 
-	if (cfid->is_valid &&
-	    !memcmp(lease_key,
-		    cfid->fid.lease_key,
-		    SMB2_LEASE_KEY_SIZE)) {
-		cfid->time = 0;
-		INIT_WORK(&cfid->lease_break,
-			  smb2_cached_lease_break);
-		queue_work(cifsiod_wq,
-			   &cfid->lease_break);
-		return true;
+	spin_lock(&cfids->cfid_list_lock);
+	list_for_each_entry(cfid, &cfids->entries, entry) {
+		if (cfid->has_lease &&
+		    !memcmp(lease_key,
+			    cfid->fid.lease_key,
+			    SMB2_LEASE_KEY_SIZE)) {
+			cfid->time = 0;
+			/*
+			 * We found a lease remove it from the list
+			 * so no threads threads can access it.
+			 */
+			list_del(&cfid->entry);
+			cfid->on_list = false;
+			cfids->num_entries--;
+
+			queue_work(cifsiod_wq,
+				   &cfid->lease_break);
+			spin_unlock(&cfids->cfid_list_lock);
+			return true;
+		}
 	}
+	spin_unlock(&cfids->cfid_list_lock);
 	return false;
 }
 
-struct cached_fid *init_cached_dir(const char *path)
+static struct cached_fid *init_cached_dir(const char *path)
 {
 	struct cached_fid *cfid;
 
-	cfid = kzalloc(sizeof(*cfid), GFP_KERNEL);
+	cfid = kzalloc(sizeof(*cfid), GFP_ATOMIC);
 	if (!cfid)
 		return NULL;
-	cfid->path = kstrdup(path, GFP_KERNEL);
+	cfid->path = kstrdup(path, GFP_ATOMIC);
 	if (!cfid->path) {
 		kfree(cfid);
 		return NULL;
 	}
 
+	INIT_WORK(&cfid->lease_break, smb2_cached_lease_break);
+	INIT_LIST_HEAD(&cfid->entry);
 	INIT_LIST_HEAD(&cfid->dirents.entries);
 	mutex_init(&cfid->dirents.de_mutex);
-	mutex_init(&cfid->fid_mutex);
+	spin_lock_init(&cfid->fid_lock);
+	kref_init(&cfid->refcount);
 	return cfid;
 }
 
-void free_cached_dir(struct cached_fid *cfid)
+static void free_cached_dir(struct cached_fid *cfid)
 {
+	struct cached_dirent *dirent, *q;
+
+	dput(cfid->dentry);
+	cfid->dentry = NULL;
+
+	/*
+	 * Delete all cached dirent names
+	 */
+	list_for_each_entry_safe(dirent, q, &cfid->dirents.entries, entry) {
+		list_del(&dirent->entry);
+		kfree(dirent->name);
+		kfree(dirent);
+	}
+
 	kfree(cfid->path);
 	cfid->path = NULL;
 	kfree(cfid);
@@ -427,15 +524,34 @@ struct cached_fids *init_cached_dirs(void)
 	cfids = kzalloc(sizeof(*cfids), GFP_KERNEL);
 	if (!cfids)
 		return NULL;
-	mutex_init(&cfids->cfid_list_mutex);
+	spin_lock_init(&cfids->cfid_list_lock);
+	INIT_LIST_HEAD(&cfids->entries);
 	return cfids;
 }
 
+/*
+ * Called from tconInfoFree when we are tearing down the tcon.
+ * There are no active users or open files/directories at this point.
+ */
 void free_cached_dirs(struct cached_fids *cfids)
 {
-	if (cfids->cfid) {
-		free_cached_dir(cfids->cfid);
-		cfids->cfid = NULL;
+	struct cached_fid *cfid, *q;
+	struct list_head entry;
+
+       	INIT_LIST_HEAD(&entry);
+	spin_lock(&cfids->cfid_list_lock);
+	list_for_each_entry_safe(cfid, q, &cfids->entries, entry) {
+		cfid->on_list = false;
+		cfid->is_open = false;
+		list_del(&cfid->entry);
+		list_add(&cfid->entry, &entry);
+	}
+	spin_unlock(&cfids->cfid_list_lock);
+
+	list_for_each_entry_safe(cfid, q, &entry, entry) {
+		list_del(&cfid->entry);
+		free_cached_dir(cfid);
 	}
-	kfree(cfids);
+
+ 	kfree(cfids);
 }
diff --git a/fs/cifs/cached_dir.h b/fs/cifs/cached_dir.h
index bdf6c3866653..e536304ca2ce 100644
--- a/fs/cifs/cached_dir.h
+++ b/fs/cifs/cached_dir.h
@@ -31,14 +31,17 @@ struct cached_dirents {
 };
 
 struct cached_fid {
+	struct list_head entry;
+	struct cached_fids *cfids;
 	const char *path;
-	bool is_valid:1;	/* Do we have a useable root fid */
-	bool file_all_info_is_valid:1;
 	bool has_lease:1;
+	bool is_open:1;
+	bool on_list:1;
+	bool file_all_info_is_valid:1;
 	unsigned long time; /* jiffies of when lease was taken */
 	struct kref refcount;
 	struct cifs_fid fid;
-	struct mutex fid_mutex;
+	spinlock_t fid_lock;
 	struct cifs_tcon *tcon;
 	struct dentry *dentry;
 	struct work_struct lease_break;
@@ -46,9 +49,14 @@ struct cached_fid {
 	struct cached_dirents dirents;
 };
 
+#define MAX_CACHED_FIDS 16
 struct cached_fids {
-	struct mutex cfid_list_mutex;
-	struct cached_fid *cfid;
+	/* Must be held when:
+	 * - accessing the cfids->entries list
+	 */
+	spinlock_t cfid_list_lock;
+	int num_entries;
+	struct list_head entries;
 };
 
 extern struct cached_fids *init_cached_dirs(void);
@@ -61,8 +69,6 @@ extern int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
 				     struct dentry *dentry,
 				     struct cached_fid **cfid);
 extern void close_cached_dir(struct cached_fid *cfid);
-extern void close_cached_dir_lease(struct cached_fid *cfid);
-extern void close_cached_dir_lease_locked(struct cached_fid *cfid);
 extern void close_all_cached_dirs(struct cifs_sb_info *cifs_sb);
 extern void invalidate_all_cached_dirs(struct cifs_tcon *tcon);
 extern int cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16]);
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index bac08c20f559..a42397b52882 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -2265,13 +2265,13 @@ cifs_dentry_needs_reval(struct dentry *dentry)
 		return true;
 
 	if (!open_cached_dir_by_dentry(tcon, dentry->d_parent, &cfid)) {
-		mutex_lock(&cfid->fid_mutex);
+		spin_lock(&cfid->fid_lock);
 		if (cfid->time && cifs_i->time > cfid->time) {
-			mutex_unlock(&cfid->fid_mutex);
+			spin_unlock(&cfid->fid_lock);
 			close_cached_dir(cfid);
 			return false;
 		}
-		mutex_unlock(&cfid->fid_mutex);
+		spin_unlock(&cfid->fid_lock);
 		close_cached_dir(cfid);
 	}
 	/*
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 96f3b0573606..1ed4b4992025 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -787,7 +787,7 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
 
 	rc = open_cached_dir(xid, tcon, full_path, cifs_sb, true, &cfid);
 	if (!rc) {
-		if (cfid->is_valid) {
+		if (cfid->has_lease) {
 			close_cached_dir(cfid);
 			return 0;
 		}
-- 
2.35.3