[PATCH] cifs: cache dirent names for cached directories

[Ronnie Sahlberg <lsahlber@redhat.com>]

Cache the names of entries for cached-directories while we have a lease held.
This allows us to avoid expensive calls to the server when re-scanning
a cached directory.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/cifsglob.h |  84 ++++++++++++++--------
 fs/cifs/misc.c     |   2 +
 fs/cifs/readdir.c  | 176 ++++++++++++++++++++++++++++++++++++++++++---
 fs/cifs/smb2ops.c  |  20 +++++-
 4 files changed, 241 insertions(+), 41 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 8de977c359b1..4ec6a3df17fa 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1009,6 +1009,58 @@ cap_unix(struct cifs_ses *ses)
 	return ses->server->vals->cap_unix & ses->capabilities;
 }
 
+/*
+ * common struct for holding inode info when searching for or updating an
+ * inode with new info
+ */
+
+#define CIFS_FATTR_DFS_REFERRAL		0x1
+#define CIFS_FATTR_DELETE_PENDING	0x2
+#define CIFS_FATTR_NEED_REVAL		0x4
+#define CIFS_FATTR_INO_COLLISION	0x8
+#define CIFS_FATTR_UNKNOWN_NLINK	0x10
+#define CIFS_FATTR_FAKE_ROOT_INO	0x20
+
+struct cifs_fattr {
+	u32		cf_flags;
+	u32		cf_cifsattrs;
+	u64		cf_uniqueid;
+	u64		cf_eof;
+	u64		cf_bytes;
+	u64		cf_createtime;
+	kuid_t		cf_uid;
+	kgid_t		cf_gid;
+	umode_t		cf_mode;
+	dev_t		cf_rdev;
+	unsigned int	cf_nlink;
+	unsigned int	cf_dtype;
+	struct timespec64 cf_atime;
+	struct timespec64 cf_mtime;
+	struct timespec64 cf_ctime;
+	u32             cf_cifstag;
+};
+
+struct cached_dirent {
+	struct list_head entry;
+	char *name;
+	int namelen;
+	loff_t pos;
+
+	struct cifs_fattr fattr;
+};
+
+struct cached_dirents {
+	bool is_valid:1;
+	bool is_failed:1;
+	struct dir_context *ctx; /*
+				  * Only used to make sure we only take entries
+				  * from a single context. Never dereferenced.
+				  */
+	struct mutex de_mutex;
+	int pos;		 /* Expected ctx->pos */
+	struct list_head entries;
+};
+
 struct cached_fid {
 	bool is_valid:1;	/* Do we have a useable root fid */
 	bool file_all_info_is_valid:1;
@@ -1021,6 +1073,7 @@ struct cached_fid {
 	struct dentry *dentry;
 	struct work_struct lease_break;
 	struct smb2_file_all_info file_all_info;
+	struct cached_dirents dirents;
 };
 
 /*
@@ -1641,37 +1694,6 @@ struct file_list {
 	struct cifsFileInfo *cfile;
 };
 
-/*
- * common struct for holding inode info when searching for or updating an
- * inode with new info
- */
-
-#define CIFS_FATTR_DFS_REFERRAL		0x1
-#define CIFS_FATTR_DELETE_PENDING	0x2
-#define CIFS_FATTR_NEED_REVAL		0x4
-#define CIFS_FATTR_INO_COLLISION	0x8
-#define CIFS_FATTR_UNKNOWN_NLINK	0x10
-#define CIFS_FATTR_FAKE_ROOT_INO	0x20
-
-struct cifs_fattr {
-	u32		cf_flags;
-	u32		cf_cifsattrs;
-	u64		cf_uniqueid;
-	u64		cf_eof;
-	u64		cf_bytes;
-	u64		cf_createtime;
-	kuid_t		cf_uid;
-	kgid_t		cf_gid;
-	umode_t		cf_mode;
-	dev_t		cf_rdev;
-	unsigned int	cf_nlink;
-	unsigned int	cf_dtype;
-	struct timespec64 cf_atime;
-	struct timespec64 cf_mtime;
-	struct timespec64 cf_ctime;
-	u32             cf_cifstag;
-};
-
 static inline void free_dfs_info_param(struct dfs_info3_param *param)
 {
 	if (param) {
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index afaf59c22193..7fef08add3bc 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -114,6 +114,8 @@ tconInfoAlloc(void)
 		kfree(ret_buf);
 		return NULL;
 	}
+	INIT_LIST_HEAD(&ret_buf->crfid.dirents.entries);
+	mutex_init(&ret_buf->crfid.dirents.de_mutex);
 
 	atomic_inc(&tconInfoAllocCount);
 	ret_buf->status = TID_NEW;
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 1929e80c09ee..8b3fbe6b3580 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -840,9 +840,112 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos,
 	return rc;
 }
 
+static bool emit_cached_dirents(struct cached_dirents *cde,
+				struct dir_context *ctx)
+{
+	struct list_head *tmp;
+	struct cached_dirent *dirent;
+	int rc;
+
+	list_for_each(tmp, &cde->entries) {
+		dirent = list_entry(tmp, struct cached_dirent, entry);
+		if (ctx->pos >= dirent->pos)
+			continue;
+		ctx->pos = dirent->pos;
+		rc = dir_emit(ctx, dirent->name, dirent->namelen,
+			      dirent->fattr.cf_uniqueid,
+			      dirent->fattr.cf_dtype);
+		if (!rc)
+			return rc;
+	}
+	return true;
+}
+
+static void update_cached_dirents_count(struct cached_dirents *cde,
+					struct dir_context *ctx)
+{
+	if (cde->ctx != ctx)
+		return;
+	if (cde->is_valid || cde->is_failed)
+		return;
+
+	cde->pos++;
+}
+
+static void finished_cached_dirents_count(struct cached_dirents *cde,
+					struct dir_context *ctx)
+{
+	if (cde->ctx != ctx)
+		return;
+	if (cde->is_valid || cde->is_failed)
+		return;
+	if (ctx->pos != cde->pos)
+		return;
+
+	cde->is_valid = 1;
+}
+
+static void add_cached_dirent(struct cached_dirents *cde,
+			      struct dir_context *ctx,
+			      const char *name, int namelen,
+			      struct cifs_fattr *fattr)
+{
+	struct cached_dirent *de;
+
+	if (cde->ctx != ctx)
+		return;
+	if (cde->is_valid || cde->is_failed)
+		return;
+	if (ctx->pos != cde->pos) {
+		cde->is_failed = 1;
+		return;
+	}
+	de = kzalloc(sizeof(*de), GFP_ATOMIC);
+	if (de == NULL) {
+		cde->is_failed = 1;
+		return;
+	}
+	de->name = kzalloc(namelen + 1, GFP_ATOMIC);
+	if (de->name == NULL) {
+		kfree(de);
+		cde->is_failed = 1;
+		return;
+	}
+	memcpy(de->name, name, namelen);
+	de->namelen = namelen;
+	de->pos = ctx->pos;
+
+	memcpy(&de->fattr, fattr, sizeof(struct cifs_fattr));
+
+	list_add_tail(&de->entry, &cde->entries);
+}
+
+static bool cifs_dir_emit(struct dir_context *ctx,
+			  const char *name, int namelen,
+			  struct cifs_fattr *fattr,
+			  struct cached_fid *cfid)
+{
+	bool rc;
+	ino_t ino = cifs_uniqueid_to_ino_t(fattr->cf_uniqueid);
+
+	rc = dir_emit(ctx, name, namelen, ino, fattr->cf_dtype);
+	if (!rc)
+		return rc;
+
+	if (cfid) {
+		mutex_lock(&cfid->dirents.de_mutex);
+		add_cached_dirent(&cfid->dirents, ctx, name, namelen,
+				  fattr);
+		mutex_unlock(&cfid->dirents.de_mutex);
+	}
+
+	return rc;
+}
+
 static int cifs_filldir(char *find_entry, struct file *file,
-		struct dir_context *ctx,
-		char *scratch_buf, unsigned int max_len)
+			struct dir_context *ctx,
+			char *scratch_buf, unsigned int max_len,
+			struct cached_fid *cfid)
 {
 	struct cifsFileInfo *file_info = file->private_data;
 	struct super_block *sb = file_inode(file)->i_sb;
@@ -851,7 +954,6 @@ static int cifs_filldir(char *find_entry, struct file *file,
 	struct cifs_fattr fattr;
 	struct qstr name;
 	int rc = 0;
-	ino_t ino;
 
 	rc = cifs_fill_dirent(&de, find_entry, file_info->srch_inf.info_level,
 			      file_info->srch_inf.unicode);
@@ -931,8 +1033,8 @@ static int cifs_filldir(char *find_entry, struct file *file,
 
 	cifs_prime_dcache(file_dentry(file), &name, &fattr);
 
-	ino = cifs_uniqueid_to_ino_t(fattr.cf_uniqueid);
-	return !dir_emit(ctx, name.name, name.len, ino, fattr.cf_dtype);
+	return !cifs_dir_emit(ctx, name.name, name.len,
+			      &fattr, cfid);
 }
 
 
@@ -942,7 +1044,7 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 	unsigned int xid;
 	int i;
 	struct cifs_tcon *tcon;
-	struct cifsFileInfo *cifsFile = NULL;
+	struct cifsFileInfo *cifsFile;
 	char *current_entry;
 	int num_to_fill = 0;
 	char *tmp_buf = NULL;
@@ -950,6 +1052,8 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 	unsigned int max_len;
 	const char *full_path;
 	void *page = alloc_dentry_path();
+	struct cached_fid *cfid = NULL;
+	struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);
 
 	xid = get_xid();
 
@@ -969,6 +1073,48 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 		if (rc)
 			goto rddir2_exit;
 	}
+	cifsFile = file->private_data;
+	tcon = tlink_tcon(cifsFile->tlink);
+	
+	rc = open_cached_dir(xid, tcon, full_path, cifs_sb, &cfid);
+	if (rc)
+		goto cache_not_found;
+
+	mutex_lock(&cfid->dirents.de_mutex);
+	/*
+	 * If this was reading from the start of the directory
+	 * we need to initialize scanning and storing the
+	 * directory content.
+	 */
+	if (ctx->pos == 0 && cfid->dirents.ctx == NULL) {
+		cfid->dirents.ctx = ctx;
+		cfid->dirents.pos = 2;
+	}
+	/*
+	 * If we already have the entire directory cached then
+	 * we can just serve the cache.
+	 */
+	if (cfid->dirents.is_valid) {
+		if (!dir_emit_dots(file, ctx)){
+			mutex_unlock(&cfid->dirents.de_mutex);
+			goto rddir2_exit;
+		}
+		emit_cached_dirents(&cfid->dirents, ctx);
+		mutex_unlock(&cfid->dirents.de_mutex);
+		goto rddir2_exit;
+	}
+	mutex_unlock(&cfid->dirents.de_mutex);
+ cache_not_found:
+
+	/* Drop the cache while calling initiate_cifs_search and
+	 * find_cifs_entry in case there will be reconnects during
+	 * query_directory.
+	 */
+	if (cfid) {
+		close_cached_dir(cfid);
+		cfid = NULL;
+	}
+
 
 	if (!dir_emit_dots(file, ctx))
 		goto rddir2_exit;
@@ -978,7 +1124,6 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 		if it before then restart search
 		if after then keep searching till find it */
 
-	cifsFile = file->private_data;
 	if (cifsFile->srch_inf.endOfSearch) {
 		if (cifsFile->srch_inf.emptyDir) {
 			cifs_dbg(FYI, "End of search, empty dir\n");
@@ -990,15 +1135,20 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 		tcon->ses->server->close(xid, tcon, &cifsFile->fid);
 	} */
 
-	tcon = tlink_tcon(cifsFile->tlink);
 	rc = find_cifs_entry(xid, tcon, ctx->pos, file, full_path,
 			     &current_entry, &num_to_fill);
+	open_cached_dir(xid, tcon, full_path, cifs_sb, &cfid);
 	if (rc) {
 		cifs_dbg(FYI, "fce error %d\n", rc);
 		goto rddir2_exit;
 	} else if (current_entry != NULL) {
 		cifs_dbg(FYI, "entry %lld found\n", ctx->pos);
 	} else {
+		if (cfid) {
+			mutex_lock(&cfid->dirents.de_mutex);
+			finished_cached_dirents_count(&cfid->dirents, ctx);
+			mutex_unlock(&cfid->dirents.de_mutex);
+		}
 		cifs_dbg(FYI, "Could not find entry\n");
 		goto rddir2_exit;
 	}
@@ -1028,7 +1178,7 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 		 */
 		*tmp_buf = 0;
 		rc = cifs_filldir(current_entry, file, ctx,
-				  tmp_buf, max_len);
+				  tmp_buf, max_len, cfid);
 		if (rc) {
 			if (rc > 0)
 				rc = 0;
@@ -1036,6 +1186,12 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 		}
 
 		ctx->pos++;
+		if (cfid) {
+			mutex_lock(&cfid->dirents.de_mutex);
+			update_cached_dirents_count(&cfid->dirents, ctx);
+			mutex_unlock(&cfid->dirents.de_mutex);
+		}
+
 		if (ctx->pos ==
 			cifsFile->srch_inf.index_of_last_entry) {
 			cifs_dbg(FYI, "last entry in buf at pos %lld %s\n",
@@ -1050,6 +1206,8 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 	kfree(tmp_buf);
 
 rddir2_exit:
+	if (cfid)
+		close_cached_dir(cfid);
 	free_dentry_path(page);
 	free_xid(xid);
 	return rc;
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index d6aaeff4a30a..10170266f44b 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -699,6 +699,8 @@ smb2_close_cached_fid(struct kref *ref)
 {
 	struct cached_fid *cfid = container_of(ref, struct cached_fid,
 					       refcount);
+	struct list_head *pos, *q;
+	struct cached_dirent *dirent;
 
 	if (cfid->is_valid) {
 		cifs_dbg(FYI, "clear cached root file handle\n");
@@ -718,6 +720,21 @@ smb2_close_cached_fid(struct kref *ref)
 		dput(cfid->dentry);
 		cfid->dentry = NULL;
 	}
+	/*
+	 * Delete all cached dirent names
+	 */
+	mutex_lock(&cfid->dirents.de_mutex);
+	list_for_each_safe(pos, q, &cfid->dirents.entries) {
+		dirent = list_entry(pos, struct cached_dirent, entry);
+		list_del(pos);
+		kfree(dirent->name);
+		kfree(dirent);
+	}
+	cfid->dirents.is_valid = 0;
+	cfid->dirents.is_failed = 0;
+	cfid->dirents.ctx = NULL;
+	cfid->dirents.pos = 0;
+	mutex_unlock(&cfid->dirents.de_mutex);
 }
 
 void close_cached_dir(struct cached_fid *cfid)
@@ -776,7 +793,8 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 	struct cifs_fid *pfid;
 	struct dentry *dentry;
 
-	if (tcon->nohandlecache)
+	if (tcon == NULL || tcon->nohandlecache ||
+	    is_smb1_server(tcon->ses->server))
 		return -ENOTSUPP;
 
 	if (cifs_sb->root == NULL)
-- 
2.30.2