Commit be4fde79 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

cifs: fix dentry lookups in directory handle cache 



Get rid of any prefix paths in @path before lookup_positive_unlocked()
as it will call ->lookup() which already adds those prefix paths
through build_path_from_dentry().

This has caused a performance regression when mounting shares with a
prefix path where readdir(2) would end up retrying several times to
open bad directory names that contained duplicate prefix paths.

Fix this by skipping any prefix paths in @path before calling
lookup_positive_unlocked().

Fixes: e4029e07 ("cifs: find and use the dentry for cached non-root directories also")
Cc: stable@vger.kernel.org # 6.1+
Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 7e0e76d9

fs/cifs/cached_dir.c

+34 −2
Original line number Diff line number Diff line
@@ -99,6 +99,23 @@ path_to_dentry(struct cifs_sb_info *cifs_sb, const char *path) 
	return dentry;

}



static const char *path_no_prefix(struct cifs_sb_info *cifs_sb,

				  const char *path)

{

	size_t len = 0;



	if (!*path)

		return path;



	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&

	    cifs_sb->prepath) {

		len = strlen(cifs_sb->prepath) + 1;

		if (unlikely(len > strlen(path)))

			return ERR_PTR(-EINVAL);

	}

	return path + len;

}



/*

 * Open the and cache a directory handle.

 * If error then *cfid is not initialized.
@@ -125,6 +142,7 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon, 
	struct dentry *dentry = NULL;

	struct cached_fid *cfid;

	struct cached_fids *cfids;

	const char *npath;



	if (tcon == NULL || tcon->cfids == NULL || tcon->nohandlecache ||

	    is_smb1_server(tcon->ses->server))
@@ -160,6 +178,20 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon, 
		return 0;

	}



	/*

	 * Skip any prefix paths in @path as lookup_positive_unlocked() ends up

	 * calling ->lookup() which already adds those through

	 * build_path_from_dentry().  Also, do it earlier as we might reconnect

	 * below when trying to send compounded request and then potentially

	 * having a different prefix path (e.g. after DFS failover).

	 */

	npath = path_no_prefix(cifs_sb, path);

	if (IS_ERR(npath)) {

		rc = PTR_ERR(npath);

		kfree(utf16_path);

		return rc;

	}



	/*

	 * We do not hold the lock for the open because in case

	 * SMB2_open needs to reconnect.
@@ -252,10 +284,10 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon, 
				(char *)&cfid->file_all_info))

		cfid->file_all_info_is_valid = true;



	if (!path[0])

	if (!npath[0])

		dentry = dget(cifs_sb->root);

	else {

		dentry = path_to_dentry(cifs_sb, path);

		dentry = path_to_dentry(cifs_sb, npath);

		if (IS_ERR(dentry)) {

			rc = -ENOENT;

			goto oshr_free;