This is a note to let you know that I've just added the patch titled
cifs: fix dentry lookups in directory handle cache
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-fix-dentry-lookups-in-directory-handle-cache.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From be4fde79812f02914e350bde0bc4cfeae8429378 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@xxxxxxxxxxxxx>
Date: Fri, 24 Mar 2023 13:56:33 -0300
Subject: cifs: fix dentry lookups in directory handle cache
From: Paulo Alcantara <pc@xxxxxxxxxxxxx>
commit be4fde79812f02914e350bde0bc4cfeae8429378 upstream.
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: e4029e072673 ("cifs: find and use the dentry for cached non-root directories also")
Cc: stable@xxxxxxxxxxxxxxx # 6.1+
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/cached_dir.c | 36 ++++++++++++++++++++++++++++++++++--
1 file changed, 34 insertions(+), 2 deletions(-)
--- a/fs/cifs/cached_dir.c
+++ b/fs/cifs/cached_dir.c
@@ -99,6 +99,23 @@ path_to_dentry(struct cifs_sb_info *cifs
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, st
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))
@@ -161,6 +179,20 @@ int open_cached_dir(unsigned int xid, st
}
/*
+ * 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.
* This is safe because no other thread will be able to get a ref
@@ -252,10 +284,10 @@ int open_cached_dir(unsigned int xid, st
(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;
Patches currently in stable-queue which might be from pc@xxxxxxxxxxxxx are
queue-6.1/cifs-lock-chan_lock-outside-match_session.patch
queue-6.1/smb3-lower-default-deferred-close-timeout-to-address-perf-regression.patch
queue-6.1/cifs-do-not-poll-server-interfaces-too-regularly.patch
queue-6.1/cifs-dump-pending-mids-for-all-channels-in-debugdata.patch
queue-6.1/smb3-fix-unusable-share-after-force-unmount-failure.patch
queue-6.1/cifs-empty-interface-list-when-server-doesn-t-support-query-interfaces.patch
queue-6.1/cifs-print-session-id-while-listing-open-files.patch
queue-6.1/cifs-fix-dentry-lookups-in-directory-handle-cache.patch
queue-6.1/cifs-append-path-to-open_enter-trace-event.patch
