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")
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
---
fs/cifs/cached_dir.c | 36 ++++++++++++++++++++++++++++++++++--
1 file changed, 34 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/cached_dir.c b/fs/cifs/cached_dir.c
index 71fabb4c09a4..bfc964b36c72 100644
--- a/fs/cifs/cached_dir.c
+++ b/fs/cifs/cached_dir.c
@@ -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;
--
2.40.0
