cifs: find and use the dentry for cached non-root directories also

This allows us to use cached attributes for the entries in a cached
directory for as long as a lease is held on the directory itself.
Previously we have always allowed "used cached attributes for 1 second"
but this extends this to the lifetime of the lease as well as making the
caching safer.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/cached_dir.c b/fs/cifs/cached_dir.c
index e5573d4..fe88b67 100644 (file)
--- a/fs/cifs/cached_dir.c
+++ b/fs/cifs/cached_dir.c
@@ -5,6 +5,7 @@
  *  Copyright (c) 2022, Ronnie Sahlberg <lsahlber@redhat.com>
  */
 
+#include <linux/namei.h>
 #include "cifsglob.h"
 #include "cifsproto.h"
 #include "cifs_debug.h"
@@ -59,6 +60,44 @@ static struct cached_fid *find_or_create_cached_dir(struct cached_fids *cfids,
        return cfid;
 }
 
+static struct dentry *
+path_to_dentry(struct cifs_sb_info *cifs_sb, const char *path)
+{
+       struct dentry *dentry;
+       const char *s, *p;
+       char sep;
+
+       sep = CIFS_DIR_SEP(cifs_sb);
+       dentry = dget(cifs_sb->root);
+       s = path;
+
+       do {
+               struct inode *dir = d_inode(dentry);
+               struct dentry *child;
+
+               if (!S_ISDIR(dir->i_mode)) {
+                       dput(dentry);
+                       dentry = ERR_PTR(-ENOTDIR);
+                       break;
+               }
+
+               /* skip separators */
+               while (*s == sep)
+                       s++;
+               if (!*s)
+                       break;
+               p = s++;
+               /* next separator */
+               while (*s && *s != sep)
+                       s++;
+
+               child = lookup_positive_unlocked(p, dentry, s - p);
+               dput(dentry);
+               dentry = child;
+       } while (!IS_ERR(dentry));
+       return dentry;
+}
+
 /*
  * Open the and cache a directory handle.
  * If error then *cfid is not initialized.
@@ -86,7 +125,6 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
        struct cached_fid *cfid;
        struct cached_fids *cfids;
 
-
        if (tcon == NULL || tcon->cfids == NULL || tcon->nohandlecache ||
            is_smb1_server(tcon->ses->server))
                return -EOPNOTSUPP;
@@ -101,13 +139,6 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
        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 (!path[0])
-               dentry = cifs_sb->root;
-
        utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
        if (!utf16_path)
                return -ENOMEM;
@@ -199,12 +230,6 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
        oparms.fid->mid = le64_to_cpu(o_rsp->hdr.MessageId);
 #endif /* CIFS_DEBUG2 */
 
-       cfid->tcon = tcon;
-       if (dentry) {
-               cfid->dentry = dentry;
-               dget(dentry);
-       }
-       /* BB TBD check to see if oplock level check can be removed below */
        if (o_rsp->OplockLevel != SMB2_OPLOCK_LEVEL_LEASE)
                goto oshr_free;
 
@@ -223,6 +248,16 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
                                &rsp_iov[1], sizeof(struct smb2_file_all_info),
                                (char *)&cfid->file_all_info))
                cfid->file_all_info_is_valid = true;
+
+       if (!path[0])
+               dentry = dget(cifs_sb->root);
+       else {
+               dentry = path_to_dentry(cifs_sb, path);
+               if (IS_ERR(dentry))
+                       goto oshr_free;
+       }
+       cfid->dentry = dentry;
+       cfid->tcon = tcon;
        cfid->time = jiffies;
        cfid->is_open = true;
        cfid->has_lease = true;