cifs: reduce roundtrips on create/qinfo requests

To work around some Window servers that return
STATUS_OBJECT_NAME_INVALID on query infos under DFS namespaces that
contain non-ASCII characters, we started checking for -ENOENT on every
file open, and if so, then send additional requests to figure out
whether it is a DFS link or not.  It means that all those requests
will be sent to every non-existing file.

So, in order to reduce the number of roundtrips, check earlier whether
status code is STATUS_OBJECT_NAME_INVALID and tcon supports dfs, and
if so, then map -ENOENT to -EREMOTE so mount or automount will take
care of chasing the DFS link -- if it isn't an DFS link, then -ENOENT
will be returned appropriately.

Before patch

  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
  SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND
  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
  SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND

After patch

  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index f51715d..b047068 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3547,9 +3547,6 @@ static int is_path_remote(struct mount_ctx *mnt_ctx)
        struct cifs_tcon *tcon = mnt_ctx->tcon;
        struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
        char *full_path;
-#ifdef CONFIG_CIFS_DFS_UPCALL
-       bool nodfs = cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS;
-#endif
 
        if (!server->ops->is_path_accessible)
                return -EOPNOTSUPP;
@@ -3566,19 +3563,6 @@ static int is_path_remote(struct mount_ctx *mnt_ctx)
 
        rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,
                                             full_path);
-#ifdef CONFIG_CIFS_DFS_UPCALL
-       if (nodfs) {
-               if (rc == -EREMOTE)
-                       rc = -EOPNOTSUPP;
-               goto out;
-       }
-
-       /* path *might* exist with non-ASCII characters in DFS root
-        * try again with full path (only if nodfs is not set) */
-       if (rc == -ENOENT && is_tcon_dfs(tcon))
-               rc = cifs_dfs_query_info_nonascii_quirk(xid, tcon, cifs_sb,
-                                                       full_path);
-#endif
        if (rc != 0 && rc != -EREMOTE)
                goto out;
 

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 286a540..f145a59 100644 (file)
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -993,12 +993,6 @@ int cifs_get_inode_info(struct inode **inode, const char *full_path,
                }
                rc = server->ops->query_path_info(xid, tcon, cifs_sb, full_path, &tmp_data,
                                                  &adjust_tz, &is_reparse_point);
-#ifdef CONFIG_CIFS_DFS_UPCALL
-               if (rc == -ENOENT && is_tcon_dfs(tcon))
-                       rc = cifs_dfs_query_info_nonascii_quirk(xid, tcon,
-                                                               cifs_sb,
-                                                               full_path);
-#endif
                data = &tmp_data;
        }
 

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 1cbecd6..0621759 100644 (file)
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -1314,49 +1314,4 @@ int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
        cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
        return 0;
 }
-
-/** cifs_dfs_query_info_nonascii_quirk
- * Handle weird Windows SMB server behaviour. It responds with
- * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request
- * for "\<server>\<dfsname>\<linkpath>" DFS reference,
- * where <dfsname> contains non-ASCII unicode symbols.
- *
- * Check such DFS reference.
- */
-int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,
-                                      struct cifs_tcon *tcon,
-                                      struct cifs_sb_info *cifs_sb,
-                                      const char *linkpath)
-{
-       char *treename, *dfspath, sep;
-       int treenamelen, linkpathlen, rc;
-
-       treename = tcon->tree_name;
-       /* MS-DFSC: All paths in REQ_GET_DFS_REFERRAL and RESP_GET_DFS_REFERRAL
-        * messages MUST be encoded with exactly one leading backslash, not two
-        * leading backslashes.
-        */
-       sep = CIFS_DIR_SEP(cifs_sb);
-       if (treename[0] == sep && treename[1] == sep)
-               treename++;
-       linkpathlen = strlen(linkpath);
-       treenamelen = strnlen(treename, MAX_TREE_SIZE + 1);
-       dfspath = kzalloc(treenamelen + linkpathlen + 1, GFP_KERNEL);
-       if (!dfspath)
-               return -ENOMEM;
-       if (treenamelen)
-               memcpy(dfspath, treename, treenamelen);
-       memcpy(dfspath + treenamelen, linkpath, linkpathlen);
-       rc = dfs_cache_find(xid, tcon->ses, cifs_sb->local_nls,
-                           cifs_remap(cifs_sb), dfspath, NULL, NULL);
-       if (rc == 0) {
-               cifs_dbg(FYI, "DFS ref '%s' is found, emulate -EREMOTE\n",
-                        dfspath);
-               rc = -EREMOTE;
-       } else {
-               cifs_dbg(FYI, "%s: dfs_cache_find returned %d\n", __func__, rc);
-       }
-       kfree(dfspath);
-       return rc;
-}
 #endif

diff --git a/fs/cifs/smb2inode.c b/fs/cifs/smb2inode.c
index fbd46db..8521adf 100644 (file)
--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -556,22 +556,42 @@ int smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
        rc = smb2_compound_op(xid, tcon, cifs_sb, full_path, FILE_READ_ATTRIBUTES, FILE_OPEN,
                              create_options, ACL_NO_MODE, data, SMB2_OP_QUERY_INFO, cfile,
                              NULL, NULL, err_iov, err_buftype);
-       if (rc == -EOPNOTSUPP) {
-               if (err_iov[0].iov_base && err_buftype[0] != CIFS_NO_BUFFER &&
-                   ((struct smb2_hdr *)err_iov[0].iov_base)->Command == SMB2_CREATE &&
-                   ((struct smb2_hdr *)err_iov[0].iov_base)->Status == STATUS_STOPPED_ON_SYMLINK) {
-                       rc = smb2_parse_symlink_response(cifs_sb, err_iov, &data->symlink_target);
+       if (rc) {
+               struct smb2_hdr *hdr = err_iov[0].iov_base;
+
+               if (unlikely(!hdr || err_buftype[0] == CIFS_NO_BUFFER))
+                       goto out;
+               if (rc == -EOPNOTSUPP && hdr->Command == SMB2_CREATE &&
+                   hdr->Status == STATUS_STOPPED_ON_SYMLINK) {
+                       rc = smb2_parse_symlink_response(cifs_sb, err_iov,
+                                                        &data->symlink_target);
                        if (rc)
                                goto out;
-               }
-               *reparse = true;
-               create_options |= OPEN_REPARSE_POINT;
 
-               /* Failed on a symbolic link - query a reparse point info */
-               cifs_get_readable_path(tcon, full_path, &cfile);
-               rc = smb2_compound_op(xid, tcon, cifs_sb, full_path, FILE_READ_ATTRIBUTES,
-                                     FILE_OPEN, create_options, ACL_NO_MODE, data,
-                                     SMB2_OP_QUERY_INFO, cfile, NULL, NULL, NULL, NULL);
+                       *reparse = true;
+                       create_options |= OPEN_REPARSE_POINT;
+
+                       /* Failed on a symbolic link - query a reparse point info */
+                       cifs_get_readable_path(tcon, full_path, &cfile);
+                       rc = smb2_compound_op(xid, tcon, cifs_sb, full_path,
+                                             FILE_READ_ATTRIBUTES, FILE_OPEN,
+                                             create_options, ACL_NO_MODE, data,
+                                             SMB2_OP_QUERY_INFO, cfile, NULL, NULL,
+                                             NULL, NULL);
+                       goto out;
+               } else if (rc != -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) &&
+                          hdr->Status == STATUS_OBJECT_NAME_INVALID) {
+                       /*
+                        * Handle weird Windows SMB server behaviour. It responds with
+                        * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request
+                        * for "\<server>\<dfsname>\<linkpath>" DFS reference,
+                        * where <dfsname> contains non-ASCII unicode symbols.
+                        */
+                       rc = -EREMOTE;
+               }
+               if (rc == -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) && cifs_sb &&
+                   (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS))
+                       rc = -EOPNOTSUPP;
        }
 
 out:

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index d33b00a..dc160de 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -796,7 +796,9 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
        int rc;
        __le16 *utf16_path;
        __u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
+       int err_buftype = CIFS_NO_BUFFER;
        struct cifs_open_parms oparms;
+       struct kvec err_iov = {};
        struct cifs_fid fid;
        struct cached_fid *cfid;
 
@@ -820,14 +822,32 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
        oparms.fid = &fid;
        oparms.reconnect = false;
 
-       rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL, NULL,
-                      NULL);
+       rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL,
+                      &err_iov, &err_buftype);
        if (rc) {
-               kfree(utf16_path);
-               return rc;
+               struct smb2_hdr *hdr = err_iov.iov_base;
+
+               if (unlikely(!hdr || err_buftype == CIFS_NO_BUFFER))
+                       goto out;
+               /*
+                * Handle weird Windows SMB server behaviour. It responds with
+                * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request
+                * for "\<server>\<dfsname>\<linkpath>" DFS reference,
+                * where <dfsname> contains non-ASCII unicode symbols.
+                */
+               if (rc != -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) &&
+                   hdr->Status == STATUS_OBJECT_NAME_INVALID)
+                       rc = -EREMOTE;
+               if (rc == -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) && cifs_sb &&
+                   (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS))
+                       rc = -EOPNOTSUPP;
+               goto out;
        }
 
        rc = SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
+
+out:
+       free_rsp_buf(err_buftype, err_iov.iov_base);
        kfree(utf16_path);
        return rc;
 }