cifs: add a helper to find an existing readable handle to a file

and convert smb2_query_path_info() to use it.
This will eliminate the need for a SMB2_Create when we already have an
open handle that can be used. This will also prevent a oplock break
in case the other handle holds a lease.

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

3 files changed, 61 insertions, 5 deletions

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 7b69037bed24..99b1b1ef558c 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -140,6 +140,8 @@ extern int cifs_get_writable_file(struct cifsInodeInfo *cifs_inode,
 extern int cifs_get_writable_path(struct cifs_tcon *tcon, const char *name,
                                   struct cifsFileInfo **ret_file);
 extern struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *, bool);
+extern int cifs_get_readable_path(struct cifs_tcon *tcon, const char *name,
+                                  struct cifsFileInfo **ret_file);
 extern unsigned int smbCalcSize(void *buf, struct TCP_Server_Info *server);
 extern int decode_negTokenInit(unsigned char *security_blob, int length,
                         struct TCP_Server_Info *server);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 6124b1d1ab05..4b95700c507c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2008,6 +2008,42 @@ cifs_get_writable_path(struct cifs_tcon *tcon, const char *name,
         return -ENOENT;
 }
 
+int
+cifs_get_readable_path(struct cifs_tcon *tcon, const char *name,
+                       struct cifsFileInfo **ret_file)
+{
+        struct list_head *tmp;
+        struct cifsFileInfo *cfile;
+        struct cifsInodeInfo *cinode;
+        char *full_path;
+
+        *ret_file = NULL;
+
+        spin_lock(&tcon->open_file_lock);
+        list_for_each(tmp, &tcon->openFileList) {
+                cfile = list_entry(tmp, struct cifsFileInfo,
+                             tlist);
+                full_path = build_path_from_dentry(cfile->dentry);
+                if (full_path == NULL) {
+                        spin_unlock(&tcon->open_file_lock);
+                        return -ENOMEM;
+                }
+                if (strcmp(full_path, name)) {
+                        kfree(full_path);
+                        continue;
+                }
+
+                kfree(full_path);
+                cinode = CIFS_I(d_inode(cfile->dentry));
+                spin_unlock(&tcon->open_file_lock);
+                *ret_file = find_readable_file(cinode, 0);
+                return *ret_file ? 0 : -ENOENT;
+        }
+
+        spin_unlock(&tcon->open_file_lock);
+        return -ENOENT;
+}
+
 static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
 {
         struct address_space *mapping = page->mapping;
diff --git a/fs/cifs/smb2inode.c b/fs/cifs/smb2inode.c
index 9bb0a5bc38c9..c866555b6278 100644
--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -125,15 +125,31 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
                 rqst[num_rqst].rq_iov = qi_iov;
                 rqst[num_rqst].rq_nvec = 1;
 
-                rc = SMB2_query_info_init(tcon, &rqst[num_rqst], COMPOUND_FID,
-                                COMPOUND_FID, FILE_ALL_INFORMATION,
+                if (cfile)
+                        rc = SMB2_query_info_init(tcon, &rqst[num_rqst],
+                                cfile->fid.persistent_fid,
+                                cfile->fid.volatile_fid,
+                                FILE_ALL_INFORMATION,
                                 SMB2_O_INFO_FILE, 0,
                                 sizeof(struct smb2_file_all_info) +
                                           PATH_MAX * 2, 0, NULL);
+                else {
+                        rc = SMB2_query_info_init(tcon, &rqst[num_rqst],
+                                COMPOUND_FID,
+                                COMPOUND_FID,
+                                 FILE_ALL_INFORMATION,
+                                SMB2_O_INFO_FILE, 0,
+                                sizeof(struct smb2_file_all_info) +
+                                          PATH_MAX * 2, 0, NULL);
+                        if (!rc) {
+                                smb2_set_next_command(tcon, &rqst[num_rqst]);
+                                smb2_set_related(&rqst[num_rqst]);
+                        }
+                }
+
                 if (rc)
                         goto finished;
-                smb2_set_next_command(tcon, &rqst[num_rqst]);
-                smb2_set_related(&rqst[num_rqst++]);
+                num_rqst++;
                 trace_smb3_query_info_compound_enter(xid, ses->Suid, tcon->tid,
                                                      full_path);
                 break;
@@ -421,6 +437,7 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
         __u32 create_options = 0;
         struct cifs_fid fid;
         bool no_cached_open = tcon->nohandlecache;
+        struct cifsFileInfo *cfile;
 
         *adjust_tz = false;
         *symlink = false;
@@ -452,9 +469,10 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
         if (backup_cred(cifs_sb))
                 create_options |= CREATE_OPEN_BACKUP_INTENT;
 
+        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,
-                              smb2_data, SMB2_OP_QUERY_INFO, NULL);
+                              smb2_data, SMB2_OP_QUERY_INFO, cfile);
         if (rc == -EOPNOTSUPP) {
                 *symlink = true;
                 create_options |= OPEN_REPARSE_POINT;