CIFS: Migrate to shared superblock model

Add cifs_match_super to use in sget to share superblock between mounts
that have the same //server/sharename, credentials and mount options.
It helps us to improve performance on work with future SMB2.1 leases.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 102 insertions, 0 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 495688115988..261ca81d5e49 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2146,6 +2146,100 @@ cifs_put_tlink(struct tcon_link *tlink)
         return;
 }
 
+static inline struct tcon_link *
+cifs_sb_master_tlink(struct cifs_sb_info *cifs_sb);
+
+static int
+compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
+{
+        struct cifs_sb_info *old = CIFS_SB(sb);
+        struct cifs_sb_info *new = mnt_data->cifs_sb;
+
+        if ((sb->s_flags & CIFS_MS_MASK) != (mnt_data->flags & CIFS_MS_MASK))
+                return 0;
+
+        if ((old->mnt_cifs_flags & CIFS_MOUNT_MASK) !=
+            (new->mnt_cifs_flags & CIFS_MOUNT_MASK))
+                return 0;
+
+        if (old->rsize != new->rsize)
+                return 0;
+
+        /*
+         * We want to share sb only if we don't specify wsize or specified wsize
+         * is greater or equal than existing one.
+         */
+        if (new->wsize && new->wsize < old->wsize)
+                return 0;
+
+        if (old->mnt_uid != new->mnt_uid || old->mnt_gid != new->mnt_gid)
+                return 0;
+
+        if (old->mnt_file_mode != new->mnt_file_mode ||
+            old->mnt_dir_mode != new->mnt_dir_mode)
+                return 0;
+
+        if (strcmp(old->local_nls->charset, new->local_nls->charset))
+                return 0;
+
+        if (old->actimeo != new->actimeo)
+                return 0;
+
+        return 1;
+}
+
+int
+cifs_match_super(struct super_block *sb, void *data)
+{
+        struct cifs_mnt_data *mnt_data = (struct cifs_mnt_data *)data;
+        struct smb_vol *volume_info;
+        struct cifs_sb_info *cifs_sb;
+        struct TCP_Server_Info *tcp_srv;
+        struct cifsSesInfo *ses;
+        struct cifsTconInfo *tcon;
+        struct tcon_link *tlink;
+        struct sockaddr_storage addr;
+        int rc = 0;
+
+        memset(&addr, 0, sizeof(struct sockaddr_storage));
+
+        spin_lock(&cifs_tcp_ses_lock);
+        cifs_sb = CIFS_SB(sb);
+        tlink = cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));
+        if (IS_ERR(tlink)) {
+                spin_unlock(&cifs_tcp_ses_lock);
+                return rc;
+        }
+        tcon = tlink_tcon(tlink);
+        ses = tcon->ses;
+        tcp_srv = ses->server;
+
+        volume_info = mnt_data->vol;
+
+        if (!volume_info->UNCip || !volume_info->UNC)
+                goto out;
+
+        rc = cifs_fill_sockaddr((struct sockaddr *)&addr,
+                                volume_info->UNCip,
+                                strlen(volume_info->UNCip),
+                                volume_info->port);
+        if (!rc)
+                goto out;
+
+        if (!match_server(tcp_srv, (struct sockaddr *)&addr, volume_info) ||
+            !match_session(ses, volume_info) ||
+            !match_tcon(tcon, volume_info->UNC)) {
+                rc = 0;
+                goto out;
+        }
+
+        rc = compare_mount_options(sb, mnt_data);
+out:
+        cifs_put_tlink(tlink);
+        spin_unlock(&cifs_tcp_ses_lock);
+        return rc;
+}
+
 int
 get_dfs_path(int xid, struct cifsSesInfo *pSesInfo, const char *old_path,
              const struct nls_table *nls_codepage, unsigned int *pnum_referrals,
@@ -2578,6 +2672,14 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
                 /* Windows ME may prefer this */
                 cFYI(1, "readsize set to minimum: 2048");
         }
+
+        /*
+         * Temporarily set wsize for matching superblock. If we end up using
+         * new sb then cifs_negotiate_wsize will later negotiate it downward
+         * if needed.
+         */
+        cifs_sb->wsize = pvolume_info->wsize;
+
         cifs_sb->mnt_uid = pvolume_info->linux_uid;
         cifs_sb->mnt_gid = pvolume_info->linux_gid;
         cifs_sb->mnt_file_mode = pvolume_info->file_mode;