xfs: add a max_open_zones mount option

Allow limiting the number of open zones used below that exported by the
device.  This is required to tune the number of write streams when zoned
RT devices are used on conventional devices, and can be useful on zoned
devices that support a very large number of open zones.

Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index ceb1a855453e8d78b48b6354430c697a4e8613ef..b59d7349dbd270e1c4c94eb3d00fabcee72c8058 100644 (file)
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -110,7 +110,7 @@ enum {
        Opt_filestreams, Opt_quota, Opt_noquota, Opt_usrquota, Opt_grpquota,
        Opt_prjquota, Opt_uquota, Opt_gquota, Opt_pquota,
        Opt_uqnoenforce, Opt_gqnoenforce, Opt_pqnoenforce, Opt_qnoenforce,
-       Opt_discard, Opt_nodiscard, Opt_dax, Opt_dax_enum,
+       Opt_discard, Opt_nodiscard, Opt_dax, Opt_dax_enum, Opt_max_open_zones,
 };
 
 static const struct fs_parameter_spec xfs_fs_parameters[] = {
@@ -155,6 +155,7 @@ static const struct fs_parameter_spec xfs_fs_parameters[] = {
        fsparam_flag("nodiscard",       Opt_nodiscard),
        fsparam_flag("dax",             Opt_dax),
        fsparam_enum("dax",             Opt_dax_enum, dax_param_enums),
+       fsparam_u32("max_open_zones",   Opt_max_open_zones),
        {}
 };
 
@@ -234,6 +235,9 @@ xfs_fs_show_options(
        if (!(mp->m_qflags & XFS_ALL_QUOTA_ACCT))
                seq_puts(m, ",noquota");
 
+       if (mp->m_max_open_zones)
+               seq_printf(m, ",max_open_zones=%u", mp->m_max_open_zones);
+
        return 0;
 }
 
@@ -1081,6 +1085,14 @@ xfs_finish_flags(
                return -EINVAL;
        }
 
+       if (!xfs_has_zoned(mp)) {
+               if (mp->m_max_open_zones) {
+                       xfs_warn(mp,
+"max_open_zones mount option only supported on zoned file systems.");
+                       return -EINVAL;
+               }
+       }
+
        return 0;
 }
 
@@ -1462,6 +1474,9 @@ xfs_fs_parse_param(
                xfs_fs_warn_deprecated(fc, param, XFS_FEAT_NOATTR2, true);
                parsing_mp->m_features |= XFS_FEAT_NOATTR2;
                return 0;
+       case Opt_max_open_zones:
+               parsing_mp->m_max_open_zones = result.uint_32;
+               return 0;
        default:
                xfs_warn(parsing_mp, "unknown mount option [%s].", param->key);
                return -EINVAL;