[PATCH 8/9] xfs: disable specific error configurations

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

Different error classes are going to need different error to be
configured, so we don't want them all to be visible in sysfs. Add a
configuration check into the config initialisation an lookup
code to determine if the default should be used for a specific
error. If so, the sysfs entry is not created, and on lookup the
default config is returned.

Add ENOMEM at this point to exercise this code, as it will be used
later when adding a kmem error failure class.

Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 fs/xfs/xfs_mount.h |  1 +
 fs/xfs/xfs_sysfs.c | 22 ++++++++++++++++++----
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index c05b500..0ff14a90 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -53,6 +53,7 @@ enum {
 	XFS_ERR_EIO,
 	XFS_ERR_ENOSPC,
 	XFS_ERR_ENODEV,
+	XFS_ERR_ENOMEM,
 	XFS_ERR_ERRNO_MAX,
 };
 enum {
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index d48dc46..c984c3e 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -522,6 +522,9 @@ static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
 	{ .name = "ENODEV",
 	  .fail_speed = XFS_ERR_FAIL_FAST,
 	},
+	{ .name = "ENOMEM",
+	  .fail_speed = XFS_ERR_FAIL_DEFAULT,
+	},
 };
 
 static int
@@ -545,12 +548,17 @@ xfs_error_sysfs_init_class(
 
 	for (i = 0; i < XFS_ERR_ERRNO_MAX; i++) {
 		cfg = &mp->m_error_cfg[class][i];
+
+		/* skip errors that are not configurable for this class */
+		cfg->fail_speed = init[i].fail_speed;
+		if (cfg->fail_speed == XFS_ERR_FAIL_DEFAULT)
+			continue;
+
 		error = xfs_sysfs_init(&cfg->kobj, &xfs_error_cfg_ktype,
 					parent_kobj, init[i].name);
 		if (error)
 			goto out_error;
 
-		cfg->fail_speed = init[i].fail_speed;
 		cfg->max_retries = init[i].max_retries;
 		cfg->retry_timeout = msecs_to_jiffies(
 					init[i].retry_timeout * MSEC_PER_SEC);
@@ -605,7 +613,8 @@ xfs_error_sysfs_del(
 		for (j = 0; j < XFS_ERR_ERRNO_MAX; j++) {
 			cfg = &mp->m_error_cfg[i][j];
 
-			xfs_sysfs_del(&cfg->kobj);
+			if (cfg->fail_speed != XFS_ERR_FAIL_DEFAULT)
+				xfs_sysfs_del(&cfg->kobj);
 		}
 	}
 	xfs_sysfs_del(&mp->m_error_meta_kobj);
@@ -630,10 +639,15 @@ xfs_error_get_cfg(
 	case ENODEV:
 		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENODEV];
 		break;
-	default:
-		cfg = &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
+	case ENOMEM:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENOMEM];
 		break;
+	default:
+		return &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
 	}
 
+	/* The error may not be not configurable, so uses default behaviour */
+	if (cfg->fail_speed == XFS_ERR_FAIL_DEFAULT)
+		return &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
 	return cfg;
 }
-- 
2.5.0