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authorAlasdair G Kergon <agk@redhat.com>2011-10-31 20:19:02 +0000
committerAlasdair G Kergon <agk@redhat.com>2011-10-31 20:19:02 +0000
commitcc6cbe141a20f6d876b161b60af38d93935bfa85 (patch)
tree82fbbc48815503683b434c74b7eb18c15960f4f9
parent3791e2fc0e4b40d4188e79b0a99bfa6bce714a10 (diff)
downloadop-kernel-dev-cc6cbe141a20f6d876b161b60af38d93935bfa85.zip
op-kernel-dev-cc6cbe141a20f6d876b161b60af38d93935bfa85.tar.gz
dm table: add always writeable feature
Add a target feature flag DM_TARGET_ALWAYS_WRITEABLE to indicate that a target does not support read-only mode. The initial implementation of the thin provisioning target uses this. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-table.c6
-rw-r--r--include/linux/device-mapper.h7
2 files changed, 13 insertions, 0 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 2ec3482..9917141 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -774,6 +774,12 @@ int dm_table_add_target(struct dm_table *t, const char *type,
t->singleton = 1;
}
+ if (dm_target_always_writeable(tgt->type) && !(t->mode & FMODE_WRITE)) {
+ DMERR("%s: target type %s may not be included in read-only tables",
+ dm_device_name(t->md), type);
+ return -EINVAL;
+ }
+
tgt->table = t;
tgt->begin = start;
tgt->len = len;
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 294e78a..cc58e2d 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -166,6 +166,13 @@ struct target_type {
#define DM_TARGET_SINGLETON 0x00000001
#define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
+/*
+ * Indicates that a target does not support read-only devices.
+ */
+#define DM_TARGET_ALWAYS_WRITEABLE 0x00000002
+#define dm_target_always_writeable(type) \
+ ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
+
struct dm_target {
struct dm_table *table;
struct target_type *type;
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