Adds input flag (DM_STATUS_INACTIVE_FLAG) for use in the ioctl STATUS
command. Introduces dm_get_inactive_table() to get a reference on the
inactive table so that it is protected during use in table_status().
Allows us to safely display the status/table of a DM device's inactive
table.
This is useful for seeing when a DM device is in the middle a complex
transition, e.g. snapshot-merge's exception handover:
Before snapshot-merge:
----------------------
# dmsetup status test-testlv
0 67108864 snapshot-origin
# dmsetup status test-testlv_snap
0 67108864 snapshot 1328904/14680064 5184
# dmsetup status --inactive test-testlv
0 0
# dmsetup status --inactive test-testlv_snap
0 0
Snapshot-merge target created, about to handover exceptions:
------------------------------------------------------------
# dmsetup status test-testlv
0 67108864 snapshot-origin
# dmsetup status test-testlv_snap
0 67108864 snapshot 1328904/14680064 5184
# dmsetup status --inactive test-testlv
0 67108864 snapshot-merge 16/14680064 16
NOTE: the snapshot-merge store is empty (handover hasn't happened yet)
After exception handover, before merge has started:
---------------------------------------------------
# dmsetup status test-testlv
0 67108864 snapshot-origin
# dmsetup status --inactive test-testlv
0 67108864 snapshot-merge 1328904/14680064 5184
Snapshot-merge table is now active and is merging:
--------------------------------------------------
# dmsetup status test-testlv
0 67108864 snapshot-merge 1114360/14680064 4344
# dmsetup table --inactive test-testlv
0 0
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm-ioctl.c | 33 ++++++++++++++++++++++++++++++++-
include/linux/dm-ioctl.h | 10 ++++++++--
2 files changed, 40 insertions(+), 3 deletions(-)
Index: linux-2.6/drivers/md/dm-ioctl.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-ioctl.c
+++ linux-2.6/drivers/md/dm-ioctl.c
@@ -650,6 +650,23 @@ static struct mapped_device *find_device
return md;
}
+static struct dm_table *dm_get_inactive_table(struct dm_ioctl *param)
+{
+ struct hash_cell *hc;
+ struct dm_table *table = NULL;
+
+ down_read(&_hash_lock);
+ hc = __find_device_hash_cell(param);
+ if (hc) {
+ table = hc->new_map;
+ if (table)
+ dm_table_get(table);
+ }
+ up_read(&_hash_lock);
+
+ return table;
+}
+
static int dev_remove(struct dm_ioctl *param, size_t param_size)
{
struct hash_cell *hc;
@@ -1226,6 +1243,20 @@ static int table_deps(struct dm_ioctl *p
return r;
}
+static struct dm_table* __dm_get_table(struct mapped_device *md,
+ struct dm_ioctl *param)
+{
+ struct dm_table *table = NULL;
+
+ if (param->flags & DM_STATUS_INACTIVE_FLAG) {
+ if (param->flags & DM_INACTIVE_PRESENT_FLAG)
+ table = dm_get_inactive_table(param);
+ } else
+ table = dm_get_table(md);
+
+ return table;
+}
+
/*
* Return the status of a device as a text string for each
* target.
@@ -1244,7 +1275,7 @@ static int table_status(struct dm_ioctl
if (r)
goto out;
- table = dm_get_table(md);
+ table = __dm_get_table(md, param);
if (table) {
retrieve_status(table, param, param_size);
dm_table_put(table);
Index: linux-2.6/include/linux/dm-ioctl.h
===================================================================
--- linux-2.6.orig/include/linux/dm-ioctl.h
+++ linux-2.6/include/linux/dm-ioctl.h
@@ -266,9 +266,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
-#define DM_VERSION_MINOR 15
+#define DM_VERSION_MINOR 16
#define DM_VERSION_PATCHLEVEL 0
-#define DM_VERSION_EXTRA "-ioctl (2009-04-01)"
+#define DM_VERSION_EXTRA "-ioctl (2009-10-20)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */
@@ -282,6 +282,12 @@ enum {
#define DM_STATUS_TABLE_FLAG (1 << 4) /* In */
/*
+ * Flag passed into ioctl STATUS command to get table information
+ * or current status from the inactive table.
+ */
+#define DM_STATUS_INACTIVE_FLAG (1 << 7) /* In */
+
+/*
* Flags that indicate whether a table is present in either of
* the two table slots that a device has.
*/
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
