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authorBenjamin Marzinski <bmarzins@redhat.com>2014-08-13 20:53:43 +0200
committerMike Snitzer <snitzer@redhat.com>2014-10-06 02:03:35 +0200
commit86f1152b117a404229fd6f08ec3faca779f37b92 (patch)
treedceee3703ab97065c3e425b55d42cb4edb9a079b /include/uapi
parentdm mpath: stop queueing IO when no valid paths exist (diff)
downloadlinux-86f1152b117a404229fd6f08ec3faca779f37b92.tar.xz
linux-86f1152b117a404229fd6f08ec3faca779f37b92.zip
dm: allow active and inactive tables to share dm_devs
Until this change, when loading a new DM table, DM core would re-open all of the devices in the DM table. Now, DM core will avoid redundant device opens (and closes when destroying the old table) if the old table already has a device open using the same mode. This is achieved by managing reference counts on the table_devices that DM core now stores in the mapped_device structure (rather than in the dm_table structure). So a mapped_device's active and inactive dm_tables' dm_dev lists now just point to the dm_devs stored in the mapped_device's table_devices list. This improvement in DM core's device reference counting has the side-effect of fixing a long-standing limitation of the multipath target: a DM multipath table couldn't include any paths that were unusable (failed). For example: if all paths have failed and you add a new, working, path to the table; you can't use it since the table load would fail due to it still containing failed paths. Now a re-load of a multipath table can include failed devices and when those devices become active again they can be used instantly. The device list code in dm.c isn't a straight copy/paste from the code in dm-table.c, but it's very close (aside from some variable renames). One subtle difference is that find_table_device for the tables_devices list will only match devices with the same name and mode. This is because we don't want to upgrade a device's mode in the active table when an inactive table is loaded. Access to the mapped_device structure's tables_devices list requires a mutex (tables_devices_lock), so that tables cannot be created and destroyed concurrently. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'include/uapi')
-rw-r--r--include/uapi/linux/dm-ioctl.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h
index c8a4302093a3..3315ab21f728 100644
--- a/include/uapi/linux/dm-ioctl.h
+++ b/include/uapi/linux/dm-ioctl.h
@@ -267,9 +267,9 @@ 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 27
+#define DM_VERSION_MINOR 28
#define DM_VERSION_PATCHLEVEL 0
-#define DM_VERSION_EXTRA "-ioctl (2013-10-30)"
+#define DM_VERSION_EXTRA "-ioctl (2014-09-17)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */