[PATCH] device-mapper ioctl: add skip lock_fs flag

Add ioctl DM_SKIP_LOCKFS_FLAG for userspace to request that lock_fs is
bypassed when suspending a device.

There's no change to the behaviour of existing code that doesn't know about
the new flag.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 17 insertions, 5 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index dbc07afd4462..561bda5011e0 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -693,14 +693,18 @@ static int dev_rename(struct dm_ioctl *param, size_t param_size)
 static int do_suspend(struct dm_ioctl *param)
 {
         int r = 0;
+        int do_lockfs = 1;
         struct mapped_device *md;
 
         md = find_device(param);
         if (!md)
                 return -ENXIO;
 
+        if (param->flags & DM_SKIP_LOCKFS_FLAG)
+                do_lockfs = 0;
+
         if (!dm_suspended(md))
-                r = dm_suspend(md, 1);
+                r = dm_suspend(md, do_lockfs);
 
         if (!r)
                 r = __dev_status(md, param);
@@ -712,6 +716,7 @@ static int do_suspend(struct dm_ioctl *param)
 static int do_resume(struct dm_ioctl *param)
 {
         int r = 0;
+        int do_lockfs = 1;
         struct hash_cell *hc;
         struct mapped_device *md;
         struct dm_table *new_map;
@@ -737,8 +742,10 @@ static int do_resume(struct dm_ioctl *param)
         /* Do we need to load a new map ? */
         if (new_map) {
                 /* Suspend if it isn't already suspended */
+                if (param->flags & DM_SKIP_LOCKFS_FLAG)
+                        do_lockfs = 0;
                 if (!dm_suspended(md))
-                        dm_suspend(md, 1);
+                        dm_suspend(md, do_lockfs);
 
                 r = dm_swap_table(md, new_map);
                 if (r) {
diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index f5eb6b6cd109..fa75ba0d635e 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -272,9 +272,9 @@ typedef char ioctl_struct[308];
 #define DM_TARGET_MSG    _IOWR(DM_IOCTL, DM_TARGET_MSG_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR        4
-#define DM_VERSION_MINOR        4
+#define DM_VERSION_MINOR        5
 #define DM_VERSION_PATCHLEVEL   0
-#define DM_VERSION_EXTRA        "-ioctl (2005-01-12)"
+#define DM_VERSION_EXTRA        "-ioctl (2005-10-04)"
 
 /* Status bits */
 #define DM_READONLY_FLAG        (1 << 0) /* In/Out */
@@ -301,8 +301,13 @@ typedef char ioctl_struct[308];
 #define DM_BUFFER_FULL_FLAG     (1 << 8) /* Out */
 
 /*
- * Set this to improve performance when you aren't going to use open_count
+ * Set this to improve performance when you aren't going to use open_count.
  */
 #define DM_SKIP_BDGET_FLAG      (1 << 9) /* In */
 
+/*
+ * Set this to avoid attempting to freeze any filesystem when suspending.
+ */
+#define DM_SKIP_LOCKFS_FLAG     (1 << 10) /* In */
+
 #endif                          /* _LINUX_DM_IOCTL_H */