From 864de9cee16696e5c764c91fe8aa670bdfe26c70 Mon Sep 17 00:00:00 2001
From: Alasdair Kergon <agk@redhat.com>
Date: Thu, 7 Apr 2005 12:17:46 +0000
Subject: [PATCH] Allow offline extension of snapshot volumes. NB Requires
 kernel patch that is not upstream.

---
 WHATS_NEW           |  3 ++-
 lib/device/dev-io.c | 29 +++++++++++++++++++++++++----
 lib/device/device.h |  4 +++-
 tools/lvresize.c    | 22 +++++++++++++++++-----
 4 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/WHATS_NEW b/WHATS_NEW
index c6facc32d..6e7cc324c 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,7 +1,8 @@
 Version 2.01.10 - 
 ================================
+  Allow offline extension of snapshot volumes.
   Move from 2-step to 3-step on-disk metadata commit.
-  Scan ramdisks too.
+  Scan ramdisks too and allow non-O_DIRECT fallback.
   Annotate, tidy and extend list.h.
   Alignment tidying.
 
diff --git a/lib/device/dev-io.c b/lib/device/dev-io.c
index 7b0b8f2ad..a9ae466a1 100644
--- a/lib/device/dev-io.c
+++ b/lib/device/dev-io.c
@@ -330,8 +330,13 @@ int dev_open_flags(struct device *dev, int flags, int direct, int quiet)
 	}
 
 #ifdef O_DIRECT_SUPPORT
-	if (direct)
-		flags |= O_DIRECT;
+	if (direct) {
+		if (!(dev->flags & DEV_O_DIRECT_TESTED))
+			dev->flags |= DEV_O_DIRECT;
+
+		if ((dev->flags & DEV_O_DIRECT))
+			flags |= O_DIRECT;
+	}
 #endif
 
 #ifdef O_NOATIME
@@ -341,6 +346,16 @@ int dev_open_flags(struct device *dev, int flags, int direct, int quiet)
 #endif
 
 	if ((dev->fd = open(name, flags, 0777)) < 0) {
+#ifdef O_DIRECT_SUPPORT
+		if (direct && !(dev->flags & DEV_O_DIRECT_TESTED)) {
+			flags &= ~O_DIRECT;
+			if ((dev->fd = open(name, flags, 0777)) >= 0) {
+				dev->flags &= ~DEV_O_DIRECT;
+				log_debug("%s: Not using O_DIRECT", name);
+				goto opened;
+			}
+		}
+#endif
 		if (quiet)
 			log_sys_debug("open", name);
 		else
@@ -348,8 +363,13 @@ int dev_open_flags(struct device *dev, int flags, int direct, int quiet)
 		return 0;
 	}
 
+      opened:
 	dev->open_count++;
 	dev->flags &= ~DEV_ACCESSED_W;
+#ifdef O_DIRECT_SUPPORT
+	if (direct)
+		dev->flags |= DEV_O_DIRECT_TESTED;
+#endif
 	if ((flags & O_ACCMODE) == O_RDWR)
 		dev->flags |= DEV_OPENED_RW;
 	else
@@ -373,8 +393,9 @@ int dev_open_flags(struct device *dev, int flags, int direct, int quiet)
 
 	list_add(&_open_devices, &dev->open_list);
 
-	log_debug("Opened %s %s", dev_name(dev),
-		  dev->flags & DEV_OPENED_RW ? "RW" : "RO");
+	log_debug("Opened %s %s%s", dev_name(dev),
+		  dev->flags & DEV_OPENED_RW ? "RW" : "RO",
+		  dev->flags & DEV_O_DIRECT ? " O_DIRECT" : "");
 
 	return 1;
 }
diff --git a/lib/device/device.h b/lib/device/device.h
index ac7bd955e..f1698a4ea 100644
--- a/lib/device/device.h
+++ b/lib/device/device.h
@@ -23,6 +23,8 @@
 #define DEV_REGULAR		0x00000002	/* Regular file? */
 #define DEV_ALLOCED		0x00000004	/* dbg_malloc used */
 #define DEV_OPENED_RW		0x00000008	/* Opened RW */
+#define DEV_O_DIRECT		0x00000010	/* Use O_DIRECT */
+#define DEV_O_DIRECT_TESTED	0x00000020	/* DEV_O_DIRECT is reliable */
 
 /*
  * All devices in LVM will be represented by one of these.
@@ -64,7 +66,7 @@ int dev_get_sectsize(struct device *dev, uint32_t *size);
 /* Use quiet version if device number could change e.g. when opening LV */
 int dev_open(struct device *dev);
 int dev_open_quiet(struct device *dev);
-int dev_open_flags(struct device *dev, int flags, int append, int quiet);
+int dev_open_flags(struct device *dev, int flags, int direct, int quiet);
 int dev_close(struct device *dev);
 int dev_close_immediate(struct device *dev);
 void dev_close_all(void);
diff --git a/tools/lvresize.c b/tools/lvresize.c
index 734fd7056..c788c988e 100644
--- a/tools/lvresize.c
+++ b/tools/lvresize.c
@@ -180,11 +180,6 @@ static int _lvresize(struct cmd_context *cmd, struct lvresize_params *lp)
 		return ECMD_FAILED;
 	}
 
-	if (lv_is_origin(lv)) {
-		log_error("Snapshot origin volumes cannot be resized yet.");
-		return ECMD_FAILED;
-	}
-
 	alloc = (alloc_policy_t) arg_uint_value(cmd, alloc_ARG, lv->alloc);
 
 	if (lp->size) {
@@ -352,6 +347,23 @@ static int _lvresize(struct cmd_context *cmd, struct lvresize_params *lp)
 			lp->resize = LV_EXTEND;
 	}
 
+
+	if (lv_is_origin(lv)) {
+		if (lp->resize == LV_REDUCE) {
+			log_error("Snapshot origin volumes cannot be reduced "
+				  "in size yet.");
+			return ECMD_FAILED;
+		}
+
+		memset(&info, 0, sizeof(info));
+
+		if (lv_info(lv, &info, 0) && info.exists) {
+			log_error("Snapshot origin volumes can be resized "
+				  "only while inactive: try lvchange -an");
+			return ECMD_FAILED;
+		}
+	}
+
 	if (lp->resize == LV_REDUCE) {
 		if (lp->argc)
 			log_print("Ignoring PVs on command line when reducing");