[linux-lvm] Snapshots with 2.4.1?
Chris Mason
mason at suse.com
Wed Feb 7 22:32:37 UTC 2001
On Wednesday, February 07, 2001 02:25:10 PM -0800 Tracy R Reed <treed at ultraviolet.org> wrote:
> On Fri, Feb 02, 2001 at 04:56:42PM +0000, Joe Thornber wrote:
>> 2.4.1 hadn't been released when we made the beta3 tarball. If you
>> want to make a beta3 patch for the kernel create an empty file call
>> PATCHES/fragments-2.4.1 (2.4.1 needs no extra fragments) then run
>> PATCHES/make. That should remove all the conflicts.
>
> I need to get snapshots working with 2.4.1. I've tried using just the
> straight LVM that comes with the kernel and I have tried applying the
> patches as described above. I either case, when I uncomment:
>
> #define LVM_VFS_ENHANCEMENT
>
> in drivers/md/lvm.c to enable the hooks for snapshots the compile fails:
>
> drivers/md/mddev.o: In function `lvm_do_lv_create':
> drivers/md/mddev.o(.text+0x11bdb): undefined reference to `fsync_dev_lockfs'
> drivers/md/mddev.o(.text+0x11c90): undefined reference to `unlockfs'
>
> Can someone point out what else I am missing?
>
This patch should do it, the reiserfs in 2.4.1 has code to take advantage of it.
diff -urN diff/linux/fs/buffer.c linux/fs/buffer.c
--- diff/linux/fs/buffer.c Tue Oct 3 12:31:22 2000
+++ linux/fs/buffer.c Tue Oct 3 12:16:16 2000
@@ -312,6 +312,28 @@
return sync_buffers(dev, 1);
}
+int fsync_dev_lockfs(kdev_t dev)
+{
+ sync_buffers(dev, 0);
+
+ lock_kernel();
+ sync_supers(dev);
+ /* note, the FS might need to start transactions to
+ ** sync the inodes, or the quota, no locking until
+ ** after these are done
+ */
+ sync_inodes(dev);
+ DQUOT_SYNC(dev);
+ /* if inodes or quotas could be dirtied during the
+ ** sync_supers_lockfs call, the FS is responsible for getting
+ ** them on disk, without deadlocking against the lock
+ */
+ sync_supers_lockfs(dev) ;
+ unlock_kernel();
+
+ return sync_buffers(dev, 1) ;
+}
+
asmlinkage long sys_sync(void)
{
fsync_dev(0);
diff -urN diff/linux/fs/super.c linux/fs/super.c
--- diff/linux/fs/super.c Tue Oct 3 12:31:23 2000
+++ linux/fs/super.c Fri Sep 29 10:01:09 2000
@@ -628,6 +628,46 @@
}
}
+/*
+ * Note: don't check the dirty flag before waiting, we want the lock
+ * to happen every time this is called.
+ */
+void sync_supers_lockfs(kdev_t dev)
+{
+ struct super_block * sb;
+
+ for (sb = sb_entry(super_blocks.next);
+ sb != sb_entry(&super_blocks);
+ sb = sb_entry(sb->s_list.next)) {
+ if (!sb->s_dev)
+ continue;
+ if (dev && sb->s_dev != dev)
+ continue;
+ lock_super(sb);
+ if (sb->s_dev && (!dev || dev == sb->s_dev))
+ if (sb->s_op && sb->s_op->write_super_lockfs)
+ sb->s_op->write_super_lockfs(sb);
+ unlock_super(sb);
+ }
+}
+
+void unlockfs(kdev_t dev)
+{
+ struct super_block * sb;
+
+ for (sb = sb_entry(super_blocks.next);
+ sb != sb_entry(&super_blocks);
+ sb = sb_entry(sb->s_list.next)) {
+ if (!sb->s_dev)
+ continue;
+ if (dev && sb->s_dev != dev)
+ continue;
+ if (sb->s_dev && (!dev || dev == sb->s_dev))
+ if (sb->s_op && sb->s_op->unlockfs)
+ sb->s_op->unlockfs(sb);
+ }
+}
+
/**
* get_super - get the superblock of a device
* @dev: device to get the superblock for
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