[dm-devel] Re: [PATCH] locking update for VFS locking patch
Joe Thornber
thornber at redhat.com
Fri Feb 27 09:11:01 UTC 2004
Kevin,
I've made some changes to the dm.c side of this patch.
- Joe
Lock the filesystem while a device is suspended. [Kevin Corry, Joe Thornber]
--- diff/drivers/md/dm.c 2004-02-27 11:06:43.000000000 +0000
+++ source/drivers/md/dm.c 2004-02-27 11:38:08.000000000 +0000
@@ -12,6 +12,7 @@
#include <linux/moduleparam.h>
#include <linux/blkpg.h>
#include <linux/bio.h>
+#include <linux/buffer_head.h>
#include <linux/mempool.h>
#include <linux/slab.h>
@@ -46,6 +47,7 @@ struct target_io {
*/
#define DMF_BLOCK_IO 0
#define DMF_SUSPENDED 1
+#define DMF_FS_LOCKED 2
struct mapped_device {
struct rw_semaphore lock;
@@ -827,6 +829,46 @@ int dm_swap_table(struct mapped_device *
}
/*
+ * Functions to lock and unlock any filesystem running on the
+ * device.
+ */
+static int __lock_fs(struct mapped_device *md)
+{
+ struct block_device *bdev;
+
+ if (test_and_set_bit(DMF_FS_LOCKED, &md->flags))
+ return 0;
+
+ bdev = bdget_disk(md->disk, 0);
+ if (!bdev) {
+ DMWARN("bdget failed in __lock_fs");
+ return -ENOMEM;
+ }
+
+ fsync_bdev_lockfs(bdev);
+ bdput(bdev);
+ return 0;
+}
+
+static int __unlock_fs(struct mapped_device *md)
+{
+ struct block_device *bdev;
+
+ if (!test_and_clear_bit(DMF_FS_LOCKED, &md->flags))
+ return 0;
+
+ bdev = bdget_disk(md->disk, 0);
+ if (!bdev) {
+ DMWARN("bdget failed in __unlock_fs");
+ return -ENOMEM;
+ }
+
+ unlockfs(bdev);
+ bdput(bdev);
+ return 0;
+}
+
+/*
* We need to be able to change a mapping table under a mounted
* filesystem. For example we might want to move some data in
* the background. Before the table can be swapped with
@@ -837,13 +879,23 @@ int dm_suspend(struct mapped_device *md)
{
DECLARE_WAITQUEUE(wait, current);
- down_write(&md->lock);
+ /* Flush I/O to the device. */
+ down_read(&md->lock);
+ if (test_bit(DMF_BLOCK_IO, &md->flags)) {
+ up_read(&md->lock);
+ return -EINVAL;
+ }
+
+ __lock_fs(md);
+ up_read(&md->lock);
/*
* First we set the BLOCK_IO flag so no more ios will be
* mapped.
*/
+ down_write(&md->lock);
if (test_bit(DMF_BLOCK_IO, &md->flags)) {
+ __unlock_fs(md);
up_write(&md->lock);
return -EINVAL;
}
@@ -872,6 +924,7 @@ int dm_suspend(struct mapped_device *md)
/* were we interrupted ? */
if (atomic_read(&md->pending)) {
+ __unlock_fs(md);
clear_bit(DMF_BLOCK_IO, &md->flags);
up_write(&md->lock);
return -EINTR;
@@ -905,6 +958,7 @@ int dm_resume(struct mapped_device *md)
__flush_deferred_io(md, def);
up_write(&md->lock);
+ __unlock_fs(md);
blk_run_queues();
return 0;
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