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authorAlasdair G Kergon <agk@redhat.com>2006-06-26 00:27:34 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-26 09:58:36 -0700
commit5c6bd75d06db512515a3781aa97e42df2faf0815 (patch)
tree43d68c6d3174e1ae8a778acd834665c122f8b2a4 /drivers/md/dm-ioctl.c
parentc2ade42dd35466d90aa6fc7cc717f396e165492f (diff)
[PATCH] dm: prevent removal if open
If you misuse the device-mapper interface (or there's a bug in your userspace tools) it's possible to end up with 'unlinked' mapped devices that cannot be removed until you reboot (along with uninterruptible processes). This patch prevents you from removing a device that is still open. It introduces dm_lock_for_deletion() which is called when a device is about to be removed to ensure that nothing has it open and nothing further can open it. It uses a private open_count for this which also lets us remove one of the problematic bdget_disk() calls elsewhere. 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>
Diffstat (limited to 'drivers/md/dm-ioctl.c')
-rw-r--r--drivers/md/dm-ioctl.c65
1 files changed, 45 insertions, 20 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index c826b3e1799a..c6ce13b18747 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -48,7 +48,7 @@ struct vers_iter {
static struct list_head _name_buckets[NUM_BUCKETS];
static struct list_head _uuid_buckets[NUM_BUCKETS];
-static void dm_hash_remove_all(void);
+static void dm_hash_remove_all(int keep_open_devices);
/*
* Guards access to both hash tables.
@@ -73,7 +73,7 @@ static int dm_hash_init(void)
static void dm_hash_exit(void)
{
- dm_hash_remove_all();
+ dm_hash_remove_all(0);
devfs_remove(DM_DIR);
}
@@ -260,19 +260,41 @@ static void __hash_remove(struct hash_cell *hc)
free_cell(hc);
}
-static void dm_hash_remove_all(void)
+static void dm_hash_remove_all(int keep_open_devices)
{
- int i;
+ int i, dev_skipped, dev_removed;
struct hash_cell *hc;
struct list_head *tmp, *n;
down_write(&_hash_lock);
+
+retry:
+ dev_skipped = dev_removed = 0;
for (i = 0; i < NUM_BUCKETS; i++) {
list_for_each_safe (tmp, n, _name_buckets + i) {
hc = list_entry(tmp, struct hash_cell, name_list);
+
+ if (keep_open_devices &&
+ dm_lock_for_deletion(hc->md)) {
+ dev_skipped++;
+ continue;
+ }
__hash_remove(hc);
+ dev_removed = 1;
}
}
+
+ /*
+ * Some mapped devices may be using other mapped devices, so if any
+ * still exist, repeat until we make no further progress.
+ */
+ if (dev_skipped) {
+ if (dev_removed)
+ goto retry;
+
+ DMWARN("remove_all left %d open device(s)", dev_skipped);
+ }
+
up_write(&_hash_lock);
}
@@ -355,7 +377,7 @@ typedef int (*ioctl_fn)(struct dm_ioctl *param, size_t param_size);
static int remove_all(struct dm_ioctl *param, size_t param_size)
{
- dm_hash_remove_all();
+ dm_hash_remove_all(1);
param->data_size = 0;
return 0;
}
@@ -535,7 +557,6 @@ static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
{
struct gendisk *disk = dm_disk(md);
struct dm_table *table;
- struct block_device *bdev;
param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
DM_ACTIVE_PRESENT_FLAG);
@@ -545,20 +566,12 @@ static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
param->dev = huge_encode_dev(MKDEV(disk->major, disk->first_minor));
- if (!(param->flags & DM_SKIP_BDGET_FLAG)) {
- bdev = bdget_disk(disk, 0);
- if (!bdev)
- return -ENXIO;
-
- /*
- * Yes, this will be out of date by the time it gets back
- * to userland, but it is still very useful for
- * debugging.
- */
- param->open_count = bdev->bd_openers;
- bdput(bdev);
- } else
- param->open_count = -1;
+ /*
+ * Yes, this will be out of date by the time it gets back
+ * to userland, but it is still very useful for
+ * debugging.
+ */
+ param->open_count = dm_open_count(md);
if (disk->policy)
param->flags |= DM_READONLY_FLAG;
@@ -661,6 +674,7 @@ static int dev_remove(struct dm_ioctl *param, size_t param_size)
{
struct hash_cell *hc;
struct mapped_device *md;
+ int r;
down_write(&_hash_lock);
hc = __find_device_hash_cell(param);
@@ -673,6 +687,17 @@ static int dev_remove(struct dm_ioctl *param, size_t param_size)
md = hc->md;
+ /*
+ * Ensure the device is not open and nothing further can open it.
+ */
+ r = dm_lock_for_deletion(md);
+ if (r) {
+ DMWARN("unable to remove open device %s", hc->name);
+ up_write(&_hash_lock);
+ dm_put(md);
+ return r;
+ }
+
__hash_remove(hc);
up_write(&_hash_lock);
dm_put(md);