[PATCH] dm: introduce a no open flag for deferred remove
From: Brian Geffon
Date: Mon Jan 24 2022 - 10:02:29 EST
When a device is being removed with deferred remove it's
still possible to open and use the device. This change
introduces a flag called DM_DEFERRED_REMOVE_NO_OPEN_FLAG
which when used with DM_DEFERRED_REMOVE will cause any
new opens to fail with -ENXIO.
If this flag is used without DM_DEFERRED_REMOVE it will
result in an -EINVAL.
Signed-off-by: Brian Geffon <bgeffon@xxxxxxxxxx>
---
drivers/md/dm-core.h | 1 +
drivers/md/dm-ioctl.c | 39 +++++++++++++++++++++++++++--------
drivers/md/dm.c | 21 ++++++++++++++++---
drivers/md/dm.h | 9 +++++++-
include/uapi/linux/dm-ioctl.h | 12 +++++++++--
5 files changed, 67 insertions(+), 15 deletions(-)
diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index b855fef4f38a..b30e59deb4a8 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -139,6 +139,7 @@ struct mapped_device {
#define DMF_SUSPENDED_INTERNALLY 7
#define DMF_POST_SUSPENDING 8
#define DMF_EMULATE_ZONE_APPEND 9
+#define DMF_DEFERRED_REMOVE_NO_OPEN 10
void disable_discard(struct mapped_device *md);
void disable_write_same(struct mapped_device *md);
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 21fe8652b095..07bb679880de 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -60,7 +60,8 @@ struct vers_iter {
static struct rb_root name_rb_tree = RB_ROOT;
static struct rb_root uuid_rb_tree = RB_ROOT;
-static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred);
+static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred,
+ bool deferred_no_open, bool only_deferred);
/*
* Guards access to both hash tables.
@@ -74,7 +75,7 @@ static DEFINE_MUTEX(dm_hash_cells_mutex);
static void dm_hash_exit(void)
{
- dm_hash_remove_all(false, false, false);
+ dm_hash_remove_all(false, false, false, false);
}
/*-----------------------------------------------------------------
@@ -315,7 +316,8 @@ static struct dm_table *__hash_remove(struct hash_cell *hc)
return table;
}
-static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred)
+static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred,
+ bool deferred_no_open, bool only_deferred)
{
int dev_skipped;
struct rb_node *n;
@@ -334,7 +336,8 @@ static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool
dm_get(md);
if (keep_open_devices &&
- dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
+ dm_lock_for_deletion(md, mark_deferred, deferred_no_open,
+ only_deferred)) {
dm_put(md);
dev_skipped++;
continue;
@@ -496,7 +499,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
void dm_deferred_remove(void)
{
- dm_hash_remove_all(true, false, true);
+ dm_hash_remove_all(true, false, false, true);
}
/*-----------------------------------------------------------------
@@ -510,7 +513,13 @@ typedef int (*ioctl_fn)(struct file *filp, struct dm_ioctl *param, size_t param_
static int remove_all(struct file *filp, struct dm_ioctl *param, size_t param_size)
{
- dm_hash_remove_all(true, !!(param->flags & DM_DEFERRED_REMOVE), false);
+ if (param->flags & DM_DEFERRED_REMOVE_NO_OPEN_FLAG &&
+ !(param->flags & DM_DEFERRED_REMOVE)) {
+ return -EINVAL;
+ }
+
+ dm_hash_remove_all(true, !!(param->flags & DM_DEFERRED_REMOVE),
+ !!(param->flags & DM_DEFERRED_REMOVE_NO_OPEN_FLAG), false);
param->data_size = 0;
return 0;
}
@@ -811,9 +820,13 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
if (dm_suspended_internally_md(md))
param->flags |= DM_INTERNAL_SUSPEND_FLAG;
- if (dm_test_deferred_remove_flag(md))
+ if (dm_test_deferred_remove_flag(md)) {
param->flags |= DM_DEFERRED_REMOVE;
+ if (dm_test_deferred_remove_no_open_flag(md))
+ param->flags |= DM_DEFERRED_REMOVE_NO_OPEN_FLAG;
+ }
+
param->dev = huge_encode_dev(disk_devt(disk));
/*
@@ -960,10 +973,18 @@ static int dev_remove(struct file *filp, struct dm_ioctl *param, size_t param_si
md = hc->md;
+ if (param->flags & DM_DEFERRED_REMOVE_NO_OPEN_FLAG &&
+ !(param->flags & DM_DEFERRED_REMOVE)) {
+ up_write(&_hash_lock);
+ dm_put(md);
+ return -EINVAL;
+ }
+
/*
* Ensure the device is not open and nothing further can open it.
*/
- r = dm_lock_for_deletion(md, !!(param->flags & DM_DEFERRED_REMOVE), false);
+ r = dm_lock_for_deletion(md, !!(param->flags & DM_DEFERRED_REMOVE),
+ !!(param->flags & DM_DEFERRED_REMOVE_NO_OPEN_FLAG), false);
if (r) {
if (r == -EBUSY && param->flags & DM_DEFERRED_REMOVE) {
up_write(&_hash_lock);
@@ -984,7 +1005,7 @@ static int dev_remove(struct file *filp, struct dm_ioctl *param, size_t param_si
dm_table_destroy(t);
}
- param->flags &= ~DM_DEFERRED_REMOVE;
+ param->flags &= ~(DM_DEFERRED_REMOVE | DM_DEFERRED_REMOVE_NO_OPEN_FLAG);
dm_ima_measure_on_device_remove(md, false);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c0ae8087c602..90b74043e162 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -315,7 +315,10 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode)
goto out;
if (test_bit(DMF_FREEING, &md->flags) ||
+ test_bit(DMF_DEFERRED_REMOVE_NO_OPEN, &md->flags) ||
dm_deleting_md(md)) {
+ BUG_ON(test_bit(DMF_DEFERRED_REMOVE_NO_OPEN, &md->flags) &&
+ !test_bit(DMF_DEFERRED_REMOVE, &md->flags));
md = NULL;
goto out;
}
@@ -355,7 +358,8 @@ int dm_open_count(struct mapped_device *md)
/*
* Guarantees nothing is using the device before it's deleted.
*/
-int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred)
+int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred,
+ bool deferred_no_open, bool only_deferred)
{
int r = 0;
@@ -363,8 +367,12 @@ int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only
if (dm_open_count(md)) {
r = -EBUSY;
- if (mark_deferred)
+ if (mark_deferred) {
set_bit(DMF_DEFERRED_REMOVE, &md->flags);
+
+ if (deferred_no_open)
+ set_bit(DMF_DEFERRED_REMOVE_NO_OPEN, &md->flags);
+ }
} else if (only_deferred && !test_bit(DMF_DEFERRED_REMOVE, &md->flags))
r = -EEXIST;
else
@@ -383,8 +391,10 @@ int dm_cancel_deferred_remove(struct mapped_device *md)
if (test_bit(DMF_DELETING, &md->flags))
r = -EBUSY;
- else
+ else {
clear_bit(DMF_DEFERRED_REMOVE, &md->flags);
+ clear_bit(DMF_DEFERRED_REMOVE_NO_OPEN, &md->flags);
+ }
spin_unlock(&_minor_lock);
@@ -2718,6 +2728,11 @@ int dm_test_deferred_remove_flag(struct mapped_device *md)
return test_bit(DMF_DEFERRED_REMOVE, &md->flags);
}
+int dm_test_deferred_remove_no_open_flag(struct mapped_device *md)
+{
+ return test_bit(DMF_DEFERRED_REMOVE_NO_OPEN, &md->flags);
+}
+
int dm_suspended(struct dm_target *ti)
{
return dm_suspended_md(ti->table->md);
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 9013dc1a7b00..8d0d4344f882 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -158,6 +158,12 @@ void dm_internal_resume(struct mapped_device *md);
*/
int dm_test_deferred_remove_flag(struct mapped_device *md);
+/*
+ * Test if the device is scheduled for deferred remove while
+ * disallowing opens.
+ */
+int dm_test_deferred_remove_no_open_flag(struct mapped_device *md);
+
/*
* Try to remove devices marked for deferred removal.
*/
@@ -198,7 +204,8 @@ void dm_stripe_exit(void);
void dm_destroy(struct mapped_device *md);
void dm_destroy_immediate(struct mapped_device *md);
int dm_open_count(struct mapped_device *md);
-int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred);
+int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred,
+ bool deferred_no_open, bool only_deferred);
int dm_cancel_deferred_remove(struct mapped_device *md);
int dm_request_based(struct mapped_device *md);
int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h
index c12ce30b52df..c0fee607b827 100644
--- a/include/uapi/linux/dm-ioctl.h
+++ b/include/uapi/linux/dm-ioctl.h
@@ -286,9 +286,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
-#define DM_VERSION_MINOR 45
+#define DM_VERSION_MINOR 46
#define DM_VERSION_PATCHLEVEL 0
-#define DM_VERSION_EXTRA "-ioctl (2021-03-22)"
+#define DM_VERSION_EXTRA "-ioctl (2022-01-21)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */
@@ -382,4 +382,12 @@ enum {
*/
#define DM_IMA_MEASUREMENT_FLAG (1 << 19) /* In */
+/* If set with DF_DEFERRED_REMOVE if an immediate remove is not
+ * possible because the device is still open any new additional
+ * opens will also be rejected.
+ *
+ * It is an error to specify this flag without DM_DEFERRED_REMOVE.
+ */
+#define DM_DEFERRED_REMOVE_NO_OPEN_FLAG (1 << 20) /* In/Out */
+
#endif /* _LINUX_DM_IOCTL_H */
--
2.35.0.rc0.227.g00780c9af4-goog