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Subject[PATCH v5 5/6] dm: add 'noexcl' option for dm-linear
Date
The 'noexcl' option allow to open underlying block-device
without FMODE_EXCL.

Signed-off-by: Sergei Shtepa <sergei.shtepa@veeam.com>
---
drivers/md/dm-linear.c | 14 +++++++++++++-
drivers/md/dm-table.c | 14 ++++++++------
drivers/md/dm.c | 26 +++++++++++++++++++-------
drivers/md/dm.h | 2 +-
include/linux/device-mapper.h | 7 +++++++
5 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 00774b5d7668..b16d89802b9d 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -33,7 +33,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
char dummy;
int ret;

- if (argc != 2) {
+ if ((argc < 2) || (argc > 3)) {
ti->error = "Invalid argument count";
return -EINVAL;
}
@@ -51,6 +51,18 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
}
lc->start = tmp;

+ ti->non_exclusive = false;
+ if (argc > 2) {
+ if (strcmp("noexcl", argv[2]) == 0)
+ ti->non_exclusive = true;
+ else if (strcmp("excl", argv[2]) == 0)
+ ti->non_exclusive = false;
+ else {
+ ti->error = "Invalid exclusive option";
+ return -EINVAL;
+ }
+ }
+
ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
if (ret) {
ti->error = "Device lookup failed";
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 4acf2342f7ad..f020459465bd 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -322,7 +322,7 @@ static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
* device and not to touch the existing bdev field in case
* it is accessed concurrently.
*/
-static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,
+static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode, bool non_exclusive,
struct mapped_device *md)
{
int r;
@@ -330,8 +330,8 @@ static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,

old_dev = dd->dm_dev;

- r = dm_get_table_device(md, dd->dm_dev->bdev->bd_dev,
- dd->dm_dev->mode | new_mode, &new_dev);
+ r = dm_get_table_device(md, dd->dm_dev->bdev->bd_dev, dd->dm_dev->mode | new_mode,
+ non_exclusive, &new_dev);
if (r)
return r;

@@ -387,7 +387,8 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
if (!dd)
return -ENOMEM;

- if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) {
+ r = dm_get_table_device(t->md, dev, mode, ti->non_exclusive, &dd->dm_dev);
+ if (r) {
kfree(dd);
return r;
}
@@ -396,8 +397,9 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
list_add(&dd->list, &t->devices);
goto out;

- } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
- r = upgrade_mode(dd, mode, t->md);
+ } else if ((dd->dm_dev->mode != (mode | dd->dm_dev->mode)) &&
+ (dd->dm_dev->non_exclusive != ti->non_exclusive)) {
+ r = upgrade_mode(dd, mode, ti->non_exclusive, t->md);
if (r)
return r;
}
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 00c41aa6d092..c25dcc2fdb89 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1117,33 +1117,44 @@ static void close_table_device(struct table_device *td, struct mapped_device *md
if (!td->dm_dev.bdev)
return;

- bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md));
- blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL);
+ if (td->dm_dev.non_exclusive)
+ blkdev_put(td->dm_dev.bdev, td->dm_dev.mode);
+ else {
+ bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md));
+ blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL);
+ }
+
+
+ blkdev_put(td->dm_dev.bdev, td->dm_dev.mode);
+
put_dax(td->dm_dev.dax_dev);
td->dm_dev.bdev = NULL;
td->dm_dev.dax_dev = NULL;
+ td->dm_dev.non_exclusive = false;
}

static struct table_device *find_table_device(struct list_head *l, dev_t dev,
- fmode_t mode)
+ fmode_t mode, bool non_exclusive)
{
struct table_device *td;

list_for_each_entry(td, l, list)
- if (td->dm_dev.bdev->bd_dev == dev && td->dm_dev.mode == mode)
+ if (td->dm_dev.bdev->bd_dev == dev &&
+ td->dm_dev.mode == mode &&
+ td->dm_dev.non_exclusive == non_exclusive)
return td;

return NULL;
}

-int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
+int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, bool non_exclusive,
struct dm_dev **result)
{
int r;
struct table_device *td;

mutex_lock(&md->table_devices_lock);
- td = find_table_device(&md->table_devices, dev, mode);
+ td = find_table_device(&md->table_devices, dev, mode, non_exclusive);
if (!td) {
td = kmalloc_node(sizeof(*td), GFP_KERNEL, md->numa_node_id);
if (!td) {
@@ -1154,7 +1165,8 @@ int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
td->dm_dev.mode = mode;
td->dm_dev.bdev = NULL;

- if ((r = open_table_device(td, dev, md))) {
+ r = open_table_device(td, dev, md, non_exclusive);
+ if (r) {
mutex_unlock(&md->table_devices_lock);
kfree(td);
return r;
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index fffe1e289c53..7bf20fb2de74 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -179,7 +179,7 @@ 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_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,
+int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, bool non_exclusive,
struct dm_dev **result);
void dm_put_table_device(struct mapped_device *md, struct dm_dev *d);

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 61a66fb8ebb3..70002363bfc0 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -150,6 +150,7 @@ struct dm_dev {
struct block_device *bdev;
struct dax_device *dax_dev;
fmode_t mode;
+ bool non_exclusive;
char name[16];
};

@@ -325,6 +326,12 @@ struct dm_target {
* whether or not its underlying devices have support.
*/
bool discards_supported:1;
+
+ /*
+ * Set if this target needs to open device without FMODE_EXCL
+ * mode.
+ */
+ bool non_exclusive:1;
};

void *dm_per_bio_data(struct bio *bio, size_t data_size);
--
2.20.1
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