kernel/linux.git/drivers/md/dm-clone-metadata.h, branch v6.6.148

dm clone metadata: Fix return type of dm_clone_nr_of_hydrated_regions()

2020-03-27T18:42:51+00:00

dm_clone_nr_of_hydrated_regions() returns the number of regions that have been hydrated so far. In order to do so it employs bitmap_weight(). Until now, the return type of dm_clone_nr_of_hydrated_regions() was unsigned long. Because bitmap_weight() returns an int, in case BITS_PER_LONG == 64 and the return value of bitmap_weight() is 2^31 (the maximum allowed number of regions for a device), the result is sign extended from 32 bits to 64 bits and an incorrect value is displayed, in the status output of dm-clone, as the number of hydrated regions. Fix this by having dm_clone_nr_of_hydrated_regions() return an unsigned int. Fixes: 7431b7835f55 ("dm: add clone target") Cc: stable@vger.kernel.org # v5.4+ Signed-off-by: Nikos Tsironis Signed-off-by: Mike Snitzer

dm clone metadata: Use a two phase commit

2019-12-05T20:27:54+00:00

Split the metadata commit in two parts: 1. dm_clone_metadata_pre_commit(): Prepare the current transaction for committing. After this is called, all subsequent metadata updates, done through either dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), will be part of the next transaction. 2. dm_clone_metadata_commit(): Actually commit the current transaction to disk and start a new transaction. This is required by the following commit. It allows dm-clone to flush the destination device after step (1) to ensure that all freshly hydrated regions, for which we are updating the metadata, are properly written to non-volatile storage and won't be lost in case of a crash. Fixes: 7431b7835f55 ("dm: add clone target") Cc: stable@vger.kernel.org # v5.4+ Signed-off-by: Nikos Tsironis Signed-off-by: Mike Snitzer

dm clone: replace spin_lock_irqsave with spin_lock_irq

2019-11-05T19:35:42+00:00

If we are in a place where it is known that interrupts are enabled, functions spin_lock_irq/spin_unlock_irq should be used instead of spin_lock_irqsave/spin_unlock_irqrestore. spin_lock_irq and spin_unlock_irq are faster because they don't need to push and pop the flags register. Signed-off-by: Mikulas Patocka Signed-off-by: Nikos Tsironis Signed-off-by: Mike Snitzer

dm: add clone target

2019-09-12T13:32:31+00:00

Add the dm-clone target, which allows cloning of arbitrary block devices. dm-clone produces a one-to-one copy of an existing, read-only source device into a writable destination device: It presents a virtual block device which makes all data appear immediately, and redirects reads and writes accordingly. The main use case of dm-clone is to clone a potentially remote, high-latency, read-only, archival-type block device into a writable, fast, primary-type device for fast, low-latency I/O. The cloned device is visible/mountable immediately and the copy of the source device to the destination device happens in the background, in parallel with user I/O. When the cloning completes, the dm-clone table can be removed altogether and be replaced, e.g., by a linear table, mapping directly to the destination device. For further information and examples of how to use dm-clone, please read Documentation/admin-guide/device-mapper/dm-clone.rst Suggested-by: Vangelis Koukis Co-developed-by: Ilias Tsitsimpis Signed-off-by: Ilias Tsitsimpis Signed-off-by: Nikos Tsironis Signed-off-by: Mike Snitzer