kernel/linux.git/drivers/md/md.h, branch v6.18.21

md: fix return value of mddev_trylock

2026-02-26T22:59:01+00:00

[ Upstream commit 05c8de4f09b08e97c6ecb190dcec0e68b167cb03 ] A return value of 0 is treaded as successful lock acquisition. In fact, a return value of 1 means getting the lock successfully. Link: https://lore.kernel.org/linux-raid/20260127073951.17248-1-xni@redhat.com Fixes: 9e59d609763f ("md: call del_gendisk in control path") Reported-by: Bart Van Assche Closes: https://lore.kernel.org/linux-raid/20250611073108.25463-1-xni@redhat.com/T/#mfa369ef5faa4aa58e13e6d9fdb88aecd862b8f2f Signed-off-by: Xiao Ni Reviewed-by: Bart Van Assche Reviewed-by: Li Nan Signed-off-by: Yu Kuai Signed-off-by: Sasha Levin

md: avoid repeated calls to del_gendisk

2025-12-18T13:02:53+00:00

[ Upstream commit 90e3bb44c0a86e245d8e5c6520206fa113acb1ee ] There is a uaf problem which is found by case 23rdev-lifetime: Oops: general protection fault, probably for non-canonical address 0xdead000000000122 RIP: 0010:bdi_unregister+0x4b/0x170 Call Trace: __del_gendisk+0x356/0x3e0 mddev_unlock+0x351/0x360 rdev_attr_store+0x217/0x280 kernfs_fop_write_iter+0x14a/0x210 vfs_write+0x29e/0x550 ksys_write+0x74/0xf0 do_syscall_64+0xbb/0x380 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff5250a177e The sequence is: 1. rdev remove path gets reconfig_mutex 2. rdev remove path release reconfig_mutex in mddev_unlock 3. md stop calls do_md_stop and sets MD_DELETED 4. rdev remove path calls del_gendisk because MD_DELETED is set 5. md stop path release reconfig_mutex and calls del_gendisk again So there is a race condition we should resolve. This patch adds a flag MD_DO_DELETE to avoid the race condition. Link: https://lore.kernel.org/linux-raid/20251029063419.21700-1-xni@redhat.com Fixes: 9e59d609763f ("md: call del_gendisk in control path") Signed-off-by: Xiao Ni Suggested-by: Yu Kuai Reviewed-by: Li Nan Signed-off-by: Yu Kuai Signed-off-by: Sasha Levin

md: fix rcu protection in md_wakeup_thread

2025-12-18T13:02:53+00:00

[ Upstream commit 0dc76205549b4c25705e54345f211b9f66e018a0 ] We attempted to use RCU to protect the pointer 'thread', but directly passed the value when calling md_wakeup_thread(). This means that the RCU pointer has been acquired before rcu_read_lock(), which renders rcu_read_lock() ineffective and could lead to a use-after-free. Link: https://lore.kernel.org/linux-raid/20251015083227.1079009-1-yun.zhou@windriver.com Fixes: 446931543982 ("md: protect md_thread with rcu") Signed-off-by: Yun Zhou Reviewed-by: Li Nan Reviewed-by: Yu Kuai Signed-off-by: Yu Kuai Signed-off-by: Sasha Levin

md/md-llbitmap: introduce new lockless bitmap

2025-09-06T09:27:51+00:00

Redundant data is used to enhance data fault tolerance, and the storage method for redundant data vary depending on the RAID levels. And it's important to maintain the consistency of redundant data. Bitmap is used to record which data blocks have been synchronized and which ones need to be resynchronized or recovered. Each bit in the bitmap represents a segment of data in the array. When a bit is set, it indicates that the multiple redundant copies of that data segment may not be consistent. Data synchronization can be performed based on the bitmap after power failure or readding a disk. If there is no bitmap, a full disk synchronization is required. Due to known performance issues with md-bitmap and the unreasonable implementations: - self-managed IO submitting like filemap_write_page(); - global spin_lock I have decided not to continue optimizing based on the current bitmap implementation, this new bitmap is invented without locking from IO fast path and can be used with fast disks. For designs and details, see the comments in drivers/md-llbitmap.c. Link: https://lore.kernel.org/linux-raid/20250829080426.1441678-12-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai Reviewed-by: Li Nan

md: add a new recovery_flag MD_RECOVERY_LAZY_RECOVER

2025-09-06T09:20:32+00:00

This flag is used by llbitmap in later patches to skip raid456 initial recover and delay building initial xor data to first write. https://lore.kernel.org/linux-raid/20250829080426.1441678-10-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai

md: add a new mddev field 'bitmap_id'

2025-09-06T09:18:48+00:00

Prepare to store the bitmap id selected by user, also refactor mddev_set_bitmap_ops a bit in case the value is invalid. Link: https://lore.kernel.org/linux-raid/20250829080426.1441678-5-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai Reviewed-by: Hannes Reinecke Reviewed-by: Li Nan Reviewed-by: Xiao Ni

md/md-bitmap: support discard for bitmap ops

2025-09-06T09:18:19+00:00

Use two new methods {start, end}_discard in bitmap_ops and a new field 'rw' in struct md_io_clone to handle discard IO, prepare to support new md bitmap. Since all bitmap functions to hanlde write IO are the same, also add typedef to make code cleaner. Link: https://lore.kernel.org/linux-raid/20250829080426.1441678-4-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai Reviewed-by: Xiao Ni Reviewed-by: Hannes Reinecke Reviewed-by: Li Nan

md: factor out a helper raid_is_456()

2025-09-06T09:17:58+00:00

There are no functional changes, the helper will be used by llbitmap in following patches. Link: https://lore.kernel.org/linux-raid/20250829080426.1441678-3-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai Reviewed-by: Xiao Ni Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: Li Nan

md: add a new parameter 'offset' to md_super_write()

2025-09-06T09:17:26+00:00

The parameter is always set to 0 for now, following patches will use this helper to write llbitmap to underlying disks, allow writing dirty sectors instead of the whole page. Also rename md_super_write to md_write_metadata since there is nothing super-block specific. Link: https://lore.kernel.org/linux-raid/20250829080426.1441678-2-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai Reviewed-by: Xiao Ni Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: Li Nan

md/md-bitmap: introduce CONFIG_MD_BITMAP

2025-09-06T09:12:22+00:00

Now that all implementations are internal, it's sensible to add a config option for md-bitmap, and it's a good way for isolation. Link: https://lore.kernel.org/linux-raid/20250707012711.376844-16-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai Reviewed-by: Xiao Ni