kernel/linux.git/fs/btrfs/dev-replace.c, branch v6.12.80

btrfs: don't take dev_replace rwsem on task already holding it

2024-12-14T19:03:36+00:00

[ Upstream commit 8cca35cb29f81eba3e96ec44dad8696c8a2f9138 ] Running fstests btrfs/011 with MKFS_OPTIONS="-O rst" to force the usage of the RAID stripe-tree, we get the following splat from lockdep: BTRFS info (device sdd): dev_replace from /dev/sdd (devid 1) to /dev/sdb started ============================================ WARNING: possible recursive locking detected 6.11.0-rc3-btrfs-for-next #599 Not tainted -------------------------------------------- btrfs/2326 is trying to acquire lock: ffff88810f215c98 (&fs_info->dev_replace.rwsem){++++}-{3:3}, at: btrfs_map_block+0x39f/0x2250 but task is already holding lock: ffff88810f215c98 (&fs_info->dev_replace.rwsem){++++}-{3:3}, at: btrfs_map_block+0x39f/0x2250 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&fs_info->dev_replace.rwsem); lock(&fs_info->dev_replace.rwsem); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by btrfs/2326: #0: ffff88810f215c98 (&fs_info->dev_replace.rwsem){++++}-{3:3}, at: btrfs_map_block+0x39f/0x2250 stack backtrace: CPU: 1 UID: 0 PID: 2326 Comm: btrfs Not tainted 6.11.0-rc3-btrfs-for-next #599 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack_lvl+0x5b/0x80 __lock_acquire+0x2798/0x69d0 ? __pfx___lock_acquire+0x10/0x10 ? __pfx___lock_acquire+0x10/0x10 lock_acquire+0x19d/0x4a0 ? btrfs_map_block+0x39f/0x2250 ? __pfx_lock_acquire+0x10/0x10 ? find_held_lock+0x2d/0x110 ? lock_is_held_type+0x8f/0x100 down_read+0x8e/0x440 ? btrfs_map_block+0x39f/0x2250 ? __pfx_down_read+0x10/0x10 ? do_raw_read_unlock+0x44/0x70 ? _raw_read_unlock+0x23/0x40 btrfs_map_block+0x39f/0x2250 ? btrfs_dev_replace_by_ioctl+0xd69/0x1d00 ? btrfs_bio_counter_inc_blocked+0xd9/0x2e0 ? __kasan_slab_alloc+0x6e/0x70 ? __pfx_btrfs_map_block+0x10/0x10 ? __pfx_btrfs_bio_counter_inc_blocked+0x10/0x10 ? kmem_cache_alloc_noprof+0x1f2/0x300 ? mempool_alloc_noprof+0xed/0x2b0 btrfs_submit_chunk+0x28d/0x17e0 ? __pfx_btrfs_submit_chunk+0x10/0x10 ? bvec_alloc+0xd7/0x1b0 ? bio_add_folio+0x171/0x270 ? __pfx_bio_add_folio+0x10/0x10 ? __kasan_check_read+0x20/0x20 btrfs_submit_bio+0x37/0x80 read_extent_buffer_pages+0x3df/0x6c0 btrfs_read_extent_buffer+0x13e/0x5f0 read_tree_block+0x81/0xe0 read_block_for_search+0x4bd/0x7a0 ? __pfx_read_block_for_search+0x10/0x10 btrfs_search_slot+0x78d/0x2720 ? __pfx_btrfs_search_slot+0x10/0x10 ? lock_is_held_type+0x8f/0x100 ? kasan_save_track+0x14/0x30 ? __kasan_slab_alloc+0x6e/0x70 ? kmem_cache_alloc_noprof+0x1f2/0x300 btrfs_get_raid_extent_offset+0x181/0x820 ? __pfx_lock_acquire+0x10/0x10 ? __pfx_btrfs_get_raid_extent_offset+0x10/0x10 ? down_read+0x194/0x440 ? __pfx_down_read+0x10/0x10 ? do_raw_read_unlock+0x44/0x70 ? _raw_read_unlock+0x23/0x40 btrfs_map_block+0x5b5/0x2250 ? __pfx_btrfs_map_block+0x10/0x10 scrub_submit_initial_read+0x8fe/0x11b0 ? __pfx_scrub_submit_initial_read+0x10/0x10 submit_initial_group_read+0x161/0x3a0 ? lock_release+0x20e/0x710 ? __pfx_submit_initial_group_read+0x10/0x10 ? __pfx_lock_release+0x10/0x10 scrub_simple_mirror.isra.0+0x3eb/0x580 scrub_stripe+0xe4d/0x1440 ? lock_release+0x20e/0x710 ? __pfx_scrub_stripe+0x10/0x10 ? __pfx_lock_release+0x10/0x10 ? do_raw_read_unlock+0x44/0x70 ? _raw_read_unlock+0x23/0x40 scrub_chunk+0x257/0x4a0 scrub_enumerate_chunks+0x64c/0xf70 ? __mutex_unlock_slowpath+0x147/0x5f0 ? __pfx_scrub_enumerate_chunks+0x10/0x10 ? bit_wait_timeout+0xb0/0x170 ? __up_read+0x189/0x700 ? scrub_workers_get+0x231/0x300 ? up_write+0x490/0x4f0 btrfs_scrub_dev+0x52e/0xcd0 ? create_pending_snapshots+0x230/0x250 ? __pfx_btrfs_scrub_dev+0x10/0x10 btrfs_dev_replace_by_ioctl+0xd69/0x1d00 ? lock_acquire+0x19d/0x4a0 ? __pfx_btrfs_dev_replace_by_ioctl+0x10/0x10 ? lock_release+0x20e/0x710 ? btrfs_ioctl+0xa09/0x74f0 ? __pfx_lock_release+0x10/0x10 ? do_raw_spin_lock+0x11e/0x240 ? __pfx_do_raw_spin_lock+0x10/0x10 btrfs_ioctl+0xa14/0x74f0 ? lock_acquire+0x19d/0x4a0 ? find_held_lock+0x2d/0x110 ? __pfx_btrfs_ioctl+0x10/0x10 ? lock_release+0x20e/0x710 ? do_sigaction+0x3f0/0x860 ? __pfx_do_vfs_ioctl+0x10/0x10 ? do_raw_spin_lock+0x11e/0x240 ? lockdep_hardirqs_on_prepare+0x270/0x3e0 ? _raw_spin_unlock_irq+0x28/0x50 ? do_sigaction+0x3f0/0x860 ? __pfx_do_sigaction+0x10/0x10 ? __x64_sys_rt_sigaction+0x18e/0x1e0 ? __pfx___x64_sys_rt_sigaction+0x10/0x10 ? __x64_sys_close+0x7c/0xd0 __x64_sys_ioctl+0x137/0x190 do_syscall_64+0x71/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f0bd1114f9b Code: Unable to access opcode bytes at 0x7f0bd1114f71. RSP: 002b:00007ffc8a8c3130 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f0bd1114f9b RDX: 00007ffc8a8c35e0 RSI: 00000000ca289435 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000007 R10: 0000000000000008 R11: 0000000000000246 R12: 00007ffc8a8c6c85 R13: 00000000398e72a0 R14: 0000000000004361 R15: 0000000000000004 This happens because on RAID stripe-tree filesystems we recurse back into btrfs_map_block() on scrub to perform the logical to device physical mapping. But as the device replace task is already holding the dev_replace::rwsem we deadlock. So don't take the dev_replace::rwsem in case our task is the task performing the device replace. Suggested-by: Filipe Manana Signed-off-by: Johannes Thumshirn Reviewed-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Sasha Levin

btrfs: more efficient chunk map iteration when device replace finishes

2024-09-10T14:51:17+00:00

When iterating the chunk maps when a device replace finishes we are doing a full rbtree search for each chunk map, which is not the most efficient thing to do, wasting CPU time. As we are holding a write lock on the tree during the whole iteration, we can simply start from the first node in the tree and then move to the next chunk map by doing a rb_next() call - the only exception is when we need to reschedule, in which case we have to do a full rbtree search since we dropped the write lock and the tree may have changed (chunk maps may have been removed and the tree got rebalanced). So just do that. Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: reschedule when updating chunk maps at the end of a device replace

2024-09-10T14:51:17+00:00

At the end of a device replace we must go over all the chunk maps and update their stripes to point to the target device instead of the source device. We iterate over the chunk maps while holding a write lock and we never reschedule, which can result in monopolizing a CPU for too long and blocking readers for too long (it's a rw lock, non-blocking). So improve on this by rescheduling if necessary. This is safe because at this point we are holding the chunk mutex, which means no new chunks can be allocated and therefore we don't risk missing a new chunk map that covers a range behind the last one we processed before rescheduling. Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: simplify range parameters of btrfs_wait_ordered_roots()

2024-07-11T13:33:19+00:00

The range is specified only in two ways, we can simplify the case for the whole filesystem range as a NULL block group parameter. Signed-off-by: David Sterba

set_blocksize(): switch to passing struct file *

2024-05-02T21:39:44+00:00

Signed-off-by: Al Viro

Merge tag 'for-6.9-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

2024-03-12T19:28:34+00:00

Pull btrfs updates from David Sterba: "Mostly stabilization, refactoring and cleanup changes. There rest are minor performance optimizations due to caching or lock contention reduction and a few notable fixes. Performance improvements: - minor speedup in logging when repeatedly allocated structure is preallocated only once, improves latency and decreases lock contention - minor throughput increase (+6%), reduced lock contention after clearing delayed allocation bits, applies to several common workload types - skip full quota rescan if a new relation is added in the same transaction Fixes: - zstd fix for inline compressed file in subpage mode, updated version from the 6.8 time - proper qgroup inheritance ioctl parameter validation - more fiemap followup fixes after reduced locking done in 6.8: - fix race when detecting delalloc ranges Core changes: - more debugging code: - added assertions for a very rare crash in raid56 calculation - tree-checker dumps page state to give more insights into possible reference counting issues - add checksum calculation offloading sysfs knob, for now enabled under DEBUG only to determine a good heuristic for deciding the offload or synchronous, depends on various factors (block group profile, device speed) and is not as clear as initially thought (checksum type) - error handling improvements, added assertions - more page to folio conversion (defrag, truncate), cached size and shift - preparation for more fine grained locking of sectors in subpage mode - cleanups and refactoring: - include cleanups, forward declarations - pointer-to-structure helpers - redundant argument removals - removed unused code - slab cache updates, last use of SLAB_MEM_SPREAD removed" * tag 'for-6.9-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (114 commits) btrfs: reuse cloned extent buffer during fiemap to avoid re-allocations btrfs: fix race when detecting delalloc ranges during fiemap btrfs: fix off-by-one chunk length calculation at contains_pending_extent() btrfs: qgroup: allow quick inherit if snapshot is created and added to the same parent btrfs: qgroup: validate btrfs_qgroup_inherit parameter btrfs: include device major and minor numbers in the device scan notice btrfs: mark btrfs_put_caching_control() static btrfs: remove SLAB_MEM_SPREAD flag use btrfs: qgroup: always free reserved space for extent records btrfs: tree-checker: dump the page status if hit something wrong btrfs: compression: remove dead comments in btrfs_compress_heuristic() btrfs: subpage: make writer lock utilize bitmap btrfs: subpage: make reader lock utilize bitmap btrfs: unexport btrfs_subpage_start_writer() and btrfs_subpage_end_and_test_writer() btrfs: pass a valid extent map cache pointer to __get_extent_map() btrfs: merge btrfs_del_delalloc_inode() helpers btrfs: pass btrfs_device to btrfs_scratch_superblocks() btrfs: handle transaction commit errors in flush_reservations() btrfs: use KMEM_CACHE() to create btrfs_free_space cache btrfs: use KMEM_CACHE() to create delayed ref caches ...

Merge tag 'vfs-6.9.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-03-11T17:52:34+00:00

Pull block handle updates from Christian Brauner: "Last cycle we changed opening of block devices, and opening a block device would return a bdev_handle. This allowed us to implement support for restricting and forbidding writes to mounted block devices. It was accompanied by converting and adding helpers to operate on bdev_handles instead of plain block devices. That was already a good step forward but ultimately it isn't necessary to have special purpose helpers for opening block devices internally that return a bdev_handle. Fundamentally, opening a block device internally should just be equivalent to opening files. So now all internal opens of block devices return files just as a userspace open would. Instead of introducing a separate indirection into bdev_open_by_*() via struct bdev_handle bdev_file_open_by_*() is made to just return a struct file. Opening and closing a block device just becomes equivalent to opening and closing a file. This all works well because internally we already have a pseudo fs for block devices and so opening block devices is simple. There's a few places where we needed to be careful such as during boot when the kernel is supposed to mount the rootfs directly without init doing it. Here we need to take care to ensure that we flush out any asynchronous file close. That's what we already do for opening, unpacking, and closing the initramfs. So nothing new here. The equivalence of opening and closing block devices to regular files is a win in and of itself. But it also has various other advantages. We can remove struct bdev_handle completely. Various low-level helpers are now private to the block layer. Other helpers were simply removable completely. A follow-up series that is already reviewed build on this and makes it possible to remove bdev->bd_inode and allows various clean ups of the buffer head code as well. All places where we stashed a bdev_handle now just stash a file and use simple accessors to get to the actual block device which was already the case for bdev_handle" * tag 'vfs-6.9.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits) block: remove bdev_handle completely block: don't rely on BLK_OPEN_RESTRICT_WRITES when yielding write access bdev: remove bdev pointer from struct bdev_handle bdev: make struct bdev_handle private to the block layer bdev: make bdev_{release, open_by_dev}() private to block layer bdev: remove bdev_open_by_path() reiserfs: port block device access to file ocfs2: port block device access to file nfs: port block device access to files jfs: port block device access to file f2fs: port block device access to files ext4: port block device access to file erofs: port device access to file btrfs: port device access to file bcachefs: port block device access to file target: port block device access to file s390: port block device access to file nvme: port block device access to file block2mtd: port device access to files bcache: port block device access to files ...

btrfs: pass btrfs_device to btrfs_scratch_superblocks()

2024-03-04T15:24:54+00:00

Replace the two parameters bdev and name by one that can be used to get them both. Reviewed-by: Josef Bacik Reviewed-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: remove unused included headers

2024-03-04T15:24:46+00:00

With help of neovim, LSP and clangd we can identify header files that are not actually needed to be included in the .c files. This is focused only on removal (with minor fixups), further cleanups are possible but will require doing the header files properly with forward declarations, minimized includes and include-what-you-use care. Reviewed-by: Josef Bacik Signed-off-by: David Sterba

btrfs: port device access to file

2024-02-25T11:05:25+00:00

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-19-adbd023e19cc@kernel.org Reviewed-by: Jan Kara Signed-off-by: Christian Brauner