wireguard-linux/fs/btrfs/extent_map.c, branch update-toolchain

btrfs: only run the extent map shrinker from kswapd tasks

2024-08-13T11:43:28Z

Currently the extent map shrinker can be run by any task when attempting to allocate memory and there's enough memory pressure to trigger it. To avoid too much latency we stop iterating over extent maps and removing them once the task needs to reschedule. This logic was introduced in commit b3ebb9b7e92a ("btrfs: stop extent map shrinker if reschedule is needed"). While that solved high latency problems for some use cases, it's still not enough because with a too high number of tasks entering the extent map shrinker code, either due to memory allocations or because they are a kswapd task, we end up having a very high level of contention on some spin locks, namely: 1) The fs_info->fs_roots_radix_lock spin lock, which we need to find roots to iterate over their inodes; 2) The spin lock of the xarray used to track open inodes for a root (struct btrfs_root::inodes) - on 6.10 kernels and below, it used to be a red black tree and the spin lock was root->inode_lock; 3) The fs_info->delayed_iput_lock spin lock since the shrinker adds delayed iputs (calls btrfs_add_delayed_iput()). Instead of allowing the extent map shrinker to be run by any task, make it run only by kswapd tasks. This still solves the problem of running into OOM situations due to an unbounded extent map creation, which is simple to trigger by direct IO writes, as described in the changelog of commit 956a17d9d050 ("btrfs: add a shrinker for extent maps"), and by a similar case when doing buffered IO on files with a very large number of holes (keeping the file open and creating many holes, whose extent maps are only released when the file is closed). Reported-by: kzd Link: https://bugzilla.kernel.org/show_bug.cgi?id=219121 Reported-by: Octavia Togami Link: https://lore.kernel.org/linux-btrfs/CAHPNGSSt-a4ZZWrtJdVyYnJFscFjP9S7rMcvEMaNSpR556DdLA@mail.gmail.com/ Fixes: 956a17d9d050 ("btrfs: add a shrinker for extent maps") CC: stable@vger.kernel.org # 6.10+ Tested-by: kzd Tested-by: Octavia Togami Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

Merge tag 'for-6.11-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

2024-07-31T02:28:36Z

Pull btrfs fixes from David Sterba: - fix regression in extent map rework when handling insertion of overlapping compressed extent - fix unexpected file length when appending to a file using direct io and buffer not faulted in - in zoned mode, fix accounting of unusable space when flipping read-only block group back to read-write - fix page locking when COWing an inline range, assertion failure found by syzbot - fix calculation of space info in debugging print - tree-checker, add validation of data reference item - fix a few -Wmaybe-uninitialized build warnings * tag 'for-6.11-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: initialize location to fix -Wmaybe-uninitialized in btrfs_lookup_dentry() btrfs: fix corruption after buffer fault in during direct IO append write btrfs: zoned: fix zone_unusable accounting on making block group read-write again btrfs: do not subtract delalloc from avail bytes btrfs: make cow_file_range_inline() honor locked_page on error btrfs: fix corrupt read due to bad offset of a compressed extent map btrfs: tree-checker: validate dref root and objectid

btrfs: fix corrupt read due to bad offset of a compressed extent map

2024-07-25T21:54:06Z

If we attempt to insert a compressed extent map that has a range that overlaps another extent map we have in the inode's extent map tree, we can end up with an incorrect offset after adjusting the new extent map at merge_extent_mapping() because we don't update the extent map's offset. For example consider the following scenario: 1) We have a file extent item for a compressed extent covering the file range [108K, 144K) and currently there's no corresponding extent map in the inode's extent map tree; 2) The inode's size is 141K; 3) We have an encoded write (compressed) into the file range [120K, 128K), which overlaps the existing file extent item. The encoded write creates a matching extent map, adds it to the inode's extent map tree and creates an ordered extent for it. Note that the corresponding file extent item is added to the subvolume tree only when the ordered extent completes (when executing btrfs_finish_one_ordered()); 4) We have a write into the file range [160K, 164K). This writes increases the i_size of the file, and there's a hole between the current i_size (141K) and the start offset of this write, and since the old i_size is in the middle of the block [140K, 144K), we have to write zeroes to the range [141K, 144K) (3072 bytes) and therefore dirty that page. We then call btrfs_set_extent_delalloc() with a start offset of 140K. We then end up at btrfs_find_new_delalloc_bytes() which will call btrfs_get_extent() for the range [140K, 144K); 5) The btrfs_get_extent() doesn't find any extent map in the inode's extent map tree covering the range [140K, 144K), so it searches the subvolume tree for any file extent items covering that range. There it finds the file extent item for the range [108K, 144K), creates a compressed extent map for that range and then calls btrfs_add_extent_mapping() with that extent map and passes the range [140K, 144K) via the "start" and "len" parameters; 6) The call to add_extent_mapping() done by btrfs_add_extent_mapping() fails with -EEXIST because there's an extent map, created at step 2 for the [120K, 128K) range, that covers that overlaps with the range of the given extent map ([108K, 144K)). Then it does a lookup for extent map from step 2 add calls merge_extent_mapping() to adjust the input extent map ([108K, 144K)). That adjust the extent map to a start offset of 128K and a length of 16K (starting just after the extent map from step 2), but it does not update the offset field of the extent map, leaving it with a value of zero instead of updating to a value of 20K (128K - 108K = 20K). As a result any read for the range [128K, 144K) can return incorrect data since we read from a wrong section of the extent (unless both the correct and incorrect ranges happen to have the same data). So fix this by changing merge_extent_mapping() to update the extent map's offset even if it's compressed. Also add a test case to the self tests. This didn't happen before the patchset that does big changes in the extent map structure (which includes the commit in the Fixes tag below) because we kept track of the original start offset in the extent map (member "orig_start") so we could always calculate the correct offset by subtracting that offset from the start offset. A test case for fstests that triggered this problem using send/receive with compressed writes will be added soon. Fixes: 3d2ac9922465 ("btrfs: introduce new members for extent_map") Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Signed-off-by: David Sterba

Merge tag 'for-6.11-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

2024-07-17T19:38:04Z

Pull btrfs updates from David Sterba: "The highlights are new logic behind background block group reclaim, automatic removal of qgroup after removing a subvolume and new 'rescue=' mount options. The rest is optimizations, cleanups and refactoring. User visible features: - dynamic block group reclaim: - tunable framework to avoid situations where eager data allocations prevent creating new metadata chunks due to lack of unallocated space - reuse sysfs knob bg_reclaim_threshold (otherwise used only in zoned mode) for a fixed value threshold - new on/off sysfs knob "dynamic_reclaim" calculating the value based on heuristics, aiming to keep spare working space for relocating chunks but not to needlessly relocate partially utilized block groups or reclaim newly allocated ones - stats are exported in sysfs per block group type, files "reclaim_*" - this may increase IO load at unexpected times but the corner case of no allocatable block groups is known to be worse - automatically remove qgroup of deleted subvolumes: - adjust qgroup removal conditions, make sure all related subvolume data are already removed, or return EBUSY, also take into account setting of sysfs drop_subtree_threshold - also works in squota mode - mount option updates: new modes of 'rescue=' that allow to mount images (read-only) that could have been partially converted by user space tools - ignoremetacsums - invalid metadata checksums are ignored - ignoresuperflags - super block flags that track conversion in progress (like UUID or checksums) Core: - size of struct btrfs_inode is now below 1024 (on a release config), improved memory packing and other secondary effects - switch tracking of open inodes from rb-tree to xarray, minor performance improvement - reduce number of empty transaction commits when there are no dirty data/metadata - memory allocation optimizations (reduced numbers, reordering out of critical sections) - extent map structure optimizations and refactoring, more sanity checks - more subpage in zoned mode preparations or fixes - general snapshot code cleanups, improvements and documentation - tree-checker updates: more file extent ram_bytes fixes, continued - raid-stripe-tree update (not backward compatible): - remove extent encoding field from the structure, can be inferred from other information - requires btrfs-progs 6.9.1 or newer - cleanups and refactoring - error message updates - error handling improvements - return type and parameter cleanups and improvements" * tag 'for-6.11-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (152 commits) btrfs: fix extent map use-after-free when adding pages to compressed bio btrfs: fix bitmap leak when loading free space cache on duplicate entry btrfs: remove the BUG_ON() inside extent_range_clear_dirty_for_io() btrfs: move extent_range_clear_dirty_for_io() into inode.c btrfs: enhance compression error messages btrfs: fix data race when accessing the last_trans field of a root btrfs: rename the extra_gfp parameter of btrfs_alloc_page_array() btrfs: remove the extra_gfp parameter from btrfs_alloc_folio_array() btrfs: introduce new "rescue=ignoresuperflags" mount option btrfs: introduce new "rescue=ignoremetacsums" mount option btrfs: output the unrecognized super block flags as hex btrfs: remove unused Opt enums btrfs: tree-checker: add extra ram_bytes and disk_num_bytes check btrfs: fix the ram_bytes assignment for truncated ordered extents btrfs: make validate_extent_map() catch ram_bytes mismatch btrfs: ignore incorrect btrfs_file_extent_item::ram_bytes btrfs: cleanup the bytenr usage inside btrfs_extent_item_to_extent_map() btrfs: fix typo in error message in btrfs_validate_super() btrfs: move the direct IO code into its own file btrfs: pass a btrfs_inode to btrfs_set_prop() ...

btrfs: avoid races when tracking progress for extent map shrinking

2024-07-11T14:50:54Z

We store the progress (root and inode numbers) of the extent map shrinker in fs_info without any synchronization but we can have multiple tasks calling into the shrinker during memory allocations when there's enough memory pressure for example. This can result in a task A reading fs_info->extent_map_shrinker_last_ino after another task B updates it, and task A reading fs_info->extent_map_shrinker_last_root before task B updates it, making task A see an odd state that isn't necessarily harmful but may make it skip certain inode ranges or do more work than necessary by going over the same inodes again. These unprotected accesses would also trigger warnings from tools like KCSAN. So add a lock to protect access to these progress fields. Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: stop extent map shrinker if reschedule is needed

2024-07-11T14:45:42Z

The extent map shrinker can be called in a variety of contexts where we are under memory pressure, and of them is when a task is trying to allocate memory. For this reason the shrinker is typically called with a value of struct shrink_control::nr_to_scan that is much smaller than what we return in the nr_cached_objects callback of struct super_operations (fs/btrfs/super.c:btrfs_nr_cached_objects()), so that the shrinker does not take a long time and cause high latencies. However we can still take a lot of time in the shrinker even for a limited amount of nr_to_scan: 1) When traversing the red black tree that tracks open inodes in a root, as for example with millions of open inodes we get a deep tree which takes time searching for an inode; 2) Iterating over the extent map tree, which is a red black tree, of an inode when doing the rb_next() calls and when removing an extent map from the tree, since often that requires rebalancing the red black tree; 3) When trying to write lock an inode's extent map tree we may wait for a significant amount of time, because there's either another task about to do IO and searching for an extent map in the tree or inserting an extent map in the tree, and we can have thousands or even millions of extent maps for an inode. Furthermore, there can be concurrent calls to the shrinker so the lock might be busy simply because there is already another task shrinking extent maps for the same inode; 4) We often reschedule if we need to, which further increases latency. So improve on this by stopping the extent map shrinking code whenever we need to reschedule and make it skip an inode if we can't immediately lock its extent map tree. Reported-by: Mikhail Gavrilov Reported-by: Andrea Gelmini Link: https://lore.kernel.org/linux-btrfs/CABXGCsMmmb36ym8hVNGTiU8yfUS_cGvoUmGCcBrGWq9OxTrs+A@mail.gmail.com/ Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: use delayed iput during extent map shrinking

2024-07-11T14:45:18Z

When putting an inode during extent map shrinking we're doing a standard iput() but that may take a long time in case the inode is dirty and we are doing the final iput that triggers eviction - the VFS will have to wait for writeback before calling the btrfs evict callback (see fs/inode.c:evict()). This slows down the task running the shrinker which may have been triggered while updating some tree for example, meaning locks are held as well as an open transaction handle. Also if the iput() ends up triggering eviction and the inode has no links anymore, then we trigger item truncation which requires flushing delayed items, space reservation to start a transaction and that may trigger the space reclaim task and wait for it, resulting in deadlocks in case the reclaim task needs for example to commit a transaction and the shrinker is being triggered from a path holding a transaction handle. Syzbot reported such a case with the following stack traces: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc2-syzkaller-00010-g2ab795141095 #0 Not tainted ------------------------------------------------------ kswapd0/111 is trying to acquire lock: ffff88801eae4610 (sb_internal#3){.+.+}-{0:0}, at: btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275 but task is already holding lock: ffffffff8dd3a9a0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xa88/0x1970 mm/vmscan.c:6924 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:3783 [inline] fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3797 might_alloc include/linux/sched/mm.h:334 [inline] slab_pre_alloc_hook mm/slub.c:3890 [inline] slab_alloc_node mm/slub.c:3980 [inline] kmem_cache_alloc_lru_noprof+0x58/0x2f0 mm/slub.c:4019 btrfs_alloc_inode+0x118/0xb20 fs/btrfs/inode.c:8411 alloc_inode+0x5d/0x230 fs/inode.c:261 iget5_locked fs/inode.c:1235 [inline] iget5_locked+0x1c9/0x2c0 fs/inode.c:1228 btrfs_iget_locked fs/btrfs/inode.c:5590 [inline] btrfs_iget_path fs/btrfs/inode.c:5607 [inline] btrfs_iget+0xfb/0x230 fs/btrfs/inode.c:5636 create_reloc_inode+0x403/0x820 fs/btrfs/relocation.c:3911 btrfs_relocate_block_group+0x471/0xe60 fs/btrfs/relocation.c:4114 btrfs_relocate_chunk+0x143/0x450 fs/btrfs/volumes.c:3373 __btrfs_balance fs/btrfs/volumes.c:4157 [inline] btrfs_balance+0x211a/0x3f00 fs/btrfs/volumes.c:4534 btrfs_ioctl_balance fs/btrfs/ioctl.c:3675 [inline] btrfs_ioctl+0x12ed/0x8290 fs/btrfs/ioctl.c:4742 __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x164/0xf40 fs/btrfs/transaction.c:315 start_transaction+0x427/0x1a70 fs/btrfs/transaction.c:700 btrfs_rebuild_free_space_tree+0xaa/0x480 fs/btrfs/free-space-tree.c:1323 btrfs_start_pre_rw_mount+0x218/0xf60 fs/btrfs/disk-io.c:2999 open_ctree+0x41ab/0x52e0 fs/btrfs/disk-io.c:3554 btrfs_fill_super fs/btrfs/super.c:946 [inline] btrfs_get_tree_super fs/btrfs/super.c:1863 [inline] btrfs_get_tree+0x11e9/0x1b90 fs/btrfs/super.c:2089 vfs_get_tree+0x8f/0x380 fs/super.c:1780 fc_mount+0x16/0xc0 fs/namespace.c:1125 btrfs_get_tree_subvol fs/btrfs/super.c:2052 [inline] btrfs_get_tree+0xa53/0x1b90 fs/btrfs/super.c:2090 vfs_get_tree+0x8f/0x380 fs/super.c:1780 do_new_mount fs/namespace.c:3352 [inline] path_mount+0x6e1/0x1f10 fs/namespace.c:3679 do_mount fs/namespace.c:3692 [inline] __do_sys_mount fs/namespace.c:3898 [inline] __se_sys_mount fs/namespace.c:3875 [inline] __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (btrfs_trans_num_writers){++++}-{0:0}: join_transaction+0x148/0xf40 fs/btrfs/transaction.c:314 start_transaction+0x427/0x1a70 fs/btrfs/transaction.c:700 btrfs_rebuild_free_space_tree+0xaa/0x480 fs/btrfs/free-space-tree.c:1323 btrfs_start_pre_rw_mount+0x218/0xf60 fs/btrfs/disk-io.c:2999 open_ctree+0x41ab/0x52e0 fs/btrfs/disk-io.c:3554 btrfs_fill_super fs/btrfs/super.c:946 [inline] btrfs_get_tree_super fs/btrfs/super.c:1863 [inline] btrfs_get_tree+0x11e9/0x1b90 fs/btrfs/super.c:2089 vfs_get_tree+0x8f/0x380 fs/super.c:1780 fc_mount+0x16/0xc0 fs/namespace.c:1125 btrfs_get_tree_subvol fs/btrfs/super.c:2052 [inline] btrfs_get_tree+0xa53/0x1b90 fs/btrfs/super.c:2090 vfs_get_tree+0x8f/0x380 fs/super.c:1780 do_new_mount fs/namespace.c:3352 [inline] path_mount+0x6e1/0x1f10 fs/namespace.c:3679 do_mount fs/namespace.c:3692 [inline] __do_sys_mount fs/namespace.c:3898 [inline] __se_sys_mount fs/namespace.c:3875 [inline] __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (sb_internal#3){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 lock_acquire kernel/locking/lockdep.c:5754 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1655 [inline] sb_start_intwrite include/linux/fs.h:1838 [inline] start_transaction+0xbc1/0x1a70 fs/btrfs/transaction.c:694 btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275 btrfs_evict_inode+0x960/0xe80 fs/btrfs/inode.c:5291 evict+0x2ed/0x6c0 fs/inode.c:667 iput_final fs/inode.c:1741 [inline] iput.part.0+0x5a8/0x7f0 fs/inode.c:1767 iput+0x5c/0x80 fs/inode.c:1757 btrfs_scan_root fs/btrfs/extent_map.c:1118 [inline] btrfs_free_extent_maps+0xbd3/0x1320 fs/btrfs/extent_map.c:1189 super_cache_scan+0x409/0x550 fs/super.c:227 do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435 shrink_slab+0x18a/0x1310 mm/shrinker.c:662 shrink_one+0x493/0x7c0 mm/vmscan.c:4790 shrink_many mm/vmscan.c:4851 [inline] lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4951 shrink_node mm/vmscan.c:5910 [inline] kswapd_shrink_node mm/vmscan.c:6720 [inline] balance_pgdat+0x1105/0x1970 mm/vmscan.c:6911 kswapd+0x5ea/0xbf0 mm/vmscan.c:7180 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Chain exists of: sb_internal#3 --> btrfs_trans_num_extwriters --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(btrfs_trans_num_extwriters); lock(fs_reclaim); rlock(sb_internal#3); *** DEADLOCK *** 2 locks held by kswapd0/111: #0: ffffffff8dd3a9a0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xa88/0x1970 mm/vmscan.c:6924 #1: ffff88801eae40e0 (&type->s_umount_key#62){++++}-{3:3}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff88801eae40e0 (&type->s_umount_key#62){++++}-{3:3}, at: super_cache_scan+0x96/0x550 fs/super.c:196 stack backtrace: CPU: 0 PID: 111 Comm: kswapd0 Not tainted 6.10.0-rc2-syzkaller-00010-g2ab795141095 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 lock_acquire kernel/locking/lockdep.c:5754 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1655 [inline] sb_start_intwrite include/linux/fs.h:1838 [inline] start_transaction+0xbc1/0x1a70 fs/btrfs/transaction.c:694 btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275 btrfs_evict_inode+0x960/0xe80 fs/btrfs/inode.c:5291 evict+0x2ed/0x6c0 fs/inode.c:667 iput_final fs/inode.c:1741 [inline] iput.part.0+0x5a8/0x7f0 fs/inode.c:1767 iput+0x5c/0x80 fs/inode.c:1757 btrfs_scan_root fs/btrfs/extent_map.c:1118 [inline] btrfs_free_extent_maps+0xbd3/0x1320 fs/btrfs/extent_map.c:1189 super_cache_scan+0x409/0x550 fs/super.c:227 do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435 shrink_slab+0x18a/0x1310 mm/shrinker.c:662 shrink_one+0x493/0x7c0 mm/vmscan.c:4790 shrink_many mm/vmscan.c:4851 [inline] lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4951 shrink_node mm/vmscan.c:5910 [inline] kswapd_shrink_node mm/vmscan.c:6720 [inline] balance_pgdat+0x1105/0x1970 mm/vmscan.c:6911 kswapd+0x5ea/0xbf0 mm/vmscan.c:7180 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 So fix this by using btrfs_add_delayed_iput() so that the final iput is delegated to the cleaner kthread. Link: https://lore.kernel.org/linux-btrfs/000000000000892280061a344581@google.com/ Reported-by: syzbot+3dad89b3993a4b275e72@syzkaller.appspotmail.com Fixes: 956a17d9d050 ("btrfs: add a shrinker for extent maps") Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: make validate_extent_map() catch ram_bytes mismatch

2024-07-11T13:33:29Z

Previously validate_extent_map() is only to catch bugs related to extent_map member cleanups. But with recent btrfs-check enhancement to catch ram_bytes mismatch with disk_num_bytes, it would be much better to catch such extent maps earlier. So this patch adds extra ram_bytes validation for extent maps. Please note that, older filesystems with such mismatch won't trigger this error: - extent_map::ram_bytes is already fixed Previous patch has already fixed the ram_bytes for affected file extents. So this enhanced sanity check should not affect end users. Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: remove extent_map::block_start member

2024-07-11T13:33:21Z

The member extent_map::block_start can be calculated from extent_map::disk_bytenr + extent_map::offset for regular extents. And otherwise just extent_map::disk_bytenr. And this is already validated by the validate_extent_map(). Now we can remove the member. However there is a special case in btrfs_create_dio_extent() where we for NOCOW/PREALLOC ordered extents cannot directly use the resulting btrfs_file_extent, as btrfs_split_ordered_extent() cannot handle them yet. So for that call site, we pass file_extent->disk_bytenr + file_extent->num_bytes as disk_bytenr for the ordered extent, and 0 for offset. Reviewed-by: Johannes Thumshirn Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove extent_map::block_len member

2024-07-11T13:33:20Z

The extent_map::block_len is either extent_map::len (non-compressed extent) or extent_map::disk_num_bytes (compressed extent). Since we already have sanity checks to do the cross-checks between the new and old members, we can drop the old extent_map::block_len now. For most call sites, they can manually select extent_map::len or extent_map::disk_num_bytes, since most if not all of them have checked if the extent is compressed. Reviewed-by: Johannes Thumshirn Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba