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2024-03-07Merge tag 'erofs-for-6.8-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs Pull erofs fixes from Gao Xiang: "The main one is a KMSAN fix which addresses an issue introduced in this cycle so it'd be much better to fix before releasing, and the remaining one fixes VMA alignment for THP. Summary: - Fix a KMSAN uninit-value issue triggered by a crafted image - Fix VMA alignment for memory mapped files on THP" * tag 'erofs-for-6.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs: erofs: apply proper VMA alignment for memory mapped files on THP erofs: fix uninitialized page cache reported by KMSAN
2024-03-07erofs: apply proper VMA alignment for memory mapped files on THPGao Xiang
There are mainly two reasons that thp_get_unmapped_area() should be used for EROFS as other filesystems: - It's needed to enable PMD mappings as a FSDAX filesystem, see commit 74d2fad1334d ("thp, dax: add thp_get_unmapped_area for pmd mappings"); - It's useful together with large folios and CONFIG_READ_ONLY_THP_FOR_FS which enable THPs for mmapped files (e.g. shared libraries) even without FSDAX. See commit 1854bc6e2420 ("mm/readahead: Align file mappings for non-DAX"). Fixes: 06252e9ce05b ("erofs: dax support for non-tailpacking regular file") Fixes: ce529cc25b18 ("erofs: enable large folios for iomap mode") Fixes: e6687b89225e ("erofs: enable large folios for fscache mode") Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com> Reviewed-by: Chao Yu <chao@kernel.org> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Link: https://lore.kernel.org/r/20240306053138.2240206-1-hsiangkao@linux.alibaba.com
2024-03-07erofs: fix uninitialized page cache reported by KMSANGao Xiang
syzbot reports a KMSAN reproducer [1] which generates a crafted filesystem image and causes IMA to read uninitialized page cache. Later, (rq->outputsize > rq->inputsize) will be formally supported after either large uncompressed pclusters (> block size) or big lclusters are landed. However, currently there is no way to generate such filesystems by using mkfs.erofs. Thus, let's mark this condition as unsupported for now. [1] https://lore.kernel.org/r/0000000000002be12a0611ca7ff8@google.com Reported-and-tested-by: syzbot+7bc44a489f0ef0670bd5@syzkaller.appspotmail.com Fixes: 1ca01520148a ("erofs: refine z_erofs_transform_plain() for sub-page block support") Reviewed-by: Sandeep Dhavale <dhavale@google.com> Reviewed-by: Yue Hu <huyue2@coolpad.com> Reviewed-by: Chao Yu <chao@kernel.org> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Link: https://lore.kernel.org/r/20240304035339.425857-1-hsiangkao@linux.alibaba.com
2024-03-06iov_iter: get rid of 'copy_mc' flagLinus Torvalds
This flag is only set by one single user: the magical core dumping code that looks up user pages one by one, and then writes them out using their kernel addresses (by using a BVEC_ITER). That actually ends up being a huge problem, because while we do use copy_mc_to_kernel() for this case and it is able to handle the possible machine checks involved, nothing else is really ready to handle the failures caused by the machine check. In particular, as reported by Tong Tiangen, we don't actually support fault_in_iov_iter_readable() on a machine check area. As a result, the usual logic for writing things to a file under a filesystem lock, which involves doing a copy with page faults disabled and then if that fails trying to fault pages in without holding the locks with fault_in_iov_iter_readable() does not work at all. We could decide to always just make the MC copy "succeed" (and filling the destination with zeroes), and that would then create a core dump file that just ignores any machine checks. But honestly, this single special case has been problematic before, and means that all the normal iov_iter code ends up slightly more complex and slower. See for example commit c9eec08bac96 ("iov_iter: Don't deal with iter->copy_mc in memcpy_from_iter_mc()") where David Howells re-organized the code just to avoid having to check the 'copy_mc' flags inside the inner iov_iter loops. So considering that we have exactly one user, and that one user is a non-critical special case that doesn't actually ever trigger in real life (Tong found this with manual error injection), the sane solution is to just decide that the onus on handling the machine check lines on that user instead. Ergo, do the copy_mc_to_kernel() in the core dump logic itself, copying the user data to a stable kernel page before writing it out. Fixes: f1982740f5e7 ("iov_iter: Convert iterate*() to inline funcs") Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> Link: https://lore.kernel.org/r/20240305133336.3804360-1-tongtiangen@huawei.com Link: https://lore.kernel.org/all/4e80924d-9c85-f13a-722a-6a5d2b1c225a@huawei.com/ Tested-by: David Howells <dhowells@redhat.com> Reviewed-by: David Howells <dhowells@redhat.com> Reviewed-by: Jens Axboe <axboe@kernel.dk> Reported-by: Tong Tiangen <tongtiangen@huawei.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-03-05fs/aio: Check IOCB_AIO_RW before the struct aio_kiocb conversionBart Van Assche
The first kiocb_set_cancel_fn() argument may point at a struct kiocb that is not embedded inside struct aio_kiocb. With the current code, depending on the compiler, the req->ki_ctx read happens either before the IOCB_AIO_RW test or after that test. Move the req->ki_ctx read such that it is guaranteed that the IOCB_AIO_RW test happens first. Reported-by: Eric Biggers <ebiggers@kernel.org> Cc: Benjamin LaHaise <ben@communityfibre.ca> Cc: Eric Biggers <ebiggers@google.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Avi Kivity <avi@scylladb.com> Cc: Sandeep Dhavale <dhavale@google.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: stable@vger.kernel.org Fixes: b820de741ae4 ("fs/aio: Restrict kiocb_set_cancel_fn() to I/O submitted via libaio") Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20240304235715.3790858-1-bvanassche@acm.org Reviewed-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-03-05Revert "fs/aio: Make io_cancel() generate completions again"Bart Van Assche
Patch "fs/aio: Make io_cancel() generate completions again" is based on the assumption that calling kiocb->ki_cancel() does not complete R/W requests. This is incorrect: the two drivers that call kiocb_set_cancel_fn() callers set a cancellation function that calls usb_ep_dequeue(). According to its documentation, usb_ep_dequeue() calls the completion routine with status -ECONNRESET. Hence this revert. Cc: Benjamin LaHaise <ben@communityfibre.ca> Cc: Eric Biggers <ebiggers@google.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Avi Kivity <avi@scylladb.com> Cc: Sandeep Dhavale <dhavale@google.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: stable@vger.kernel.org Reported-by: syzbot+b91eb2ed18f599dd3c31@syzkaller.appspotmail.com Fixes: 54cbc058d86b ("fs/aio: Make io_cancel() generate completions again") Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20240304182945.3646109-1-bvanassche@acm.org Acked-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-03-02Merge tag 'xfs-6.8-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linuxLinus Torvalds
Pull xfs fix from Chandan Babu: "Drop experimental warning message when mounting an xfs filesystem on an fsdax device. We now consider xfs on fsdax to be stable" * tag 'xfs-6.8-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: xfs: drop experimental warning for FSDAX
2024-03-01Merge tag 'ceph-for-6.8-rc7' of https://github.com/ceph/ceph-clientLinus Torvalds
Pull ceph fix from Ilya Dryomov: "Catch up with mdsmap encoding rectification which ended up being necessary after all to enable cluster upgrades from problematic v18.2.0 and v18.2.1 releases" * tag 'ceph-for-6.8-rc7' of https://github.com/ceph/ceph-client: ceph: switch to corrected encoding of max_xattr_size in mdsmap
2024-03-01Merge tag 'for-6.8-rc6-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs fixes from David Sterba: - fix freeing allocated id for anon dev when snapshot creation fails - fiemap fixes: - followup for a recent deadlock fix, ranges that fiemap can access can still race with ordered extent completion - make sure fiemap with SYNC flag does not race with writes * tag 'for-6.8-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: fix double free of anonymous device after snapshot creation failure btrfs: ensure fiemap doesn't race with writes when FIEMAP_FLAG_SYNC is given btrfs: fix race between ordered extent completion and fiemap
2024-03-01Merge tag 'exfat-for-6.8-rc7' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat Pull exfat fix from Namjae Jeon: - Fix ftruncate failure when allocating non-contiguous clusters * tag 'exfat-for-6.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat: exfat: fix appending discontinuous clusters to empty file
2024-03-01Merge tag 'vfs-6.8-rc7.fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs fixes from Christian Brauner: "Two small fixes: - Fix an endless loop during afs directory iteration caused by not skipping silly-rename files correctly. - Fix reporting of completion events for aio causing leaks in userspace. This is based on the fix last week as it's now possible to recognize aio events submitted through the old aio interface" * tag 'vfs-6.8-rc7.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: fs/aio: Make io_cancel() generate completions again afs: Fix endless loop in directory parsing
2024-03-01Merge tag 'efi-fixes-for-v6.8-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi Pull EFI fixes from Ard Biesheuvel: "Only the EFI variable name size change is significant, and will be backported once it lands. The others are cleanup. - Fix phys_addr_t size confusion in 32-bit capsule loader - Reduce maximum EFI variable name size to 512 to work around buggy firmware - Drop some redundant code from efivarfs while at it" * tag 'efi-fixes-for-v6.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi: efivarfs: Drop 'duplicates' bool parameter on efivar_init() efivarfs: Drop redundant cleanup on fill_super() failure efivarfs: Request at most 512 bytes for variable names efi/capsule-loader: fix incorrect allocation size
2024-02-29btrfs: fix double free of anonymous device after snapshot creation failureFilipe Manana
When creating a snapshot we may do a double free of an anonymous device in case there's an error committing the transaction. The second free may result in freeing an anonymous device number that was allocated by some other subsystem in the kernel or another btrfs filesystem. The steps that lead to this: 1) At ioctl.c:create_snapshot() we allocate an anonymous device number and assign it to pending_snapshot->anon_dev; 2) Then we call btrfs_commit_transaction() and end up at transaction.c:create_pending_snapshot(); 3) There we call btrfs_get_new_fs_root() and pass it the anonymous device number stored in pending_snapshot->anon_dev; 4) btrfs_get_new_fs_root() frees that anonymous device number because btrfs_lookup_fs_root() returned a root - someone else did a lookup of the new root already, which could some task doing backref walking; 5) After that some error happens in the transaction commit path, and at ioctl.c:create_snapshot() we jump to the 'fail' label, and after that we free again the same anonymous device number, which in the meanwhile may have been reallocated somewhere else, because pending_snapshot->anon_dev still has the same value as in step 1. Recently syzbot ran into this and reported the following trace: ------------[ cut here ]------------ ida_free called for id=51 which is not allocated. WARNING: CPU: 1 PID: 31038 at lib/idr.c:525 ida_free+0x370/0x420 lib/idr.c:525 Modules linked in: CPU: 1 PID: 31038 Comm: syz-executor.2 Not tainted 6.8.0-rc4-syzkaller-00410-gc02197fc9076 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 RIP: 0010:ida_free+0x370/0x420 lib/idr.c:525 Code: 10 42 80 3c 28 (...) RSP: 0018:ffffc90015a67300 EFLAGS: 00010246 RAX: be5130472f5dd000 RBX: 0000000000000033 RCX: 0000000000040000 RDX: ffffc90009a7a000 RSI: 000000000003ffff RDI: 0000000000040000 RBP: ffffc90015a673f0 R08: ffffffff81577992 R09: 1ffff92002b4cdb4 R10: dffffc0000000000 R11: fffff52002b4cdb5 R12: 0000000000000246 R13: dffffc0000000000 R14: ffffffff8e256b80 R15: 0000000000000246 FS: 00007fca3f4b46c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f167a17b978 CR3: 000000001ed26000 CR4: 0000000000350ef0 Call Trace: <TASK> btrfs_get_root_ref+0xa48/0xaf0 fs/btrfs/disk-io.c:1346 create_pending_snapshot+0xff2/0x2bc0 fs/btrfs/transaction.c:1837 create_pending_snapshots+0x195/0x1d0 fs/btrfs/transaction.c:1931 btrfs_commit_transaction+0xf1c/0x3740 fs/btrfs/transaction.c:2404 create_snapshot+0x507/0x880 fs/btrfs/ioctl.c:848 btrfs_mksubvol+0x5d0/0x750 fs/btrfs/ioctl.c:998 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1044 __btrfs_ioctl_snap_create+0x387/0x4b0 fs/btrfs/ioctl.c:1306 btrfs_ioctl_snap_create_v2+0x1ca/0x400 fs/btrfs/ioctl.c:1393 btrfs_ioctl+0xa74/0xd40 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfe/0x170 fs/ioctl.c:857 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 RIP: 0033:0x7fca3e67dda9 Code: 28 00 00 00 (...) RSP: 002b:00007fca3f4b40c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fca3e7abf80 RCX: 00007fca3e67dda9 RDX: 00000000200005c0 RSI: 0000000050009417 RDI: 0000000000000003 RBP: 00007fca3e6ca47a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007fca3e7abf80 R15: 00007fff6bf95658 </TASK> Where we get an explicit message where we attempt to free an anonymous device number that is not currently allocated. It happens in a different code path from the example below, at btrfs_get_root_ref(), so this change may not fix the case triggered by syzbot. To fix at least the code path from the example above, change btrfs_get_root_ref() and its callers to receive a dev_t pointer argument for the anonymous device number, so that in case it frees the number, it also resets it to 0, so that up in the call chain we don't attempt to do the double free. CC: stable@vger.kernel.org # 5.10+ Link: https://lore.kernel.org/linux-btrfs/000000000000f673a1061202f630@google.com/ Fixes: e03ee2fe873e ("btrfs: do not ASSERT() if the newly created subvolume already got read") Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-02-29btrfs: ensure fiemap doesn't race with writes when FIEMAP_FLAG_SYNC is givenFilipe Manana
When FIEMAP_FLAG_SYNC is given to fiemap the expectation is that that are no concurrent writes and we get a stable view of the inode's extent layout. When the flag is given we flush all IO (and wait for ordered extents to complete) and then lock the inode in shared mode, however that leaves open the possibility that a write might happen right after the flushing and before locking the inode. So fix this by flushing again after locking the inode - we leave the initial flushing before locking the inode to avoid holding the lock and blocking other RO operations while waiting for IO and ordered extents to complete. The second flushing while holding the inode's lock will most of the time do nothing or very little since the time window for new writes to have happened is small. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-02-29btrfs: fix race between ordered extent completion and fiemapFilipe Manana
For fiemap we recently stopped locking the target extent range for the whole duration of the fiemap call, in order to avoid a deadlock in a scenario where the fiemap buffer happens to be a memory mapped range of the same file. This use case is very unlikely to be useful in practice but it may be triggered by fuzz testing (syzbot, etc). However by not locking the target extent range for the whole duration of the fiemap call we can race with an ordered extent. This happens like this: 1) The fiemap task finishes processing a file extent item that covers the file range [512K, 1M[, and that file extent item is the last item in the leaf currently being processed; 2) And ordered extent for the file range [768K, 2M[, in COW mode, completes (btrfs_finish_one_ordered()) and the file extent item covering the range [512K, 1M[ is trimmed to cover the range [512K, 768K[ and then a new file extent item for the range [768K, 2M[ is inserted in the inode's subvolume tree; 3) The fiemap task calls fiemap_next_leaf_item(), which then calls btrfs_next_leaf() to find the next leaf / item. This finds that the the next key following the one we previously processed (its type is BTRFS_EXTENT_DATA_KEY and its offset is 512K), is the key corresponding to the new file extent item inserted by the ordered extent, which has a type of BTRFS_EXTENT_DATA_KEY and an offset of 768K; 4) Later the fiemap code ends up at emit_fiemap_extent() and triggers the warning: if (cache->offset + cache->len > offset) { WARN_ON(1); return -EINVAL; } Since we get 1M > 768K, because the previously emitted entry for the old extent covering the file range [512K, 1M[ ends at an offset that is greater than the new extent's start offset (768K). This makes fiemap fail with -EINVAL besides triggering the warning that produces a stack trace like the following: [1621.677651] ------------[ cut here ]------------ [1621.677656] WARNING: CPU: 1 PID: 204366 at fs/btrfs/extent_io.c:2492 emit_fiemap_extent+0x84/0x90 [btrfs] [1621.677899] Modules linked in: btrfs blake2b_generic (...) [1621.677951] CPU: 1 PID: 204366 Comm: pool Not tainted 6.8.0-rc5-btrfs-next-151+ #1 [1621.677954] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [1621.677956] RIP: 0010:emit_fiemap_extent+0x84/0x90 [btrfs] [1621.678033] Code: 2b 4c 89 63 (...) [1621.678035] RSP: 0018:ffffab16089ffd20 EFLAGS: 00010206 [1621.678037] RAX: 00000000004fa000 RBX: ffffab16089ffe08 RCX: 0000000000009000 [1621.678039] RDX: 00000000004f9000 RSI: 00000000004f1000 RDI: ffffab16089ffe90 [1621.678040] RBP: 00000000004f9000 R08: 0000000000001000 R09: 0000000000000000 [1621.678041] R10: 0000000000000000 R11: 0000000000001000 R12: 0000000041d78000 [1621.678043] R13: 0000000000001000 R14: 0000000000000000 R15: ffff9434f0b17850 [1621.678044] FS: 00007fa6e20006c0(0000) GS:ffff943bdfa40000(0000) knlGS:0000000000000000 [1621.678046] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [1621.678048] CR2: 00007fa6b0801000 CR3: 000000012d404002 CR4: 0000000000370ef0 [1621.678053] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [1621.678055] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [1621.678056] Call Trace: [1621.678074] <TASK> [1621.678076] ? __warn+0x80/0x130 [1621.678082] ? emit_fiemap_extent+0x84/0x90 [btrfs] [1621.678159] ? report_bug+0x1f4/0x200 [1621.678164] ? handle_bug+0x42/0x70 [1621.678167] ? exc_invalid_op+0x14/0x70 [1621.678170] ? asm_exc_invalid_op+0x16/0x20 [1621.678178] ? emit_fiemap_extent+0x84/0x90 [btrfs] [1621.678253] extent_fiemap+0x766/0xa30 [btrfs] [1621.678339] btrfs_fiemap+0x45/0x80 [btrfs] [1621.678420] do_vfs_ioctl+0x1e4/0x870 [1621.678431] __x64_sys_ioctl+0x6a/0xc0 [1621.678434] do_syscall_64+0x52/0x120 [1621.678445] entry_SYSCALL_64_after_hwframe+0x6e/0x76 There's also another case where before calling btrfs_next_leaf() we are processing a hole or a prealloc extent and we had several delalloc ranges within that hole or prealloc extent. In that case if the ordered extents complete before we find the next key, we may end up finding an extent item with an offset smaller than (or equals to) the offset in cache->offset. So fix this by changing emit_fiemap_extent() to address these three scenarios like this: 1) For the first case, steps listed above, adjust the length of the previously cached extent so that it does not overlap with the current extent, emit the previous one and cache the current file extent item; 2) For the second case where he had a hole or prealloc extent with multiple delalloc ranges inside the hole or prealloc extent's range, and the current file extent item has an offset that matches the offset in the fiemap cache, just discard what we have in the fiemap cache and assign the current file extent item to the cache, since it's more up to date; 3) For the third case where he had a hole or prealloc extent with multiple delalloc ranges inside the hole or prealloc extent's range and the offset of the file extent item we just found is smaller than what we have in the cache, just skip the current file extent item if its range end at or behind the cached extent's end, because we may have emitted (to the fiemap user space buffer) delalloc ranges that overlap with the current file extent item's range. If the file extent item's range goes beyond the end offset of the cached extent, just emit the cached extent and cache a subrange of the file extent item, that goes from the end offset of the cached extent to the end offset of the file extent item. Dealing with those cases in those ways makes everything consistent by reflecting the current state of file extent items in the btree and without emitting extents that have overlapping ranges (which would be confusing and violating expectations). This issue could be triggered often with test case generic/561, and was also hit and reported by Wang Yugui. Reported-by: Wang Yugui <wangyugui@e16-tech.com> Link: https://lore.kernel.org/linux-btrfs/20240223104619.701F.409509F4@e16-tech.com/ Fixes: b0ad381fa769 ("btrfs: fix deadlock with fiemap and extent locking") Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-02-27fs/aio: Make io_cancel() generate completions againBart Van Assche
The following patch accidentally removed the code for delivering completions for cancelled reads and writes to user space: "[PATCH 04/33] aio: remove retry-based AIO" (https://lore.kernel.org/all/1363883754-27966-5-git-send-email-koverstreet@google.com/) >From that patch: - if (kiocbIsCancelled(iocb)) { - ret = -EINTR; - aio_complete(iocb, ret, 0); - /* must not access the iocb after this */ - goto out; - } This leads to a leak in user space of a struct iocb. Hence this patch that restores the code that reports to user space that a read or write has been cancelled successfully. Fixes: 41003a7bcfed ("aio: remove retry-based AIO") Cc: Christoph Hellwig <hch@lst.de> Cc: Avi Kivity <avi@scylladb.com> Cc: Sandeep Dhavale <dhavale@google.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: stable@vger.kernel.org Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20240215204739.2677806-3-bvanassche@acm.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-27afs: Fix endless loop in directory parsingDavid Howells
If a directory has a block with only ".__afsXXXX" files in it (from uncompleted silly-rename), these .__afsXXXX files are skipped but without advancing the file position in the dir_context. This leads to afs_dir_iterate() repeating the block again and again. Fix this by making the code that skips the .__afsXXXX file also manually advance the file position. The symptoms are a soft lookup: watchdog: BUG: soft lockup - CPU#3 stuck for 52s! [check:5737] ... RIP: 0010:afs_dir_iterate_block+0x39/0x1fd ... ? watchdog_timer_fn+0x1a6/0x213 ... ? asm_sysvec_apic_timer_interrupt+0x16/0x20 ? afs_dir_iterate_block+0x39/0x1fd afs_dir_iterate+0x10a/0x148 afs_readdir+0x30/0x4a iterate_dir+0x93/0xd3 __do_sys_getdents64+0x6b/0xd4 This is almost certainly the actual fix for: https://bugzilla.kernel.org/show_bug.cgi?id=218496 Fixes: 57e9d49c5452 ("afs: Hide silly-rename files from userspace") Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/786185.1708694102@warthog.procyon.org.uk Reviewed-by: Marc Dionne <marc.dionne@auristor.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: Markus Suvanto <markus.suvanto@gmail.com> cc: linux-afs@lists.infradead.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-27xfs: drop experimental warning for FSDAXShiyang Ruan
FSDAX and reflink can work together now, let's drop this warning. Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Acked-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-02-26Merge tag 'for-6.8-rc6-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs fixes from David Sterba: "A more fixes for recently reported or discovered problems: - fix corner case of send that would generate potentially large stream of zeros if there's a hole at the end of the file - fix chunk validation in zoned mode on conventional zones, it was possible to create chunks that would not be allowed on sequential zones - fix validation of dev-replace ioctl filenames - fix KCSAN warnings about access to block reserve struct members" * tag 'for-6.8-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: fix data race at btrfs_use_block_rsv() when accessing block reserve btrfs: fix data races when accessing the reserved amount of block reserves btrfs: send: don't issue unnecessary zero writes for trailing hole btrfs: dev-replace: properly validate device names btrfs: zoned: don't skip block group profile checks on conventional zones
2024-02-26ceph: switch to corrected encoding of max_xattr_size in mdsmapXiubo Li
The addition of bal_rank_mask with encoding version 17 was merged into ceph.git in Oct 2022 and made it into v18.2.0 release normally. A few months later, the much delayed addition of max_xattr_size got merged, also with encoding version 17, placed before bal_rank_mask in the encoding -- but it didn't make v18.2.0 release. The way this ended up being resolved on the MDS side is that bal_rank_mask will continue to be encoded in version 17 while max_xattr_size is now encoded in version 18. This does mean that older kernels will misdecode version 17, but this is also true for v18.2.0 and v18.2.1 clients in userspace. The best we can do is backport this adjustment -- see ceph.git commit 78abfeaff27fee343fb664db633de5b221699a73 for details. [ idryomov: changelog ] Cc: stable@vger.kernel.org Link: https://tracker.ceph.com/issues/64440 Fixes: d93231a6bc8a ("ceph: prevent a client from exceeding the MDS maximum xattr size") Signed-off-by: Xiubo Li <xiubli@redhat.com> Reviewed-by: Patrick Donnelly <pdonnell@ibm.com> Reviewed-by: Venky Shankar <vshankar@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2024-02-26fs/ntfs3: fix build without CONFIG_NTFS3_LZX_XPRESSMark O'Donovan
When CONFIG_NTFS3_LZX_XPRESS is not set then we get the following build error: fs/ntfs3/frecord.c:2460:16: error: unused variable ‘i_size’ Signed-off-by: Mark O'Donovan <shiftee@posteo.net> Fixes: 4fd6c08a16d7 ("fs/ntfs3: Use i_size_read and i_size_write") Tested-by: Chris Clayton <chris2553@googlemail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-02-25Merge tag 'bcachefs-2024-02-25' of https://evilpiepirate.org/git/bcachefsLinus Torvalds
Pull bcachefs fixes from Kent Overstreet: "Some more mostly boring fixes, but some not User reported ones: - the BTREE_ITER_FILTER_SNAPSHOTS one fixes a really nasty performance bug; user reported an untar initially taking two seconds and then ~2 minutes - kill a __GFP_NOFAIL in the buffered read path; this was a leftover from the trickier fix to kill __GFP_NOFAIL in readahead, where we can't return errors (and have to silently truncate the read ourselves). bcachefs can't use GFP_NOFAIL for folio state unlike iomap based filesystems because our folio state is just barely too big, 2MB hugepages cause us to exceed the 2 page threshhold for GFP_NOFAIL. additionally, the flags argument was just buggy, we weren't supplying GFP_KERNEL previously (!)" * tag 'bcachefs-2024-02-25' of https://evilpiepirate.org/git/bcachefs: bcachefs: fix bch2_save_backtrace() bcachefs: Fix check_snapshot() memcpy bcachefs: Fix bch2_journal_flush_device_pins() bcachefs: fix iov_iter count underflow on sub-block dio read bcachefs: Fix BTREE_ITER_FILTER_SNAPSHOTS on inodes btree bcachefs: Kill __GFP_NOFAIL in buffered read path bcachefs: fix backpointer_to_text() when dev does not exist
2024-02-25bcachefs: fix bch2_save_backtrace()Kent Overstreet
Missed a call in the previous fix. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-25Merge tag 'erofs-for-6.8-rc6-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs Pull erofs fix from Gao Xiang: - Fix page refcount leak when looking up specific inodes introduced by metabuf reworking * tag 'erofs-for-6.8-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs: erofs: fix refcount on the metabuf used for inode lookup
2024-02-25Merge tag 'pull-fixes.pathwalk-rcu-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull RCU pathwalk fixes from Al Viro: "We still have some races in filesystem methods when exposed to RCU pathwalk. This series is a result of code audit (the second round of it) and it should deal with most of that stuff. Still pending: ntfs3 ->d_hash()/->d_compare() and ceph_d_revalidate(). Up to maintainers (a note for NTFS folks - when documentation says that a method may not block, it *does* imply that blocking allocations are to be avoided. Really)" [ More explanations for people who aren't familiar with the vagaries of RCU path walking: most of it is hidden from filesystems, but if a filesystem actively participates in the low-level path walking it needs to make sure the fields involved in that walk are RCU-safe. That "actively participate in low-level path walking" includes things like having its own ->d_hash()/->d_compare() routines, or by having its own directory permission function that doesn't just use the common helpers. Having a ->d_revalidate() function will also have this issue. Note that instead of making everything RCU safe you can also choose to abort the RCU pathwalk if your operation cannot be done safely under RCU, but that obviously comes with a performance penalty. One common pattern is to allow the simple cases under RCU, and abort only if you need to do something more complicated. So not everything needs to be RCU-safe, and things like the inode etc that the VFS itself maintains obviously already are. But these fixes tend to be about properly RCU-delaying things like ->s_fs_info that are maintained by the filesystem and that got potentially released too early. - Linus ] * tag 'pull-fixes.pathwalk-rcu-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: ext4_get_link(): fix breakage in RCU mode cifs_get_link(): bail out in unsafe case fuse: fix UAF in rcu pathwalks procfs: make freeing proc_fs_info rcu-delayed procfs: move dropping pde and pid from ->evict_inode() to ->free_inode() nfs: fix UAF on pathwalk running into umount nfs: make nfs_set_verifier() safe for use in RCU pathwalk afs: fix __afs_break_callback() / afs_drop_open_mmap() race hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_info exfat: move freeing sbi, upcase table and dropping nls into rcu-delayed helper affs: free affs_sb_info with kfree_rcu() rcu pathwalk: prevent bogus hard errors from may_lookup() fs/super.c: don't drop ->s_user_ns until we free struct super_block itself
2024-02-25Merge tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds
Pull vfs fixes from Al Viro: "A couple of fixes - revert of regression from this cycle and a fix for erofs failure exit breakage (had been there since way back)" * tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: erofs: fix handling kern_mount() failure Revert "get rid of DCACHE_GENOCIDE"
2024-02-25efivarfs: Drop 'duplicates' bool parameter on efivar_init()Ard Biesheuvel
The 'duplicates' bool argument is always true when efivar_init() is called from its only caller so let's just drop it instead. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2024-02-25efivarfs: Drop redundant cleanup on fill_super() failureArd Biesheuvel
Al points out that kill_sb() will be called if efivarfs_fill_super() fails and so there is no point in cleaning up the efivar entry list. Reported-by: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2024-02-25efivarfs: Request at most 512 bytes for variable namesTim Schumacher
Work around a quirk in a few old (2011-ish) UEFI implementations, where a call to `GetNextVariableName` with a buffer size larger than 512 bytes will always return EFI_INVALID_PARAMETER. There is some lore around EFI variable names being up to 1024 bytes in size, but this has no basis in the UEFI specification, and the upper bounds are typically platform specific, and apply to the entire variable (name plus payload). Given that Linux does not permit creating files with names longer than NAME_MAX (255) bytes, 512 bytes (== 256 UTF-16 characters) is a reasonable limit. Cc: <stable@vger.kernel.org> # 6.1+ Signed-off-by: Tim Schumacher <timschumi@gmx.de> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2024-02-25ext4_get_link(): fix breakage in RCU modeAl Viro
1) errors from ext4_getblk() should not be propagated to caller unless we are really sure that we would've gotten the same error in non-RCU pathwalk. 2) we leak buffer_heads if ext4_getblk() is successful, but bh is not uptodate. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25cifs_get_link(): bail out in unsafe caseAl Viro
->d_revalidate() bails out there, anyway. It's not enough to prevent getting into ->get_link() in RCU mode, but that could happen only in a very contrieved setup. Not worth trying to do anything fancy here unless ->d_revalidate() stops kicking out of RCU mode at least in some cases. Reviewed-by: Christian Brauner <brauner@kernel.org> Acked-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25fuse: fix UAF in rcu pathwalksAl Viro
->permission(), ->get_link() and ->inode_get_acl() might dereference ->s_fs_info (and, in case of ->permission(), ->s_fs_info->fc->user_ns as well) when called from rcu pathwalk. Freeing ->s_fs_info->fc is rcu-delayed; we need to make freeing ->s_fs_info and dropping ->user_ns rcu-delayed too. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25procfs: make freeing proc_fs_info rcu-delayedAl Viro
makes proc_pid_ns() safe from rcu pathwalk (put_pid_ns() is still synchronous, but that's not a problem - it does rcu-delay everything that needs to be) Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25procfs: move dropping pde and pid from ->evict_inode() to ->free_inode()Al Viro
that keeps both around until struct inode is freed, making access to them safe from rcu-pathwalk Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25nfs: fix UAF on pathwalk running into umountAl Viro
NFS ->d_revalidate(), ->permission() and ->get_link() need to access some parts of nfs_server when called in RCU mode: server->flags server->caps *(server->io_stats) and, worst of all, call server->nfs_client->rpc_ops->have_delegation (the last one - as NFS_PROTO(inode)->have_delegation()). We really don't want to RCU-delay the entire nfs_free_server() (it would have to be done with schedule_work() from RCU callback, since it can't be made to run from interrupt context), but actual freeing of nfs_server and ->io_stats can be done via call_rcu() just fine. nfs_client part is handled simply by making nfs_free_client() use kfree_rcu(). Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25nfs: make nfs_set_verifier() safe for use in RCU pathwalkAl Viro
nfs_set_verifier() relies upon dentry being pinned; if that's the case, grabbing ->d_lock stabilizes ->d_parent and guarantees that ->d_parent points to a positive dentry. For something we'd run into in RCU mode that is *not* true - dentry might've been through dentry_kill() just as we grabbed ->d_lock, with its parent going through the same just as we get to into nfs_set_verifier_locked(). It might get to detaching inode (and zeroing ->d_inode) before nfs_set_verifier_locked() gets to fetching that; we get an oops as the result. That can happen in nfs{,4} ->d_revalidate(); the call chain in question is nfs_set_verifier_locked() <- nfs_set_verifier() <- nfs_lookup_revalidate_delegated() <- nfs{,4}_do_lookup_revalidate(). We have checked that the parent had been positive, but that's done before we get to nfs_set_verifier() and it's possible for memory pressure to pick our dentry as eviction candidate by that time. If that happens, back-to-back attempts to kill dentry and its parent are quite normal. Sure, in case of eviction we'll fail the ->d_seq check in the caller, but we need to survive until we return there... Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25afs: fix __afs_break_callback() / afs_drop_open_mmap() raceAl Viro
In __afs_break_callback() we might check ->cb_nr_mmap and if it's non-zero do queue_work(&vnode->cb_work). In afs_drop_open_mmap() we decrement ->cb_nr_mmap and do flush_work(&vnode->cb_work) if it reaches zero. The trouble is, there's nothing to prevent __afs_break_callback() from seeing ->cb_nr_mmap before the decrement and do queue_work() after both the decrement and flush_work(). If that happens, we might be in trouble - vnode might get freed before the queued work runs. __afs_break_callback() is always done under ->cb_lock, so let's make sure that ->cb_nr_mmap can change from non-zero to zero while holding ->cb_lock (the spinlock component of it - it's a seqlock and we don't need to mess with the counter). Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_infoAl Viro
->d_hash() and ->d_compare() use those, so we need to delay freeing them. Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25exfat: move freeing sbi, upcase table and dropping nls into rcu-delayed helperAl Viro
That stuff can be accessed by ->d_hash()/->d_compare(); as it is, we have a hard-to-hit UAF if rcu pathwalk manages to get into ->d_hash() on a filesystem that is in process of getting shut down. Besides, having nls and upcase table cleanup moved from ->put_super() towards the place where sbi is freed makes for simpler failure exits. Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25affs: free affs_sb_info with kfree_rcu()Al Viro
one of the flags in it is used by ->d_hash()/->d_compare() Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25rcu pathwalk: prevent bogus hard errors from may_lookup()Al Viro
If lazy call of ->permission() returns a hard error, check that try_to_unlazy() succeeds before returning it. That both makes life easier for ->permission() instances and closes the race in ENOTDIR handling - it is possible that positive d_can_lookup() seen in link_path_walk() applies to the state *after* unlink() + mkdir(), while nd->inode matches the state prior to that. Normally seeing e.g. EACCES from permission check in rcu pathwalk means that with some timings non-rcu pathwalk would've run into the same; however, running into a non-executable regular file in the middle of a pathname would not get to permission check - it would fail with ENOTDIR instead. Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-25fs/super.c: don't drop ->s_user_ns until we free struct super_block itselfAl Viro
Avoids fun races in RCU pathwalk... Same goes for freeing LSM shite hanging off super_block's arse. Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-02-24bcachefs: Fix check_snapshot() memcpyKent Overstreet
check_snapshot() copies the bch_snapshot to a temporary to easily handle older versions that don't have all the fields of the current version, but it lacked a min() to correctly handle keys newer and larger than the current version. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-24bcachefs: Fix bch2_journal_flush_device_pins()Kent Overstreet
If a journal write errored, the list of devices it was written to could be empty - we're not supposed to mark an empty replicas list. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-24bcachefs: fix iov_iter count underflow on sub-block dio readBrian Foster
bch2_direct_IO_read() checks the request offset and size for sector alignment and then falls through to a couple calculations to shrink the size of the request based on the inode size. The problem is that these checks round up to the fs block size, which runs the risk of underflowing iter->count if the block size happens to be large enough. This is triggered by fstest generic/361 with a 4k block size, which subsequently leads to a crash. To avoid this crash, check that the shorten length doesn't exceed the overall length of the iter. Fixes: Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Su Yue <glass.su@suse.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-24bcachefs: Fix BTREE_ITER_FILTER_SNAPSHOTS on inodes btreeKent Overstreet
If we're in FILTER_SNAPSHOTS mode and we start scanning a range of the keyspace where no keys are visible in the current snapshot, we have a problem - we'll scan for a very long time before scanning terminates. Awhile back, this was fixed for most cases with peek_upto() (and assertions that enforce that it's being used). But the fix missed the fact that the inodes btree is different - every key offset is in a different snapshot tree, not just the inode field. Fixes: Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-24bcachefs: Kill __GFP_NOFAIL in buffered read pathKent Overstreet
Recently, we fixed our __GFP_NOFAIL usage in the readahead path, but the easy one in read_single_folio() (where wa can return an error) was missed - oops. Fixes: Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-24bcachefs: fix backpointer_to_text() when dev does not existKent Overstreet
Fixes: Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-22Merge tag 'vfs-6.8-rc6.fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs fixes from Christian Brauner: - Fix a memory leak in cachefiles - Restrict aio cancellations to I/O submitted through the aio interfaces as this is otherwise causing issues for I/O submitted via io_uring - Increase buffer for afs volume status to avoid overflow - Fix a missing zero-length check in unbuffered writes in the netfs library. If generic_write_checks() returns zero make netfs_unbuffered_write_iter() return right away - Prevent a leak in i_dio_count caused by netfs_begin_read() operating past i_size. It will return early and leave i_dio_count incremented - Account for ipv4 addresses as well as ipv6 addresses when processing incoming callbacks in afs * tag 'vfs-6.8-rc6.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: fs/aio: Restrict kiocb_set_cancel_fn() to I/O submitted via libaio afs: Increase buffer size in afs_update_volume_status() afs: Fix ignored callbacks over ipv4 cachefiles: fix memory leak in cachefiles_add_cache() netfs: Fix missing zero-length check in unbuffered write netfs: Fix i_dio_count leak on DIO read past i_size
2024-02-22btrfs: fix data race at btrfs_use_block_rsv() when accessing block reserveFilipe Manana
At btrfs_use_block_rsv() we read the size of a block reserve without locking its spinlock, which makes KCSAN complain because the size of a block reserve is always updated while holding its spinlock. The report from KCSAN is the following: [653.313148] BUG: KCSAN: data-race in btrfs_update_delayed_refs_rsv [btrfs] / btrfs_use_block_rsv [btrfs] [653.314755] read to 0x000000017f5871b8 of 8 bytes by task 7519 on cpu 0: [653.314779] btrfs_use_block_rsv+0xe4/0x2f8 [btrfs] [653.315606] btrfs_alloc_tree_block+0xdc/0x998 [btrfs] [653.316421] btrfs_force_cow_block+0x220/0xe38 [btrfs] [653.317242] btrfs_cow_block+0x1ac/0x568 [btrfs] [653.318060] btrfs_search_slot+0xda2/0x19b8 [btrfs] [653.318879] btrfs_del_csums+0x1dc/0x798 [btrfs] [653.319702] __btrfs_free_extent.isra.0+0xc24/0x2028 [btrfs] [653.320538] __btrfs_run_delayed_refs+0xd3c/0x2390 [btrfs] [653.321340] btrfs_run_delayed_refs+0xae/0x290 [btrfs] [653.322140] flush_space+0x5e4/0x718 [btrfs] [653.322958] btrfs_preempt_reclaim_metadata_space+0x102/0x2f8 [btrfs] [653.323781] process_one_work+0x3b6/0x838 [653.323800] worker_thread+0x75e/0xb10 [653.323817] kthread+0x21a/0x230 [653.323836] __ret_from_fork+0x6c/0xb8 [653.323855] ret_from_fork+0xa/0x30 [653.323887] write to 0x000000017f5871b8 of 8 bytes by task 576 on cpu 3: [653.323906] btrfs_update_delayed_refs_rsv+0x1a4/0x250 [btrfs] [653.324699] btrfs_add_delayed_data_ref+0x468/0x6d8 [btrfs] [653.325494] btrfs_free_extent+0x76/0x120 [btrfs] [653.326280] __btrfs_mod_ref+0x6a8/0x6b8 [btrfs] [653.327064] btrfs_dec_ref+0x50/0x70 [btrfs] [653.327849] walk_up_proc+0x236/0xa50 [btrfs] [653.328633] walk_up_tree+0x21c/0x448 [btrfs] [653.329418] btrfs_drop_snapshot+0x802/0x1328 [btrfs] [653.330205] btrfs_clean_one_deleted_snapshot+0x184/0x238 [btrfs] [653.330995] cleaner_kthread+0x2b0/0x2f0 [btrfs] [653.331781] kthread+0x21a/0x230 [653.331800] __ret_from_fork+0x6c/0xb8 [653.331818] ret_from_fork+0xa/0x30 So add a helper to get the size of a block reserve while holding the lock. Reading the field while holding the lock instead of using the data_race() annotation is used in order to prevent load tearing. Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>