kernel/linux.git/fs/ceph/dir.c, branch v6.12.80

ceph: fix i_nlink underrun during async unlink

2026-03-25T10:08:33+00:00

commit ce0123cbb4a40a2f1bbb815f292b26e96088639f upstream. During async unlink, we drop the `i_nlink` counter before we receive the completion (that will eventually update the `i_nlink`) because "we assume that the unlink will succeed". That is not a bad idea, but it races against deletions by other clients (or against the completion of our own unlink) and can lead to an underrun which emits a WARNING like this one: WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68 Modules linked in: CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655 Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : drop_nlink+0x50/0x68 lr : ceph_unlink+0x6c4/0x720 sp : ffff80012173bc90 x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680 x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647 x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203 x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365 x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74 x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94 x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002 x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8 Call trace: drop_nlink+0x50/0x68 (P) vfs_unlink+0xb0/0x2e8 do_unlinkat+0x204/0x288 __arm64_sys_unlinkat+0x3c/0x80 invoke_syscall.constprop.0+0x54/0xe8 do_el0_svc+0xa4/0xc8 el0_svc+0x18/0x58 el0t_64_sync_handler+0x104/0x130 el0t_64_sync+0x154/0x158 In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion. Meanwhile, between this call and the following drop_nlink() call, a worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own completion). These will lead to a set_nlink() call, updating the `i_nlink` counter to the value received from the MDS. If that new `i_nlink` value happens to be zero, it is illegal to decrement it further. But that is exactly what ceph_unlink() will do then. The WARNING can be reproduced this way: 1. Force async unlink; only the async code path is affected. Having no real clue about Ceph internals, I was unable to find out why the MDS wouldn't give me the "Fxr" capabilities, so I patched get_caps_for_async_unlink() to always succeed. (Note that the WARNING dump above was found on an unpatched kernel, without this kludge - this is not a theoretical bug.) 2. Add a sleep call after ceph_mdsc_submit_request() so the unlink completion gets handled by a worker thread before drop_nlink() is called. This guarantees that the `i_nlink` is already zero before drop_nlink() runs. The solution is to skip the counter decrement when it is already zero, but doing so without a lock is still racy (TOCTOU). Since ceph_fill_inode() and handle_cap_grant() both hold the `ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this seems like the proper lock to protect the `i_nlink` updates. I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using `afs_vnode.cb_lock`). All three have the zero check as well. Cc: stable@vger.kernel.org Fixes: 2ccb45462aea ("ceph: perform asynchronous unlink if we have sufficient caps") Signed-off-by: Max Kellermann Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: add a bunch of missing ceph_path_info initializers

2026-03-25T10:08:33+00:00

commit 43323a5934b660afae687e8e4e95ac328615a5c4 upstream. ceph_mdsc_build_path() must be called with a zero-initialized ceph_path_info parameter, or else the following ceph_mdsc_free_path_info() may crash. Example crash (on Linux 6.18.12): virt_to_cache: Object is not a Slab page! WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6732 kmem_cache_free+0x316/0x400 [...] Call Trace: [...] ceph_open+0x13d/0x3e0 do_dentry_open+0x134/0x480 vfs_open+0x2a/0xe0 path_openat+0x9a3/0x1160 [...] cache_from_obj: Wrong slab cache. names_cache but object is from ceph_inode_info WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6746 kmem_cache_free+0x2dd/0x400 [...] kernel BUG at mm/slub.c:634! Oops: invalid opcode: 0000 [#1] SMP NOPTI RIP: 0010:__slab_free+0x1a4/0x350 Some of the ceph_mdsc_build_path() callers had initializers, but others had not, even though they were all added by commit 15f519e9f883 ("ceph: fix race condition validating r_parent before applying state"). The ones without initializer are suspectible to random crashes. (I can imagine it could even be possible to exploit this bug to elevate privileges.) Unfortunately, these Ceph functions are undocumented and its semantics can only be derived from the code. I see that ceph_mdsc_build_path() initializes the structure only on success, but not on error. Calling ceph_mdsc_free_path_info() after a failed ceph_mdsc_build_path() call does not even make sense, but that's what all callers do, and for it to be safe, the structure must be zero-initialized. The least intrusive approach to fix this is therefore to add initializers everywhere. Cc: stable@vger.kernel.org Fixes: 15f519e9f883 ("ceph: fix race condition validating r_parent before applying state") Signed-off-by: Max Kellermann Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: refactor wake_up_bit() pattern of calling

2025-11-13T20:34:35+00:00

[ Upstream commit 53db6f25ee47cb1265141d31562604e56146919a ] The wake_up_bit() is called in ceph_async_unlink_cb(), wake_async_create_waiters(), and ceph_finish_async_create(). It makes sense to switch on clear_bit() function, because it makes the code much cleaner and easier to understand. More important rework is the adding of smp_mb__after_atomic() memory barrier after the bit modification and before wake_up_bit() call. It can prevent potential race condition of accessing the modified bit in other threads. Luckily, clear_and_wake_up_bit() already implements the required functionality pattern: static inline void clear_and_wake_up_bit(int bit, unsigned long *word) { clear_bit_unlock(bit, word); /* See wake_up_bit() for which memory barrier you need to use. */ smp_mb__after_atomic(); wake_up_bit(word, bit); } Signed-off-by: Viacheslav Dubeyko Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin

ceph: fix race condition validating r_parent before applying state

2025-09-19T14:35:47+00:00

commit 15f519e9f883b316d86e2bb6b767a023aafd9d83 upstream. Add validation to ensure the cached parent directory inode matches the directory info in MDS replies. This prevents client-side race conditions where concurrent operations (e.g. rename) cause r_parent to become stale between request initiation and reply processing, which could lead to applying state changes to incorrect directory inodes. [ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to move CEPH_CAP_PIN reference when r_parent is updated: When the parent directory lock is not held, req->r_parent can become stale and is updated to point to the correct inode. However, the associated CEPH_CAP_PIN reference was not being adjusted. The CEPH_CAP_PIN is a reference on an inode that is tracked for accounting purposes. Moving this pin is important to keep the accounting balanced. When the pin was not moved from the old parent to the new one, it created two problems: The reference on the old, stale parent was never released, causing a reference leak. A reference for the new parent was never acquired, creating the risk of a reference underflow later in ceph_mdsc_release_request(). This patch corrects the logic by releasing the pin from the old parent and acquiring it for the new parent when r_parent is switched. This ensures reference accounting stays balanced. ] Cc: stable@vger.kernel.org Signed-off-by: Alex Markuze Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

Merge tag 'ceph-for-6.12-rc1' of https://github.com/ceph/ceph-client

2024-09-28T15:40:36+00:00

Pull ceph updates from Ilya Dryomov: "Three CephFS fixes from Xiubo and Luis and a bunch of assorted cleanups" * tag 'ceph-for-6.12-rc1' of https://github.com/ceph/ceph-client: ceph: remove the incorrect Fw reference check when dirtying pages ceph: Remove empty definition in header file ceph: Fix typo in the comment ceph: fix a memory leak on cap_auths in MDS client ceph: flush all caps releases when syncing the whole filesystem ceph: rename ceph_flush_cap_releases() to ceph_flush_session_cap_releases() libceph: use min() to simplify code in ceph_dns_resolve_name() ceph: Convert to use jiffies macro ceph: Remove unused declarations

ceph: Fix typo in the comment

2024-09-24T20:51:33+00:00

Correctly spelled comments make it easier for the reader to understand the code. replace 'tagert' with 'target' in the comment & replace 'vaild' with 'valid' in the comment & replace 'carefull' with 'careful' in the comment & replace 'trsaverse' with 'traverse' in the comment. Signed-off-by: Yan Zhen Reviewed-by: Xiubo Li Signed-off-by: Ilya Dryomov

ceph: remove unused f_version

2024-09-09T09:58:06+00:00

It's not used for ceph so don't bother with it at all. Link: https://lore.kernel.org/r/20240830-vfs-file-f_version-v1-3-6d3e4816aa7b@kernel.org Reviewed-by: Jan Kara Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner

Merge tag 'ceph-for-6.11-rc1' of https://github.com/ceph/ceph-client

2024-07-26T17:34:42+00:00

Pull ceph updates from Ilya Dryomov: "A small patchset to address bogus I/O errors and ultimately an assertion failure in the face of watch errors with -o exclusive mappings in RBD marked for stable and some assorted CephFS fixes" * tag 'ceph-for-6.11-rc1' of https://github.com/ceph/ceph-client: rbd: don't assume rbd_is_lock_owner() for exclusive mappings rbd: don't assume RBD_LOCK_STATE_LOCKED for exclusive mappings rbd: rename RBD_LOCK_STATE_RELEASING and releasing_wait ceph: fix incorrect kmalloc size of pagevec mempool ceph: periodically flush the cap releases ceph: convert comma to semicolon in __ceph_dentry_dir_lease_touch() ceph: use cap_wait_list only if debugfs is enabled

ceph: convert comma to semicolon in __ceph_dentry_dir_lease_touch()

2024-07-23T08:01:57+00:00

Replace a comma between expression statements by a semicolon. Signed-off-by: Chen Ni Reviewed-by: Xiubo Li Signed-off-by: Ilya Dryomov

ceph: drop usage of page_index

2024-07-04T02:29:55+00:00

page_index is needed for mixed usage of page cache and swap cache, for pure page cache usage, the caller can just use page->index instead. It can't be a swap cache page here, so just drop it. Link: https://lkml.kernel.org/r/20240521175854.96038-4-ryncsn@gmail.com Signed-off-by: Kairui Song Cc: Xiubo Li Cc: Ilya Dryomov Cc: Jeff Layton Cc: Anna Schumaker Cc: Barry Song Cc: Chao Yu Cc: Chris Li Cc: David Hildenbrand Cc: David Howells Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Jaegeuk Kim Cc: Marc Dionne Cc: Matthew Wilcox (Oracle) Cc: Minchan Kim Cc: NeilBrown Cc: Ryan Roberts Cc: Ryusuke Konishi Cc: Trond Myklebust Cc: Yosry Ahmed Signed-off-by: Andrew Morton