The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x 7081929ab2572920e94d70be3d332e5c9f97095a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024012750-shore-gradually-d4bb@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..
Possible dependencies:
7081929ab257 ("btrfs: don't abort filesystem when attempting to snapshot deleted subvolume") 813febdbe6c9 ("btrfs: disable snapshot creation/deletion for extent tree v2") 4467af880929 ("btrfs: remove root argument from btrfs_unlink_inode()") bd54f381a12a ("btrfs: do not pin logs too early during renames") 9a56fcd15a9c ("btrfs: make btrfs_update_inode take btrfs_inode") 76aea5379678 ("btrfs: make btrfs_inode_safe_disk_i_size_write take btrfs_inode") 2766ff61762c ("btrfs: update the number of bytes used by an inode atomically") 5893dfb98f25 ("btrfs: refactor btrfs_drop_extents() to make it easier to extend") ac5887c8e013 ("btrfs: locking: remove all the blocking helpers") a14b78ad06ab ("btrfs: introduce btrfs_inode_lock()/unlock()") b8d8e1fd570a ("btrfs: introduce btrfs_write_check()") c86537a42f86 ("btrfs: check FS error state bit early during write") 5e8b9ef30392 ("btrfs: move pos increment and pagecache extension to btrfs_buffered_write") 4e4cabece9f9 ("btrfs: split btrfs_direct_IO to read and write") 196d59ab9ccc ("btrfs: switch extent buffer tree lock to rw_semaphore") 0425e7badbdc ("btrfs: don't fallback to buffered read if we don't need to") 3c38c877fcb9 ("btrfs: sink inode argument in insert_ordered_extent_file_extent") fc0d82e103c7 ("btrfs: sink total_data parameter in setup_items_for_insert") 3dc9dc8969dc ("btrfs: eliminate total_size parameter from setup_items_for_insert") 0cbb5bdfea26 ("btrfs: rename btrfs_insert_clone_extent() to a more generic name")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 7081929ab2572920e94d70be3d332e5c9f97095a Mon Sep 17 00:00:00 2001 From: Omar Sandoval osandov@fb.com Date: Thu, 4 Jan 2024 11:48:46 -0800 Subject: [PATCH] btrfs: don't abort filesystem when attempting to snapshot deleted subvolume
If the source file descriptor to the snapshot ioctl refers to a deleted subvolume, we get the following abort:
BTRFS: Transaction aborted (error -2) WARNING: CPU: 0 PID: 833 at fs/btrfs/transaction.c:1875 create_pending_snapshot+0x1040/0x1190 [btrfs] Modules linked in: pata_acpi btrfs ata_piix libata scsi_mod virtio_net blake2b_generic xor net_failover virtio_rng failover scsi_common rng_core raid6_pq libcrc32c CPU: 0 PID: 833 Comm: t_snapshot_dele Not tainted 6.7.0-rc6 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014 RIP: 0010:create_pending_snapshot+0x1040/0x1190 [btrfs] RSP: 0018:ffffa09c01337af8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff9982053e7c78 RCX: 0000000000000027 RDX: ffff99827dc20848 RSI: 0000000000000001 RDI: ffff99827dc20840 RBP: ffffa09c01337c00 R08: 0000000000000000 R09: ffffa09c01337998 R10: 0000000000000003 R11: ffffffffb96da248 R12: fffffffffffffffe R13: ffff99820535bb28 R14: ffff99820b7bd000 R15: ffff99820381ea80 FS: 00007fe20aadabc0(0000) GS:ffff99827dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000559a120b502f CR3: 00000000055b6000 CR4: 00000000000006f0 Call Trace: <TASK> ? create_pending_snapshot+0x1040/0x1190 [btrfs] ? __warn+0x81/0x130 ? create_pending_snapshot+0x1040/0x1190 [btrfs] ? report_bug+0x171/0x1a0 ? handle_bug+0x3a/0x70 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? create_pending_snapshot+0x1040/0x1190 [btrfs] ? create_pending_snapshot+0x1040/0x1190 [btrfs] create_pending_snapshots+0x92/0xc0 [btrfs] btrfs_commit_transaction+0x66b/0xf40 [btrfs] btrfs_mksubvol+0x301/0x4d0 [btrfs] btrfs_mksnapshot+0x80/0xb0 [btrfs] __btrfs_ioctl_snap_create+0x1c2/0x1d0 [btrfs] btrfs_ioctl_snap_create_v2+0xc4/0x150 [btrfs] btrfs_ioctl+0x8a6/0x2650 [btrfs] ? kmem_cache_free+0x22/0x340 ? do_sys_openat2+0x97/0xe0 __x64_sys_ioctl+0x97/0xd0 do_syscall_64+0x46/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 RIP: 0033:0x7fe20abe83af RSP: 002b:00007ffe6eff1360 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fe20abe83af RDX: 00007ffe6eff23c0 RSI: 0000000050009417 RDI: 0000000000000003 RBP: 0000000000000003 R08: 0000000000000000 R09: 00007fe20ad16cd0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe6eff13c0 R14: 00007fe20ad45000 R15: 0000559a120b6d58 </TASK> ---[ end trace 0000000000000000 ]--- BTRFS: error (device vdc: state A) in create_pending_snapshot:1875: errno=-2 No such entry BTRFS info (device vdc: state EA): forced readonly BTRFS warning (device vdc: state EA): Skipping commit of aborted transaction. BTRFS: error (device vdc: state EA) in cleanup_transaction:2055: errno=-2 No such entry
This happens because create_pending_snapshot() initializes the new root item as a copy of the source root item. This includes the refs field, which is 0 for a deleted subvolume. The call to btrfs_insert_root() therefore inserts a root with refs == 0. btrfs_get_new_fs_root() then finds the root and returns -ENOENT if refs == 0, which causes create_pending_snapshot() to abort.
Fix it by checking the source root's refs before attempting the snapshot, but after locking subvol_sem to avoid racing with deletion.
CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Sweet Tea Dorminy sweettea-kernel@dorminy.me Reviewed-by: Anand Jain anand.jain@oracle.com Signed-off-by: Omar Sandoval osandov@fb.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 4e50b62db2a8..fea5d37528b8 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -790,6 +790,9 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir, return -EOPNOTSUPP; }
+ if (btrfs_root_refs(&root->root_item) == 0) + return -ENOENT; + if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) return -EINVAL;