From 5a4041f2c47247575a6c2e53ce14f7b0ac946c33 Mon Sep 17 00:00:00 2001 From: Naohiro Aota Date: Wed, 19 Feb 2025 16:02:11 +0900 Subject: [PATCH 1/3] btrfs: zoned: fix extent range end unlock in cow_file_range() Running generic/751 on the for-next branch often results in a hang like below. They are both stack by locking an extent. This suggests someone forget to unlock an extent. INFO: task kworker/u128:1:12 blocked for more than 323 seconds. Not tainted 6.13.0-BTRFS-ZNS+ #503 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u128:1 state:D stack:0 pid:12 tgid:12 ppid:2 flags:0x00004000 Workqueue: btrfs-fixup btrfs_work_helper [btrfs] Call Trace: __schedule+0x534/0xdd0 schedule+0x39/0x140 __lock_extent+0x31b/0x380 [btrfs] ? __pfx_autoremove_wake_function+0x10/0x10 btrfs_writepage_fixup_worker+0xf1/0x3a0 [btrfs] btrfs_work_helper+0xff/0x480 [btrfs] ? lock_release+0x178/0x2c0 process_one_work+0x1ee/0x570 ? srso_return_thunk+0x5/0x5f worker_thread+0x1d1/0x3b0 ? __pfx_worker_thread+0x10/0x10 kthread+0x10b/0x230 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x30/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 INFO: task kworker/u134:0:184 blocked for more than 323 seconds. Not tainted 6.13.0-BTRFS-ZNS+ #503 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u134:0 state:D stack:0 pid:184 tgid:184 ppid:2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-btrfs-4) Call Trace: __schedule+0x534/0xdd0 schedule+0x39/0x140 __lock_extent+0x31b/0x380 [btrfs] ? __pfx_autoremove_wake_function+0x10/0x10 find_lock_delalloc_range+0xdb/0x260 [btrfs] writepage_delalloc+0x12f/0x500 [btrfs] ? srso_return_thunk+0x5/0x5f extent_write_cache_pages+0x232/0x840 [btrfs] btrfs_writepages+0x72/0x130 [btrfs] do_writepages+0xe7/0x260 ? srso_return_thunk+0x5/0x5f ? lock_acquire+0xd2/0x300 ? srso_return_thunk+0x5/0x5f ? find_held_lock+0x2b/0x80 ? wbc_attach_and_unlock_inode.part.0+0x102/0x250 ? wbc_attach_and_unlock_inode.part.0+0x102/0x250 __writeback_single_inode+0x5c/0x4b0 writeback_sb_inodes+0x22d/0x550 __writeback_inodes_wb+0x4c/0xe0 wb_writeback+0x2f6/0x3f0 wb_workfn+0x32a/0x510 process_one_work+0x1ee/0x570 ? srso_return_thunk+0x5/0x5f worker_thread+0x1d1/0x3b0 ? __pfx_worker_thread+0x10/0x10 kthread+0x10b/0x230 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x30/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 This happens because we have another success path for the zoned mode. When there is no active zone available, btrfs_reserve_extent() returns -EAGAIN. In this case, we have two reactions. (1) If the given range is never allocated, we can only wait for someone to finish a zone, so wait on BTRFS_FS_NEED_ZONE_FINISH bit and retry afterward. (2) Or, if some allocations are already done, we must bail out and let the caller to send IOs for the allocation. This is because these IOs may be necessary to finish a zone. The commit 06f364284794 ("btrfs: do proper folio cleanup when cow_file_range() failed") moved the unlock code from the inside of the loop to the outside. So, previously, the allocated extents are unlocked just after the allocation and so before returning from the function. However, they are no longer unlocked on the case (2) above. That caused the hang issue. Fix the issue by modifying the 'end' to the end of the allocated range. Then, we can exit the loop and the same unlock code can properly handle the case. Reported-by: Shin'ichiro Kawasaki Tested-by: Johannes Thumshirn Fixes: 06f364284794 ("btrfs: do proper folio cleanup when cow_file_range() failed") CC: stable@vger.kernel.org Reviewed-by: Qu Wenruo Reviewed-by: Johannes Thumshirn Signed-off-by: Naohiro Aota Signed-off-by: David Sterba --- fs/btrfs/inode.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index fe2c810335ff0..69e90ed33cfe5 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1382,8 +1382,13 @@ static noinline int cow_file_range(struct btrfs_inode *inode, continue; } if (done_offset) { - *done_offset = start - 1; - return 0; + /* + * Move @end to the end of the processed range, + * and exit the loop to unlock the processed extents. + */ + end = start - 1; + ret = 0; + break; } ret = -ENOSPC; } From 2df2c6ed89600a02e1c7a581a6a55e53c38ce0f5 Mon Sep 17 00:00:00 2001 From: Thorsten Blum Date: Tue, 25 Feb 2025 20:26:14 +0100 Subject: [PATCH 2/3] btrfs: replace deprecated strncpy() with strscpy() strncpy() is deprecated for NUL-terminated destination buffers. Use strscpy() instead and don't zero-initialize the param array. Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Thorsten Blum Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/sysfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 53b846d99ecea..14f53f7575553 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -1330,13 +1330,13 @@ MODULE_PARM_DESC(read_policy, int btrfs_read_policy_to_enum(const char *str, s64 *value_ret) { - char param[32] = { 0 }; + char param[32]; char __maybe_unused *value_str; if (!str || strlen(str) == 0) return 0; - strncpy(param, str, sizeof(param) - 1); + strscpy(param, str); #ifdef CONFIG_BTRFS_EXPERIMENTAL /* Separate value from input in policy:value format. */ From 35d99c68af40a8ca175babc5a89ef7e2226fb3ca Mon Sep 17 00:00:00 2001 From: Haoxiang Li Date: Mon, 3 Mar 2025 10:42:33 +0800 Subject: [PATCH 3/3] btrfs: fix a leaked chunk map issue in read_one_chunk() Add btrfs_free_chunk_map() to free the memory allocated by btrfs_alloc_chunk_map() if btrfs_add_chunk_map() fails. Fixes: 7dc66abb5a47 ("btrfs: use a dedicated data structure for chunk maps") CC: stable@vger.kernel.org Reviewed-by: Qu Wenruo Reviewed-by: Filipe Manana Signed-off-by: Haoxiang Li Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index f6ae76815e4b5..6f8dcf59b5257 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -7151,6 +7151,7 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf, btrfs_err(fs_info, "failed to add chunk map, start=%llu len=%llu: %d", map->start, map->chunk_len, ret); + btrfs_free_chunk_map(map); } return ret;