+++ /dev/null
-From f9baa501b4fd6962257853d46ddffbc21f27e344 Mon Sep 17 00:00:00 2001
-From: Filipe Manana <fdmanana@suse.com>
-Date: Thu, 22 Apr 2021 12:08:05 +0100
-Subject: btrfs: fix deadlock when cloning inline extents and using qgroups
-
-From: Filipe Manana <fdmanana@suse.com>
-
-commit f9baa501b4fd6962257853d46ddffbc21f27e344 upstream.
-
-There are a few exceptional cases where cloning an inline extent needs to
-copy the inline extent data into a page of the destination inode.
-
-When this happens, we end up starting a transaction while having a dirty
-page for the destination inode and while having the range locked in the
-destination's inode iotree too. Because when reserving metadata space
-for a transaction we may need to flush existing delalloc in case there is
-not enough free space, we have a mechanism in place to prevent a deadlock,
-which was introduced in commit 3d45f221ce627d ("btrfs: fix deadlock when
-cloning inline extent and low on free metadata space").
-
-However when using qgroups, a transaction also reserves metadata qgroup
-space, which can also result in flushing delalloc in case there is not
-enough available space at the moment. When this happens we deadlock, since
-flushing delalloc requires locking the file range in the inode's iotree
-and the range was already locked at the very beginning of the clone
-operation, before attempting to start the transaction.
-
-When this issue happens, stack traces like the following are reported:
-
- [72747.556262] task:kworker/u81:9 state:D stack: 0 pid: 225 ppid: 2 flags:0x00004000
- [72747.556268] Workqueue: writeback wb_workfn (flush-btrfs-1142)
- [72747.556271] Call Trace:
- [72747.556273] __schedule+0x296/0x760
- [72747.556277] schedule+0x3c/0xa0
- [72747.556279] io_schedule+0x12/0x40
- [72747.556284] __lock_page+0x13c/0x280
- [72747.556287] ? generic_file_readonly_mmap+0x70/0x70
- [72747.556325] extent_write_cache_pages+0x22a/0x440 [btrfs]
- [72747.556331] ? __set_page_dirty_nobuffers+0xe7/0x160
- [72747.556358] ? set_extent_buffer_dirty+0x5e/0x80 [btrfs]
- [72747.556362] ? update_group_capacity+0x25/0x210
- [72747.556366] ? cpumask_next_and+0x1a/0x20
- [72747.556391] extent_writepages+0x44/0xa0 [btrfs]
- [72747.556394] do_writepages+0x41/0xd0
- [72747.556398] __writeback_single_inode+0x39/0x2a0
- [72747.556403] writeback_sb_inodes+0x1ea/0x440
- [72747.556407] __writeback_inodes_wb+0x5f/0xc0
- [72747.556410] wb_writeback+0x235/0x2b0
- [72747.556414] ? get_nr_inodes+0x35/0x50
- [72747.556417] wb_workfn+0x354/0x490
- [72747.556420] ? newidle_balance+0x2c5/0x3e0
- [72747.556424] process_one_work+0x1aa/0x340
- [72747.556426] worker_thread+0x30/0x390
- [72747.556429] ? create_worker+0x1a0/0x1a0
- [72747.556432] kthread+0x116/0x130
- [72747.556435] ? kthread_park+0x80/0x80
- [72747.556438] ret_from_fork+0x1f/0x30
-
- [72747.566958] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs]
- [72747.566961] Call Trace:
- [72747.566964] __schedule+0x296/0x760
- [72747.566968] ? finish_wait+0x80/0x80
- [72747.566970] schedule+0x3c/0xa0
- [72747.566995] wait_extent_bit.constprop.68+0x13b/0x1c0 [btrfs]
- [72747.566999] ? finish_wait+0x80/0x80
- [72747.567024] lock_extent_bits+0x37/0x90 [btrfs]
- [72747.567047] btrfs_invalidatepage+0x299/0x2c0 [btrfs]
- [72747.567051] ? find_get_pages_range_tag+0x2cd/0x380
- [72747.567076] __extent_writepage+0x203/0x320 [btrfs]
- [72747.567102] extent_write_cache_pages+0x2bb/0x440 [btrfs]
- [72747.567106] ? update_load_avg+0x7e/0x5f0
- [72747.567109] ? enqueue_entity+0xf4/0x6f0
- [72747.567134] extent_writepages+0x44/0xa0 [btrfs]
- [72747.567137] ? enqueue_task_fair+0x93/0x6f0
- [72747.567140] do_writepages+0x41/0xd0
- [72747.567144] __filemap_fdatawrite_range+0xc7/0x100
- [72747.567167] btrfs_run_delalloc_work+0x17/0x40 [btrfs]
- [72747.567195] btrfs_work_helper+0xc2/0x300 [btrfs]
- [72747.567200] process_one_work+0x1aa/0x340
- [72747.567202] worker_thread+0x30/0x390
- [72747.567205] ? create_worker+0x1a0/0x1a0
- [72747.567208] kthread+0x116/0x130
- [72747.567211] ? kthread_park+0x80/0x80
- [72747.567214] ret_from_fork+0x1f/0x30
-
- [72747.569686] task:fsstress state:D stack: 0 pid:841421 ppid:841417 flags:0x00000000
- [72747.569689] Call Trace:
- [72747.569691] __schedule+0x296/0x760
- [72747.569694] schedule+0x3c/0xa0
- [72747.569721] try_flush_qgroup+0x95/0x140 [btrfs]
- [72747.569725] ? finish_wait+0x80/0x80
- [72747.569753] btrfs_qgroup_reserve_data+0x34/0x50 [btrfs]
- [72747.569781] btrfs_check_data_free_space+0x5f/0xa0 [btrfs]
- [72747.569804] btrfs_buffered_write+0x1f7/0x7f0 [btrfs]
- [72747.569810] ? path_lookupat.isra.48+0x97/0x140
- [72747.569833] btrfs_file_write_iter+0x81/0x410 [btrfs]
- [72747.569836] ? __kmalloc+0x16a/0x2c0
- [72747.569839] do_iter_readv_writev+0x160/0x1c0
- [72747.569843] do_iter_write+0x80/0x1b0
- [72747.569847] vfs_writev+0x84/0x140
- [72747.569869] ? btrfs_file_llseek+0x38/0x270 [btrfs]
- [72747.569873] do_writev+0x65/0x100
- [72747.569876] do_syscall_64+0x33/0x40
- [72747.569879] entry_SYSCALL_64_after_hwframe+0x44/0xa9
-
- [72747.569899] task:fsstress state:D stack: 0 pid:841424 ppid:841417 flags:0x00004000
- [72747.569903] Call Trace:
- [72747.569906] __schedule+0x296/0x760
- [72747.569909] schedule+0x3c/0xa0
- [72747.569936] try_flush_qgroup+0x95/0x140 [btrfs]
- [72747.569940] ? finish_wait+0x80/0x80
- [72747.569967] __btrfs_qgroup_reserve_meta+0x36/0x50 [btrfs]
- [72747.569989] start_transaction+0x279/0x580 [btrfs]
- [72747.570014] clone_copy_inline_extent+0x332/0x490 [btrfs]
- [72747.570041] btrfs_clone+0x5b7/0x7a0 [btrfs]
- [72747.570068] ? lock_extent_bits+0x64/0x90 [btrfs]
- [72747.570095] btrfs_clone_files+0xfc/0x150 [btrfs]
- [72747.570122] btrfs_remap_file_range+0x3d8/0x4a0 [btrfs]
- [72747.570126] do_clone_file_range+0xed/0x200
- [72747.570131] vfs_clone_file_range+0x37/0x110
- [72747.570134] ioctl_file_clone+0x7d/0xb0
- [72747.570137] do_vfs_ioctl+0x138/0x630
- [72747.570140] __x64_sys_ioctl+0x62/0xc0
- [72747.570143] do_syscall_64+0x33/0x40
- [72747.570146] entry_SYSCALL_64_after_hwframe+0x44/0xa9
-
-So fix this by skipping the flush of delalloc for an inode that is
-flagged with BTRFS_INODE_NO_DELALLOC_FLUSH, meaning it is currently under
-such a special case of cloning an inline extent, when flushing delalloc
-during qgroup metadata reservation.
-
-The special cases for cloning inline extents were added in kernel 5.7 by
-by commit 05a5a7621ce66c ("Btrfs: implement full reflink support for
-inline extents"), while having qgroup metadata space reservation flushing
-delalloc when low on space was added in kernel 5.9 by commit
-c53e9653605dbf ("btrfs: qgroup: try to flush qgroup space when we get
--EDQUOT"). So use a "Fixes:" tag for the later commit to ease stable
-kernel backports.
-
-Reported-by: Wang Yugui <wangyugui@e16-tech.com>
-Link: https://lore.kernel.org/linux-btrfs/20210421083137.31E3.409509F4@e16-tech.com/
-Fixes: c53e9653605dbf ("btrfs: qgroup: try to flush qgroup space when we get -EDQUOT")
-CC: stable@vger.kernel.org # 5.9+
-Reviewed-by: Qu Wenruo <wqu@suse.com>
-Signed-off-by: Filipe Manana <fdmanana@suse.com>
-Reviewed-by: David Sterba <dsterba@suse.com>
-Signed-off-by: David Sterba <dsterba@suse.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- fs/btrfs/ctree.h | 2 +-
- fs/btrfs/inode.c | 4 ++--
- fs/btrfs/ioctl.c | 2 +-
- fs/btrfs/qgroup.c | 2 +-
- fs/btrfs/send.c | 4 ++--
- 5 files changed, 7 insertions(+), 7 deletions(-)
-
---- a/fs/btrfs/ctree.h
-+++ b/fs/btrfs/ctree.h
-@@ -3008,7 +3008,7 @@ int btrfs_truncate_inode_items(struct bt
- struct inode *inode, u64 new_size,
- u32 min_type);
-
--int btrfs_start_delalloc_snapshot(struct btrfs_root *root);
-+int btrfs_start_delalloc_snapshot(struct btrfs_root *root, bool in_reclaim_context);
- int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr,
- bool in_reclaim_context);
- int btrfs_set_extent_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
---- a/fs/btrfs/inode.c
-+++ b/fs/btrfs/inode.c
-@@ -9474,7 +9474,7 @@ out:
- return ret;
- }
-
--int btrfs_start_delalloc_snapshot(struct btrfs_root *root)
-+int btrfs_start_delalloc_snapshot(struct btrfs_root *root, bool in_reclaim_context)
- {
- struct writeback_control wbc = {
- .nr_to_write = LONG_MAX,
-@@ -9487,7 +9487,7 @@ int btrfs_start_delalloc_snapshot(struct
- if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
- return -EROFS;
-
-- return start_delalloc_inodes(root, &wbc, true, false);
-+ return start_delalloc_inodes(root, &wbc, true, in_reclaim_context);
- }
-
- int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr,
---- a/fs/btrfs/ioctl.c
-+++ b/fs/btrfs/ioctl.c
-@@ -1030,7 +1030,7 @@ static noinline int btrfs_mksnapshot(con
- */
- btrfs_drew_read_lock(&root->snapshot_lock);
-
-- ret = btrfs_start_delalloc_snapshot(root);
-+ ret = btrfs_start_delalloc_snapshot(root, false);
- if (ret)
- goto out;
-
---- a/fs/btrfs/qgroup.c
-+++ b/fs/btrfs/qgroup.c
-@@ -3613,7 +3613,7 @@ static int try_flush_qgroup(struct btrfs
- return 0;
- }
-
-- ret = btrfs_start_delalloc_snapshot(root);
-+ ret = btrfs_start_delalloc_snapshot(root, true);
- if (ret < 0)
- goto out;
- btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
---- a/fs/btrfs/send.c
-+++ b/fs/btrfs/send.c
-@@ -7159,7 +7159,7 @@ static int flush_delalloc_roots(struct s
- int i;
-
- if (root) {
-- ret = btrfs_start_delalloc_snapshot(root);
-+ ret = btrfs_start_delalloc_snapshot(root, false);
- if (ret)
- return ret;
- btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
-@@ -7167,7 +7167,7 @@ static int flush_delalloc_roots(struct s
-
- for (i = 0; i < sctx->clone_roots_cnt; i++) {
- root = sctx->clone_roots[i].root;
-- ret = btrfs_start_delalloc_snapshot(root);
-+ ret = btrfs_start_delalloc_snapshot(root, false);
- if (ret)
- return ret;
- btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
projects / thirdparty / kernel / stable-queue.git / commitdiff
