- 25 5月, 2020 34 次提交
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由 Qu Wenruo 提交于
[BUG] When balance is canceled, there is a pretty high chance that unmounting the fs can lead to lead the NULL pointer dereference: BTRFS warning (device dm-3): page private not zero on page 223158272 ... BTRFS warning (device dm-3): page private not zero on page 223162368 BTRFS error (device dm-3): leaked root 18446744073709551608-304 refcount 1 BUG: kernel NULL pointer dereference, address: 0000000000000168 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 2 PID: 5793 Comm: umount Tainted: G O 5.7.0-rc5-custom+ #53 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:__lock_acquire+0x5dc/0x24c0 Call Trace: lock_acquire+0xab/0x390 _raw_spin_lock+0x39/0x80 btrfs_release_extent_buffer_pages+0xd7/0x200 [btrfs] release_extent_buffer+0xb2/0x170 [btrfs] free_extent_buffer+0x66/0xb0 [btrfs] btrfs_put_root+0x8e/0x130 [btrfs] btrfs_check_leaked_roots.cold+0x5/0x5d [btrfs] btrfs_free_fs_info+0xe5/0x120 [btrfs] btrfs_kill_super+0x1f/0x30 [btrfs] deactivate_locked_super+0x3b/0x80 deactivate_super+0x3e/0x50 cleanup_mnt+0x109/0x160 __cleanup_mnt+0x12/0x20 task_work_run+0x67/0xa0 exit_to_usermode_loop+0xc5/0xd0 syscall_return_slowpath+0x205/0x360 do_syscall_64+0x6e/0xb0 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x7fd028ef740b [CAUSE] When balance is canceled, all reloc roots are marked as orphan, and orphan reloc roots are going to be cleaned up. However for orphan reloc roots and merged reloc roots, their lifespan are quite different: Merged reloc roots | Orphan reloc roots by cancel -------------------------------------------------------------------- create_reloc_root() | create_reloc_root() |- refs == 1 | |- refs == 1 | btrfs_grab_root(reloc_root); | btrfs_grab_root(reloc_root); |- refs == 2 | |- refs == 2 | root->reloc_root = reloc_root; | root->reloc_root = reloc_root; >>> No difference so far <<< | prepare_to_merge() | prepare_to_merge() |- btrfs_set_root_refs(item, 1);| |- if (!err) (err == -EINTR) | merge_reloc_roots() | merge_reloc_roots() |- merge_reloc_root() | |- Doing nothing to put reloc root |- insert_dirty_subvol() | |- refs == 2 |- __del_reloc_root() | |- btrfs_put_root() | |- refs == 1 | >>> Now orphan reloc roots still have refs 2 <<< | clean_dirty_subvols() | clean_dirty_subvols() |- btrfs_drop_snapshot() | |- btrfS_drop_snapshot() |- reloc_root get freed | |- reloc_root still has refs 2 | related ebs get freed, but | reloc_root still recorded in | allocated_roots btrfs_check_leaked_roots() | btrfs_check_leaked_roots() |- No leaked roots | |- Leaked reloc_roots detected | |- btrfs_put_root() | |- free_extent_buffer(root->node); | |- eb already freed, caused NULL | pointer dereference [FIX] The fix is to clear fs_root->reloc_root and put it at merge_reloc_roots() time, so that we won't leak reloc roots. Fixes: d2311e69 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") CC: stable@vger.kernel.org # 5.1+ Tested-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
SHAREABLE flag is set for subvolumes because users can create snapshot for subvolumes, thus sharing tree blocks of them. But data reloc tree is not exposed to user space, as it's only an internal tree for data relocation, thus it doesn't need the full path replacement handling at all. This patch will make data reloc tree a non-shareable tree, and add btrfs_fs_info::data_reloc_root for data reloc tree, so relocation code can grab it from fs_info directly. This would slightly improve tree relocation, as now data reloc tree can go through regular COW routine to get relocated, without bothering the complex tree reloc tree routine. Signed-off-by: NQu Wenruo <wqu@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
The name BTRFS_ROOT_REF_COWS is not very clear about the meaning. In fact, that bit can only be set to those trees: - Subvolume roots - Data reloc root - Reloc roots for above roots All other trees won't get this bit set. So just by the result, it is obvious that, roots with this bit set can have tree blocks shared with other trees. Either shared by snapshots, or by reloc roots (an special snapshot created by relocation). This patch will rename BTRFS_ROOT_REF_COWS to BTRFS_ROOT_SHAREABLE to make it easier to understand, and update all comment mentioning "reference counted" to follow the rename. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
All callers pass the eb::level so we can get read it directly inside the btrfs_bin_search and key_search. This is inspired by the work of Marek in U-boot. CC: Marek Behun <marek.behun@nic.cz> Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: NNikolay Borisov <nborisov@suse.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Nikolay Borisov 提交于
The function always works on a local copy of the reloc root list, which cannot be modified outside of it so using list_for_each_entry is fine. Additionally the macro handles empty lists so drop list_empty checks of callers. No semantic changes. Reviewed-by: NQu Wenruo <wqu@suse.com> Signed-off-by: NNikolay Borisov <nborisov@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
The error cleanup will be extracted as a new function, btrfs_backref_error_cleanup(), and moved to backref.c and exported for later usage. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
This the the 2nd major part of generic backref cache. Move it to backref.c so we can reuse it. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
This function is the major part of backref cache build process, move it to backref.c so we can reuse it later. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
The backref code is going to be moved to backref.c, and read_fs_root() is just a simple wrapper, open-code it to prepare to the incoming code move. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
This function is mostly single purpose to relocation backref cache, but since we're moving the main part of backref cache to backref.c, we need to export such function. And to avoid confusion, rename the function to btrfs_should_ignore_reloc_root() make the name a little more clear. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Also change the parameter, since all callers can easily grab an fs_info, there is no need for all the pointer chasing. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Since we're releasing all existing nodes/edges, other than cleanup the mess after error, "release" is a more proper naming here. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Also add comment explaining the cleanup progress, to differ it from btrfs_backref_drop_node(). Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
With extra comment for drop_backref_node() as it has some similarity with remove_backref_node(), thus we need extra comment explaining the difference. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Structure tree_entry provides a very simple rb_tree which only uses bytenr as search index. That tree_entry is used in 3 structures: backref_node, mapping_node and tree_block. Since we're going to make backref_node independnt from relocation, it's a good time to extract the tree_entry into rb_simple_node, and export it into misc.h. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
These 3 structures are the main part of btrfs backref cache, move them to backref.h to build the basis for later reuse. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Those three structures are the main elements of backref cache. Add the "btrfs_" prefix for later export. Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
This patch will also add some comment for the cleanup. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
After handle_one_tree_backref(), all newly added (not cached) edges and nodes have the following features: - Only backref_edge::list[LOWER] is linked. This means, we can only iterate from botton to top, not the other direction. - Newly added nodes are not added to cache rb_tree yet So to finish the backref cache, we still need to finish the links and add all nodes into backref cache rb_tree. This patch will refactor the existing code into finish_upper_links(), add more comments of each branch, and why we need to do all the work. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
build_backref_tree() uses "goto again;" to implement a breadth-first search to build backref cache. This patch will extract most of its work into a wrapper, handle_one_tree_block(), and use a do {} while() loop to implement the same thing. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Bytenr and level are essential parameters for backref_node, thus it makes sense to initialize them at allocation time. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Reviewed-by: NNikolay Borisov <nborisov@suse.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Since backref_edge is used to connect upper and lower backref nodes, and needs to access both nodes, some code can look pretty nasty: list_add_tail(&edge->list[LOWER], &cur->upper); The above code will link @cur to the LOWER side of the edge, while both "LOWER" and "upper" words show up. This can sometimes be very confusing for reader to grasp. This patch introduces a new wrapper, link_backref_edge(), to handle the linking behavior. Which also has extra ASSERT() to ensure caller won't pass wrong nodes. Also, this updates the comment of related lists of backref_node and backref_edge, to make it more clear that each list points to what. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Reviewed-by: NNikolay Borisov <nborisov@suse.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
The processing of indirect tree backref (TREE_BLOCK_REF) is the most complex work. We need to grab the fs root, do a tree search to locate all its parent nodes, link all needed edges, and put all uncached edges to pending edge list. This is definitely worth a helper function. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
For BTRFS_SHARED_BLOCK_REF_KEY, its processing is straightforward, as we now the parent node bytenr directly. If the parent is already cached, or a root, call it a day. If the parent is not cached, add it pending list. This patch will just refactor this part into its own function, handle_direct_tree_backref() and add some comment explaining the @ref_key parameter. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
find_reloc_root() searches reloc_control::reloc_root_tree to find the reloc root. This behavior is only useful for relocation backref cache. For the incoming more generic purpose backref cache, we don't care about who owns the reloc root, but only care if it's a reloc root. So this patch makes the following modifications to make the reloc root search more specific to relocation backref: - Add backref_node::is_reloc_root This will be an extra indicator for generic purposed backref cache. User doesn't need to read root key from backref_node::root to determine if it's a reloc root. Also for reloc tree root, it's useless and will be queued to useless list. - Add backref_cache::is_reloc This will allow backref cache code to do different behavior for generic purpose backref cache and relocation backref cache. - Pass fs_info to find_reloc_root() - Export find_reloc_root() So backref.c can utilize this function. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
Add this member so that we can grab fs_info without the help from reloc_control. Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
These two new members will act the same as the existing local lists, @useless and @list in build_backref_tree(). Currently build_backref_tree() is only executed serially, thus moving such local list into backref_cache is still safe. Also since we're here, use list_first_entry() to replace a lot of list_entry() calls after !list_empty(). Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
These two functions are weirdly named, mark_block_processed() in fact just marks a range dirty unconditionally, while __mark_block_processed() does extra check before doing the marking. This patch will open code old mark_block_processed, and rename __mark_block_processed() to remove the "__" prefix. Since we're here, also kill the forward declaration, which could also kill in_block_group() with in_range() macro. Reviewed-by: NNikolay Borisov <nborisov@suse.com> Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Qu Wenruo 提交于
In the core function of relocation, build_backref_tree, it needs to iterate all backref items of one tree block. Use btrfs_backref_iter infrastructure to do the loop and make the code more readable. The backref items look would be much more easier to read: ret = btrfs_backref_iter_start(iter, cur->bytenr); for (; ret == 0; ret = btrfs_backref_iter_next(iter)) { /* The really important work */ } Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NQu Wenruo <wqu@suse.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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- 23 4月, 2020 1 次提交
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由 Xiyu Yang 提交于
btrfs_recover_relocation() invokes btrfs_join_transaction(), which joins a btrfs_trans_handle object into transactions and returns a reference of it with increased refcount to "trans". When btrfs_recover_relocation() returns, "trans" becomes invalid, so the refcount should be decreased to keep refcount balanced. The reference counting issue happens in one exception handling path of btrfs_recover_relocation(). When read_fs_root() failed, the refcnt increased by btrfs_join_transaction() is not decreased, causing a refcnt leak. Fix this issue by calling btrfs_end_transaction() on this error path when read_fs_root() failed. Fixes: 79787eaa ("btrfs: replace many BUG_ONs with proper error handling") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: NFilipe Manana <fdmanana@suse.com> Signed-off-by: NXiyu Yang <xiyuyang19@fudan.edu.cn> Signed-off-by: NXin Tan <tanxin.ctf@gmail.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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- 17 4月, 2020 1 次提交
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由 Josef Bacik 提交于
I made a mistake with my previous fix, I assumed that we didn't need to mess with the reloc roots once we were out of the part of relocation where we are actually moving the extents. The subtle thing that I missed is that btrfs_init_reloc_root() also updates the last_trans for the reloc root when we do btrfs_record_root_in_trans() for the corresponding fs_root. I've added a comment to make sure future me doesn't make this mistake again. This showed up as a WARN_ON() in btrfs_copy_root() because our last_trans didn't == the current transid. This could happen if we snapshotted a fs root with a reloc root after we set rc->create_reloc_tree = 0, but before we actually merge the reloc root. Worth mentioning that the regression produced the following warning when running snapshot creation and balance in parallel: BTRFS info (device sdc): relocating block group 30408704 flags metadata|dup ------------[ cut here ]------------ WARNING: CPU: 0 PID: 12823 at fs/btrfs/ctree.c:191 btrfs_copy_root+0x26f/0x430 [btrfs] CPU: 0 PID: 12823 Comm: btrfs Tainted: G W 5.6.0-rc7-btrfs-next-58 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 RIP: 0010:btrfs_copy_root+0x26f/0x430 [btrfs] RSP: 0018:ffffb96e044279b8 EFLAGS: 00010202 RAX: 0000000000000009 RBX: ffff9da70bf61000 RCX: ffffb96e04427a48 RDX: ffff9da733a770c8 RSI: ffff9da70bf61000 RDI: ffff9da694163818 RBP: ffff9da733a770c8 R08: fffffffffffffff8 R09: 0000000000000002 R10: ffffb96e044279a0 R11: 0000000000000000 R12: ffff9da694163818 R13: fffffffffffffff8 R14: ffff9da6d2512000 R15: ffff9da714cdac00 FS: 00007fdeacf328c0(0000) GS:ffff9da735e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055a2a5b8a118 CR3: 00000001eed78002 CR4: 00000000003606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? create_reloc_root+0x49/0x2b0 [btrfs] ? kmem_cache_alloc_trace+0xe5/0x200 create_reloc_root+0x8b/0x2b0 [btrfs] btrfs_reloc_post_snapshot+0x96/0x5b0 [btrfs] create_pending_snapshot+0x610/0x1010 [btrfs] create_pending_snapshots+0xa8/0xd0 [btrfs] btrfs_commit_transaction+0x4c7/0xc50 [btrfs] ? btrfs_mksubvol+0x3cd/0x560 [btrfs] btrfs_mksubvol+0x455/0x560 [btrfs] __btrfs_ioctl_snap_create+0x15f/0x190 [btrfs] btrfs_ioctl_snap_create_v2+0xa4/0xf0 [btrfs] ? mem_cgroup_commit_charge+0x6e/0x540 btrfs_ioctl+0x12d8/0x3760 [btrfs] ? do_raw_spin_unlock+0x49/0xc0 ? _raw_spin_unlock+0x29/0x40 ? __handle_mm_fault+0x11b3/0x14b0 ? ksys_ioctl+0x92/0xb0 ksys_ioctl+0x92/0xb0 ? trace_hardirqs_off_thunk+0x1a/0x1c __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x5c/0x280 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fdeabd3bdd7 Fixes: 2abc726a ("btrfs: do not init a reloc root if we aren't relocating") Reviewed-by: NFilipe Manana <fdmanana@suse.com> Signed-off-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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- 09 4月, 2020 1 次提交
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由 Josef Bacik 提交于
Previously we would set the reloc root's last snapshot to transid - 1. However there was a problem with doing this, and we changed it to setting the last snapshot to the generation of the commit node of the fs root. This however broke should_ignore_root(). The assumption is that if we are in a generation newer than when the reloc root was created, then we would find the reloc root through normal backref lookups, and thus can ignore any fs roots we find with an old enough reloc root. Now that the last snapshot could be considerably further in the past than before, we'd end up incorrectly ignoring an fs root. Thus we'd find no nodes for the bytenr we were searching for, and we'd fail to relocate anything. We'd loop through the relocate code again and see that there were still used space in that block group, attempt to relocate those bytenr's again, fail in the same way, and just loop like this forever. This is tricky in that we have to not modify the fs root at all during this time, so we need to have a block group that has data in this fs root that is not shared by any other root, which is why this has been difficult to reproduce. Fixes: 054570a1 ("Btrfs: fix relocation incorrectly dropping data references") CC: stable@vger.kernel.org # 4.9+ Reviewed-by: NFilipe Manana <fdmanana@suse.com> Signed-off-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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- 24 3月, 2020 3 次提交
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由 Josef Bacik 提交于
We always search the commit root of the extent tree for looking up back references, however we track the reloc roots based on their current bytenr. This is wrong, if we commit the transaction between relocating tree blocks we could end up in this code in build_backref_tree if (key.objectid == key.offset) { /* * Only root blocks of reloc trees use backref * pointing to itself. */ root = find_reloc_root(rc, cur->bytenr); ASSERT(root); cur->root = root; break; } find_reloc_root() is looking based on the bytenr we had in the commit root, but if we've COWed this reloc root we will not find that bytenr, and we will trip over the ASSERT(root). Fix this by using the commit_root->start bytenr for indexing the commit root. Then we change the __update_reloc_root() caller to be used when we switch the commit root for the reloc root during commit. This fixes the panic I was seeing when we started throttling relocation for delayed refs. Signed-off-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Josef Bacik 提交于
There are two bugs here, but fixing them independently would just result in pain if you happened to bisect between the two patches. First is how we handle the -EAGAIN from relocate_tree_block(). We don't set error, unless we happen to be the first node, which makes no sense, I have no idea what the code was trying to accomplish here. We in fact _do_ want err set here so that we know we need to restart in relocate_block_group(). Also we need finish_pending_nodes() to not actually call link_to_upper(), because we didn't actually relocate the block. And then if we do get -EAGAIN we do not want to set our backref cache last_trans to the one before ours. This would force us to update our backref cache if we didn't cross transaction ids, which would mean we'd have some nodes updated to their new_bytenr, but still able to find their old bytenr because we're searching the same commit root as the last time we went through relocate_tree_blocks. Fixing these two things keeps us from panicing when we start breaking out of relocate_tree_blocks() either for delayed ref flushing or enospc. Signed-off-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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由 Josef Bacik 提交于
Since we're not only checking for metadata reservations but also if we need to throttle our delayed ref generation, reorder reserve_metadata_space() above the select_one_root() call in relocate_tree_block(). The reason we want this is because select_reloc_root() will mess with the backref cache, and if we're going to bail we want to be able to cleanly remove this node from the backref cache and come back along to regenerate it. Move it up so this is the first thing we do to make restarting cleaner. Signed-off-by: NJosef Bacik <josef@toxicpanda.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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