| Age | Commit message (Collapse) | Author |
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In order to properly set the lockdep class of a newly allocated block we
need to know the owner of the block. For non-refcounted trees this is
straightforward, we always know in advance what tree we're reading from.
For refcounted trees we don't necessarily know, however all refcounted
trees share the same lockdep class name, tree-<level>.
Fix all the callers of read_tree_block() to pass in the root objectid
we're using. In places like relocation and backref we could probably
unconditionally use 0, but just in case use the root when we have it,
otherwise use 0 in the cases we don't have the root as it's going to be
a refcounted tree anyway.
This is a preparation patch for further changes.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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We no longer distinguish between blocking and spinning, so rip out all
this code.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Now that we're using a rw_semaphore we no longer need to indicate if a
lock is blocking or not, nor do we need to flip the entire path from
blocking to spinning. Remove these helpers and all the places they are
called.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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I got the following lockdep splat with tree locks converted to rwsem
patches on btrfs/104:
======================================================
WARNING: possible circular locking dependency detected
5.9.0+ #102 Not tainted
------------------------------------------------------
btrfs-cleaner/903 is trying to acquire lock:
ffff8e7fab6ffe30 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x170
but task is already holding lock:
ffff8e7fab628a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&fs_info->commit_root_sem){++++}-{3:3}:
down_read+0x40/0x130
caching_thread+0x53/0x5a0
btrfs_work_helper+0xfa/0x520
process_one_work+0x238/0x540
worker_thread+0x55/0x3c0
kthread+0x13a/0x150
ret_from_fork+0x1f/0x30
-> #2 (&caching_ctl->mutex){+.+.}-{3:3}:
__mutex_lock+0x7e/0x7b0
btrfs_cache_block_group+0x1e0/0x510
find_free_extent+0xb6e/0x12f0
btrfs_reserve_extent+0xb3/0x1b0
btrfs_alloc_tree_block+0xb1/0x330
alloc_tree_block_no_bg_flush+0x4f/0x60
__btrfs_cow_block+0x11d/0x580
btrfs_cow_block+0x10c/0x220
commit_cowonly_roots+0x47/0x2e0
btrfs_commit_transaction+0x595/0xbd0
sync_filesystem+0x74/0x90
generic_shutdown_super+0x22/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20
deactivate_locked_super+0x36/0xa0
cleanup_mnt+0x12d/0x190
task_work_run+0x5c/0xa0
exit_to_user_mode_prepare+0x1df/0x200
syscall_exit_to_user_mode+0x54/0x280
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #1 (&space_info->groups_sem){++++}-{3:3}:
down_read+0x40/0x130
find_free_extent+0x2ed/0x12f0
btrfs_reserve_extent+0xb3/0x1b0
btrfs_alloc_tree_block+0xb1/0x330
alloc_tree_block_no_bg_flush+0x4f/0x60
__btrfs_cow_block+0x11d/0x580
btrfs_cow_block+0x10c/0x220
commit_cowonly_roots+0x47/0x2e0
btrfs_commit_transaction+0x595/0xbd0
sync_filesystem+0x74/0x90
generic_shutdown_super+0x22/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20
deactivate_locked_super+0x36/0xa0
cleanup_mnt+0x12d/0x190
task_work_run+0x5c/0xa0
exit_to_user_mode_prepare+0x1df/0x200
syscall_exit_to_user_mode+0x54/0x280
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #0 (btrfs-root-00){++++}-{3:3}:
__lock_acquire+0x1167/0x2150
lock_acquire+0xb9/0x3d0
down_read_nested+0x43/0x130
__btrfs_tree_read_lock+0x32/0x170
__btrfs_read_lock_root_node+0x3a/0x50
btrfs_search_slot+0x614/0x9d0
btrfs_find_root+0x35/0x1b0
btrfs_read_tree_root+0x61/0x120
btrfs_get_root_ref+0x14b/0x600
find_parent_nodes+0x3e6/0x1b30
btrfs_find_all_roots_safe+0xb4/0x130
btrfs_find_all_roots+0x60/0x80
btrfs_qgroup_trace_extent_post+0x27/0x40
btrfs_add_delayed_data_ref+0x3fd/0x460
btrfs_free_extent+0x42/0x100
__btrfs_mod_ref+0x1d7/0x2f0
walk_up_proc+0x11c/0x400
walk_up_tree+0xf0/0x180
btrfs_drop_snapshot+0x1c7/0x780
btrfs_clean_one_deleted_snapshot+0xfb/0x110
cleaner_kthread+0xd4/0x140
kthread+0x13a/0x150
ret_from_fork+0x1f/0x30
other info that might help us debug this:
Chain exists of:
btrfs-root-00 --> &caching_ctl->mutex --> &fs_info->commit_root_sem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&fs_info->commit_root_sem);
lock(&caching_ctl->mutex);
lock(&fs_info->commit_root_sem);
lock(btrfs-root-00);
*** DEADLOCK ***
3 locks held by btrfs-cleaner/903:
#0: ffff8e7fab628838 (&fs_info->cleaner_mutex){+.+.}-{3:3}, at: cleaner_kthread+0x6e/0x140
#1: ffff8e7faadac640 (sb_internal){.+.+}-{0:0}, at: start_transaction+0x40b/0x5c0
#2: ffff8e7fab628a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80
stack backtrace:
CPU: 0 PID: 903 Comm: btrfs-cleaner Not tainted 5.9.0+ #102
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack+0x8b/0xb0
check_noncircular+0xcf/0xf0
__lock_acquire+0x1167/0x2150
? __bfs+0x42/0x210
lock_acquire+0xb9/0x3d0
? __btrfs_tree_read_lock+0x32/0x170
down_read_nested+0x43/0x130
? __btrfs_tree_read_lock+0x32/0x170
__btrfs_tree_read_lock+0x32/0x170
__btrfs_read_lock_root_node+0x3a/0x50
btrfs_search_slot+0x614/0x9d0
? find_held_lock+0x2b/0x80
btrfs_find_root+0x35/0x1b0
? do_raw_spin_unlock+0x4b/0xa0
btrfs_read_tree_root+0x61/0x120
btrfs_get_root_ref+0x14b/0x600
find_parent_nodes+0x3e6/0x1b30
btrfs_find_all_roots_safe+0xb4/0x130
btrfs_find_all_roots+0x60/0x80
btrfs_qgroup_trace_extent_post+0x27/0x40
btrfs_add_delayed_data_ref+0x3fd/0x460
btrfs_free_extent+0x42/0x100
__btrfs_mod_ref+0x1d7/0x2f0
walk_up_proc+0x11c/0x400
walk_up_tree+0xf0/0x180
btrfs_drop_snapshot+0x1c7/0x780
? btrfs_clean_one_deleted_snapshot+0x73/0x110
btrfs_clean_one_deleted_snapshot+0xfb/0x110
cleaner_kthread+0xd4/0x140
? btrfs_alloc_root+0x50/0x50
kthread+0x13a/0x150
? kthread_create_worker_on_cpu+0x40/0x40
ret_from_fork+0x1f/0x30
BTRFS info (device sdb): disk space caching is enabled
BTRFS info (device sdb): has skinny extents
This happens because qgroups does a backref lookup when we create a
delayed ref. From here it may have to look up a root from an indirect
ref, which does a normal lookup on the tree_root, which takes the read
lock on the tree_root nodes.
To fix this we need to add a variant for looking up roots that searches
the commit root of the tree_root. Then when we do the backref search
using the commit root we are sure to not take any locks on the tree_root
nodes. This gets rid of the lockdep splat when running btrfs/104.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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In btrfs_orphan_cleanup, there's another instance of fs_info, but it's
the same as the one we already have.
In btrfs_backref_finish_upper_links, rb_node is same type and used
as temporary cursor to the tree.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The `if (!ret)` check will always be false and it may result in
ret->path being dereferenced while it is a NULL pointer.
Fixes: a37f232b7b65 ("btrfs: backref: introduce the skeleton of btrfs_backref_iter")
CC: stable@vger.kernel.org # 5.8+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boleyn Su <boleynsu@google.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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At btrfs_find_all_roots_safe() we allocate a ulist and set the **roots
argument to point to it. However if later we fail due to an error returned
by find_parent_nodes(), we free that ulist but leave a dangling pointer in
the **roots argument. Upon receiving the error, a caller of this function
can attempt to free the same ulist again, resulting in an invalid memory
access.
One such scenario is during qgroup accounting:
btrfs_qgroup_account_extents()
--> calls btrfs_find_all_roots() passes &new_roots (a stack allocated
pointer) to btrfs_find_all_roots()
--> btrfs_find_all_roots() just calls btrfs_find_all_roots_safe()
passing &new_roots to it
--> allocates ulist and assigns its address to **roots (which
points to new_roots from btrfs_qgroup_account_extents())
--> find_parent_nodes() returns an error, so we free the ulist
and leave **roots pointing to it after returning
--> btrfs_qgroup_account_extents() sees btrfs_find_all_roots() returned
an error and jumps to the label 'cleanup', which just tries to
free again the same ulist
Stack trace example:
------------[ cut here ]------------
BTRFS: tree first key check failed
WARNING: CPU: 1 PID: 1763215 at fs/btrfs/disk-io.c:422 btrfs_verify_level_key+0xe0/0x180 [btrfs]
Modules linked in: dm_snapshot dm_thin_pool (...)
CPU: 1 PID: 1763215 Comm: fsstress Tainted: G W 5.8.0-rc3-btrfs-next-64 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_verify_level_key+0xe0/0x180 [btrfs]
Code: 28 5b 5d (...)
RSP: 0018:ffffb89b473779a0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff90397759bf08 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000027 RDI: 00000000ffffffff
RBP: ffff9039a419c000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: ffffb89b43301000 R12: 000000000000005e
R13: ffffb89b47377a2e R14: ffffb89b473779af R15: 0000000000000000
FS: 00007fc47e1e1000(0000) GS:ffff9039ac200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc47e1df000 CR3: 00000003d9e4e001 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
read_block_for_search+0xf6/0x350 [btrfs]
btrfs_next_old_leaf+0x242/0x650 [btrfs]
resolve_indirect_refs+0x7cf/0x9e0 [btrfs]
find_parent_nodes+0x4ea/0x12c0 [btrfs]
btrfs_find_all_roots_safe+0xbf/0x130 [btrfs]
btrfs_qgroup_account_extents+0x9d/0x390 [btrfs]
btrfs_commit_transaction+0x4f7/0xb20 [btrfs]
btrfs_sync_file+0x3d4/0x4d0 [btrfs]
do_fsync+0x38/0x70
__x64_sys_fdatasync+0x13/0x20
do_syscall_64+0x5c/0xe0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fc47e2d72e3
Code: Bad RIP value.
RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3
RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003
RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8
R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffffb8eb5e85>] copy_process+0x755/0x1eb0
softirqs last enabled at (0): [<ffffffffb8eb5e85>] copy_process+0x755/0x1eb0
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace 8639237550317b48 ]---
BTRFS error (device sdc): tree first key mismatch detected, bytenr=62324736 parent_transid=94 key expected=(262,108,1351680) has=(259,108,1921024)
general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
CPU: 2 PID: 1763215 Comm: fsstress Tainted: G W 5.8.0-rc3-btrfs-next-64 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:ulist_release+0x14/0x60 [btrfs]
Code: c7 07 00 (...)
RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282
RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840
RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840
R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840
FS: 00007fc47e1e1000(0000) GS:ffff9039ac600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c1c0a51c8 CR3: 00000003d9e4e004 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
ulist_free+0x13/0x20 [btrfs]
btrfs_qgroup_account_extents+0xf3/0x390 [btrfs]
btrfs_commit_transaction+0x4f7/0xb20 [btrfs]
btrfs_sync_file+0x3d4/0x4d0 [btrfs]
do_fsync+0x38/0x70
__x64_sys_fdatasync+0x13/0x20
do_syscall_64+0x5c/0xe0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fc47e2d72e3
Code: Bad RIP value.
RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3
RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003
RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8
R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50
Modules linked in: dm_snapshot dm_thin_pool (...)
---[ end trace 8639237550317b49 ]---
RIP: 0010:ulist_release+0x14/0x60 [btrfs]
Code: c7 07 00 (...)
RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282
RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840
RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840
R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840
FS: 00007fc47e1e1000(0000) GS:ffff9039ad200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6a776f7d40 CR3: 00000003d9e4e002 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Fix this by making btrfs_find_all_roots_safe() set *roots to NULL after
it frees the ulist.
Fixes: 8da6d5815c592b ("Btrfs: added btrfs_find_all_roots()")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The main function to lookup a root by its id btrfs_get_fs_root takes the
whole key, while only using the objectid. The value of offset is preset
to (u64)-1 but not actually used until btrfs_find_root that does the
actual search.
Switch btrfs_get_fs_root to use only objectid and remove all local
variables that existed just for the lookup. The actual key for search is
set up in btrfs_get_fs_root, reusing another key variable.
Signed-off-by: David Sterba <dsterba@suse.com>
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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: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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For relocation tree detection, relocation backref cache uses
btrfs_should_ignore_reloc_root() which uses relocation-specific checks
like checking the DEAD_RELOC_ROOT bit.
However for general purpose backref cache, we can rely on that check, as
it's possible that relocation is also running.
For generic purposed backref cache, we detect reloc root by
SHARED_BLOCK_REF item. Only reloc root node has its parent bytenr
pointing back to itself.
And in that case, backref cache will mark the reloc root node useless,
dropping any child orphan nodes.
So only call btrfs_should_ignore_reloc_root() if the backref cache is
for relocation.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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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: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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This the the 2nd major part of generic backref cache. Move it to
backref.c so we can reuse it.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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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: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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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: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Also add comment explaining the cleanup progress, to differ it from
btrfs_backref_drop_node().
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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This function will go to the next inline/keyed backref for
btrfs_backref_iter infrastructure.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Due to the complex nature of btrfs extent tree, when we want to iterate
all backrefs of one extent, this involves quite a lot of work, like
searching the EXTENT_ITEM/METADATA_ITEM, iteration through inline and keyed
backrefs.
Normally this would result in a complex code, something like:
btrfs_search_slot()
/* Ensure we are at EXTENT_ITEM/METADATA_ITEM */
while (1) { /* Loop for extent tree items */
while (ptr < end) { /* Loop for inlined items */
/* Real work here */
}
next:
ret = btrfs_next_item()
/* Ensure we're still at keyed item for specified bytenr */
}
The idea of btrfs_backref_iter is to avoid such complex and hard to
read code structure, but something like the following:
iter = btrfs_backref_iter_alloc();
ret = btrfs_backref_iter_start(iter, bytenr);
if (ret < 0)
goto out;
for (; ; ret = btrfs_backref_iter_next(iter)) {
/* Real work here */
}
out:
btrfs_backref_iter_free(iter);
This patch is just the skeleton + btrfs_backref_iter_start() code.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Some older compilers like gcc-4.8 warn about mismatched curly braces in
a initializer:
fs/btrfs/backref.c: In function 'is_shared_data_backref':
fs/btrfs/backref.c:394:9: error: missing braces around
initializer [-Werror=missing-braces]
struct prelim_ref target = {0};
^
fs/btrfs/backref.c:394:9: error: (near initialization for
'target.rbnode') [-Werror=missing-braces]
Use the GNU empty initializer extension to avoid this.
Fixes: ed58f2e66e84 ("btrfs: backref, don't add refs from shared block when resolving normal backref")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Zygo reported a deadlock where a task was stuck in the inode logical
resolve code. The deadlock looks like this
Task 1
btrfs_ioctl_logical_to_ino
->iterate_inodes_from_logical
->iterate_extent_inodes
->path->search_commit_root isn't set, so a transaction is started
->resolve_indirect_ref for a root that's being deleted
->search for our key, attempt to lock a node, DEADLOCK
Task 2
btrfs_drop_snapshot
->walk down to a leaf, lock it, walk up, lock node
->end transaction
->start transaction
-> wait_cur_trans
Task 3
btrfs_commit_transaction
->wait_event(cur_trans->write_wait, num_writers == 1) DEADLOCK
We are holding a transaction open in btrfs_ioctl_logical_to_ino while we
try to resolve our references. btrfs_drop_snapshot() holds onto its
locks while it stops and starts transaction handles, because it assumes
nobody is going to touch the root now. Commit just does what commit
does, waiting for the writers to finish, blocking any new trans handles
from starting.
Fix this by making the backref code not try to resolve backrefs of roots
that are currently being deleted. This will keep us from walking into a
snapshot that's currently being deleted.
This problem was harder to hit before because we rarely broke out of the
snapshot delete halfway through, but with my delayed ref throttling code
it happened much more often. However we've always been able to do this,
so it's not a new problem.
Fixes: 8da6d5815c59 ("Btrfs: added btrfs_find_all_roots()")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Now that we have proper root ref counting everywhere we can kill the
subvol_srcu.
* removal of fs_info::subvol_srcu reduces size of fs_info by 1176 bytes
* the refcount_t used for the references checks for accidental 0->1
in cases where the root lifetime would not be properly protected
* there's a leak detector for roots to catch unfreed roots at umount
time
* SRCU served us well over the years but is was not a proper
synchronization mechanism for some cases
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
tree leaves
In relocation, we need to locate all parent tree leaves referring to one
data extent, thus we have a complex mechanism to iterate throught extent
tree and subvolume trees to locate the related leaves.
However this is already done in backref.c, we have
btrfs_find_all_leafs(), which can return a ulist containing all leaves
referring to that data extent.
Use btrfs_find_all_leafs() to replace find_data_references().
There is a special handling for v1 space cache data extents, where we
need to delete the v1 space cache data extents, to avoid those data
extents to hang the data relocation.
In this patch, the special handling is done by re-iterating the root
tree leaf. Although it's a little less efficient than the old handling,
considering we can reuse a lot of code, it should be acceptable.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
With the following patches:
- btrfs: backref, only collect file extent items matching backref offset
- btrfs: backref, not adding refs from shared block when resolving normal backref
- btrfs: backref, only search backref entries from leaves of the same root
we only collect the normal data refs we want, so the imprecise upper
bound total_refs of that EXTENT_ITEM could now be changed to the count
of the normal backref entry we want to search.
Background and how the patches fit together:
Btrfs has two types of data backref.
For BTRFS_EXTENT_DATA_REF_KEY type of backref, we don't have the
exact block number. Therefore, we need to call resolve_indirect_refs.
It uses btrfs_search_slot to locate the leaf block. Then
we need to walk through the leaves to search for the EXTENT_DATA items
that have disk bytenr matching the extent item (add_all_parents).
When resolving indirect refs, we could take entries that don't
belong to the backref entry we are searching for right now.
For that reason when searching backref entry, we always use total
refs of that EXTENT_ITEM rather than individual count.
For example:
item 11 key (40831553536 EXTENT_ITEM 4194304) itemoff 15460 itemsize
extent refs 24 gen 7302 flags DATA
shared data backref parent 394985472 count 10 #1
extent data backref root 257 objectid 260 offset 1048576 count 3 #2
extent data backref root 256 objectid 260 offset 65536 count 6 #3
extent data backref root 257 objectid 260 offset 65536 count 5 #4
For example, when searching backref entry #4, we'll use total_refs
24, a very loose loop ending condition, instead of total_refs = 5.
But using total_refs = 24 is not accurate. Sometimes, we'll never find
all the refs from specific root. As a result, the loop keeps on going
until we reach the end of that inode.
The first 3 patches, handle 3 different types refs we might encounter.
These refs do not belong to the normal backref we are searching, and
hence need to be skipped.
This patch changes the total_refs to correct number so that we could
end loop as soon as we find all the refs we want.
btrfs send uses backref to find possible clone sources, the following
is a simple test to compare the results with and without this patch:
$ btrfs subvolume create /sub1
$ for i in `seq 1 163840`; do
dd if=/dev/zero of=/sub1/file bs=64K count=1 seek=$((i-1)) conv=notrunc oflag=direct
done
$ btrfs subvolume snapshot /sub1 /sub2
$ for i in `seq 1 163840`; do
dd if=/dev/zero of=/sub1/file bs=4K count=1 seek=$(((i-1)*16+10)) conv=notrunc oflag=direct
done
$ btrfs subvolume snapshot -r /sub1 /snap1
$ time btrfs send /snap1 | btrfs receive /volume2
Without this patch:
real 69m48.124s
user 0m50.199s
sys 70m15.600s
With this patch:
real 1m59.683s
user 0m35.421s
sys 2m42.684s
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: ethanwu <ethanwu@synology.com>
[ add patchset cover letter with background and numbers ]
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We could have some nodes/leaves in subvolume whose owner are not the
that subvolume. In this way, when we resolve normal backrefs of that
subvolume, we should avoid collecting those references from these blocks.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: ethanwu <ethanwu@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
All references from the block of SHARED_DATA_REF belong to that shared
block backref.
For example:
item 11 key (40831553536 EXTENT_ITEM 4194304) itemoff 15460 itemsize 95
extent refs 24 gen 7302 flags DATA
extent data backref root 257 objectid 260 offset 65536 count 5
extent data backref root 258 objectid 265 offset 0 count 9
shared data backref parent 394985472 count 10
Block 394985472 might be leaf from root 257, and the item obejctid and
(file_pos - file_extent_item::offset) in that leaf just happens to be
260 and 65536 which is equal to the first extent data backref entry.
Before this patch, when we resolve backref:
root 257 objectid 260 offset 65536
we will add those refs in block 394985472 and wrongly treat those as the
refs we want.
Fix this by checking if the leaf we are processing is shared data
backref, if so, just skip this leaf.
Shared data refs added into preftrees.direct have all entry value = 0
(root_id = 0, key = NULL, level = 0) except parent entry.
Other refs from indirect tree will have key value and root id != 0, and
these values won't be changed when their parent is resolved and added to
preftrees.direct. Therefore, we could reuse the preftrees.direct and
search ref with all values = 0 except parent is set to avoid getting
those resolved refs block.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: ethanwu <ethanwu@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
When resolving one backref of type EXTENT_DATA_REF, we collect all
references that simply reference the EXTENT_ITEM even though their
(file_pos - file_extent_item::offset) are not the same as the
btrfs_extent_data_ref::offset we are searching for.
This patch adds additional check so that we only collect references whose
(file_pos - file_extent_item::offset) == btrfs_extent_data_ref::offset.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: ethanwu <ethanwu@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We are now using these for all roots, rename them to btrfs_put_root()
and btrfs_grab_root();
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Now that all callers of btrfs_get_fs_root are subsequently calling
btrfs_grab_fs_root and handling dropping the ref when they are done
appropriately, go ahead and push btrfs_grab_fs_root up into
btrfs_get_fs_root.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We're looking up a random root, we need to hold a ref on it while we're
using it.
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
The fiemap handler locks a file range that can have unflushed delalloc,
and after locking the range, it tries to attach to a running transaction.
If the running transaction started its commit, that is, it is in state
TRANS_STATE_COMMIT_START, and either the filesystem was mounted with the
flushoncommit option or the transaction is creating a snapshot for the
subvolume that contains the file that fiemap is operating on, we end up
deadlocking. This happens because fiemap is blocked on the transaction,
waiting for it to complete, and the transaction is waiting for the flushed
dealloc to complete, which requires locking the file range that the fiemap
task already locked. The following stack traces serve as an example of
when this deadlock happens:
(...)
[404571.515510] Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
[404571.515956] Call Trace:
[404571.516360] ? __schedule+0x3ae/0x7b0
[404571.516730] schedule+0x3a/0xb0
[404571.517104] lock_extent_bits+0x1ec/0x2a0 [btrfs]
[404571.517465] ? remove_wait_queue+0x60/0x60
[404571.517832] btrfs_finish_ordered_io+0x292/0x800 [btrfs]
[404571.518202] normal_work_helper+0xea/0x530 [btrfs]
[404571.518566] process_one_work+0x21e/0x5c0
[404571.518990] worker_thread+0x4f/0x3b0
[404571.519413] ? process_one_work+0x5c0/0x5c0
[404571.519829] kthread+0x103/0x140
[404571.520191] ? kthread_create_worker_on_cpu+0x70/0x70
[404571.520565] ret_from_fork+0x3a/0x50
[404571.520915] kworker/u8:6 D 0 31651 2 0x80004000
[404571.521290] Workqueue: btrfs-flush_delalloc btrfs_flush_delalloc_helper [btrfs]
(...)
[404571.537000] fsstress D 0 13117 13115 0x00004000
[404571.537263] Call Trace:
[404571.537524] ? __schedule+0x3ae/0x7b0
[404571.537788] schedule+0x3a/0xb0
[404571.538066] wait_current_trans+0xc8/0x100 [btrfs]
[404571.538349] ? remove_wait_queue+0x60/0x60
[404571.538680] start_transaction+0x33c/0x500 [btrfs]
[404571.539076] btrfs_check_shared+0xa3/0x1f0 [btrfs]
[404571.539513] ? extent_fiemap+0x2ce/0x650 [btrfs]
[404571.539866] extent_fiemap+0x2ce/0x650 [btrfs]
[404571.540170] do_vfs_ioctl+0x526/0x6f0
[404571.540436] ksys_ioctl+0x70/0x80
[404571.540734] __x64_sys_ioctl+0x16/0x20
[404571.540997] do_syscall_64+0x60/0x1d0
[404571.541279] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
[404571.543729] btrfs D 0 14210 14208 0x00004000
[404571.544023] Call Trace:
[404571.544275] ? __schedule+0x3ae/0x7b0
[404571.544526] ? wait_for_completion+0x112/0x1a0
[404571.544795] schedule+0x3a/0xb0
[404571.545064] schedule_timeout+0x1ff/0x390
[404571.545351] ? lock_acquire+0xa6/0x190
[404571.545638] ? wait_for_completion+0x49/0x1a0
[404571.545890] ? wait_for_completion+0x112/0x1a0
[404571.546228] wait_for_completion+0x131/0x1a0
[404571.546503] ? wake_up_q+0x70/0x70
[404571.546775] btrfs_wait_ordered_extents+0x27c/0x400 [btrfs]
[404571.547159] btrfs_commit_transaction+0x3b0/0xae0 [btrfs]
[404571.547449] ? btrfs_mksubvol+0x4a4/0x640 [btrfs]
[404571.547703] ? remove_wait_queue+0x60/0x60
[404571.547969] btrfs_mksubvol+0x605/0x640 [btrfs]
[404571.548226] ? __sb_start_write+0xd4/0x1c0
[404571.548512] ? mnt_want_write_file+0x24/0x50
[404571.548789] btrfs_ioctl_snap_create_transid+0x169/0x1a0 [btrfs]
[404571.549048] btrfs_ioctl_snap_create_v2+0x11d/0x170 [btrfs]
[404571.549307] btrfs_ioctl+0x133f/0x3150 [btrfs]
[404571.549549] ? mem_cgroup_charge_statistics+0x4c/0xd0
[404571.549792] ? mem_cgroup_commit_charge+0x84/0x4b0
[404571.550064] ? __handle_mm_fault+0xe3e/0x11f0
[404571.550306] ? do_raw_spin_unlock+0x49/0xc0
[404571.550608] ? _raw_spin_unlock+0x24/0x30
[404571.550976] ? __handle_mm_fault+0xedf/0x11f0
[404571.551319] ? do_vfs_ioctl+0xa2/0x6f0
[404571.551659] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[404571.552087] do_vfs_ioctl+0xa2/0x6f0
[404571.552355] ksys_ioctl+0x70/0x80
[404571.552621] __x64_sys_ioctl+0x16/0x20
[404571.552864] do_syscall_64+0x60/0x1d0
[404571.553104] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
If we were joining the transaction instead of attaching to it, we would
not risk a deadlock because a join only blocks if the transaction is in a
state greater then or equals to TRANS_STATE_COMMIT_DOING, and the delalloc
flush performed by a transaction is done before it reaches that state,
when it is in the state TRANS_STATE_COMMIT_START. However a transaction
join is intended for use cases where we do modify the filesystem, and
fiemap only needs to peek at delayed references from the current
transaction in order to determine if extents are shared, and, besides
that, when there is no current transaction or when it blocks to wait for
a current committing transaction to complete, it creates a new transaction
without reserving any space. Such unnecessary transactions, besides doing
unnecessary IO, can cause transaction aborts (-ENOSPC) and unnecessary
rotation of the precious backup roots.
So fix this by adding a new transaction join variant, named join_nostart,
which behaves like the regular join, but it does not create a transaction
when none currently exists or after waiting for a committing transaction
to complete.
Fixes: 03628cdbc64db6 ("Btrfs: do not start a transaction during fiemap")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
btrfs_check_shared looks up parents of a given extent and uses ulists
for that. These are allocated and freed repeatedly. Preallocation in the
caller will avoid the overhead and also allow us to use the GFP_KERNEL
as it is happens before the extent locks are taken.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
During fiemap, for regular extents (non inline) we need to check if they
are shared and if they are, set the shared bit. Checking if an extent is
shared requires checking the delayed references of the currently running
transaction, since some reference might have not yet hit the extent tree
and be only in the in-memory delayed references.
However we were using a transaction join for this, which creates a new
transaction when there is no transaction currently running. That means
that two more potential failures can happen: creating the transaction and
committing it. Further, if no write activity is currently happening in the
system, and fiemap calls keep being done, we end up creating and
committing transactions that do nothing.
In some extreme cases this can result in the commit of the transaction
created by fiemap to fail with ENOSPC when updating the root item of a
subvolume tree because a join does not reserve any space, leading to a
trace like the following:
heisenberg kernel: ------------[ cut here ]------------
heisenberg kernel: BTRFS: Transaction aborted (error -28)
heisenberg kernel: WARNING: CPU: 0 PID: 7137 at fs/btrfs/root-tree.c:136 btrfs_update_root+0x22b/0x320 [btrfs]
(...)
heisenberg kernel: CPU: 0 PID: 7137 Comm: btrfs-transacti Not tainted 4.19.0-4-amd64 #1 Debian 4.19.28-2
heisenberg kernel: Hardware name: FUJITSU LIFEBOOK U757/FJNB2A5, BIOS Version 1.21 03/19/2018
heisenberg kernel: RIP: 0010:btrfs_update_root+0x22b/0x320 [btrfs]
(...)
heisenberg kernel: RSP: 0018:ffffb5448828bd40 EFLAGS: 00010286
heisenberg kernel: RAX: 0000000000000000 RBX: ffff8ed56bccef50 RCX: 0000000000000006
heisenberg kernel: RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff8ed6bda166a0
heisenberg kernel: RBP: 00000000ffffffe4 R08: 00000000000003df R09: 0000000000000007
heisenberg kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff8ed63396a078
heisenberg kernel: R13: ffff8ed092d7c800 R14: ffff8ed64f5db028 R15: ffff8ed6bd03d068
heisenberg kernel: FS: 0000000000000000(0000) GS:ffff8ed6bda00000(0000) knlGS:0000000000000000
heisenberg kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
heisenberg kernel: CR2: 00007f46f75f8000 CR3: 0000000310a0a002 CR4: 00000000003606f0
heisenberg kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
heisenberg kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
heisenberg kernel: Call Trace:
heisenberg kernel: commit_fs_roots+0x166/0x1d0 [btrfs]
heisenberg kernel: ? _cond_resched+0x15/0x30
heisenberg kernel: ? btrfs_run_delayed_refs+0xac/0x180 [btrfs]
heisenberg kernel: btrfs_commit_transaction+0x2bd/0x870 [btrfs]
heisenberg kernel: ? start_transaction+0x9d/0x3f0 [btrfs]
heisenberg kernel: transaction_kthread+0x147/0x180 [btrfs]
heisenberg kernel: ? btrfs_cleanup_transaction+0x530/0x530 [btrfs]
heisenberg kernel: kthread+0x112/0x130
heisenberg kernel: ? kthread_bind+0x30/0x30
heisenberg kernel: ret_from_fork+0x35/0x40
heisenberg kernel: ---[ end trace 05de912e30e012d9 ]---
Since fiemap (and btrfs_check_shared()) is a read-only operation, do not do
a transaction join to avoid the overhead of creating a new transaction (if
there is currently no running transaction) and introducing a potential
point of failure when the new transaction gets committed, instead use a
transaction attach to grab a handle for the currently running transaction
if any.
Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
Link: https://lore.kernel.org/linux-btrfs/b2a668d7124f1d3e410367f587926f622b3f03a4.camel@scientia.net/
Fixes: afce772e87c36c ("btrfs: fix check_shared for fiemap ioctl")
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
When finding out which inodes have references on a particular extent, done
by backref.c:iterate_extent_inodes(), from the BTRFS_IOC_LOGICAL_INO (both
v1 and v2) ioctl and from scrub we use the transaction join API to grab a
reference on the currently running transaction, since in order to give
accurate results we need to inspect the delayed references of the currently
running transaction.
However, if there is currently no running transaction, the join operation
will create a new transaction. This is inefficient as the transaction will
eventually be committed, doing unnecessary IO and introducing a potential
point of failure that will lead to a transaction abort due to -ENOSPC, as
recently reported [1].
That's because the join, creates the transaction but does not reserve any
space, so when attempting to update the root item of the root passed to
btrfs_join_transaction(), during the transaction commit, we can end up
failling with -ENOSPC. Users of a join operation are supposed to actually
do some filesystem changes and reserve space by some means, which is not
the case of iterate_extent_inodes(), it is a read-only operation for all
contextes from which it is called.
The reported [1] -ENOSPC failure stack trace is the following:
heisenberg kernel: ------------[ cut here ]------------
heisenberg kernel: BTRFS: Transaction aborted (error -28)
heisenberg kernel: WARNING: CPU: 0 PID: 7137 at fs/btrfs/root-tree.c:136 btrfs_update_root+0x22b/0x320 [btrfs]
(...)
heisenberg kernel: CPU: 0 PID: 7137 Comm: btrfs-transacti Not tainted 4.19.0-4-amd64 #1 Debian 4.19.28-2
heisenberg kernel: Hardware name: FUJITSU LIFEBOOK U757/FJNB2A5, BIOS Version 1.21 03/19/2018
heisenberg kernel: RIP: 0010:btrfs_update_root+0x22b/0x320 [btrfs]
(...)
heisenberg kernel: RSP: 0018:ffffb5448828bd40 EFLAGS: 00010286
heisenberg kernel: RAX: 0000000000000000 RBX: ffff8ed56bccef50 RCX: 0000000000000006
heisenberg kernel: RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff8ed6bda166a0
heisenberg kernel: RBP: 00000000ffffffe4 R08: 00000000000003df R09: 0000000000000007
heisenberg kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff8ed63396a078
heisenberg kernel: R13: ffff8ed092d7c800 R14: ffff8ed64f5db028 R15: ffff8ed6bd03d068
heisenberg kernel: FS: 0000000000000000(0000) GS:ffff8ed6bda00000(0000) knlGS:0000000000000000
heisenberg kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
heisenberg kernel: CR2: 00007f46f75f8000 CR3: 0000000310a0a002 CR4: 00000000003606f0
heisenberg kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
heisenberg kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
heisenberg kernel: Call Trace:
heisenberg kernel: commit_fs_roots+0x166/0x1d0 [btrfs]
heisenberg kernel: ? _cond_resched+0x15/0x30
heisenberg kernel: ? btrfs_run_delayed_refs+0xac/0x180 [btrfs]
heisenberg kernel: btrfs_commit_transaction+0x2bd/0x870 [btrfs]
heisenberg kernel: ? start_transaction+0x9d/0x3f0 [btrfs]
heisenberg kernel: transaction_kthread+0x147/0x180 [btrfs]
heisenberg kernel: ? btrfs_cleanup_transaction+0x530/0x530 [btrfs]
heisenberg kernel: kthread+0x112/0x130
heisenberg kernel: ? kthread_bind+0x30/0x30
heisenberg kernel: ret_from_fork+0x35/0x40
heisenberg kernel: ---[ end trace 05de912e30e012d9 ]---
So fix that by using the attach API, which does not create a transaction
when there is currently no running transaction.
[1] https://lore.kernel.org/linux-btrfs/b2a668d7124f1d3e410367f587926f622b3f03a4.camel@scientia.net/
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
BUG_ON(1) leads to bogus warnings from clang when
CONFIG_PROFILE_ANNOTATED_BRANCHES is set:
fs/btrfs/volumes.c:5041:3: error: variable 'max_chunk_size' is used uninitialized whenever 'if' condition is false
[-Werror,-Wsometimes-uninitialized]
BUG_ON(1);
^~~~~~~~~
include/asm-generic/bug.h:61:36: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:48:23: note: expanded from macro 'unlikely'
# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/btrfs/volumes.c:5046:9: note: uninitialized use occurs here
max_chunk_size);
^~~~~~~~~~~~~~
include/linux/kernel.h:860:36: note: expanded from macro 'min'
#define min(x, y) __careful_cmp(x, y, <)
^
include/linux/kernel.h:853:17: note: expanded from macro '__careful_cmp'
__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
^
include/linux/kernel.h:847:25: note: expanded from macro '__cmp_once'
typeof(y) unique_y = (y); \
^
fs/btrfs/volumes.c:5041:3: note: remove the 'if' if its condition is always true
BUG_ON(1);
^
include/asm-generic/bug.h:61:32: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^
fs/btrfs/volumes.c:4993:20: note: initialize the variable 'max_chunk_size' to silence this warning
u64 max_chunk_size;
^
= 0
Change it to BUG() so clang can see that this code path can never
continue.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Sterba <dsterba@suse.com>
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Qgroups will do the old roots lookup at delayed ref time, which could be
while walking down the extent root while running a delayed ref. This
should be fine, except we specifically lock eb's in the backref walking
code irrespective of path->skip_locking, which deadlocks the system.
Fix up the backref code to honor path->skip_locking, nobody will be
modifying the commit_root when we're searching so it's completely safe
to do.
This happens since fb235dc06fac ("btrfs: qgroup: Move half of the qgroup
accounting time out of commit trans"), kernel may lockup with quota
enabled.
There is one backref trace triggered by snapshot dropping along with
write operation in the source subvolume. The example can be reliably
reproduced:
btrfs-cleaner D 0 4062 2 0x80000000
Call Trace:
schedule+0x32/0x90
btrfs_tree_read_lock+0x93/0x130 [btrfs]
find_parent_nodes+0x29b/0x1170 [btrfs]
btrfs_find_all_roots_safe+0xa8/0x120 [btrfs]
btrfs_find_all_roots+0x57/0x70 [btrfs]
btrfs_qgroup_trace_extent_post+0x37/0x70 [btrfs]
btrfs_qgroup_trace_leaf_items+0x10b/0x140 [btrfs]
btrfs_qgroup_trace_subtree+0xc8/0xe0 [btrfs]
do_walk_down+0x541/0x5e3 [btrfs]
walk_down_tree+0xab/0xe7 [btrfs]
btrfs_drop_snapshot+0x356/0x71a [btrfs]
btrfs_clean_one_deleted_ |
