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linux/fs/btrfs
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Josef Bacik 39dba8739c btrfs: do not resolve backrefs for roots that are being deleted 
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: 8da6d5815c ("Btrfs: added btrfs_find_all_roots()")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-03-23 17:03:51 +01:00
..
tests btrfs: kill the subvol_srcu 2020-03-23 17:02:00 +01:00
acl.c btrfs: cleanup btrfs_setxattr_trans and drop transaction parameter 2019-04-29 19:02:44 +02:00
async-thread.c Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
async-thread.h Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
backref.c btrfs: do not resolve backrefs for roots that are being deleted 2020-03-23 17:03:51 +01:00
backref.h btrfs: relocation: Use btrfs_find_all_leafs to locate data extent parent tree leaves 2020-03-23 17:01:57 +01:00
block-group.c btrfs: add RCU locks around block group initialization 2020-03-23 17:01:53 +01:00
block-group.h btrfs: Move and unexport btrfs_rmap_block 2020-01-23 17:24:34 +01:00
block-rsv.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
block-rsv.h btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
btrfs_inode.h btrfs: introduce per-inode file extent tree 2020-03-23 17:01:24 +01:00
check-integrity.c btrfs: remove buffer_heads form super block mirror integrity checking 2020-03-23 17:01:40 +01:00
check-integrity.h btrfs: remove btrfsic_submit_bh() 2020-03-23 17:01:39 +01:00
compression.c btrfs: use larger zlib buffer for s390 hardware compression 2020-01-31 10:30:40 -08:00
compression.h btrfs: compression: remove ops pointer from workspace_manager 2019-11-18 12:46:59 +01:00
ctree.c btrfs: inline checksum name and driver definitions 2020-03-23 17:01:52 +01:00
ctree.h btrfs: kill the subvol_srcu 2020-03-23 17:02:00 +01:00
delalloc-space.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
delalloc-space.h btrfs: migrate the delalloc space stuff to it's own home 2019-07-04 17:26:17 +02:00
delayed-inode.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
delayed-inode.h btrfs: delayed-inode: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
delayed-ref.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
delayed-ref.h btrfs: migrate the delayed refs rsv code 2019-07-04 17:26:17 +02:00
dev-replace.c btrfs: sysfs, rename device_link add/remove functions 2020-03-23 17:01:35 +01:00
dev-replace.h btrfs: add __pure attribute to functions 2019-11-18 12:46:52 +01:00
dir-item.c btrfs: remove unused parameter fs_info from btrfs_extend_item 2019-04-29 19:02:50 +02:00
discard.c btrfs: add correction to handle -1 edge case in async discard 2020-01-20 16:41:01 +01:00
discard.h btrfs: have multiple discard lists 2020-01-20 16:41:00 +01:00
disk-io.c btrfs: kill the subvol_srcu 2020-03-23 17:02:00 +01:00
disk-io.h btrfs: move the root freeing stuff into btrfs_put_root 2020-03-23 17:01:59 +01:00
export.c btrfs: kill the subvol_srcu 2020-03-23 17:02:00 +01:00
export.h btrfs: export helpers for subvolume name/id resolution 2020-03-23 17:01:42 +01:00
extent-io-tree.h btrfs: switch to per-transaction pinned extents 2020-03-23 17:01:38 +01:00
extent-tree.c btrfs: do not use readahead for running delayed refs 2020-03-23 17:03:50 +01:00
extent_io.c btrfs: move the root freeing stuff into btrfs_put_root 2020-03-23 17:01:59 +01:00
extent_io.h btrfs: make the extent buffer leak check per fs info 2020-03-23 17:01:58 +01:00
extent_map.c Btrfs: fix race between using extent maps and merging them 2020-02-12 17:16:46 +01:00
extent_map.h btrfs: remove extent_map::bdev 2019-11-18 23:43:44 +01:00
file-item.c btrfs: add helper to get the end offset of a file extent item 2020-03-23 17:01:56 +01:00
file.c btrfs: kill the subvol_srcu 2020-03-23 17:02:00 +01:00
free-space-cache.c btrfs: simplify error handling in __btrfs_write_out_cache() 2020-03-23 17:01:43 +01:00
free-space-cache.h btrfs: have multiple discard lists 2020-01-20 16:41:00 +01:00
free-space-tree.c btrfs: move the root freeing stuff into btrfs_put_root 2020-03-23 17:01:59 +01:00
free-space-tree.h btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
inode-item.c btrfs: Make btrfs_find_name_in_ext_backref return struct btrfs_inode_extref 2019-09-09 14:59:16 +02:00
inode-map.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
inode-map.h
inode.c btrfs: kill the subvol_srcu 2020-03-23 17:02:00 +01:00
ioctl.c btrfs: Remove async_transid from btrfs_mksubvol/create_subvol/create_snapshot 2020-03-23 17:02:00 +01:00
Kconfig btrfs: add Kconfig dependency for BLAKE2B 2019-12-09 17:56:06 +01:00
locking.c btrfs: Implement DREW lock 2020-03-23 17:01:43 +01:00
locking.h btrfs: Implement DREW lock 2020-03-23 17:01:43 +01:00
lzo.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00
Makefile Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
misc.h btrfs: add 64bit safe helper for power of two checks 2019-11-18 12:46:50 +01:00
ordered-data.c btrfs: drop argument tree from btrfs_lock_and_flush_ordered_range 2020-03-23 17:01:34 +01:00
ordered-data.h btrfs: drop argument tree from btrfs_lock_and_flush_ordered_range 2020-03-23 17:01:34 +01:00
orphan.c
print-tree.c btrfs: Remove unneeded semicolon 2020-01-20 16:40:55 +01:00
print-tree.h
props.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
props.h btrfs: delete unused function btrfs_set_prop_trans 2019-04-29 19:02:54 +02:00
qgroup.c btrfs: move the root freeing stuff into btrfs_put_root 2020-03-23 17:01:59 +01:00
qgroup.h btrfs: destroy qgroup extent records on transaction abort 2020-02-19 00:35:54 +01:00
raid56.c btrfs: use struct_size to calculate size of raid hash table 2020-03-23 17:01:44 +01:00
raid56.h btrfs: constify map parameter for nr_parity_stripes and nr_data_stripes 2019-07-01 13:34:58 +02:00
rcu-string.h btrfs: rcu-string: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
reada.c btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
ref-verify.c btrfs: fix ref-verify to catch operations on 0 ref extents 2020-03-23 17:01:56 +01:00
ref-verify.h btrfs: ref-verify: Use btrfs_ref to refactor btrfs_ref_tree_mod() 2019-04-29 19:02:49 +02:00
reflink.c Btrfs: implement full reflink support for inline extents 2020-03-23 17:01:54 +01:00
reflink.h Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
relocation.c btrfs: track reloc roots based on their commit root bytenr 2020-03-23 17:03:51 +01:00
root-tree.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
scrub.c btrfs: scrub: Replace zero-length array with flexible-array member 2020-03-23 17:01:54 +01:00
send.c btrfs: kill the subvol_srcu 2020-03-23 17:02:00 +01:00
send.h
space-info.c btrfs: account ticket size at add/delete time 2020-03-23 17:01:55 +01:00
space-info.h btrfs: account ticket size at add/delete time 2020-03-23 17:01:55 +01:00
struct-funcs.c btrfs: tie extent buffer and it's token together 2019-09-09 14:59:16 +02:00
super.c btrfs: adjust message level for unrecognized mount option 2020-03-23 17:01:45 +01:00
sysfs.c btrfs: sysfs, unify handler name of devinfo/missing 2020-03-23 17:01:36 +01:00
sysfs.h btrfs: sysfs, rename device_link add/remove functions 2020-03-23 17:01:35 +01:00
transaction.c btrfs: hold a ref on the root on the dead roots list 2020-03-23 17:01:59 +01:00
transaction.h btrfs: switch to per-transaction pinned extents 2020-03-23 17:01:38 +01:00
tree-checker.c btrfs: tree-checker: Verify location key for DIR_ITEM/DIR_INDEX 2020-01-20 16:40:56 +01:00
tree-checker.h btrfs: get fs_info from eb in btrfs_check_chunk_valid 2019-04-29 19:02:39 +02:00
tree-defrag.c btrfs: open code now trivial btrfs_set_lock_blocking 2019-02-25 14:13:27 +01:00
tree-log.c btrfs: move the root freeing stuff into btrfs_put_root 2020-03-23 17:01:59 +01:00
tree-log.h btrfs: get fs_info from trans in btrfs_set_log_full_commit 2019-04-29 19:02:41 +02:00
ulist.c
ulist.h
uuid-tree.c btrfs: bail out of uuid tree scanning if we're closing 2020-03-23 17:01:41 +01:00
volumes.c btrfs: relocation: add error injection points for cancelling balance 2020-03-23 17:01:54 +01:00
volumes.h btrfs: introduce chunk allocation policy 2020-03-23 17:01:48 +01:00
xattr.c Btrfs: fix failure to persist compression property xattr deletion on fsync 2019-06-17 16:37:17 +02:00
xattr.h btrfs: cleanup btrfs_setxattr_trans and drop transaction parameter 2019-04-29 19:02:44 +02:00
zlib.c btrfs: use larger zlib buffer for s390 hardware compression 2020-01-31 10:30:40 -08:00
zstd.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00