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| author |   Naohiro Aota <naohiro.aota@wdc.com> | 2021-03-24 23:23:11 +0900 |
|---|---|---|
| committer |   David Sterba <dsterba@suse.com> | 2021-04-19 17:25:17 +0200 |
| commit | e75f9fd194090e69c5ffd856ba89160683d343da (patch) | |
| tree | 05b633aa7269268f347323cd9f07303abc2a2231 /fs/btrfs/tree-log.c | |
| parent | btrfs: use percpu_read_positive instead of sum_positive for need_preempt (diff) | |
| download | linux-dev-e75f9fd194090e69c5ffd856ba89160683d343da.tar.xz linux-dev-e75f9fd194090e69c5ffd856ba89160683d343da.zip | |
btrfs: zoned: move log tree node allocation out of log_root_tree->log_mutex
Commit 6e37d2459941 ("btrfs: zoned: fix deadlock on log sync") pointed out
a deadlock warning and removed mutex_{lock,unlock} of fs_info::tree_root->log_mutex.
While it looks like it always cause a deadlock, we didn't see actual
deadlock in fstests runs. The reason is log_root_tree->log_mutex !=
fs_info->tree_root->log_mutex, not taking the same lock. So, the warning
was actually a false-positive.
Since btrfs_alloc_log_tree_node() is protected only by
fs_info->tree_root->log_mutex, we can (and should) move the code out of
the lock scope of log_root_tree->log_mutex and silence the warning.
Fixes: 6e37d2459941 ("btrfs: zoned: fix deadlock on log sync")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/tree-log.c')
| -rw-r--r-- | fs/btrfs/tree-log.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 92a368627791..72c4b66ed516 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -3165,20 +3165,22 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, */ mutex_unlock(&root->log_mutex); - btrfs_init_log_ctx(&root_log_ctx, NULL); - - mutex_lock(&log_root_tree->log_mutex); - if (btrfs_is_zoned(fs_info)) { + mutex_lock(&fs_info->tree_root->log_mutex); if (!log_root_tree->node) { ret = btrfs_alloc_log_tree_node(trans, log_root_tree); if (ret) { - mutex_unlock(&log_root_tree->log_mutex); + mutex_unlock(&fs_info->tree_log_mutex); goto out; } } + mutex_unlock(&fs_info->tree_root->log_mutex); } + btrfs_init_log_ctx(&root_log_ctx, NULL); + + mutex_lock(&log_root_tree->log_mutex); + index2 = log_root_tree->log_transid % 2; list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]); root_log_ctx.log_transid = log_root_tree->log_transid; |