From fd7ba1c1202d15ac96d7b42256550973e12686b5 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 20 Aug 2020 11:46:02 -0400 Subject: btrfs: add nesting tags to the locking helpers We will need these when we switch to an rwsem, so plumb in the infrastructure here to use later on. I violate the 80 character limit some here because it'll be cleaned up later. Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/ctree.c | 11 ++++++++--- fs/btrfs/locking.c | 14 ++++++++++---- fs/btrfs/locking.h | 25 ++++++++++++++++++++++++- 3 files changed, 42 insertions(+), 8 deletions(-) (limited to 'fs') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 7c99bf112960..71e3fa30082c 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2875,7 +2875,8 @@ cow_done: } else { if (!btrfs_tree_read_lock_atomic(b)) { btrfs_set_path_blocking(p); - __btrfs_tree_read_lock(b, p->recurse); + __btrfs_tree_read_lock(b, BTRFS_NESTING_NORMAL, + p->recurse); } p->locks[level] = BTRFS_READ_LOCK; } @@ -5453,7 +5454,9 @@ again: } if (!ret) { btrfs_set_path_blocking(path); - __btrfs_tree_read_lock(next, path->recurse); + __btrfs_tree_read_lock(next, + BTRFS_NESTING_NORMAL, + path->recurse); } next_rw_lock = BTRFS_READ_LOCK; } @@ -5488,7 +5491,9 @@ again: ret = btrfs_try_tree_read_lock(next); if (!ret) { btrfs_set_path_blocking(path); - __btrfs_tree_read_lock(next, path->recurse); + __btrfs_tree_read_lock(next, + BTRFS_NESTING_NORMAL, + path->recurse); } next_rw_lock = BTRFS_READ_LOCK; } diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 740a0cde5731..66e02ebdd340 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -244,7 +244,8 @@ void btrfs_set_lock_blocking_write(struct extent_buffer *eb) * * The rwlock is held upon exit. */ -void __btrfs_tree_read_lock(struct extent_buffer *eb, bool recurse) +void __btrfs_tree_read_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest, + bool recurse) { u64 start_ns = 0; @@ -282,7 +283,7 @@ again: void btrfs_tree_read_lock(struct extent_buffer *eb) { - __btrfs_tree_read_lock(eb, false); + __btrfs_tree_read_lock(eb, BTRFS_NESTING_NORMAL, false); } /* @@ -415,7 +416,7 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb) * * The rwlock is held for write upon exit. */ -void btrfs_tree_lock(struct extent_buffer *eb) +void __btrfs_tree_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest) __acquires(&eb->lock) { u64 start_ns = 0; @@ -440,6 +441,11 @@ again: trace_btrfs_tree_lock(eb, start_ns); } +void btrfs_tree_lock(struct extent_buffer *eb) +{ + __btrfs_tree_lock(eb, BTRFS_NESTING_NORMAL); +} + /* * Release the write lock, either blocking or spinning (ie. there's no need * for an explicit blocking unlock, like btrfs_tree_read_unlock_blocking). @@ -565,7 +571,7 @@ struct extent_buffer *__btrfs_read_lock_root_node(struct btrfs_root *root, while (1) { eb = btrfs_root_node(root); - __btrfs_tree_read_lock(eb, recurse); + __btrfs_tree_read_lock(eb, BTRFS_NESTING_NORMAL, recurse); if (eb == root->node) break; btrfs_tree_read_unlock(eb); diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h index 31f6d6405c1d..5fabda8f0a80 100644 --- a/fs/btrfs/locking.h +++ b/fs/btrfs/locking.h @@ -16,12 +16,35 @@ #define BTRFS_WRITE_LOCK_BLOCKING 3 #define BTRFS_READ_LOCK_BLOCKING 4 +/* + * We are limited in number of subclasses by MAX_LOCKDEP_SUBCLASSES, which at + * the time of this patch is 8, which is how many we use. Keep this in mind if + * you decide you want to add another subclass. + */ +enum btrfs_lock_nesting { + BTRFS_NESTING_NORMAL, + + /* + * We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so + * add this in here and add a static_assert to keep us from going over + * the limit. As of this writing we're limited to 8, and we're + * definitely using 8, hence this check to keep us from messing up in + * the future. + */ + BTRFS_NESTING_MAX, +}; + +static_assert(BTRFS_NESTING_MAX <= MAX_LOCKDEP_SUBCLASSES, + "too many lock subclasses defined"); + struct btrfs_path; +void __btrfs_tree_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest); void btrfs_tree_lock(struct extent_buffer *eb); void btrfs_tree_unlock(struct extent_buffer *eb); -void __btrfs_tree_read_lock(struct extent_buffer *eb, bool recurse); +void __btrfs_tree_read_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest, + bool recurse); void btrfs_tree_read_lock(struct extent_buffer *eb); void btrfs_tree_read_unlock(struct extent_buffer *eb); void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb); -- cgit v1.2.3