From: Filipe Manana <fdmanana@suse.com>
Date: Mon, 2 Jun 2025 12:27:49 +0000 (+0100)
Subject: btrfs: reorganize logic at free_extent_buffer() for better readability
X-Git-Tag: block-6.17-20250808~77^2~132
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=71c086b30d4373a01bd5627f54516a72891a026a;p=linux-block.git

btrfs: reorganize logic at free_extent_buffer() for better readability

It's hard to read the logic to break out of the while loop since it's a
very long expression consisting of a logical or of two composite
expressions, each one composed by a logical and. Further each one is also
testing for the EXTENT_BUFFER_UNMAPPED bit, making it more verbose than
necessary.

So change from this:

    if ((!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs <= 3)
        || (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) &&
            refs == 1))
       break;

To this:

    if (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags)) {
        if (refs == 1)
            break;
    } else if (refs <= 3) {
            break;
    }

At least on x86_64 using gcc 9.3.0, this doesn't change the object size.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d11e1d192784..21d2cb7f538e 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3486,10 +3486,13 @@ void free_extent_buffer(struct extent_buffer *eb)
 
 	refs = atomic_read(&eb->refs);
 	while (1) {
-		if ((!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs <= 3)
-		    || (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) &&
-			refs == 1))
+		if (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags)) {
+			if (refs == 1)
+				break;
+		} else if (refs <= 3) {
 			break;
+		}
+
 		if (atomic_try_cmpxchg(&eb->refs, &refs, refs - 1))
 			return;
 	}