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btrfs: reorganize logic at free_extent_buffer() for better readability

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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>
This commit is contained in:
Filipe Manana 2025-06-02 13:27:49 +01:00 committed by David Sterba
parent 41e4ea0bf5
commit 71c086b30d
1 changed files with 6 additions and 3 deletions
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9
fs/btrfs/extent_io.c
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@ -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;
}