Re: [PATCH] btrfs: remove dead assignment to dirid in btrfs_search_path_in_tree()

[Miquel Sabaté Solà]

Filipe Manana @ 2026-02-17 10:53 GMT:

> On Tue, Feb 17, 2026 at 10:18 AM Miquel Sabaté Solà <mssola@xxxxxxxxxx> wrote:
>>
>> Hello,
>>
>> Burenchev Evgenii @ 2026-02-16 16:16 GMT:
>>
>> > From ff2df73ba6483b0dc67b3ed89d2a43c49f1c2eb8 Mon Sep 17 00:00:00 2001
>> > From: Evgenii Burenchev <eburenchev@xxxxxxxxxxxx>
>> > Date: Mon, 16 Feb 2026 18:39:30 +0300
>> > Subject: [PATCH] btrfs: remove dead assignment to dirid in
>> >  btrfs_search_path_in_tree()
>> >
>> > After the introduction of btrfs_search_backwards(), the directory
>> > traversal state in btrfs_search_path_in_tree() is fully maintained via
>> > struct btrfs_key. The local variable 'dirid' is no longer used to control
>> > the search and the assignment
>> >
>> >     dirid = key.objectid;
>> >
>> > has no observable effect and is dead code.
>> >
>> > Remove the unused assignment to avoid confusion and silence static
>> > analysis warnings.
>> >
>> > No functional change.
>> >
>> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
>> >
>> > Signed-off-by: Evgenii Burenchev <eburenchev@xxxxxxxxxxxx>
>> > ---
>> >  fs/btrfs/ioctl.c | 1 -
>> >  1 file changed, 1 deletion(-)
>> >
>> > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>> > index a6cc2d3b414c..292043b11207 100644
>> > --- a/fs/btrfs/ioctl.c
>> > +++ b/fs/btrfs/ioctl.c
>> > @@ -1708,7 +1708,6 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
>> >               btrfs_release_path(path);
>> >               key.objectid = key.offset;
>> >               key.offset = (u64)-1;
>> > -             dirid = key.objectid;
>> >       }
>> >       memmove(name, ptr, total_len);
>> >       name[total_len] = '\0';
>>
>> I would add a Fixes tag with the commit that made this assignment
>> useless.
>
> No. We add Fixes tags for patches we want to backport to stable
> releases, things that fix a problem affecting users, like functional
> bugs or performance regressions for example.
> For cleanups, removing unnecessary code, we don't want a Fixes tag, as
> that will trigger unnecessary backport overhead.
>

Got it, thanks for the explanation!

>> As far as I can tell this is commit 98d377a0894e ("Btrfs: don't
>> miss inode ref items in BTRFS_IOC_INO_LOOKUP"), which made the update
>> inside of the loop of 'dirid' no longer needed. This way it's easier to
>> track from where this was no longer needed and whether that's really the
>> case.
>>
>> Other than that, and taking a quick look at this function, I can already
>> tell that the 'ret' variable could be initialized to 0 in the beginning
>> and make the last assignment to it (just before the "out" label) not
>> needed. Hence, while we are at it, could you also remove that
>> assignment?
>>
>> Cheers,
>> Miquel

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