[Devel] [PATCH VZ10 1/2] anon_inode: rework assertions

[Pavel Tikhomirov]

On 7/27/26 17:18, Vladimir Riabchun wrote:
> 
> 
> On 7/27/26 14:22, Pavel Tikhomirov wrote:
>> From: Christian Brauner <brauner at kernel.org>
>>
>> Making anonymous inodes regular files comes with a lot of risk and
>> regression potential as evidenced by a recent hickup in io_uring. We're
>> better of continuing to not have them be regular files. Since we have
>> S_ANON_INODE we can port all of our assertions easily.
>>
>> Link: https://lore.kernel.org/20250702-work-fixes-v1-1-ff76ea589e33@kernel.org
>> Fixes: cfd86ef7e8e7 ("anon_inode: use a proper mode internally")
>> Acked-by: Jens Axboe <axboe at kernel.dk>
>> Cc: stable at kernel.org
>> Reported-by: Jens Axboe <axboe at kernel.dk>
>> Signed-off-by: Christian Brauner <brauner at kernel.org>
>>
>> (cherry picked from commit 1e7ab6f67824343ee3e96f100f0937c393749a8a)
>>
>> This fixes CRIU dump of processes that use AIO, since CRIU does not
>> expect S_IFREG on AIO inodes.
>>
>> vz10 backport notes:
>> - drop debug with missing VFS_WARN_ON_ONCE/VFS_BUG_ON_INODE
> 
> Any particular reason for this drop? These checks seem harmless and
> dropping them may add some work during the rebase.

We don't have those warning-helpers, so I drop related hunks to avoid
porting not directly related patches.

> 
> Other than that looks good.
> Reviewed-by: Vladimir Riabchun <vladimir.riabchun at virtuozzo.com>
> 
>> - add fput(file) on the introduced error paths in do_open_execat()
>>
>> Feature: ve: CRIU support
>> https://virtuozzo.atlassian.net/browse/VSTOR-139264
>> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
>> ---
>>   fs/exec.c  | 8 ++++++--
>>   fs/libfs.c | 8 +++-----
>>   2 files changed, 9 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/exec.c b/fs/exec.c
>> index dd5de1a4a9d6a..e861a54b491f8 100644
>> --- a/fs/exec.c
>> +++ b/fs/exec.c
>> @@ -921,13 +921,17 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
>>       if (IS_ERR(file))
>>           return file;
>>   +    if (path_noexec(&file->f_path)) {
>> +        fput(file);
>> +        return ERR_PTR(-EACCES);
>> +    }
>> +
>>       /*
>>        * In the past the regular type check was here. It moved to may_open() in
>>        * 633fb6ac3980 ("exec: move S_ISREG() check earlier"). Since then it is
>>        * an invariant that all non-regular files error out before we get here.
>>        */
>> -    if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)) ||
>> -        path_noexec(&file->f_path)) {
>> +    if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode))) {
>>           fput(file);
>>           return ERR_PTR(-EACCES);
>>       }
>> diff --git a/fs/libfs.c b/fs/libfs.c
>> index c4a305967619f..af191a388303c 100644
>> --- a/fs/libfs.c
>> +++ b/fs/libfs.c
>> @@ -1652,12 +1652,10 @@ struct inode *alloc_anon_inode(struct super_block *s)
>>        */
>>       inode->i_state = I_DIRTY;
>>       /*
>> -     * Historically anonymous inodes didn't have a type at all and
>> -     * userspace has come to rely on this. Internally they're just
>> -     * regular files but S_IFREG is masked off when reporting
>> -     * information to userspace.
>> +     * Historically anonymous inodes don't have a type at all and
>> +     * userspace has come to rely on this.
>>        */
>> -    inode->i_mode = S_IFREG | S_IRUSR | S_IWUSR;
>> +    inode->i_mode = S_IRUSR | S_IWUSR;
>>       inode->i_uid = current_fsuid();
>>       inode->i_gid = current_fsgid();
>>       inode->i_flags |= S_PRIVATE | S_ANON_INODE;
> 

-- 
Best regards, Pavel Tikhomirov
Senior Software Developer, Virtuozzo.